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Zhao Y, Xiong L, Yin J, Zha X, Li W, Han Y. Understanding the effects of flash drought on vegetation photosynthesis and potential drivers over China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 931:172926. [PMID: 38697519 DOI: 10.1016/j.scitotenv.2024.172926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 04/26/2024] [Accepted: 04/29/2024] [Indexed: 05/05/2024]
Abstract
Flash droughts characterized by rapid onset and intensification are expected to be a new normal under climate change and potentially affect vegetation photosynthesis and terrestrial carbon sink. However, the effects of flash drought on vegetation photosynthesis and their potential dominant driving factors remain uncertain. Here, we quantify the susceptibility and response magnitude of vegetation photosynthesis to flash drought across different ecosystems (i.e., forest, shrubland, grassland, and cropland) in China based on reanalysis and satellite observations. By employing the extreme gradient boosting model, we also identify the dominant factors that influence these flash drought-photosynthesis relationships. We show that over 51.46 % of ecosystems across China are susceptible to flash drought, and grasslands are substantially suppressed, as reflected in both sensitivity and response magnitude (with median gross primary productivity anomalies of -0.13). We further demonstrate that background climate differences (e.g., mean annual temperature and aridity) predominantly regulate the response variation in forest and shrubland, with hotter/colder or drier ecosystems being more severely suppressed by flash drought. However, in grasslands and croplands, the differential vegetation responses are attributed to the intensity of abnormal hydro-meteorological conditions during flash drought (e.g., vapor pressure deficit (VPD) and temperature anomalies). The effects of flash droughts intensify with increasing VPD and nonmonotonically relate to temperature, with colder or hotter temperatures leading to more severe vegetation loss. Our results identify the vulnerable ecological regions under flash drought and enable a better understanding of vegetation photosynthesis response to climate extremes, which may be useful for developing effective management strategies.
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Affiliation(s)
- Yue Zhao
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, PR China.
| | - Lihua Xiong
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, PR China.
| | - Jiabo Yin
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, PR China.
| | - Xini Zha
- Changjiang Water Resources Protection Institute, Wuhan 430051, PR China; Key Laboratory of Ecological Regulation of Non-point Source Pollution in Lake and Reservoir Water Sources, Changjiang Water Resources Commission, Wuhan 430051, PR China.
| | - Wenbin Li
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, PR China.
| | - Yajing Han
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, PR China.
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2
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Liu X, Feng Y, Hu T, Luo Y, Zhao X, Wu J, Maeda EE, Ju W, Liu L, Guo Q, Su Y. Enhancing ecosystem productivity and stability with increasing canopy structural complexity in global forests. SCIENCE ADVANCES 2024; 10:eadl1947. [PMID: 38748796 PMCID: PMC11095460 DOI: 10.1126/sciadv.adl1947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 04/12/2024] [Indexed: 05/19/2024]
Abstract
Forest canopy structural complexity (CSC) plays a crucial role in shaping forest ecosystem productivity and stability, but the precise nature of their relationships remains controversial. Here, we mapped the global distribution of forest CSC and revealed the factors influencing its distribution using worldwide light detection and ranging data. We find that forest CSC predominantly demonstrates significant positive relationships with forest ecosystem productivity and stability globally, although substantial variations exist among forest ecoregions. The effects of forest CSC on productivity and stability are the balanced results of biodiversity and resource availability, providing valuable insights for comprehending forest ecosystem functions. Managed forests are found to have lower CSC but more potent enhancing effects of forest CSC on ecosystem productivity and stability than intact forests, highlighting the urgent need to integrate forest CSC into the development of forest management plans for effective climate change mitigation.
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Affiliation(s)
- Xiaoqiang Liu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuhao Feng
- Institute of Ecology, College of Urban and Environmental Science, Peking University, Beijing 100871, China
| | - Tianyu Hu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yue Luo
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoxia Zhao
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jin Wu
- School of Biological Sciences and Institute for Climate and Carbon Neutrality, The University of Hong Kong, Pok Fu Lam, Hong Kong, China
| | - Eduardo E. Maeda
- Department of Geosciences and Geography, University of Helsinki, Helsinki FI-00014, Finland
- Finnish Meteorological Institute, FMI, Helsinki, Finland
| | - Weiming Ju
- Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, International Institute for Earth System Science, Nanjing University, Nanjing 210023, China
| | - Lingli Liu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qinghua Guo
- Institute of Ecology, College of Urban and Environmental Science, Peking University, Beijing 100871, China
- Institute of Remote Sensing and Geographical Information Systems, School of Earth and Space Sciences, Peking University, Beijing 100871, China
| | - Yanjun Su
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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3
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Knapp PA, Soulé PT, Mitchell TJ, Catherwood AA, Lewis HS. Increasing radial growth in old-growth high-elevation conifers in Southern California, USA, during the exceptional "hot drought" of 2000-2020. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2024; 68:743-748. [PMID: 38214750 DOI: 10.1007/s00484-024-02619-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 12/15/2023] [Accepted: 01/04/2024] [Indexed: 01/13/2024]
Abstract
Hot droughts, droughts attributed to below-average precipitation and exceptional warmth, are increasingly common in the twenty-first century, yet little is known about their effect on coniferous tree growth because of their historical rarity. In much of the American West, including California, radial tree growth is principally driven by precipitation, and narrow ring widths are typically associated with either drier or drought conditions. However, for species growing at high elevations (e.g., Larix lyalli, Pinus albicaulis), growth can be closely aligned with above-average temperatures with maximum growth coinciding with meteorological drought, suggesting that the growth effects of drought span from adverse to beneficial depending on location. Here, we compare radial growth responses of three high-elevation old-growth pines (Pinus jeffreyi, P. lambertiana, and P. contorta) growing in the San Jacinto Mountains, California, during a twenty-first-century hot drought (2000-2020) largely caused by exceptional warmth and a twentieth-century drought (1959-1966) principally driven by precipitation deficits. Mean radial growth during the hot drought was 12% above average while 18% below average during the mid-century drought illustrating that the consequences of environmental stress exhibit spatiotemporal variability. We conclude that the effects of hot droughts on tree growth in high-elevation forests may produce responses different than what is commonly associated with extended dry periods for much of western North America's forested lands at lower elevational ranges and likely applies to other mountainous regions (e.g., Mediterranean Europe) defined by summer-dry conditions. Thus, the climatological/biological interactions discovered in Southern California may offer clues to the unique nature of high-elevation forested ecosystems globally.
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Affiliation(s)
- Paul A Knapp
- Carolina Tree-Ring Science Laboratory, Department of Geography, Environment and Sustainability, University of North Carolina Greensboro, Greensboro, NC, USA.
| | - Peter T Soulé
- Appalachian Tree Ring Lab, Department of Geography and Planning, Appalachian State University, Boone, NC, USA
| | - Tyler J Mitchell
- Carolina Tree-Ring Science Laboratory, Department of Geography, Environment and Sustainability, University of North Carolina Greensboro, Greensboro, NC, USA
| | - Avery A Catherwood
- Carolina Tree-Ring Science Laboratory, Department of Geography, Environment and Sustainability, University of North Carolina Greensboro, Greensboro, NC, USA
| | - Hunter S Lewis
- Carolina Tree-Ring Science Laboratory, Department of Geography, Environment and Sustainability, University of North Carolina Greensboro, Greensboro, NC, USA
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Neycken A, Wohlgemuth T, Frei ER, Klesse S, Baltensweiler A, Lévesque M. Slower growth prior to the 2018 drought and a high growth sensitivity to previous year summer conditions predisposed European beech to crown dieback. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169068. [PMID: 38049004 DOI: 10.1016/j.scitotenv.2023.169068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 11/21/2023] [Accepted: 12/01/2023] [Indexed: 12/06/2023]
Abstract
The record-breaking drought in 2018 caused premature leaf discoloration and shedding (early browning) in many beech (Fagus sylvatica L.) dominated forests in Central Europe. However, a high degree of variability in drought response among individual beech trees was observed. While some trees were severely impacted by the prolonged water deficits and high temperatures, others remained vital with no or only minor signs of crown vitality loss. Why some beech trees were more susceptible to drought-induced crown damage than others and whether growth recovery is possible are poorly understood. Here, we aimed to identify growth characteristics associated with the variability in drought response between individual beech trees based on a sample of 470 trees in northern Switzerland. By combining tree growth measurements and crown condition assessments, we also investigated the possible link between crown dieback and growth recovery after drought. Beech trees with early browning exhibited an overall lower growth vigor before the 2018 drought than co-occurring vital beech trees. This lower vigor is mainly indicated by lower overall growth rates, stronger growth declines in the past decades, and higher growth-climate sensitivity. Particularly, warm previous year summer conditions negatively affected current growth of the early-browning trees. These findings suggest that the affected trees had less access to critical resources and were physiologically limited in their growth predisposing them to early browning. Following the 2018 drought, observed growth recovery potential corresponded to the amount of crown dieback and the local climatic water balance. Overall, our findings emphasize that beech-dominated forests in Central Europe are under increasing pressure from severe droughts, ultimately reducing the competitive ability of this species, especially on lowland sites with shallow soils and low water holding capacity.
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Affiliation(s)
- Anna Neycken
- Silviculture Group, Institute of Terrestrial Ecosystems, ETH Zurich, Universitätsstrasse 16, Zurich 8092, Switzerland.
| | - Thomas Wohlgemuth
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Esther R Frei
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland; Alpine Environment and Natural Hazards, WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, 7260 Davos Dorf, Switzerland; Climate Change and Extremes in Alpine Regions Research Centre CERC, 7260 Davos Dorf, Switzerland
| | - Stefan Klesse
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland; Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - Andri Baltensweiler
- Forest Resources and Management, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Mathieu Lévesque
- Silviculture Group, Institute of Terrestrial Ecosystems, ETH Zurich, Universitätsstrasse 16, Zurich 8092, Switzerland
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5
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Aldea J, Dahlgren J, Holmström E, Löf M. Current and future drought vulnerability for three dominant boreal tree species. GLOBAL CHANGE BIOLOGY 2024; 30:e17079. [PMID: 38273579 DOI: 10.1111/gcb.17079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 01/27/2024]
Abstract
Climate change is projected to increase the frequency and severity of droughts, possibly causing sudden and elevated tree mortality. Better understanding and predictions of boreal forest responses to climate change are needed to efficiently adapt forest management. We used tree-ring width chronologies from the Swedish National Forest Inventory, sampled between 2010 and 2018, and a random forest machine-learning algorithm to identify the tree, stand, and site variables that determine drought damage risk, and to predict their future spatial-temporal evolution. The dataset consisted of 16,455 cores of Norway spruce, Scots pine, and birch trees from all over Sweden. The risk of drought damage was calculated as the probability of growth anomaly occurrence caused by past drought events during 1960-2010. We used the block cross-validation method to compute model predictions for drought damage risk under current climate and climate predicted for 2040-2070 under the RCP.2.6, RCP.4.5, and RCP.8.5 emission scenarios. We found local climatic variables to be the most important predictors, although stand competition also affects drought damage risk. Norway spruce is currently the most susceptible species to drought in southern Sweden. This species currently faces high vulnerability in 28% of the country and future increases in spring temperatures would greatly increase this area to almost half of the total area of Sweden. Warmer annual temperatures will also increase the current forested area where birch suffers from drought, especially in northern and central Sweden. In contrast, for Scots pine, drought damage coincided with cold winter and early-spring temperatures. Consequently, the current area with high drought damage risk would decrease in a future warmer climate for Scots pine. We suggest active selection of tree species, promoting the right species mixtures and thinning to reduce tree competition as promising strategies for adapting boreal forests to future droughts.
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Affiliation(s)
- Jorge Aldea
- Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Lomma, Sweden
- Instituto de Ciencias Forestales ICIFOR-INIA, CSIC, Madrid, Spain
| | - Jonas Dahlgren
- Department of Forest Resource Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Emma Holmström
- Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Lomma, Sweden
| | - Magnus Löf
- Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Lomma, Sweden
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6
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Tarbill GL, White AM, Sollmann R. Response of pollinator taxa to fire is consistent with historic fire regimes in the Sierra Nevada and mediated through floral richness †. Ecol Evol 2023; 13:e10761. [PMID: 38107425 PMCID: PMC10721959 DOI: 10.1002/ece3.10761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 09/12/2023] [Accepted: 11/11/2023] [Indexed: 12/19/2023] Open
Abstract
Many fire-prone forests are experiencing wildfires that burn outside the historical range of variation in extent and severity. These fires impact pollinators and the ecosystem services they provide, but how the effects of fire are mediated by burn severity in different habitats is not well understood. We used generalized linear mixed models in a Bayesian framework to model the abundance of pollinators as a function of burn severity, habitat, and floral resources in post-fire, mid-elevation, conifer forest, and meadow in the Sierra Nevada, California. Although most species-level effects were not significant, we found highly consistent negative impacts of burn severity in meadows where pollinators were most abundant, with only hummingbirds and some butterfly families responding positively to burn severity in meadows. Moderate-severity fire tended to increase the abundance of most pollinator taxa in upland forest habitat, indicating that even in large fires that burn primarily at high- and moderate-severity patches may be associated with improved habitat conditions for pollinator species in upland forest. Nearly all pollinator taxa responded positively to floral richness but not necessarily to floral abundance. Given that much of the Sierra Nevada is predicted to burn at high severity, limiting high-severity effects in meadow and upland habitats may help conserve pollinator communities whereas low- to moderate-severity fire may be needed in both systems.
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Affiliation(s)
- Gina L. Tarbill
- Pacific Southwest Research StationUSDA, Forest ServiceDavisCaliforniaUSA
- Wildlife, Fish, & Conservation BiologyUniversity of California, DavisDavisCaliforniaUSA
| | - Angela M. White
- Pacific Southwest Research StationUSDA, Forest ServiceDavisCaliforniaUSA
| | - Rahel Sollmann
- Wildlife, Fish, & Conservation BiologyUniversity of California, DavisDavisCaliforniaUSA
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
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7
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Ma Q, Su Y, Niu C, Ma Q, Hu T, Luo X, Tai X, Qiu T, Zhang Y, Bales RC, Liu L, Kelly M, Guo Q. Tree mortality during long-term droughts is lower in structurally complex forest stands. Nat Commun 2023; 14:7467. [PMID: 37978191 PMCID: PMC10656564 DOI: 10.1038/s41467-023-43083-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 10/31/2023] [Indexed: 11/19/2023] Open
Abstract
Increasing drought frequency and severity in a warming climate threaten forest ecosystems with widespread tree deaths. Canopy structure is important in regulating tree mortality during drought, but how it functions remains controversial. Here, we show that the interplay between tree size and forest structure explains drought-induced tree mortality during the 2012-2016 California drought. Through an analysis of over one million trees, we find that tree mortality rate follows a "negative-positive-negative" piecewise relationship with tree height, and maintains a consistent negative relationship with neighborhood canopy structure (a measure of tree competition). Trees overshadowed by tall neighboring trees experienced lower mortality, likely due to reduced exposure to solar radiation load and lower water demand from evapotranspiration. Our findings demonstrate the significance of neighborhood canopy structure in influencing tree mortality and suggest that re-establishing heterogeneity in canopy structure could improve drought resiliency. Our study also indicates the potential of advances in remote-sensing technologies for silvicultural design, supporting the transition to multi-benefit forest management.
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Affiliation(s)
- Qin Ma
- School of Geography, Nanjing Normal University, Nanjing, 210023, China
- Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing, 210023, China
- Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, 210023, China
| | - Yanjun Su
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 100093, Beijing, China.
- China National Botanical Garden, 100093, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
| | - Chunyue Niu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 100093, Beijing, China
- China National Botanical Garden, 100093, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Qin Ma
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 100093, Beijing, China
- China National Botanical Garden, 100093, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Tianyu Hu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 100093, Beijing, China
- China National Botanical Garden, 100093, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Xiangzhong Luo
- Department of Geography, National University of Singapore, Singapore, 117570, Singapore
| | - Xiaonan Tai
- Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Tong Qiu
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA, 16802, USA
| | - Yao Zhang
- Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, 100871, Beijing, China
| | - Roger C Bales
- Sierra Nevada Research Institute and School of Engineering, University of California, Merced, CA, 95343, USA
| | - Lingli Liu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 100093, Beijing, China
- China National Botanical Garden, 100093, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Maggi Kelly
- Department of Environmental Sciences, Policy and Management, University of California, Berkeley, CA, 94720, USA
- Division of Agriculture and Natural Resources, University of California, Berkeley, CA, 94720, USA
| | - Qinghua Guo
- Institute of Remote Sensing and Geographical Information Systems, School of Earth and Space Sciences, Peking University, Beijing, 100871, China
- Institute of Ecology, College of Urban and Environmental Science, Peking University, 100871, Beijing, China
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8
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Muche M, Yemata G, Molla E, Adnew W, Muasya AM. Land use and land cover changes and their impact on ecosystem service values in the north-eastern highlands of Ethiopia. PLoS One 2023; 18:e0289962. [PMID: 37682896 PMCID: PMC10490966 DOI: 10.1371/journal.pone.0289962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 07/31/2023] [Indexed: 09/10/2023] Open
Abstract
The land use and land cover (LULC) changes driven by the growing demands of mankind have a considerable effect on ecosystem services and functions. The study was carried out in the north-eastern highlands of Ethiopia to (1) analyze the effect of LULC changes between 1984 and 2021 and (2) assess the spatiotemporal variations in ecosystem service values (ESVs) and elasticity in response to LULC changes. Using Landsat imageries from 1984 to 2021, the spatiotemporal changes in LULC were evaluated with supervised image classification using maximum likelihood algorithm in ArcGIS software. Six LULC types were subsequently categorized, with overall accuracy and Kappa coefficients above 87% and 0.87, respectively. The ESVs were then estimated based on the Benefit Value Transfer (BVT) approach employing modified conservative value coefficients. The findings revealed a significant increase in cultivated land (9759.1ha) and built-up area (10174.41ha) during the stipulated periods and a drop in other land use types. The forest loss gradually decreased from 4.1% in the second period (1991-2001) to 0.58% in the third (2001-2021), compared to the first of the 1.1% conversion rates. Similarly, the proportion of grassland and water bodies steadily reduced over the stipulated periods, by 1.15% and 2.3% per annum, respectively. The overall loss of ESVs in the study landscape was estimated to be 54.4 million US$ (67.3%), drastically decreasing from 80.3 million US$ in 1984 to 26.4 million US$ in 2021, driven by the declining area coverage of water bodies, grassland, and forestland. Regardless of the loss, the ecosystem functions of hydrological regulation (37.2, 35.0, 6.1, and 5.1 US$ ha-1yr-1), water supply (14.5, 13.6, 2.4, and 2 US$ ha-1yr-1), and food production (9.8, 10.0, 9.1, and 9.9 US$ ha-1yr-1) contributed the most to the total ESV of each year while disturbance regulation and cultural values were the least throughout the study periods. The coefficient of sensitivity (CS) analysis revealed that our estimates were relatively robust. The findings further showed that human-dominated land-uses at the expense of natural ecosystems are the primary drivers of LULC transitions and the ensuing loss of ecosystem services in the region. Thus, this calls for intensive work on more effective land use policies that encourage an integrated management approach, with a focus on safeguarding the sustainability of natural ecosystems.
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Affiliation(s)
- Meseret Muche
- Department of Biology, College of Science, Bahir Dar University, Bahir Dar, Ethiopia
- Department of Biology, Woldia University, Woldia, Ethiopia
| | - Getahun Yemata
- Department of Biology, College of Science, Bahir Dar University, Bahir Dar, Ethiopia
| | - Eyayu Molla
- Department of Natural Resource Management, College of Agriculture and Environmental Sciences, Bahir Dar University, Bahir Dar, Ethiopia
| | - Wubetie Adnew
- Department of Biology, College of Science, Bahir Dar University, Bahir Dar, Ethiopia
| | - A. Muthama Muasya
- Department of Biological Sciences, University of Cape Town, Rondebosch, Cape Town, South Africa
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9
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Young DJN, Estes BL, Gross S, Wuenschel A, Restaino C, Meyer MD. Effectiveness of forest density reduction treatments for increasing drought resistance of ponderosa pine growth. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2854. [PMID: 37032063 DOI: 10.1002/eap.2854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 03/10/2023] [Indexed: 06/02/2023]
Abstract
As the climate changes, it is increasingly important to understand how forests will respond to drought and how forest management can influence those outcomes. In many forests that have become unnaturally dense, "restoration treatments," which decrease stand density using fire and/or mechanical thinning, are generally associated with reduced mortality during drought. However, the effects of such treatments on tree growth during drought are less clear. Previous studies have yielded apparently contradictory results, which may stem from differences in underlying aridity or drought intensity across studies. To address this uncertainty, we studied the growth of ponderosa pine (Pinus ponderosa) in paired treated and untreated areas before and during the extreme California drought of 2012-2016. Our study spanned gradients in climate and tree size and found that density reduction treatments could completely ameliorate drought-driven declines in growth under some contexts, specifically in more mesic areas and in medium-sized trees (i.e., normal annual precipitation > ca. 1100 mm and tree diameter at breast height < ca. 65 cm). Treatments were much less effective in ameliorating drought-associated growth declines in the most water-limited sites and largest trees, consistent with underlying ecophysiology. In medium-sized trees and wetter sites, growth of trees in untreated stands decreased by more than 15% during drought, while treatment-associated increases in growth of 25% or more persisted during the drought. Trees that ultimately died due to drought showed greater growth reductions during drought relative to trees that survived. Our results suggest that density reduction treatments can increase tree resistance to water stress, and they highlight an important pathway for treatments to influence carbon sequestration and other ecosystem services beyond mitigating tree mortality.
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Affiliation(s)
- Derek J N Young
- Department of Plant Sciences, University of California, Davis, Davis, California, USA
| | - Becky L Estes
- USDA Forest Service, Pacific Southwest Region, Vallejo, California, USA
| | - Shana Gross
- USDA Forest Service, Pacific Southwest Region, Vallejo, California, USA
| | - Amarina Wuenschel
- USDA Forest Service, Pacific Southwest Region, Vallejo, California, USA
| | | | - Marc D Meyer
- USDA Forest Service, Pacific Southwest Region, Vallejo, California, USA
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10
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Barkaoui K, Volaire F. Drought survival and recovery in grasses: Stress intensity and plant-plant interactions impact plant dehydration tolerance. PLANT, CELL & ENVIRONMENT 2023; 46:1489-1503. [PMID: 36655754 DOI: 10.1111/pce.14543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 01/07/2023] [Accepted: 01/16/2023] [Indexed: 06/17/2023]
Abstract
Plant dehydration tolerance confers drought survival in grasses, but the mortality thresholds according to soil water content (SWC), vapour pressure deficit (VPD) and plant-plant interactions are little explored. We compared the dehydration dynamics of leaf meristems, which are the key surviving organs, plant mortality, and recovery of Mediterranean and temperate populations of two perennial grass species, Dactylis glomerata and Festuca arundinacea, grown in monocultures and mixtures under a low-VPD (1.5 kPa) versus a high-VPD drought (2.2 kPa). The lethal drought index (LD50 ), that is, SWC associated with 50% plant mortality, ranged from 2.87% (ψs = -1.68 MPa) to 2.19% (ψs = -4.47 MPa) and reached the lowest values under the low-VPD drought. Populations of D. glomerata were more dehydration-tolerant (lower LD50 ), survived and recovered better than F. arundinacea populations. Plant-plant interactions modified dehydration tolerance and improved post-drought recovery in mixtures compared with monocultures. Water content as low as 20.7%-36.1% in leaf meristems allowed 50% of plants to survive. We conclude that meristem dehydration causes plant mortality and that drought acclimation can increase dehydration tolerance. Genetic diversity, acclimation and plant-plant interactions are essential sources of dehydration tolerance variability to consider when predicting drought-induced mortality.
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Affiliation(s)
- Karim Barkaoui
- CIRAD, UMR ABSys, F-34398 Montpellier, France
- ABSys, Univ Montpellier, CIHEAM-IAMM, CIRAD, INRAE, Institut Agro, Montpellier, France
| | - Florence Volaire
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, INRAE, Montpellier, France
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11
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Hasik AZ, King KC, Hawlena H. Interspecific host competition and parasite virulence evolution. Biol Lett 2023; 19:20220553. [PMID: 37130550 PMCID: PMC10734695 DOI: 10.1098/rsbl.2022.0553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 04/17/2023] [Indexed: 05/04/2023] Open
Abstract
Virulence, the harm to hosts caused by parasite infection, can be selected for by several ecological factors acting synergistically or antagonistically. Here, we focus on the potential for interspecific host competition to shape virulence through such a network of effects. We first summarize how host natural mortality, body mass changes, population density and community diversity affect virulence evolution. We then introduce an initial conceptual framework highlighting how these host factors, which change during host competition, may drive virulence evolution via impacts on life-history trade-offs. We argue that the multi-faceted nature of both interspecific host competition and virulence evolution still requires consideration and experimentation to disentangle contrasting mechanisms. It also necessitates a differential treatment for parasites with various transmission strategies. However, such a comprehensive approach focusing on the role of interspecific host competition is essential to understand the processes driving the evolution of virulence in a tangled bank.
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Affiliation(s)
- Adam Z. Hasik
- Jacob Blaustein Center for
Scientific Cooperation, Ben-Gurion University of the
Negev, 8499000 Midreshet Ben-Gurion,
Israel
| | - Kayla C. King
- Department of Biology,
University of Oxford, 11a Mansfield Road,
Oxford OX1 3SZ, UK
| | - Hadas Hawlena
- Mitrani Department of Desert
Ecology, Swiss Institute for Dryland Environmental and Energy Research, The
Jacob Blaustein Institutes for Desert Research, Ben-Gurion
University of the Negev, 849900 Midreshet Ben-Gurion,
Israel
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12
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van Mantgem PJ, Milano ER, Dudney J, Nesmith JCB, Vandergast AG, Zald HSJ. Growth, drought response, and climate-associated genomic structure in whitebark pine in the Sierra Nevada of California. Ecol Evol 2023; 13:e10072. [PMID: 37206686 PMCID: PMC10191741 DOI: 10.1002/ece3.10072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 04/19/2023] [Accepted: 04/26/2023] [Indexed: 05/21/2023] Open
Abstract
Whitebark pine (Pinus albicaulis Engelm.) has experienced rapid population declines and is listed as threatened under the Endangered Species Act in the United States. Whitebark pine in the Sierra Nevada of California represents the southernmost end of the species' distribution and, like other portions of its range, faces threats from an introduced pathogen, native bark beetles, and a rapidly warming climate. Beyond these chronic stressors, there is also concern about how this species will respond to acute stressors, such as drought. We present patterns of stem growth from 766 large (average diameter at breast height >25 cm), disease-free whitebark pine across the Sierra Nevada before and during a recent period of drought. We contextualize growth patterns using population genomic diversity and structure from a subset of 327 trees. Sampled whitebark pine generally had positive to neutral stem growth trends from 1970 to 2011, which was positively correlated with minimum temperature and precipitation. Indices of stem growth during drought years (2012 to 2015) relative to a predrought interval were mostly positive to neutral at our sampled sites. Individual tree growth response phenotypes appeared to be linked to genotypic variation in climate-associated loci, suggesting that some genotypes can take better advantage of local climatic conditions than others. We speculate that reduced snowpack during the 2012 to 2015 drought years may have lengthened the growing season while retaining sufficient moisture to maintain growth at most study sites. Growth responses may differ under future warming, however, particularly if drought severity increases and modifies interactions with pests and pathogens.
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Affiliation(s)
| | - Elizabeth R. Milano
- U.S. Geological SurveyWestern Ecological Research CenterSan DiegoCaliforniaUSA
- Present address:
USDA Forest ServiceRocky Mountain Research StationMoscowIdahoUSA
| | - Joan Dudney
- Environmental Studies ProgramUC Santa BarbaraSanta BarbaraCaliforniaUSA
- Department of Environmental Science, Policy, & ManagementUC BerkeleyBerkeleyCaliforniaUSA
- Department of Plant SciencesUniversity of CaliforniaDavisCaliforniaUSA
| | | | - Amy G. Vandergast
- U.S. Geological SurveyWestern Ecological Research CenterSan DiegoCaliforniaUSA
| | - Harold S. J. Zald
- USDA Forest ServicePacific Northwest Research StationCorvallisOregonUSA
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13
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Asaro C, Koch FH, Potter KM. Denser forests across the USA experience more damage from insects and pathogens. Sci Rep 2023; 13:3666. [PMID: 36871063 PMCID: PMC9985637 DOI: 10.1038/s41598-023-30675-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
Forests across much of the United States are becoming denser. Trees growing in denser stands experience more competition for essential resources, which can make them more vulnerable to disturbances. Forest density can be expressed in terms of basal area, a metric that has been used to assess vulnerability of some forests to damage by certain insects or pathogens. A raster map of total tree basal area (TBA) for the conterminous United States was compared with annual (2000-2019) survey maps of forest damage due to insects and pathogens. Across each of four regions, median TBA was significantly higher within forest areas defoliated or killed by insects or pathogens than in areas without recorded damage. Therefore, TBA may serve as a regional-scale indicator of forest health and a first filter for identifying areas that merit finer-scale analysis of forest conditions.
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Affiliation(s)
- Christopher Asaro
- USDA Forest Service, State and Private Forestry, Forest Health Protection, Atlanta, GA, 30309, USA
| | - Frank H Koch
- USDA Forest Service, Southern Research Station, Research Triangle Park, NC, 27709, USA.
| | - Kevin M Potter
- Department of Forestry and Environmental Resources, North Carolina State University, Research Triangle Park, NC, 27709, USA.,USDA Forest Service, Southern Research Station, Research Triangle Park, NC, 27709, USA
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14
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Robinson W, Kerhoulas LP, Sherriff RL, Roletti G, van Mantgem PJ. Drought survival strategies differ between coastal and montane conifers in northern California. Ecosphere 2023. [DOI: 10.1002/ecs2.4480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
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15
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Tai X, Trugman AT, Anderegg WRL. Linking remotely sensed ecosystem resilience with forest mortality across the continental United States. GLOBAL CHANGE BIOLOGY 2023; 29:1096-1105. [PMID: 36468232 DOI: 10.1111/gcb.16529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 11/10/2022] [Accepted: 11/14/2022] [Indexed: 06/17/2023]
Abstract
Episodes of forest mortality have been observed worldwide associated with climate change, impacting species composition and ecosystem services such as water resources and carbon sequestration. Yet our ability to predict forest mortality remains limited, especially across large scales. Time series of satellite imagery has been used to document ecosystem resilience globally, but it is not clear how well remotely sensed resilience can inform the prediction of forest mortality across continental, multi-biome scales. Here, we leverage forest inventories across the continental United States to systematically assess the potential of ecosystem resilience derived using different data sets and methods to predict forest mortality. We found high resilience was associated with low mortality in eastern forests but was associated with high mortality in western regions. The unexpected resilience-mortality relation in western United States may be due to several factors including plant trait acclimation, insect population dynamics, or resource competition. Overall, our results not only supported the opportunity to use remotely sensed ecosystem resilience to predict forest mortality but also highlighted that ecological factors may have crucial influences because they can reverse the sign of the resilience-mortality relationships.
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Affiliation(s)
- Xiaonan Tai
- Department of Biological Sciences, New Jersey Institute of Technology, Newark, New Jersey, USA
| | - Anna T Trugman
- Department of Geography, University of California Santa Barbara, Santa Barbara, California, USA
| | - William R L Anderegg
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
- Wilkes Center for Climate Science and Policy, University of Utah, Salt Lake City, Utah, USA
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16
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Young DJN, Slaton MR, Koltunov A. Temperature is positively associated with tree mortality in California subalpine forests containing whitebark pine. Ecosphere 2023. [DOI: 10.1002/ecs2.4400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Affiliation(s)
- Derek J. N. Young
- Department of Plant Sciences University of California Davis California USA
| | - Michèle R. Slaton
- USDA Forest Service Pacific Southwest Region Remote Sensing Lab McClellan California USA
| | - Alexander Koltunov
- USDA Forest Service Pacific Southwest Region Remote Sensing Lab McClellan California USA
- Center for Spatial Technologies and Remote Sensing (CSTARS), Department of Land, Air and Water Resources University of California Davis California USA
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17
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Klesse S, Wohlgemuth T, Meusburger K, Vitasse Y, von Arx G, Lévesque M, Neycken A, Braun S, Dubach V, Gessler A, Ginzler C, Gossner MM, Hagedorn F, Queloz V, Samblás Vives E, Rigling A, Frei ER. Long-term soil water limitation and previous tree vigor drive local variability of drought-induced crown dieback in Fagus sylvatica. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 851:157926. [PMID: 35985592 DOI: 10.1016/j.scitotenv.2022.157926] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 08/03/2022] [Accepted: 08/05/2022] [Indexed: 06/15/2023]
Abstract
Ongoing climate warming is increasing evapotranspiration, a process that reduces plant-available water and aggravates the impact of extreme droughts during the growing season. Such an exceptional hot drought occurred in Central Europe in 2018 and caused widespread defoliation in mid-summer in European beech (Fagus sylvatica L.) forests. Here, we recorded crown damage in 2021 in nine mature even-aged beech-dominated stands in northwestern Switzerland along a crown damage severity gradient (low, medium, high) and analyzed tree-ring widths of 21 mature trees per stand. We aimed at identifying predisposing factors responsible for differences in crown damage across and within stands such as tree growth characteristics (average growth rates and year-to-year variability) and site-level variables (mean canopy height, soil properties). We found that stand-level crown damage severity was strongly related to soil water availability, inferred from tree canopy height and plant available soil water storage capacity (AWC). Trees were shorter in drier stands, had higher year-to-year variability in radial growth, and showed higher growth sensitivity to moisture conditions of previous late summer than trees growing on soils with sufficient AWC, indicating that radial growth in these forests is principally limited by soil water availability. Within-stand variation of post-drought crown damage corresponded to growth rate and tree size (diameter at breast height, DBH), i.e., smaller and slower-growing trees that face more competition, were associated with increased crown damage after the 2018 drought. These findings point to tree vigor before the extreme 2018 drought (long-term relative growth rate) as an important driver of damage severity within and across stands. Our results suggest that European beech is less likely to be able to cope with future climate change-induced extreme droughts on shallow soils with limited water retention capacity.
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Affiliation(s)
- S Klesse
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland.
| | - T Wohlgemuth
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland
| | - K Meusburger
- Forest Soils and Biogeochemistry, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland
| | - Y Vitasse
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland
| | - G von Arx
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland; Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - M Lévesque
- Institute of Terrestrial Ecosystems, ETH Zurich, 8092 Zurich, Switzerland
| | - A Neycken
- Institute of Terrestrial Ecosystems, ETH Zurich, 8092 Zurich, Switzerland
| | - S Braun
- Institute for Applied Plant Biology AG, Witterswil, Switzerland
| | - V Dubach
- Forest Health & Biotic Interactions, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland
| | - A Gessler
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland; Institute of Terrestrial Ecosystems, ETH Zurich, 8092 Zurich, Switzerland
| | - C Ginzler
- Land Change Science, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland
| | - M M Gossner
- Institute of Terrestrial Ecosystems, ETH Zurich, 8092 Zurich, Switzerland; Forest Health & Biotic Interactions, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland
| | - F Hagedorn
- Forest Soils and Biogeochemistry, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland
| | - V Queloz
- Forest Health & Biotic Interactions, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland
| | - E Samblás Vives
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland; Autonomous University of Barcelona (UAB), 08193 Cerdanyola del Valles, Spain
| | - A Rigling
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland; Institute of Terrestrial Ecosystems, ETH Zurich, 8092 Zurich, Switzerland
| | - E R Frei
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland; Alpine Environment and Natural Hazards, WSL Institute for Snow and Avalanche Research SLF, 7260 Davos Dorf, Switzerland; Climate Change and Extremes in Alpine Regions Research Centre CERC, 7260 Davos Dorf, Switzerland
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18
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Ursell T, Safford HD. Nucleation sites and forest recovery under high shrub competition. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2711. [PMID: 36161678 PMCID: PMC10078307 DOI: 10.1002/eap.2711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 05/05/2022] [Accepted: 05/23/2022] [Indexed: 06/16/2023]
Abstract
Forests currently face numerous stressors, raising questions about processes of forest recovery as well as the role of humans in stimulating recovery by planting trees that might not otherwise regenerate. Theoretically, planted trees can also provide a seed source for further recruitment once the planted trees become reproductive, acting as "nucleation" sites; however, it is unclear whether changing site conditions over time (e.g., through the growth of competitors like woody shrubs) influences establishment in the long term, even if seed availability increases. We tested the nucleation concept in a system where shrub competition is known to influence tree establishment and growth, performing an observational study of sites within and close to newly reproductive planted stands in yellow-pine (YP) and mixed-conifer ecosystems in the Sierra Nevada, California. We surveyed and then modeled both seedling occurrence and density as a function of distance to seed sources, competing woody vegetation, and other environmental characteristics. We found that proximity to a planted stand was associated with an increase in the probability of YP seedlings (species more likely to originate from the planted stand) from 0.33 at 35 m from the planted stand to 0.56 directly adjacent to the stand and 0.65 within the stand. However, we found no significant effect of proximity on YP seedling density. This proximity effect suggests that seed availability continues to be a driver of recruitment several decades postwildfire, though other processes may influence the expected density of recruits. Proxies for competitive pressure (shrub volume and shrub cover) were not significant, suggesting that competing vegetation did not have a major influence on recruitment. Though seedling presence and density appeared to be independent of shrub impacts, we did find that shrubs were significantly taller than seedlings. Therefore, we suggest that shrubs may not limit seedling establishment, but they may negatively affect seedlings' ability to grow and serve as a seed source for further recruitment and forest expansion. Altogether, we find that planting may provide a statistically significant but small role in driving recruitment outside of the planted site.
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Affiliation(s)
- Tara Ursell
- Graduate Group in EcologyUniversity of CaliforniaDavisCaliforniaUSA
| | - Hugh D. Safford
- Department of Environmental Science and PolicyUniversity of CaliforniaDavisCaliforniaUSA
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19
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Wang X, Schönbeck L, Gessler A, Yang Y, Rigling A, Yu D, He P, Li M. The effects of previous summer drought and fertilization on winter non-structural carbon reserves and spring leaf development of downy oak saplings. FRONTIERS IN PLANT SCIENCE 2022; 13:1035191. [PMID: 36407605 PMCID: PMC9669721 DOI: 10.3389/fpls.2022.1035191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 10/20/2022] [Indexed: 06/16/2023]
Abstract
It is still unknown whether the previous summer season drought and fertilization will affect the winter non-structural carbohydrate (NSC) reserves, spring leaf development, and mortality of trees in the next year. We, therefore, conducted an experiment with Quercus pubescens (downy oaks) saplings grown under four drought levels from field capacity (well-watered; ~25% volumetric water content) to wilting point (extreme drought; ~6%), in combination with two fertilizer treatments (0 vs. 50 kg/ha/year blended) for one growing season to answer this question. We measured the pre- and post-winter NSC, and calculated the over-winter NSC consumption in storage tissues (i.e. shoots and roots) following drought and fertilization treatment, and recorded the spring leaf phenology, leaf biomass, and mortality next year. The results showed that, irrespective of drought intensity, carbon reserves were abundant in storage tissues, especially in roots. Extreme drought did not significantly alter NSC levels in tissues, but delayed the spring leaf expansion and reduced the leaf biomass. Previous season fertilization promoted shoot NSC use in extreme drought-stressed saplings over winter (showing reduced carbon reserves in shoots after winter), but it also showed positive effects on survival next year. We conclude that: (1) drought-stressed downy oak saplings seem to be able to maintain sufficient mobile carbohydrates for survival, (2) fertilization can alleviate the negative effects of extreme drought on survival and recovery growth of tree saplings.
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Affiliation(s)
- Xiaoyu Wang
- Jiyang College, Zhejiang Provincial Key Laboratory of Germplasm Innovation and Utilization for Garden Plants, Zhejiang Agriculture and Forestry University, Hangzhou, China
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
| | - Leonie Schönbeck
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, United States
- Plant Ecology Research Laboratory, School of Architecture, Civil and Environmental Engineering, Swiss Federal Institute of Technology Lausanne, Lausanne, Geneva, Switzerland
| | - Arthur Gessler
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
- Institute of Terrestrial Ecosystems, Eidgenössische Technische Hochschule Zürich (ETH Zürich), Zurich, Switzerland
| | - Yue Yang
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
- College of Ecology and Environment, Hainan University, Haikou, Hainan, China
| | - Andreas Rigling
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
- Institute of Terrestrial Ecosystems, Eidgenössische Technische Hochschule Zürich (ETH Zürich), Zurich, Switzerland
| | - Dapao Yu
- Institute of Applied Ecology, Chinese Academy of Sciences (CAS), Shenyang, Liaoning, China
| | - Peng He
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, Tianjin, China
| | - Maihe Li
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, School of Geographical Sciences, Northeast Normal University, Changchun, Jilin, China
- School of Life Science, Hebei University, Baoding, Hebei, China
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20
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Liu Y, Erbilgin N, Ratcliffe B, Klutsch JG, Wei X, Ullah A, Cappa EP, Chen C, Thomas BR, El-Kassaby YA. Pest defences under weak selection exert a limited influence on the evolution of height growth and drought avoidance in marginal pine populations. Proc Biol Sci 2022; 289:20221034. [PMID: 36069017 PMCID: PMC9449467 DOI: 10.1098/rspb.2022.1034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
While droughts, intensified by climate change, have been affecting forests worldwide, pest epidemics are a major source of uncertainty for assessing drought impacts on forest trees. Thus far, little information has documented the adaptability and evolvability of traits related to drought and pests simultaneously. We conducted common-garden experiments to investigate how several phenotypic traits (i.e. height growth, drought avoidance based on water-use efficiency inferred from δ13C and pest resistance based on defence traits) interact in five mature lodgepole pine populations established in four progeny trials in western Canada. The relevance of interpopulation variation in climate sensitivity highlighted that seed-source warm populations had greater adaptive capability than cold populations. In test sites, warming generated taller trees with higher δ13C and increased the evolutionary potential of height growth and δ13C across populations. We found, however, no pronounced gradient in defences and their evolutionary potential along populations or test sites. Response to selection was weak in defences across test sites, but high for height growth particularly at warm test sites. Response to the selection of δ13C varied depending on its selective strength relative to height growth. We conclude that warming could promote the adaptability and evolvability of growth response and drought avoidance with a limited evolutionary influence from pest (biotic) pressures.
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Affiliation(s)
- Yang Liu
- Department of Forest and Conservation Sciences, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada.,McDonald Institute for Archaeological Research, University of Cambridge, Downing Street, Cambridge CB2 3DZ, UK.,Wolfson College, University of Cambridge, Barton Road, Cambridge CB3 9BB, UK
| | - Nadir Erbilgin
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta T6G 2E3, Canada
| | - Blaise Ratcliffe
- Department of Forest and Conservation Sciences, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - Jennifer G Klutsch
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta T6G 2E3, Canada
| | - Xiaojing Wei
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta T6G 2E3, Canada
| | - Aziz Ullah
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta T6G 2E3, Canada
| | - Eduardo Pablo Cappa
- Instituto Nacional de Tecnología Agropecuaria (INTA), Instituto de Recursos Biológicos, Centro de Investigación en Recursos Naturales, De Los Reseros y Doctor Nicolás Repetto s/n, 1686, Hurlingham, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Charles Chen
- Department of Biochemistry and Molecular Biology, 246 Noble Research Center, Oklahoma State University, Stillwater, OK 74078, USA
| | - Barb R Thomas
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta T6G 2E3, Canada
| | - Yousry A El-Kassaby
- Department of Forest and Conservation Sciences, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
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21
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Robust Satellite-Based Identification and Monitoring of Forests Having Undergone Climate-Change-Related Stress. LAND 2022. [DOI: 10.3390/land11060825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Climate-induced drought events are responsible for forest decline and mortality in different areas of the world. Forest response to drought stress periods may be different, in time and space, depending on vegetation type and local factors. Stress analysis may be carried out by using field methods, but the use of remote sensing may be needed to highlight the effects of climate-change-induced phenomena at a larger spatial and temporal scale. In this context, satellite-based analyses are presented in this work to evaluate the drought effects during the 2000s and the possible climatological forcing over oak forests in Southern Italy. To this aim, two approaches based on the well-known Normalized Difference Vegetation Index (NDVI) were used: one based on NDVI values, averaged over selected decaying and non-decaying forests; another based on the Robust Satellite Techniques (RST). The analysis of the first approach mainly gave us overall information about 1984–2011 rising NDVI trends, despite a general decrease around the 2000s. The second, more refined approach was able to highlight a different drought stress impact over decaying and non-decaying forests. The combined use of the RST-based approach, Landsat satellite data, and Google Earth Engine (GEE) platform allowed us to identify in space domain and monitor over time significant oak forest changes and climate-driven effects (e.g., in 2001) from the local to the Basilicata region scale. By this way, the decaying status of the Gorgoglione forest was highlighted two years before the first visual field evidence (e.g., dryness of apical branches, bark detachment, root rot disease). The RST exportability to different satellite sensors and vegetation types, the availability of suitable satellite data, and the potential of GEE suggest the possibility of long-term monitoring of forest health, from the local to the global scale, to provide useful information to different end-user classes.
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22
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Sclerophyllous Forest Tree Growth Under the Influence of a Historic Megadrought in the Mediterranean Ecoregion of Chile. Ecosystems 2022. [DOI: 10.1007/s10021-022-00760-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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23
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Comparing Geography and Severity of Managed Wildfires in California and the Southwest USA before and after the Implementation of the 2009 Policy Guidance. FORESTS 2022. [DOI: 10.3390/f13050793] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Managed wildfires, i.e., naturally ignited wildfires that are managed for resource benefits, have the potential to reduce fuel loads, minimize the effects of future wildfires, and restore critical natural processes across many forest landscapes. In the United States, the 2009 federal wildland fire policy guidance was designed to provide greater flexibility in the use of managed wildfires, but the effects of this policy on wildfires in the western US are not yet fully understood. Our goal was to compare managed and full suppression wildfires and to also analyze the differences between managed wildfires across space (Arizona/New Mexico and California) and time (before and after 2009) using four metrics for each wildfire: (1) distance to wilderness, (2) distance to the wildland–urban interface (WUI), (3) the percentage of area burned with high severity, and (4) the number of land management agencies. Across the study area, we found that managed wildfires were significantly closer to wilderness areas, were farther from the WUI, had a lower percentage of area that was burned at high severity, and had fewer agencies involved in managing the fire compared to full suppression wildfires. In California, managed wildfires occurred closer to wilderness and had a larger percentage of high-severity burn area compared to those in the southwest US (Arizona and New Mexico). Within each region, however, there were no significant geographic differences between managed wildfires before and after the implementation of the 2009 policy guidance. Despite the greater flexibility of the 2009 policy guidance, the basic geographic properties of managed wildfires in these two regions have not changed. As the climate warms and droughts intensify, the use of managed wildfires will need to expand during favorable weather conditions in order to address the threat of large and uncharacteristic wildfires to people and ecosystems.
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Gazol A, Camarero JJ. Compound climate events increase tree drought mortality across European forests. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 816:151604. [PMID: 34780817 DOI: 10.1016/j.scitotenv.2021.151604] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 11/03/2021] [Accepted: 11/07/2021] [Indexed: 06/13/2023]
Abstract
Climate change can lead to the simultaneous occurrence of extreme droughts and heat waves increasing the frequency of compound events with unknown impacts on forests. Here we use two independent datasets, a compiled database of tree drought mortality events and the ICP-Forest level I plots, to study the impacts of the simultaneous occurrence of hot summers, with elevated vapour pressure deficit (VPD), and dry years on forest defoliation and mortality across Europe. We focused on tree drought mortality and background mortality rates, and we studied their co-occurrence with compound events of hot summers and dry years. In total, 143 out of 310 mortality events across Europe, i.e. 46% of cases, corresponded with rare compound events characterized by hot summers and dry years. Over the past decades, summer temperature increased in most sites and severe droughts resulted in compound events not observed before the 1980s. From the ICP-Forest plots we identified 291 (1718 trees) and 61 plots (128 trees) where severe defoliation and mortality, respectively, were caused by drought. The analyses of these events showed that 34% and 27% of the defoliation and mortality cases corresponded with rare compound climate events, respectively. Background mortality rates across Europe in the period 1993-2013 presented higher values in regions where summer temperature and VPD more steeply rose, where drought frequency increased. The steady increase in summer temperatures and VPD in Southern and Eastern Europe may favor the occurrence of compound events of hot summers and dry conditions. Giving that both, local and intense tree drought mortality events and background forest mortality rates, are linked to such compound events we can expect an increase in forest drought mortality in these European regions over the next decades.
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Affiliation(s)
- Antonio Gazol
- Instituto Pirenaico de Ecología (IPE-CSIC), E-50059 Zaragoza, Spain.
| | - J Julio Camarero
- Instituto Pirenaico de Ecología (IPE-CSIC), E-50059 Zaragoza, Spain.
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25
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Antonarakis AS, Bogan SA, Goulden ML, Moorcroft PR. Impacts of the 2012-2015 Californian drought on carbon, water and energy fluxes in the Californian Sierras: Results from an imaging spectrometry-constrained terrestrial biosphere model. GLOBAL CHANGE BIOLOGY 2022; 28:1823-1852. [PMID: 34779555 DOI: 10.1111/gcb.15995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 10/15/2021] [Accepted: 10/28/2021] [Indexed: 06/13/2023]
Abstract
Accurate descriptions of current ecosystem composition are essential for improving terrestrial biosphere model predictions of how ecosystems are responding to climate variability and change. This study investigates how imaging spectrometry-derived ecosystem composition can constrain and improve terrestrial biosphere model predictions of regional-scale carbon, water and energy fluxes. Incorporating imaging spectrometry-derived composition of five plant functional types (Grasses/Shrubs, Oaks/Western Hardwoods, Western Pines, Fir/Cedar and High-elevation Pines) into the Ecosystem Demography (ED2) terrestrial biosphere model improves predictions of net ecosystem productivity (NEP) and gross primary productivity (GPP) across four flux towers of the Southern Sierra Critical Zone Observatory (SSCZO) spanning a 2250 m elevational gradient in the western Sierra Nevada. NEP and GPP root-mean-square-errors were reduced by 23%-82% and 19%-89%, respectively, and water flux predictions improved at the mid-elevation pine (Soaproot), fir/cedar (P301) and high-elevation pine (Shorthair) flux tower sites, but not at the oak savanna (San Joaquin Experimental Range [SJER]) site. These improvements in carbon and water predictions are similar to those achieved with model initializations using ground-based inventory composition. The imaging spectrometry-constrained ED2 model was then used to predict carbon, water and energy fluxes and above-ground biomass (AGB) dynamics over a 737 km2 region to gain insight into the regional ecosystem impacts of the 2012-2015 Californian drought. The analysis indicates that the drought reduced regional NEP, GPP and transpiration by 83%, 40% and 33%, respectively, with the largest reductions occurring in the functionally diverse, high basal area mid-elevation forests. This was accompanied by a 54% decline in AGB growth in 2012, followed by a marked increase (823%) in AGB mortality in 2014, reflecting an approximately 10-fold increase in per capita tree mortality from ~55 trees km-2 year-1 in 2010-2011, to ~535 trees km-2 year-1 in 2014. These findings illustrate how imaging spectrometry estimates of ecosystem composition can constrain and improve terrestrial biosphere model predictions of regional carbon, water, and energy fluxes, and biomass dynamics.
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Affiliation(s)
| | - Stacy A Bogan
- Department of Geography, Sussex University, Brighton, UK
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Michael L Goulden
- Department of Earth Sciences, University of California, Irvine, California, USA
| | - Paul R Moorcroft
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
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26
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Wu D, Vargas G G, Powers JS, McDowell NG, Becknell JM, Pérez-Aviles D, Medvigy D, Liu Y, Katul GG, Calvo-Alvarado JC, Calvo-Obando A, Sanchez-Azofeifa A, Xu X. Reduced ecosystem resilience quantifies fine-scale heterogeneity in tropical forest mortality responses to drought. GLOBAL CHANGE BIOLOGY 2022; 28:2081-2094. [PMID: 34921474 DOI: 10.1111/gcb.16046] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/07/2021] [Accepted: 12/07/2021] [Indexed: 06/14/2023]
Abstract
Sensitivity of forest mortality to drought in carbon-dense tropical forests remains fraught with uncertainty, while extreme droughts are predicted to be more frequent and intense. Here, the potential of temporal autocorrelation of high-frequency variability in Landsat Enhanced Vegetation Index (EVI), an indicator of ecosystem resilience, to predict spatial and temporal variations of forest biomass mortality is evaluated against in situ census observations for 64 site-year combinations in Costa Rican tropical dry forests during the 2015 ENSO drought. Temporal autocorrelation, within the optimal moving window of 24 months, demonstrated robust predictive power for in situ mortality (leave-one-out cross-validation R2 = 0.54), which allows for estimates of annual biomass mortality patterns at 30 m resolution. Subsequent spatial analysis showed substantial fine-scale heterogeneity of forest mortality patterns, largely driven by drought intensity and ecosystem properties related to plant water use such as forest deciduousness and topography. Highly deciduous forest patches demonstrated much lower mortality sensitivity to drought stress than less deciduous forest patches after elevation was controlled. Our results highlight the potential of high-resolution remote sensing to "fingerprint" forest mortality and the significant role of ecosystem heterogeneity in forest biomass resistance to drought.
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Affiliation(s)
- Donghai Wu
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, USA
| | - German Vargas G
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA
| | - Jennifer S Powers
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, Minnesota, USA
| | - Nate G McDowell
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Lab, Richland, Washington, USA
- School of Biological Sciences, Washington State University, Pullman, Washington, USA
| | - Justin M Becknell
- Environmental Studies Program, Colby College, Waterville, Maine, USA
| | - Daniel Pérez-Aviles
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, Minnesota, USA
| | - David Medvigy
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Yanlan Liu
- School of Earth Sciences, The Ohio State University, Columbus, Ohio, USA
| | - Gabriel G Katul
- Department of Civil and Environmental Engineering and the Nicholas School of the Environment, Duke University, Durham, North Carolina, USA
| | | | - Ana Calvo-Obando
- Escuela de Ing. Forestal, Instituto Tecnológico de Costa Rica, Barrio Los Ángeles, Cartago, Costa Rica
| | | | - Xiangtao Xu
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, USA
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27
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Furniss TJ, Das AJ, van Mantgem PJ, Stephenson NL, Lutz JA. Crowding, climate, and the case for social distancing among trees. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2507. [PMID: 34870871 DOI: 10.1002/eap.2507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 06/25/2021] [Accepted: 07/30/2021] [Indexed: 06/13/2023]
Abstract
In an emerging era of megadisturbance, bolstering forest resilience to wildfire, insects, and drought has become a central objective in many western forests. Climate has received considerable attention as a driver of these disturbances, but few studies have examined the complexities of climate-vegetation-disturbance interactions. Current strategies for creating resilient forests often rely on retrospective approaches, seeking to impart resilience by restoring historical conditions to contemporary landscapes, but historical conditions are becoming increasingly unattainable amidst modern bioclimatic conditions. What becomes an appropriate benchmark for resilience when we have novel forests, rapidly changing climate, and unprecedented disturbance regimes? We combined two longitudinal datasets-each representing some of the most comprehensive spatially explicit, annual tree mortality data in existence-in a post-hoc factorial design to examine the nonlinear relationships between fire, climate, forest spatial structure, and bark beetles. We found that while prefire drought elevated mortality risk, advantageous local neighborhoods could offset these effects. Surprisingly, mortality risk (Pm ) was higher in crowded local neighborhoods that burned in wet years (Pm = 42%) compared with sparse neighborhoods that burned during drought (Pm = 30%). Risk of beetle attack was also increased by drought, but lower conspecific crowding impeded the otherwise positive interaction between fire and beetle attack. Antecedent fire increased drought-related mortality over short timespans (<7 years) but reduced mortality over longer intervals. These results clarify interacting disturbance dynamics and provide a mechanistic underpinning for forest restoration strategies. Importantly, they demonstrate the potential for managed fire and silvicultural strategies to offset climate effects and bolster resilience to fire, beetles, and drought.
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Affiliation(s)
- Tucker J Furniss
- Wildland Resources Department and Ecology Center, Utah State University, Logan, Utah, USA
- USDA Forest Service, Pacific Northwest Research Station, Wenatchee, Washington, USA
| | - Adrian J Das
- U.S. Geological Survey, Western Ecological Research Center, Three Rivers, California, USA
| | | | - Nathan L Stephenson
- U.S. Geological Survey, Western Ecological Research Center, Three Rivers, California, USA
| | - James A Lutz
- Wildland Resources Department and Ecology Center, Utah State University, Logan, Utah, USA
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28
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Britton TG, Brodribb TJ, Richards SA, Ridley C, Hovenden MJ. Canopy damage during a natural drought depends on species identity, physiology and stand composition. THE NEW PHYTOLOGIST 2022; 233:2058-2070. [PMID: 34850394 DOI: 10.1111/nph.17888] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 11/21/2021] [Indexed: 06/13/2023]
Abstract
Vulnerability to xylem cavitation is a strong predictor of drought-induced damage in forest communities. However, biotic features of the community itself can influence water availability at the individual tree-level, thereby modifying patterns of drought damage. Using an experimental forest in Tasmania, Australia, we determined the vulnerability to cavitation (leaf P50 ) of four tree species and assessed the drought-induced canopy damage of 2944 6-yr-old trees after an extreme natural drought episode. We examined how individual damage was related to their size and the density and species identity of neighbouring trees. The two co-occurring dominant tree species, Eucalyptus delegatensis and Eucalyptus regnans, were the most vulnerable to drought-induced xylem cavitation and both species suffered significantly greater damage than neighbouring, subdominant species Pomaderris apetala and Acacia dealbata. While the two eucalypts had similar leaf P50 values, E. delegatensis suffered significantly greater damage, which was strongly related to the density of neighbouring P. apetala. Damage in E. regnans was less impacted by neighbouring plants and smaller trees of both eucalypts sustained significantly more damage than larger trees. Our findings demonstrate that natural drought damage is influenced by individual plant physiology as well as the composition, physiology and density of the surrounding stand.
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Affiliation(s)
- Travis G Britton
- Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tas., 7001, Australia
- ARC Training Centre for Forest Value, University of Tasmania, Hobart, Tas., 7001, Australia
| | - Timothy J Brodribb
- Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tas., 7001, Australia
| | - Shane A Richards
- School of Natural Sciences, University of Tasmania, Hobart, Tas., 7001, Australia
| | - Chantelle Ridley
- Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tas., 7001, Australia
| | - Mark J Hovenden
- Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tas., 7001, Australia
- ARC Training Centre for Forest Value, University of Tasmania, Hobart, Tas., 7001, Australia
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29
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Weithmann G, Link RM, Banzragch BE, Würzberg L, Leuschner C, Schuldt B. Soil water availability and branch age explain variability in xylem safety of European beech in Central Europe. Oecologia 2022; 198:629-644. [PMID: 35212818 PMCID: PMC8956530 DOI: 10.1007/s00442-022-05124-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 01/24/2022] [Indexed: 12/17/2022]
Abstract
Xylem embolism resistance has been identified as a key trait with a causal relation to drought-induced tree mortality, but not much is known about its intra-specific trait variability (ITV) in dependence on environmental variation. We measured xylem safety and efficiency in 300 European beech (Fagus sylvatica L.) trees across 30 sites in Central Europe, covering a precipitation reduction from 886 to 522 mm year−1. A broad range of variables that might affect embolism resistance in mature trees, including climatic and soil water availability, competition, and branch age, were examined. The average P50 value varied by up to 1 MPa between sites. Neither climatic aridity nor structural variables had a significant influence on P50. However, P50 was less negative for trees with a higher soil water storage capacity, and positively related to branch age, while specific conductivity (Ks) was not significantly associated with either of these variables. The greatest part of the ITV for xylem safety and efficiency was attributed to random variability within populations. We conclude that the influence of site water availability on P50 and Ks is low in European beech, and that the high degree of within-population variability for P50, partly due to variation in branch age, hampers the identification of a clear environmental signal.
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Affiliation(s)
- Greta Weithmann
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany
| | - Roman M Link
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany.,Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute of Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz, 97082, Würzburg, Germany
| | - Bat-Enerel Banzragch
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany
| | - Laura Würzberg
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany
| | - Christoph Leuschner
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany.,Centre for Biodiversity and Sustainable Land Use (CBL), University of Goettingen, 37075, Göttingen, Germany
| | - Bernhard Schuldt
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany. .,Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute of Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz, 97082, Würzburg, Germany.
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30
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Werner CM, Harrison SP, Safford HD, Bohlman GN, Serata R. Extreme pre-fire drought decreases shrub regeneration on fertile soils. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e02464. [PMID: 34614281 DOI: 10.1002/eap.2464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/16/2021] [Accepted: 05/26/2021] [Indexed: 06/13/2023]
Abstract
Extreme drought and increasing temperatures can decrease the resilience of plant communities to fires. Not only may extremely dry conditions during or after fires lead to higher plant mortality and poorer recruitment, but severe pre-fire droughts may reduce the seed production and belowground vigor that are essential to post-fire plant recovery, and may indirectly facilitate invasion. We studied survival, recruitment, and growth of shrubs and herbs in chaparral (shrubland) communities in Northern California after a 2015 fire that immediately followed California's extreme 3-yr drought. We followed the same protocols used to study similar, adjacent communities after a 1999 fire that did not follow a drought, and we compared the two recovery trajectories. Overall, the 2015 fire was not more severe than the 1999 fire, yet it caused higher mortality and lower growth of resprouting shrubs on fertile (sandstone) soils. In contrast, the 2015 fire did not affect the mortality or growth of resprouting shrubs on infertile (serpentine) soils, the density of shrub seedlings, or the richness or cover of native herbs differently than the 1999 fire. However, the 2015 fire facilitated a massive increase in exotic herbaceous cover, especially on fertile soils, possibly portending the early stages of a type conversion to exotic-dominated grassland. Our findings indicate that the consequences of climate change on fire-dependent communities will include effects of pre-fire as well as post-fire climate, and that resprouting shrubs are particularly likely to be sensitive to pre-fire drought.
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Affiliation(s)
- Chhaya M Werner
- Department of Plant Sciences and Graduate Group in Population Biology, University of California, Davis, California, 95616, USA
- Department of Environmental Science and Policy, University of California, Davis, California, 95616, USA
| | - Susan P Harrison
- Department of Environmental Science and Policy, University of California, Davis, California, 95616, USA
| | - Hugh D Safford
- Department of Environmental Science and Policy, University of California, Davis, California, 95616, USA
- USDA Forest Service Region 5, Vallejo, California, 94592, USA
| | | | - Rebecca Serata
- Department of Environmental Science and Policy, University of California, Davis, California, 95616, USA
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31
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Hagmann RK, Hessburg PF, Prichard SJ, Povak NA, Brown PM, Fulé PZ, Keane RE, Knapp EE, Lydersen JM, Metlen KL, Reilly MJ, Sánchez Meador AJ, Stephens SL, Stevens JT, Taylor AH, Yocom LL, Battaglia MA, Churchill DJ, Daniels LD, Falk DA, Henson P, Johnston JD, Krawchuk MA, Levine CR, Meigs GW, Merschel AG, North MP, Safford HD, Swetnam TW, Waltz AEM. Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02431. [PMID: 34339067 PMCID: PMC9285092 DOI: 10.1002/eap.2431] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 03/04/2021] [Accepted: 03/22/2021] [Indexed: 05/06/2023]
Abstract
Implementation of wildfire- and climate-adaptation strategies in seasonally dry forests of western North America is impeded by numerous constraints and uncertainties. After more than a century of resource and land use change, some question the need for proactive management, particularly given novel social, ecological, and climatic conditions. To address this question, we first provide a framework for assessing changes in landscape conditions and fire regimes. Using this framework, we then evaluate evidence of change in contemporary conditions relative to those maintained by active fire regimes, i.e., those uninterrupted by a century or more of human-induced fire exclusion. The cumulative results of more than a century of research document a persistent and substantial fire deficit and widespread alterations to ecological structures and functions. These changes are not necessarily apparent at all spatial scales or in all dimensions of fire regimes and forest and nonforest conditions. Nonetheless, loss of the once abundant influence of low- and moderate-severity fires suggests that even the least fire-prone ecosystems may be affected by alteration of the surrounding landscape and, consequently, ecosystem functions. Vegetation spatial patterns in fire-excluded forested landscapes no longer reflect the heterogeneity maintained by interacting fires of active fire regimes. Live and dead vegetation (surface and canopy fuels) is generally more abundant and continuous than before European colonization. As a result, current conditions are more vulnerable to the direct and indirect effects of seasonal and episodic increases in drought and fire, especially under a rapidly warming climate. Long-term fire exclusion and contemporaneous social-ecological influences continue to extensively modify seasonally dry forested landscapes. Management that realigns or adapts fire-excluded conditions to seasonal and episodic increases in drought and fire can moderate ecosystem transitions as forests and human communities adapt to changing climatic and disturbance regimes. As adaptation strategies are developed, evaluated, and implemented, objective scientific evaluation of ongoing research and monitoring can aid differentiation of warranted and unwarranted uncertainties.
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Affiliation(s)
- R. K. Hagmann
- College of the Environment‐SEFSUniversity of WashingtonSeattleWashington98195USA
- Applegate Forestry LLCCorvallisOregon97330USA
| | - P. F. Hessburg
- College of the Environment‐SEFSUniversity of WashingtonSeattleWashington98195USA
- USDA‐FS, Forestry Sciences LaboratoryPacific Northwest Research StationWenatcheeWashington98801USA
| | - S. J. Prichard
- College of the Environment‐SEFSUniversity of WashingtonSeattleWashington98195USA
| | - N. A. Povak
- USDA‐FS, Forestry Sciences LaboratoryPacific Northwest Research StationWenatcheeWashington98801USA
- USDA‐FS, Pacific Southwest Research StationPlacervilleCalifornia95667USA
| | - P. M. Brown
- Rocky Mountain Tree‐Ring ResearchFort CollinsColorado80526USA
| | - P. Z. Fulé
- School of ForestryNorthern Arizona UniversityFlagstaffArizona86011USA
| | - R. E. Keane
- Missoula Fire Sciences LaboratoryUSDA‐FS, Rocky Mountain Research StationMissoulaMontana59808USA
| | - E. E. Knapp
- USDA‐FS, Pacific Southwest Research StationReddingCalifornia96002USA
| | - J. M. Lydersen
- Fire and Resource Assessment ProgramCalifornia Department of Forestry and Fire ProtectionSacramentoCalifornia94244USA
| | | | - M. J. Reilly
- USDA‐FS, Pacific Northwest Research StationCorvallisOregon97333USA
| | - A. J. Sánchez Meador
- Ecological Restoration InstituteNorthern Arizona UniversityFlagstaffArizona86011USA
| | - S. L. Stephens
- Department of Environmental Science, Policy, and ManagementUniversity of California–BerkeleyBerkeleyCalifornia94720USA
| | - J. T. Stevens
- U.S. Geological SurveyFort Collins Science CenterNew Mexico Landscapes Field StationSanta FeNew Mexico87508USA
| | - A. H. Taylor
- Department of Geography, Earth and Environmental Systems InstituteThe Pennsylvania State UniversityUniversity ParkPennsylvania16802USA
| | - L. L. Yocom
- Department of Wildland Resources and the Ecology CenterUtah State UniversityLoganUtah84322USA
| | - M. A. Battaglia
- USDA‐FS, Rocky Mountain Research StationFort CollinsColorado80526USA
| | - D. J. Churchill
- Washington State Department of Natural ResourcesOlympiaWashington98504USA
| | - L. D. Daniels
- Department of Forest and Conservation SciencesUniversity of British ColumbiaVancouverBritish ColumbiaV6T 1Z4Canada
| | - D. A. Falk
- School of Natural Resources and the EnvironmentUniversity of ArizonaTucsonArizona85721USA
- Laboratory of Tree‐Ring ResearchUniversity of ArizonaTucsonArizona85721USA
| | - P. Henson
- Oregon Fish and Wildlife OfficeUSDI Fish & Wildlife ServicePortlandOregon97232USA
| | - J. D. Johnston
- College of ForestryOregon State UniversityCorvallisOregon97333USA
| | - M. A. Krawchuk
- College of ForestryOregon State UniversityCorvallisOregon97333USA
| | - C. R. Levine
- Spatial Informatics GroupPleasantonCalifornia94566USA
| | - G. W. Meigs
- Washington State Department of Natural ResourcesOlympiaWashington98504USA
| | - A. G. Merschel
- College of ForestryOregon State UniversityCorvallisOregon97333USA
| | - M. P. North
- USDA‐FS, Pacific Southwest Research StationMammoth LakesCalifornia93546USA
| | - H. D. Safford
- USDA‐FS, Pacific Southwest RegionVallejoCalifornia94592USA
| | - T. W. Swetnam
- Laboratory of Tree‐Ring ResearchUniversity of ArizonaTucsonArizona85721USA
| | - A. E. M. Waltz
- Ecological Restoration InstituteNorthern Arizona UniversityFlagstaffArizona86011USA
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32
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Erbilgin N, Zanganeh L, Klutsch JG, Chen SH, Zhao S, Ishangulyyeva G, Burr SJ, Gaylord M, Hofstetter R, Keefover-Ring K, Raffa KF, Kolb T. Combined drought and bark beetle attacks deplete non-structural carbohydrates and promote death of mature pine trees. PLANT, CELL & ENVIRONMENT 2021; 44:3636-3651. [PMID: 34612515 DOI: 10.1111/pce.14197] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 06/13/2023]
Abstract
How carbohydrate reserves in conifers respond to drought and bark beetle attacks are poorly understood. We investigated changes in carbohydrate reserves and carbon-dependent diterpene defences in ponderosa pine trees that were experimentally subjected to two levels of drought stress (via root trenching) and two types of biotic challenge treatments (pheromone-induced bark beetle attacks or inoculations with crushed beetles that include beetle-associated fungi) for two consecutive years. Our results showed that trenching did not influence carbohydrates, whereas both biotic challenges reduced amounts of starch and sugars of trees. However, only the combined trenched-bark beetle attacked trees depleted carbohydrates and died during the first year of attacks. While live trees contained higher carbohydrates than dying trees, amounts of constitutive and induced diterpenes produced did not vary between live and beetle-attacked dying trees, respectively. Based on these results we propose that reallocation of carbohydrates to diterpenes during the early stages of beetle attacks is limited in drought-stricken trees, and that the combination of biotic and abiotic stress leads to tree death. The process of tree death is subsequently aggravated by beetle girdling of phloem, occlusion of vascular tissue by bark beetle-vectored fungi, and potential exploitation of host carbohydrates by bark beetle symbionts as nutrients.
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Affiliation(s)
- Nadir Erbilgin
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Leila Zanganeh
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
- Department of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
| | - Jennifer G Klutsch
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
- Department of Forestry, New Mexico Highlands University, Las Vegas, New Mexico, USA
| | - Shih-Hsuan Chen
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Shiyang Zhao
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Guncha Ishangulyyeva
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Stephen J Burr
- Forest Health Protection, USDA Forest Service, Milwaukee, Wisconsin, USA
| | - Monica Gaylord
- Forest Health Protection, USDA Forest Service, Flagstaff, Arizona, USA
| | - Richard Hofstetter
- School of Forestry, Northern Arizona University, Flagstaff, Arizona, USA
| | - Ken Keefover-Ring
- Departments of Botany and Geography, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kenneth F Raffa
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Thomas Kolb
- School of Forestry, Northern Arizona University, Flagstaff, Arizona, USA
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Bradford JB, Shriver RK, Robles MD, McCauley LA, Woolley TJ, Andrews CA, Crimmins M, Bell DM. Tree mortality response to drought‐density interactions suggests opportunities to enhance drought resistance. J Appl Ecol 2021. [DOI: 10.1111/1365-2664.14073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- John. B. Bradford
- Southwest Biological Science Center U.S. Geological Survey Flagstaff AZ USA
| | - Robert K. Shriver
- Department of Natural Resources and Environmental Science University of Nevada Reno NV USA
| | - Marcos D. Robles
- Center for Science and Public Policy The Nature Conservancy Tucson AZ USA
| | - Lisa A. McCauley
- Center for Science and Public Policy The Nature Conservancy Tucson AZ USA
| | - Travis J. Woolley
- Center for Science and Public Policy The Nature Conservancy Tucson AZ USA
| | - Caitlin A. Andrews
- Southwest Biological Science Center U.S. Geological Survey Flagstaff AZ USA
| | - Michael Crimmins
- Department of Environmental Science University of Arizona Tucson AZ USA
| | - David M. Bell
- Pacific Northwest Research Station USDA Forest Service Corvallis OR USA
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Bohner T, Diez J. Tree resistance and recovery from drought mediated by multiple abiotic and biotic processes across a large geographic gradient. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 789:147744. [PMID: 34051506 DOI: 10.1016/j.scitotenv.2021.147744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 05/07/2021] [Accepted: 05/09/2021] [Indexed: 06/12/2023]
Abstract
Worldwide, increasing severity of droughts threatens to change forest ecosystem functioning and community structure. Understanding how forest resilience is determined by its two underlying components, resistance and recovery, will help elucidate the mechanisms of drought responses and help inform management strategies. However, drought responses are shaped by complex processes across different scales, including species-specific drought strategies, tree size, competition, local environmental conditions, and the intensity of the drought event. Here, we quantified the reduction in tree growth during drought (an inverse measure of drought resistance) and post-drought recovery for three montane conifers (Abies concolor, Pinus jeffreyi, and Pinus lambertiana) in California. We used tree ring analysis to quantify responses to drought events of varying intensity between 1895 and 2018 across a geographic climatic gradient, to examine the roles of tree size (DBH) and competition (tree density) in mediating drought responses. We found that years of more intense drought corresponded with larger growth reductions and recovery rates were lower following drought years where trees suffered larger reductions. We found little variation among species in their growth reductions during drought events, but significant differences among species in their recovery post-drought. Across the geographic gradient, trees in the driest locations were susceptible to large growth reductions, signaling either strong sensitivity to drought intensity or exposure to the most extreme drought conditions. These growth reductions were not always compensated for by higher recovery rates. We also found that larger trees were more susceptible to drought due to a steeper negative relationship between recovery rates and the intensity of growth reduction during the drought. Contrary to expectations, recovery rates following the most detrimental drought years were higher in denser forests. Our results demonstrate the importance of considering how factors at various spatial and temporal scales affect the different components of drought responses.
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Affiliation(s)
- Teresa Bohner
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA.
| | - Jeffrey Diez
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA
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35
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Different Temporal Stability and Responses to Droughts between Needleleaf Forests and Broadleaf Forests in North China during 2001–2018. FORESTS 2021. [DOI: 10.3390/f12101331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Droughts can affect the physiological activity of trees, damage tissues, and even trigger mortality, yet the response of different forest types to drought at the decadal time scale remains uncertain. In this study, we used two remote sensing-based vegetation products, the MODIS enhanced vegetation index (EVI) and MODIS gross primary productivity (GPP), to explore the temporal stability of deciduous needleleaf forests (DNFs) and deciduous broadleaf forests (DBFs) in droughts and their legacy effects in North China from 2001 to 2018. The results of both products showed that the temporal stability of DBFs was consistently much higher than that of DNFs, even though the DBFs experienced extreme droughts and the DNFs did not. The DBFs also exhibited similar patterns in their legacy effects from droughts, with these effects extending up to 4 years after the droughts. These results indicate that DBFs have been better acclimated to drought events in North China. Furthermore, the results suggest that the GPP was more sensitive to water variability than EVI. These findings will be helpful for forest modeling, management, and conservation.
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36
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Forest Resistance to Extended Drought Enhanced by Prescribed Fire in Low Elevation Forests of the Sierra Nevada. FORESTS 2021. [DOI: 10.3390/f12091248] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Prescribed fire reduces fire hazards by removing dead and live fuels (small trees and shrubs). Reductions in forest density following prescribed fire treatments (often in concert with mechanical treatments) may also lessen competition so that residual trees might be more likely to survive when confronted with additional stressors, such as drought. The current evidence for these effects is mixed and additional study is needed. Previous work found increased tree survivorship in low elevation forests with a recent history of fire during the early years of an intense drought (2012 to 2014) in national parks in the southern Sierra Nevada. We extend these observations through additional years of intense drought and continuing elevated tree mortality through 2017 at Sequoia and Kings Canyon National Parks. Relative to unburned sites, we found that burned sites had lower stem density and had lower proportions of recently dead trees (for stems ≤47.5 cm dbh) that presumably died during the drought. Differences in recent tree mortality among burned and unburned sites held for both fir (white fir and red fir) and pine (sugar pine and ponderosa pine) species. Unlike earlier results, models of individual tree mortality probability supported an interaction between plot burn status and tree size, suggesting the effect of prescribed fire was limited to small trees. We consider differences with other recent results and discuss potential management implications including trade-offs between large tree mortality following prescribed fire and increased drought resistance.
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Du B, Kruse J, Winkler JB, Alfarraj S, Albasher G, Schnitzler JP, Ache P, Hedrich R, Rennenberg H. Metabolic responses of date palm (Phoenix dactylifera L.) leaves to drought differ in summer and winter climate. TREE PHYSIOLOGY 2021; 41:1685-1700. [PMID: 33607652 DOI: 10.1093/treephys/tpab027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 01/11/2021] [Accepted: 02/04/2021] [Indexed: 06/12/2023]
Abstract
Drought negatively impacts growth and productivity of plants, particularly in arid and semi-arid regions. Although drought events can take place in summer and winter, differences in the impact of drought on physiological processes between seasons are largely unknown. The aim of this study was to elucidate metabolic strategies of date palms in response to drought in summer and winter season. To identify such differences, we exposed date palm seedlings to a drought-recovery regime, both in simulated summer and winter climate. Leaf hydration, carbon discrimination (${\Delta}$13C), and primary and secondary metabolite composition and contents were analyzed. Depending on season, drought differently affected physiological and biochemical traits of the leaves. In summer, drought induced significantly decreased leaf hydration, concentrations of ascorbate, most sugars, primary and secondary organic acids, as well as phenolic compounds, while thiol, amino acid, raffinose and individual fatty acid contents were increased compared with well-watered plants. In winter, drought had no effect on leaf hydration, ascorbate and fatty acids contents, but resulted in increased foliar thiol and amino acid levels as observed in summer. Compared with winter, foliar traits of plants exposed to drought in summer only partly recovered after re-watering. Memory effects on water relations, and primary and secondary metabolites seem to prepare foliar traits of date palms for repeated drought events in summer. Apparently, a well-orchestrated metabolic network, including the anti-oxidative system, compatible solutes accumulation and osmotic adjustment, and maintenance of cell-membrane stability strongly reduces the susceptibility of date palms to drought. These mechanisms of drought compensation may be more frequently required in summer.
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Affiliation(s)
- Baoguo Du
- College of Life Science and Biotechnology, Mianyang Normal University, Mianxing Road West 166, 621000 Mianyang, China
- Chair of Tree Physiology, Institute of Forest Sciences, Albert-Ludwigs-Universität Freiburg, Georges-Koehler-Allee 53, 79110 Freiburg, Germany
| | - Joerg Kruse
- Chair of Tree Physiology, Institute of Forest Sciences, Albert-Ludwigs-Universität Freiburg, Georges-Koehler-Allee 53, 79110 Freiburg, Germany
| | - Jana Barbro Winkler
- Helmholtz Zentrum München, Research Unit Environmental Simulation (EUS), Institute of Biochemical Plant Pathology, Ingolstädter, Landstraße 1, 85764 Neuherberg, Germany
| | - Saleh Alfarraj
- King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia
| | - Gadah Albasher
- King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia
| | - Joerg-Peter Schnitzler
- Helmholtz Zentrum München, Research Unit Environmental Simulation (EUS), Institute of Biochemical Plant Pathology, Ingolstädter, Landstraße 1, 85764 Neuherberg, Germany
| | - Peter Ache
- Institute for Molecular Plant Physiology and Biophysics, Biocenter, University of Würzburg, 97082 Würzburg, Germany
| | - Rainer Hedrich
- Institute for Molecular Plant Physiology and Biophysics, Biocenter, University of Würzburg, 97082 Würzburg, Germany
| | - Heinz Rennenberg
- Chair of Tree Physiology, Institute of Forest Sciences, Albert-Ludwigs-Universität Freiburg, Georges-Koehler-Allee 53, 79110 Freiburg, Germany
- King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia
- Center of Molecular Ecophysiology (CMEP), College of Resources and Environment, Southwest University No. 2, Tiansheng Road, Beibei District, 400715 Chongqing,China
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38
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Nelson KN, O'Dean E, Knapp EE, Parker AJ, Bisbing SM. Persistent yet vulnerable: resurvey of an Abies ecotone reveals few differences but vulnerability to climate change. Ecology 2021; 102:e03525. [PMID: 34467519 DOI: 10.1002/ecy.3525] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 04/02/2021] [Accepted: 05/20/2021] [Indexed: 11/09/2022]
Abstract
Climate change is shifting forest tree species distributions across elevational and latitudinal gradients, and these changes are often pronounced at ecotones where species meet their climatic bounds and are replaced by other species. Using an extensive ecotone composed of lower-montane white fir (Abies concolor var. lowiana) and upper-montane red fir (Abies magnifica var. magnifica) in the central Sierra Nevada range of California, USA, we (1) examined how the demographics of the ecotone have responded to recent climate using a field observational study and a historical dataset, (2) quantified climate drivers across species life stages using contemporary demographic data, and (3) tested the potential impacts of future climate on species-specific seedling survival and growth in a fully factorial growth chamber experiment that varied temperature, growing season length, and water availability. A re-examination of the ecotone midpoint after 35 yr suggested a reduction in A. concolor sapling and tree densities and a rise in A. magnifica proportional dominance between surveys. Seedling abundances across the ecotone indicated that A. magnifica tends to dominate the regeneration layer and currently forms an important component of the seedling community at elevations below those where A. magnifica saplings or trees begin to co-dominate stands. Observational and experimental assessments suggest that temperature and precipitation serve as important drivers, differentiating A. concolor vs. A. magnifica distributions, and are primary stressors at the seedling stage. Seedlings of both species were adversely affected by experimental climate treatments, although A. concolor exhibited greater survival and a more conservative growth strategy under extreme climatic stress than A. magnifica. Projections indicate that historical climate conditions will rise by an amount greater than the ecotone's current elevational extent by the end of the 21st century. Differential drivers of species abundances suggest that the projected climate will expand conditions that promote A. concolor abundance and impede A. magnifica abundance across the ecotone; however, disturbance activity and microclimatic conditions will also influence regeneration and overstory tree dynamics. Our study demonstrates the importance of quantifying species-specific responses to climate and indicates that widespread regeneration failure may be one possible consequence in which species exhibit strong sensitivity to projected climate conditions.
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Affiliation(s)
- Kellen N Nelson
- Pacific Northwest Research Station, USDA Forest Service, 11175 Auke Lake Way, Juneau, Alaska, 99801, USA.,Department of Natural Resources & Environmental Science, University of Nevada, Reno, 1664 N. Virginia Ave, Reno, Nevada, 89557, USA
| | - Emily O'Dean
- Department of Geological Sciences and Engineering, University of Nevada, Reno, 1664 N. Virginia Ave, Reno, Nevada, 89557, USA.,Department of Natural Resource Management & Environmental Science, California Polytechnic State University, 1 Grand Ave, San Luis Obispo, California, 93407, USA
| | - Eric E Knapp
- Pacific Southwest Research Station, USDA Forest Service, 3644 Avtech Parkway, Redding, California, 96002, USA
| | - Albert J Parker
- Department of Geography, University of Georgia, Athens, Georgia, 30605, USA
| | - Sarah M Bisbing
- Department of Natural Resources & Environmental Science, University of Nevada, Reno, 1664 N. Virginia Ave, Reno, Nevada, 89557, USA
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Haberstroh S, Caldeira MC, Lobo-do-Vale R, Martins JI, Moemken J, Pinto JG, Werner C. Nonlinear plant-plant interactions modulate impact of extreme drought and recovery on a Mediterranean ecosystem. THE NEW PHYTOLOGIST 2021; 231:1784-1797. [PMID: 34076289 DOI: 10.1111/nph.17522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 05/20/2021] [Indexed: 06/12/2023]
Abstract
Interaction effects of different stressors, such as extreme drought and plant invasion, can have detrimental effects on ecosystem functioning and recovery after drought. With ongoing climate change and increasing plant invasion, there is an urgent need to predict the short- and long-term interaction impacts of these stressors on ecosystems. We established a combined precipitation exclusion and shrub invasion (Cistus ladanifer) experiment in a Mediterranean cork oak (Quercus suber) ecosystem with four treatments: (1) Q. suber control; (2) Q. suber with rain exclusion; (3) Q. suber invaded by shrubs; and (4) Q. suber with rain exclusion and shrub invasion. As key parameter, we continuously measured ecosystem water fluxes. In an average precipitation year, the interaction effects of both stressors were neutral. However, the combination of imposed drought and shrub invasion led to amplifying interaction effects during an extreme drought by strongly reducing tree transpiration. Contrarily, the imposed drought reduced the competitiveness of the shrubs in the following recovery period, which buffered the negative effects of shrub invasion on Q. suber. Our results demonstrate the highly dynamic and nonlinear effects of interacting stressors on ecosystems and urges for further investigations on biotic interactions in a context of climate change pressures.
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Affiliation(s)
- Simon Haberstroh
- Ecosystem Physiology, Faculty of Environment and Natural Resources, University Freiburg, Freiburg, 79110, Germany
- Forest Research Centre, School of Agriculture, University of Lisbon, Lisbon, 1349-017, Portugal
| | - Maria C Caldeira
- Forest Research Centre, School of Agriculture, University of Lisbon, Lisbon, 1349-017, Portugal
| | - Raquel Lobo-do-Vale
- Forest Research Centre, School of Agriculture, University of Lisbon, Lisbon, 1349-017, Portugal
| | - Joana I Martins
- Forest Research Centre, School of Agriculture, University of Lisbon, Lisbon, 1349-017, Portugal
| | - Julia Moemken
- Institute for Meteorology and Climate Research (IMK-TRO), Karlsruhe Institute of Technology (KIT), Karlsruhe, 76131, Germany
| | - Joaquim G Pinto
- Institute for Meteorology and Climate Research (IMK-TRO), Karlsruhe Institute of Technology (KIT), Karlsruhe, 76131, Germany
| | - Christiane Werner
- Ecosystem Physiology, Faculty of Environment and Natural Resources, University Freiburg, Freiburg, 79110, Germany
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40
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Continent-wide synthesis of the long-term population dynamics of quaking aspen in the face of accelerating human impacts. Oecologia 2021; 197:25-42. [PMID: 34365517 DOI: 10.1007/s00442-021-05013-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 08/03/2021] [Indexed: 10/20/2022]
Abstract
In recent decades, climate change has disrupted forest functioning by promoting large-scale mortality events, declines in productivity and reduced regeneration. Understanding the temporal dynamics and spatial extent of these changes is critical given the essential ecosystem services provided by forests. As the most widespread tree species in North America, quaking aspen (Populus tremuloides) is well suited for studying the dynamics of tree populations during a period of unprecedented climate change. Synthesizing continent-wide data, we show that mortality rates of mature aspen stems have increased over the past two-to-three decades, while relative gains in aspen basal area have decreased during the same period. Patterns were pervasive across multiple stand size classes and composition types in western North America biomes, suggesting that trends in demographic rates were not simply a reflection of stand development and succession. Our review of the literature revealed that increased aspen mortality and reduced growth rates were most often associated with hotter, drier conditions, whereas reduced recruitment was most often associated with herbivory. Furthermore, interactions between climate and competition, as well as climate and insect herbivory, had important, context-dependent effects on mortality and growth, respectively. Our analyses of aspen across its entire geographic range indicate that this important tree species is experiencing substantial increases in mortality and decreases in population growth rates across multiple biomes. If such trends are not accompanied by increased recruitment, we expect that the reduced dominance of aspen in forests will lead to major declines in the many essential ecosystem services it provides.
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41
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Peters JMR, López R, Nolf M, Hutley LB, Wardlaw T, Cernusak LA, Choat B. Living on the edge: A continental-scale assessment of forest vulnerability to drought. GLOBAL CHANGE BIOLOGY 2021; 27:3620-3641. [PMID: 33852767 DOI: 10.1111/gcb.15641] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/12/2021] [Indexed: 06/12/2023]
Abstract
Globally, forests are facing an increasing risk of mass tree mortality events associated with extreme droughts and higher temperatures. Hydraulic dysfunction is considered a key mechanism of drought-triggered dieback. By leveraging the climate breadth of the Australian landscape and a national network of research sites (Terrestrial Ecosystem Research Network), we conducted a continental-scale study of physiological and hydraulic traits of 33 native tree species from contrasting environments to disentangle the complexities of plant response to drought across communities. We found strong relationships between key plant hydraulic traits and site aridity. Leaf turgor loss point and xylem embolism resistance were correlated with minimum water potential experienced by each species. Across the data set, there was a strong coordination between hydraulic traits, including those linked to hydraulic safety, stomatal regulation and the cost of carbon investment into woody tissue. These results illustrate that aridity has acted as a strong selective pressure, shaping hydraulic traits of tree species across the Australian landscape. Hydraulic safety margins were constrained across sites, with species from wetter sites tending to have smaller safety margin compared with species at drier sites, suggesting trees are operating close to their hydraulic thresholds and forest biomes across the spectrum may be susceptible to shifts in climate that result in the intensification of drought.
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Affiliation(s)
- Jennifer M R Peters
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Rosana López
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Markus Nolf
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Lindsay B Hutley
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT, Australia
| | - Tim Wardlaw
- ARC Centre for Forest Value, University of Tasmania, Hobart, Tas, Australia
| | - Lucas A Cernusak
- College of Science and Engineering, James Cook University, Cairns, Qld, Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
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42
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Kordosky JR, Gese EM, Thompson CM, Terletzky PA, Neuman-Lee LA, Schneiderman JD, Purcell KL, French SS. Landscape of stress: Tree mortality influences physiological stress and survival in a native mesocarnivore. PLoS One 2021; 16:e0253604. [PMID: 34197517 PMCID: PMC8248622 DOI: 10.1371/journal.pone.0253604] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 06/09/2021] [Indexed: 11/18/2022] Open
Abstract
Climate change and anthropogenic modifications to the landscape can have both positive and negative effects on an animal. Linking landscape change to physiological stress and fitness of an animal is a fundamental tenet to be examined in applied ecology. Cortisol is a glucocorticoid hormone that can be used to indicate an animal's physiological stress response. In the Sierra Nevada Mountains of California, fishers (Pekania pennanti) are a threatened mesocarnivore that have been subjected to rapid landscape changes due to anthropogenic modifications and tree mortality related to a 4-year drought. We measured cortisol concentrations in the hair of 64 fishers (41 females, 23 males) captured and radio-collared in the Sierra National Forest, California. We addressed two main questions: (1) Is the physiological stress response of fishers influenced by anthropogenic factors, habitat type, canopy cover, and tree mortality due to drought in their home range? (2) Does the physiological stress response influence survival, reproduction, or body condition? We examined these factors within a fisher home range at 3 scales (30, 60, 95% isopleths). Using model selection, we found that tree mortality was the principle driver influencing stress levels among individual fishers with female and male fishers having increasing cortisol levels in home ranges with increasing tree mortality. Most importantly, we also found a link between physiological stress and demography where female fishers with low cortisol levels had the highest annual survival rate (0.94), whereas females with medium and high cortisol had lower annual survival rates, 0.78 and 0.81, respectively. We found no significant relationships between cortisol levels and body condition, male survival, or litter size. We concluded that tree mortality related to a 4-year drought has created a "landscape of stress" for this small, isolated fisher population.
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Affiliation(s)
- Jennifer R. Kordosky
- Department of Wildland Resources, Utah State University, Logan, Utah, United States of America
| | - Eric M. Gese
- U.S. Department of Agriculture, Wildlife Services, National Wildlife Research Center, Logan, Utah, United States of America
- * E-mail:
| | - Craig M. Thompson
- U.S. Department of Agriculture, Forest Service, Missoula, Montana, United States of America
| | - Patricia A. Terletzky
- Department of Wildland Resources, Utah State University, Logan, Utah, United States of America
| | - Lorin A. Neuman-Lee
- Department of Biology, Utah State University, Logan, Utah, United States of America
| | - Jon D. Schneiderman
- U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station, Fresno, California, United States of America
| | - Kathryn L. Purcell
- U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station, Fresno, California, United States of America
| | - Susannah S. French
- Department of Biology, Utah State University, Logan, Utah, United States of America
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43
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Guan H, Dong X, Yan G, Searls T, Bourque CPA, Meng FR. Conditional inference trees in the assessment of tree mortality rates in the transitional mixed forests of Atlantic Canada. PLoS One 2021; 16:e0250991. [PMID: 34143806 PMCID: PMC8213180 DOI: 10.1371/journal.pone.0250991] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 04/16/2021] [Indexed: 11/19/2022] Open
Abstract
Long-term predictions of forest dynamics, including forecasts of tree growth and mortality, are central to sustainable forest-management planning. Although often difficult to evaluate, tree mortality rates under different abiotic and biotic conditions are vital in defining the long-term dynamics of forest ecosystems. In this study, we have modeled tree mortality rates using conditional inference trees (CTREE) and multi-year permanent sample plot data sourced from an inventory with coverage of New Brunswick (NB), Canada. The final CTREE mortality model was based on four tree- and three stand-level terms together with two climatic terms. The correlation coefficient (R2) between observed and predicted mortality rates was 0.67. High cumulative annual growing degree-days (GDD) was found to lead to increased mortality in 18 tree species, including Betula papyrifera, Picea mariana, Acer saccharum, and Larix laricina. In another ten species, including Abies balsamea, Tsuga canadensis, Fraxinus americana, and Fagus grandifolia, mortality rates tended to be higher in areas with high incident solar radiation. High amounts of precipitation in NB’s humid maritime climate were also found to contribute to heightened tree mortality. The relationship between high GDD, solar radiation, and high mortality rates was particularly strong when precipitation was also low. This would suggest that although excessive soil water can contribute to heightened tree mortality by reducing the supply of air to the roots, occasional drought in NB can also contribute to increased mortality events. These results would have significant implications when considered alongside regional climate projections which generally entail both components of warming and increased precipitation.
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Affiliation(s)
- Huiwen Guan
- College of Economics & Management, Zhejiang University of Water Resources and Electric Power, Hangzhou, Zhejiang, China
- Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Xibin Dong
- College of Engineering and Technology, Northeast Forestry University, Harbin, Heilongjiang, China
- * E-mail: (FRM); (XD)
| | - Guohua Yan
- Department of Mathematics and Statistics, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Tyler Searls
- Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Charles P. -A. Bourque
- Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Fan-Rui Meng
- Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, New Brunswick, Canada
- * E-mail: (FRM); (XD)
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44
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Venturas MD, Todd HN, Trugman AT, Anderegg WRL. Understanding and predicting forest mortality in the western United States using long-term forest inventory data and modeled hydraulic damage. THE NEW PHYTOLOGIST 2021; 230:1896-1910. [PMID: 33112415 DOI: 10.1111/nph.17043] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 10/20/2020] [Indexed: 06/11/2023]
Abstract
Global warming is expected to exacerbate the duration and intensity of droughts in the western United States, which may lead to increased tree mortality. A prevailing proximal mechanism of drought-induced tree mortality is hydraulic damage, but predicting tree mortality from hydraulic theory and climate data still remains a major scientific challenge. We used forest inventory data and a plant hydraulic model (HM) to address three questions: can we capture regional patterns of drought-induced tree mortality with HM-predicted damage thresholds; do HM metrics improve predictions of mortality across broad spatial areas; and what are the dominant controls of forest mortality when considering stand characteristics, climate metrics, and simulated hydraulic stress? We found that the amount of variance explained by models predicting mortality was limited (R2 median = 0.10, R2 range: 0.00-0.52). HM outputs, including hydraulic damage and carbon assimilation diagnostics, moderately improve mortality prediction across the western US compared with models using stand and climate predictors alone. Among factors considered, metrics of stand density and tree size tended to be some of the most critical factors explaining mortality, probably highlighting the important roles of structural overshoot, stand development, and biotic agent host selection and outbreaks in mortality patterns.
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Affiliation(s)
- Martin D Venturas
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Henry N Todd
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Anna T Trugman
- Department of Geography, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - William R L Anderegg
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
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Meta-analysis Reveals Different Competition Effects on Tree Growth Resistance and Resilience to Drought. Ecosystems 2021. [DOI: 10.1007/s10021-021-00638-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AbstractDrought will increasingly threaten forest ecosystems worldwide. Understanding how competition influences tree growth response to drought is essential for forest management aiming at climate change adaptation. However, published results from individual case studies are heterogeneous and sometimes contradictory. We reviewed 166 cases from the peer-reviewed literature to assess the influence of stand-level competition on tree growth response to drought. We monitored five indicators of tree growth response: mean sensitivity (inter-annual tree ring width variability); association between inter-annual growth variability and water availability; resistance; recovery; and resilience to drought. Vote counting did not indicate a consistent effect of competition on mean sensitivity. Conversely, higher competition for resources strengthened the association between water availability and inter-annual growth rates. Meta-analysis showed that higher competition reduced resistance (p < 0.001) and improved recovery (p < 0.05), but did not consistently affect resilience. Species, site and stand characteristics, and drought intensity were insignificant or poor predictors for the large variability among the investigated cases. Our review and meta-analysis show that competition does not affect the response of tree growth to drought in a unidirectional and universal way. Although density reduction (thinning) can alleviate growth declines during drought, the effects on growth after stress are uncertain. The large variability among investigated cases suggests that local-scale processes play a crucial role in determining such responses and should be explicitly evaluated and integrated into specific strategies for adaptation of forests to climate change.
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Bogdziewicz M, Hacket-Pain A, Kelly D, Thomas PA, Lageard J, Tanentzap AJ. Climate warming causes mast seeding to break down by reducing sensitivity to weather cues. GLOBAL CHANGE BIOLOGY 2021; 27:1952-1961. [PMID: 33604979 DOI: 10.1111/gcb.15560] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/14/2021] [Indexed: 06/12/2023]
Abstract
Climate change is altering patterns of seed production worldwide with consequences for population recruitment and migration potential. For the many species that regenerate through synchronized, quasiperiodic reproductive events termed masting, these changes include decreases in the synchrony and interannual variation in seed production. This breakdown in the occurrence of masting features harms reproduction by decreasing the efficiency of pollination and increasing seed predation. Changes in masting are often paralleled by warming temperatures, but the underlying proximate mechanisms are unknown. We used a unique 39-year study of 139 European beech (Fagus sylvatica) trees that experienced masting breakdown to track the seed developmental cycle and pinpoint phases where weather effects on seed production have changed over time. A cold followed by warm summer led to large coordinated flowering efforts among plants. However, trees failed to respond to the weather signal as summers warmed and the frequency of reproductive cues changed fivefold. Less synchronous flowering resulted in less efficient pollination that further decreased the synchrony of seed maturation. As global temperatures are expected to increase this century, perennial plants that fine-tune their reproductive schedules based on temperature cues may suffer regeneration failures.
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Affiliation(s)
- Michał Bogdziewicz
- Department of Systematic Zoology, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Andrew Hacket-Pain
- Department of Geography and Planning, School of Environmental Sciences, University of Liverpool, Liverpool, UK
| | - Dave Kelly
- Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Peter A Thomas
- School of Life Sciences, Keele University, Staffordshire, UK
| | - Jonathan Lageard
- Department of Natural Sciences, Manchester Metropolitan University, Manchester, UK
| | - Andrew J Tanentzap
- Ecosystems and Global Change Group, Department of Plant Sciences, University of Cambridge, Cambridge, UK
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Kordosky JR, Gese EM, Thompson CM, Terletzky PA, Purcell KL, Schneiderman JD. Landscape use by fishers ( Pekania pennanti): core areas differ in habitat than the entire home range. CAN J ZOOL 2021. [DOI: 10.1139/cjz-2020-0073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Home ranges have long been studied in animal ecology. Core areas may be used at a greater proportion than the rest of the home range, implying the core contains dependable resources. The Pacific fisher (Pekania pennanti (Erxleben, 1777)) is a rare mesocarnivore occupying a small area in the Sierra Nevada Mountains, California, USA. Once statewide, fishers declined in the 1900s due to trapping, habitat fragmentation, and development. Recently, drought induced by climate change may be affecting this population. We examined space use of fishers in their core versus their home range for levels of anthropogenic modifications (housing density, road density, silvicultural treatments), habitat types, and tree mortality. We found core areas contained more late-successional forest and minimal human activity compared with their territory. Their core had higher levels of dense canopy and higher amounts of conifer cover, while minimizing the amount of buildings, developed habitat, and low canopy cover. Fishers may in effect be seeking refugia by minimizing their exposure to these elements in their core. Conserving landscape components used by fishers in their core areas will be important for the persistence of this isolated population.
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Affiliation(s)
| | - Eric M. Gese
- U.S. Department of Agriculture, Wildlife Services, National Wildlife Research Center, Department of Wildland Resources, Utah State University, Logan, UT 84322, USA
| | - Craig M. Thompson
- U.S. Department of Agriculture, Forest Service, Region 1, Missoula, MT 59804, USA
| | | | - Kathryn L. Purcell
- U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station, Fresno, CA 93710, USA
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Wayman RB, Safford HD. Recent bark beetle outbreaks influence wildfire severity in mixed-conifer forests of the Sierra Nevada, California, USA. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02287. [PMID: 33426715 DOI: 10.1002/eap.2287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 09/11/2020] [Accepted: 10/06/2020] [Indexed: 06/12/2023]
Abstract
In temperate forests, elevated frequency of drought related disturbances will likely increase the incidence of interactions between disturbances such as bark beetle epidemics and wildfires. Our understanding of the influence of recent drought and insect-induced tree mortality on wildfire severity has largely lacked information from forests adapted to frequent fire. A recent unprecedented tree mortality event in California's Sierra Nevada provides an opportunity to examine this disturbance interaction in historically frequent-fire forests. Using field data collected within areas of recent tree mortality that subsequently burned in wildfire, we examined whether and under what conditions wildfire severity relates to severity of prefire tree mortality in Sierra Nevada mixed-conifer forests. We collected data on 180 plots within the 2015 Rough Fire and 2016 Cedar Fire footprints (California, USA). Our analyses identified prefire tree mortality as influential on all measures of wildfire severity (basal area killed by fire, RdNBR, and canopy torch) on the Cedar Fire, although it was less influential than fire weather (relative humidity). Prefire tree mortality was influential on two of three fire-severity measures on the Rough Fire, and was the most important predictor of basal area killed by fire; topographic position was influential on two metrics. On the Cedar Fire, the influence of prefire mortality on basal area killed by fire was greater under milder weather conditions. All measures of fire severity increased as prefire mortality increased up to prefire mortality levels of approximately 30-40%; further increases did not result in greater fire severity. The interacting disturbances shifted a pine-dominated system (Rough Fire) to a cedar-pine-fir system, while the pre-disturbance fir-cedar system (Cedar Fire) saw its dominant species unchanged. Managers of historically frequent-fire forests will benefit from utilizing this information when prioritizing fuels reduction treatments in areas of recent tree mortality, as it is the first empirical study to document a relationship between prefire mortality and subsequent wildfire severity in these systems. This study contributes to a growing body of evidence that the influence of prefire tree mortality on wildfire severity in temperate coniferous forests may depend on other conditions capable of driving extreme wildfire behavior, such as weather.
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Affiliation(s)
- Rebecca B Wayman
- Department of Environmental Science and Policy, University of California, Davis, 95616, USA
| | - Hugh D Safford
- Department of Environmental Science and Policy, University of California, Davis, 95616, USA
- Pacific Southwest Region, USDA Forest Service, Vallejo, California, 94592, USA
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Analyzing the Suitability of Remotely Sensed ET for Calibrating a Watershed Model of a Mediterranean Montane Forest. REMOTE SENSING 2021. [DOI: 10.3390/rs13071258] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The ability to spatially characterize runoff generation and forest health depends partly on the accuracy and resolution of evapotranspiration (ET) simulated by numerical models. A possible strategy to increase the accuracy and resolution of numerically modeled ET is the use of remotely sensed ET products as an observational basis for parameter estimation (model calibration) of those numerical models. However, the extent to which that calibration strategy leads to a realistic representation of ET, relative to ground conditions, is not well understood. We examined this by comparing the spatiotemporal accuracy of ET from a remote sensing product, MODIS MOD16A2, to that from a watershed model (SWAT) calibrated to flow measured at an outlet streamgage. We examined this in the upper Kings River watershed (3999 km2) of California’s Sierra Nevada, a snow-influenced watershed in a Mediterranean climate. We assessed ET accuracies against observations from three eddy-covariance flux towers at elevations of 1160–2700 m. The accuracy of ET from the stream-calibrated watershed model surpassed that of MODIS in terms of Nash-Sutcliffe efficiency (+0.36 versus −0.43) and error in elevational trend (+7.7% versus +81%). These results indicate that for this particular experiment, an outlet streamgage would provide a more effective observational basis than remotely sensed ET product for watershed-model parameter estimation. Based on analysis of ET-weather relationships, the relatively large errors we found in MODIS ET may be related to weather-based corrections to water limitation not representative of the hydrology of this snow-influenced, Mediterranean-climate area.
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50
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Climate Change Effects on Trophic Interactions of Bark Beetles in Inner Alpine Scots Pine Forests. FORESTS 2021. [DOI: 10.3390/f12020136] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Increased tree mortality has become a widespread phenomenon and is largely attributed to climate change. Little field research has addressed the complex interactions between trees, herbivores, and their natural enemies as affected by temperature. We recorded the densities of bark insects and their natural enemies emerging from felled trees in Scots pine forests at 17 study sites along 6 elevation gradients encompassing different temperature ranges in 3 regions in Switzerland and Italy. We additionally measured tree resin defense at different elevations. The density of aggressive bark beetles decreased with increasing temperatures while that of non-aggressive species did not respond to temperature. Contrasting patterns were also found for natural enemies, with the densities of most predatory taxa decreasing with increasing temperature whereas densities of parasitoids increased. Consequently, bark beetle mortality by predators decreased and that by parasitoids increased with temperature. Exudation of resin increased with temperature. As the number of resin ducts did not change with temperature, this is assumed a physical effect of reduced viscosity. Despite lower densities of aggressive bark beetles and improved tree resin flow under higher temperatures, the currently experienced drought-induced reduction in tree vigor is likely to increase tree mortality under the ongoing climate warming.
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