1
|
Lecomte X, Bugalho MN, Catry FX, Fernandes PM, Cera A, Caldeira MC. Ungulates mitigate the effects of drought and shrub encroachment on the fire hazard of Mediterranean oak woodlands. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2024:e2971. [PMID: 38581136 DOI: 10.1002/eap.2971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 12/16/2023] [Accepted: 01/31/2024] [Indexed: 04/08/2024]
Abstract
Climate change is increasing the frequency of droughts and the risk of severe wildfires, which can interact with shrub encroachment and browsing by wild ungulates. Wild ungulate populations are expanding due, among other factors, to favorable habitat changes resulting from land abandonment or land-use changes. Understanding how ungulate browsing interacts with drought to affect woody plant mortality, plant flammability, and fire hazard is especially relevant in the context of climate change and increasing frequency of wildfires. The aim of this study is to explore the combined effects of cumulative drought, shrub encroachment, and ungulate browsing on the fire hazard of Mediterranean oak woodlands in Portugal. In a long-term (18 years) ungulate fencing exclusion experiment that simulated land abandonment and management neglect, we investigated the population dynamics of the native shrub Cistus ladanifer, which naturally dominates the understory of woodlands and is browsed by ungulates, comparing areas with (no fencing) and without (fencing) wild ungulate browsing. We also modeled fire behavior in browsed and unbrowsed plots considering drought and nondrought scenarios. Specifically, we estimated C. ladanifer population density, biomass, and fuel load characteristics, which were used to model fire behavior in drought and nondrought scenarios. Overall, drought increased the proportion of dead C. ladanifer shrub individuals, which was higher in the browsed plots. Drought decreased the ratio of live to dead shrub plant material, increased total fuel loading, shrub stand flammability, and the modeled fire parameters, that is, rate of surface fire spread, fireline intensity, and flame length. However, total fuel load and fire hazard were lower in browsed than unbrowsed plots, both in drought and nondrought scenarios. Browsing also decreased the population density of living shrubs, halting shrub encroachment. Our study provides long-term experimental evidence showing the role of wild ungulates in mitigating drought effects on fire hazard in shrub-encroached Mediterranean oak woodlands. Our results also emphasize that the long-term effects of land abandonment can interact with climate change drivers, affecting wildfire hazard. This is particularly relevant given the increasing incidence of land abandonment.
Collapse
Affiliation(s)
- Xavier Lecomte
- Forest Research Center, Associate Laboratory TERRA, School of Agriculture, University of Lisbon, Lisbon, Portugal
- Center for Applied Ecology "Prof. Baeta Neves" (CEABN-InBIO), School of Agriculture, University of Lisbon, Lisbon, Portugal
| | - Miguel N Bugalho
- Center for Applied Ecology "Prof. Baeta Neves" (CEABN-InBIO), School of Agriculture, University of Lisbon, Lisbon, Portugal
| | - Filipe X Catry
- Center for Applied Ecology "Prof. Baeta Neves" (CEABN-InBIO), School of Agriculture, University of Lisbon, Lisbon, Portugal
| | - Paulo M Fernandes
- Center for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), University of Trás-os-Montes and Alto Douro (UTAD), Vila Real, Portugal
- ForestWISE-Collaborative Laboratory for Integrated Forest and Fire Management, Vila Real, Portugal
| | - Andreu Cera
- Center for Applied Ecology "Prof. Baeta Neves" (CEABN-InBIO), School of Agriculture, University of Lisbon, Lisbon, Portugal
| | - Maria C Caldeira
- Forest Research Center, Associate Laboratory TERRA, School of Agriculture, University of Lisbon, Lisbon, Portugal
| |
Collapse
|
2
|
Hecht H, Krofcheck DJ, Carril D, Hurteau MD. Estimating the influence of field inventory sampling intensity on forest landscape model performance for determining high-severity wildfire risk. Sci Rep 2024; 14:3073. [PMID: 38321185 PMCID: PMC10847129 DOI: 10.1038/s41598-024-53359-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 01/31/2024] [Indexed: 02/08/2024] Open
Abstract
Historically, fire has been essential in Southwestern US forests. However, a century of fire-exclusion and changing climate created forests which are more susceptible to uncharacteristically severe wildfires. Forest managers use a combination of thinning and prescribed burning to reduce forest density to help mitigate the risk of high-severity fires. These treatments are laborious and expensive, therefore optimizing their impact is crucial. Landscape simulation models can be useful in identifying high risk areas and assessing treatment effects, but uncertainties in these models can limit their utility in decision making. In this study we examined underlying uncertainties in the initial vegetation layer by leveraging a previous study from the Santa Fe fireshed and using new inventory plots from 111 stands to interpolate the initial forest conditions. We found that more inventory plots resulted in a different geographic distribution and wider range of the modelled biomass. This changed the location of areas with high probability of high-severity fires, shifting the optimal location for management. The increased range of biomass variability from using a larger number of plots to interpolate the initial vegetation layer also influenced ecosystem carbon dynamics, resulting in simulated forest conditions that had higher rates of carbon uptake. We conclude that the initial forest layer significantly affects fire and carbon dynamics and is dependent on both number of plots, and sufficient representation of the range of forest types and biomass density.
Collapse
Affiliation(s)
- Hagar Hecht
- Spatial Informatics Group Natural Assets Lab, Pleasanton, CA, USA.
- Department of Biology, University of New Mexico, Albuquerque, NM, USA.
| | - Dan J Krofcheck
- Sandia National Laboratory, Albuquerque, NM, USA
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Dennis Carril
- US Forest Service, Santa Fe National Forest, Santa Fe, NM, USA
| | - Matthew D Hurteau
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| |
Collapse
|
3
|
Cheng Y, Oehmcke S, Brandt M, Rosenthal L, Das A, Vrieling A, Saatchi S, Wagner F, Mugabowindekwe M, Verbruggen W, Beier C, Horion S. Scattered tree death contributes to substantial forest loss in California. Nat Commun 2024; 15:641. [PMID: 38245523 PMCID: PMC10799937 DOI: 10.1038/s41467-024-44991-z] [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: 07/10/2023] [Accepted: 01/11/2024] [Indexed: 01/22/2024] Open
Abstract
In recent years, large-scale tree mortality events linked to global change have occurred around the world. Current forest monitoring methods are crucial for identifying mortality hotspots, but systematic assessments of isolated or scattered dead trees over large areas are needed to reduce uncertainty on the actual extent of tree mortality. Here, we mapped individual dead trees in California using sub-meter resolution aerial photographs from 2020 and deep learning-based dead tree detection. We identified 91.4 million dead trees over 27.8 million hectares of vegetated areas (16.7-24.7% underestimation bias when compared to field data). Among these, a total of 19.5 million dead trees appeared isolated, and 60% of all dead trees occurred in small groups ( ≤ 3 dead trees within a 30 × 30 m grid), which is largely undetected by other state-level monitoring methods. The widespread mortality of individual trees impacts the carbon budget and sequestration capacity of California forests and can be considered a threat to forest health and a fuel source for future wildfires.
Collapse
Affiliation(s)
- Yan Cheng
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark.
| | - Stefan Oehmcke
- Department of Computer Science, University of Copenhagen, Copenhagen, Denmark
| | - Martin Brandt
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Lisa Rosenthal
- US Geological Survey, Western Ecological Research Center, Three Rivers, Sequoia and Kings Canyon Field Station, Three Rivers, CA, USA
| | - Adrian Das
- US Geological Survey, Western Ecological Research Center, Three Rivers, Sequoia and Kings Canyon Field Station, Three Rivers, CA, USA
| | - Anton Vrieling
- Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Enschede, The Netherlands
| | - Sassan Saatchi
- University of California, Los Angeles, CA, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Fabien Wagner
- University of California, Los Angeles, CA, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Maurice Mugabowindekwe
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Wim Verbruggen
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Claus Beier
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Stéphanie Horion
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark.
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
Swain DL, Abatzoglou JT, Kolden C, Shive K, Kalashnikov DA, Singh D, Smith E. Climate change is narrowing and shifting prescribed fire windows in western United States. COMMUNICATIONS EARTH & ENVIRONMENT 2023; 4:340. [PMID: 38665191 PMCID: PMC11041722 DOI: 10.1038/s43247-023-00993-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 09/08/2023] [Indexed: 04/28/2024]
Abstract
Escalating wildfire activity in the western United States has accelerated adverse societal impacts. Observed increases in wildfire severity and impacts to communities have diverse anthropogenic causes-including the legacy of fire suppression policies, increased development in high-risk zones, and aridification by a warming climate. However, the intentional use of fire as a vegetation management tool, known as "prescribed fire," can reduce the risk of destructive fires and restore ecosystem resilience. Prescribed fire implementation is subject to multiple constraints, including the number of days characterized by weather and vegetation conditions conducive to achieving desired outcomes. Here, we quantify observed and projected trends in the frequency and seasonality of western United States prescribed fire days. We find that while ~2 C of global warming by 2060 will reduce such days overall (-17%), particularly during spring (-25%) and summer (-31%), winter (+4%) may increasingly emerge as a comparatively favorable window for prescribed fire especially in northern states.
Collapse
Affiliation(s)
- Daniel L. Swain
- Institute of the Environment and Sustainability, University of California, Los Angeles, Los Angeles, CA USA
- Capacity Center for Climate and Weather Extremes, National Center for Atmospheric Research, Boulder, CO USA
- The Nature Conservancy of California, Sacramento, CA USA
| | - John T. Abatzoglou
- Management of Complex Systems Department, University of California, Merced, Merced, CA USA
| | - Crystal Kolden
- Management of Complex Systems Department, University of California, Merced, Merced, CA USA
| | - Kristen Shive
- The Nature Conservancy of California, Sacramento, CA USA
- Environmental Science, Policy and Management Department, University of California, Berkeley, Berkeley, CA USA
| | | | - Deepti Singh
- School of the Environment, Washington State University, Vancouver, WA USA
| | - Edward Smith
- The Nature Conservancy of California, Sacramento, CA USA
| |
Collapse
|
6
|
Brown PT, Hanley H, Mahesh A, Reed C, Strenfel SJ, Davis SJ, Kochanski AK, Clements CB. Climate warming increases extreme daily wildfire growth risk in California. Nature 2023; 621:760-766. [PMID: 37648863 DOI: 10.1038/s41586-023-06444-3] [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: 07/22/2022] [Accepted: 07/17/2023] [Indexed: 09/01/2023]
Abstract
California has experienced enhanced extreme wildfire behaviour in recent years1-3, leading to substantial loss of life and property4,5. Some portion of the change in wildfire behaviour is attributable to anthropogenic climate warming, but formally quantifying this contribution is difficult because of numerous confounding factors6,7 and because wildfires are below the grid scale of global climate models. Here we use machine learning to quantify empirical relationships between temperature (as well as the influence of temperature on aridity) and the risk of extreme daily wildfire growth (>10,000 acres) in California and find that the influence of temperature on the risk is primarily mediated through its influence on fuel moisture. We use the uncovered relationships to estimate the changes in extreme daily wildfire growth risk under anthropogenic warming by subjecting historical fires from 2003 to 2020 to differing background climatological temperatures and aridity conditions. We find that the influence of anthropogenic warming on the risk of extreme daily wildfire growth varies appreciably on a fire-by-fire and day-by-day basis, depending on whether or not climate warming pushes conditions over certain thresholds of aridity, such as 1.5 kPa of vapour-pressure deficit and 10% dead fuel moisture. So far, anthropogenic warming has enhanced the aggregate expected frequency of extreme daily wildfire growth by 25% (5-95 range of 14-36%), on average, relative to preindustrial conditions. But for some fires, there was approximately no change, and for other fires, the enhancement has been as much as 461%. When historical fires are subjected to a range of projected end-of-century conditions, the aggregate expected frequency of extreme daily wildfire growth events increases by 59% (5-95 range of 47-71%) under a low SSP1-2.6 emissions scenario compared with an increase of 172% (5-95 range of 156-188%) under a very high SSP5-8.5 emissions scenario, relative to preindustrial conditions.
Collapse
Affiliation(s)
- Patrick T Brown
- Climate and Energy Team, The Breakthrough Institute, Berkeley, CA, USA.
- Wildfire Interdisciplinary Research Center (WIRC), San José State University, San Jose, CA, USA.
- Energy Policy and Climate Program, Johns Hopkins University, Baltimore, MD, USA.
| | - Holt Hanley
- Wildfire Interdisciplinary Research Center (WIRC), San José State University, San Jose, CA, USA
- Department of Meteorology and Climate Science, San José State University, San Jose, CA, USA
- KSBW News, Salinas, CA, USA
| | - Ankur Mahesh
- Climate and Ecosystems Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Earth and Planetary Science, University of California, Berkeley, Berkeley, CA, USA
| | - Colorado Reed
- Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | | | - Steven J Davis
- Department of Earth System Science, University of California, Irvine, Irvine, CA, USA
| | - Adam K Kochanski
- Wildfire Interdisciplinary Research Center (WIRC), San José State University, San Jose, CA, USA
- Department of Meteorology and Climate Science, San José State University, San Jose, CA, USA
| | - Craig B Clements
- Wildfire Interdisciplinary Research Center (WIRC), San José State University, San Jose, CA, USA
- Department of Meteorology and Climate Science, San José State University, San Jose, CA, USA
| |
Collapse
|
7
|
Guo H, Goulden M, Chung MG, Nyelele C, Egoh B, Keske C, Conklin M, Bales R. Valuing the benefits of forest restoration on enhancing hydropower and water supply in California's Sierra Nevada. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 876:162836. [PMID: 36924953 DOI: 10.1016/j.scitotenv.2023.162836] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 03/08/2023] [Accepted: 03/09/2023] [Indexed: 06/18/2023]
Abstract
Forest restoration through mechanical thinning, prescribed burning, and other management actions is vital to improving forest resilience to fire and drought across the Western United States, and yields benefits that can be monetized, including improvements in water supply and hydropower. Using California's Sierra Nevada as a study area, we assess the water and energy benefits of forest-restoration projects. By using a scalable top-down approach to track annual evapotranspiration following forest disturbance, coupled with hydropower simulations that include energy-price information, and marginal prices for water sales, we project the potential economic benefits of hydropower and water sales accruing to water-rights holders. The results found that water-related benefits from strategically planned fuels-reduction treatments now being carried out can be sufficient to offset costs of management actions aimed at forest restoration, especially in the face of climate change. Our findings justified investments in restoring forests and reinforce the central role of water and hydropower providers in partnerships for management of source-water watersheds. Results also highlighted the importance of accurate, scalable data and tools from the hydrology and water-resources community.
Collapse
Affiliation(s)
- Han Guo
- Environmental Systems Graduate Group, University of California Merced, Merced, CA, USA.
| | - Michael Goulden
- Department of Earth System Science, University of California Irvine, Irvine, CA, USA
| | - Min Gon Chung
- Department of Earth System Science, University of California Irvine, Irvine, CA, USA; Sierra Nevada Research Institute, University of California Merced, Merced, CA, USA
| | - Charity Nyelele
- Department of Environmental Sciences, University of Virginia, Charlottesville, VA, USA
| | - Benis Egoh
- Department of Earth System Science, University of California Irvine, Irvine, CA, USA
| | - Catherine Keske
- Environmental Systems Graduate Group, University of California Merced, Merced, CA, USA; Sierra Nevada Research Institute, University of California Merced, Merced, CA, USA
| | - Martha Conklin
- Environmental Systems Graduate Group, University of California Merced, Merced, CA, USA; Sierra Nevada Research Institute, University of California Merced, Merced, CA, USA
| | - Roger Bales
- Environmental Systems Graduate Group, University of California Merced, Merced, CA, USA; Sierra Nevada Research Institute, University of California Merced, Merced, CA, USA; Department of Civil and Environmental Engineering, University of California Berkeley, Berkeley, CA, USA
| |
Collapse
|
8
|
Stephens SL, Steel ZL, Collins BM, Fry DL, Gill SJ, Rivera-Huerta H, Skinner CN. Climate and fire impacts on tree recruitment in mixed conifer forests in northwestern Mexico and California. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2844. [PMID: 36922398 DOI: 10.1002/eap.2844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 12/27/2022] [Accepted: 03/08/2023] [Indexed: 06/02/2023]
Abstract
Frequent-fire forests were once heterogeneous at multiple spatial scales, which contributed to their resilience to severe fire. While many studies have characterized historical spatial patterns in frequent-fire forests, fewer studies have investigated their temporal dynamics. We investigated the influences of fire and climate on the timing of conifer recruitment in old-growth Jeffrey pine-mixed conifer forests in the Sierra San Pedro Martir (SSPM) and the eastern slope of the Sierra Nevada. Additionally, we evaluated the impacts of fire exclusion and recent climate change on recruitment levels using statistical models with realized as well as fire suppression and climate change-free counterfactual scenarios. Excessive soil drying from anthropogenic climate change resulted in diminished recruitment in the SSPM but not in the Sierra Nevada. Longer fire-free intervals attributable to fire suppression and exclusion resulted in greater rates of recruitment across all sites but was particularly pronounced in the Sierra Nevada, where suppression began >100 years ago and recruitment was 28 times higher than the historical fire return interval scenario. This demonstrates the profound impact of fire's removal on tree recruitment in Sierra Nevada forests even in the context of recent climate change. Tree recruitment at the SSPM coincided with the early-20th-century North American pluvial, as well as a fire-quiescent period in the late 18th and early 19th centuries. Episodic recruitment occurred in the SSPM with no "average" recruitment over the last three centuries. We found that temporal heterogeneity, in conjunction with spatial heterogeneity, are critical components of frequent-fire-adapted forests. Episodic recruitment could be a desirable characteristic of frequent-fire-adapted forests, and this might be more amenable to climate change impacts that forecast more variable precipitation patterns in the future. One key to this outcome would be for frequent fire to continue to shape these forests versus continued emphasis on fire suppression in California.
Collapse
Affiliation(s)
- Scott L Stephens
- Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, California, USA
| | - Zachary L Steel
- Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, California, USA
- USDA Forest Service, Rocky Mountain Research Station, Fort Collins, Colorado, USA
| | - Brandon M Collins
- Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, California, USA
- Center for Fire Research and Outreach, University of California, Berkeley, Berkeley, California, USA
| | - Danny L Fry
- Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, California, USA
| | - Samantha J Gill
- Natural Resources Management and Bioresource and Agricultural Engineering Departments, California Polytechnic State University, San Luis Obispo, California, USA
| | - Hiram Rivera-Huerta
- Facultad de Ciencias Marinas, Universidad Autonoma de Baja California, Ensenada, Mexico
| | - Carl N Skinner
- USDA Forest Service, Pacific Southwest Research Station, Redding, California, USA
| |
Collapse
|
9
|
Adie H, Lawes MJ. Solutions to fire and shade: resprouting, growing tall and the origin of Eurasian temperate broadleaved forest. Biol Rev Camb Philos Soc 2023; 98:643-661. [PMID: 36444419 DOI: 10.1111/brv.12923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 11/11/2022] [Accepted: 11/16/2022] [Indexed: 12/03/2022]
Abstract
Tree species of Eurasian broadleaved forest possess two divergent trait syndromes with contrasting patterns of resource allocation adapted to different selection environments: short-stature basal resprouters that divert resources to a bud bank adapted to frequent and severe disturbances such as fire and herbivory, and tall trees that delay reproduction by investing in rapid height growth to escape shading. Drawing on theory developed in savanna ecosystems, we propose a conceptual framework showing that the possession of contrasting trait syndromes is essential for the persistence of broadleaved trees in an open ecosystem that burns. Consistent with this hypothesis, trees of modern Eurasian broadleaved forest bear a suite of traits that are adaptive to surface and crown-fire regimes. We contend that limited opportunities in grassland restricts recruitment to disturbance-free refugia, and en masse establishment creates a wooded environment where shade limits the growth of light-demanding savanna plants. Rapid height growth, which involves investment in structural support and the switch from a multi-stemmed to a monopodial growth form, is adaptive in this shaded environment. Although clustering reduces surface fuel loads, these establishment nuclei are vulnerable to high-intensity crown fires. The lethal effects of canopy fire are avoided by seasonal leaf shedding, and aerial resprouting enhances rapid post-fire recovery of photosynthetic capacity. While these woody formations satisfy the structural definition of forest, their constituents are clearly derived from savanna. Contrasting trait syndromes thus represent the shift from consumer to resource regulation in savanna ecosystems. Consistent with global trends, the diversification of most contemporary broadleaved taxa coincided with the spread of grasslands, a surge in fire activity and a decline in wooded ecosystems in the late Miocene-Pliocene. Recognition that Eurasian broadleaved forest has savanna origins and persists as an alternative state with adjacent grassy ecosystems has far-reaching management implications in accordance with functional rather than structural criteria. Shade is a severe constraint to the regeneration and growth of both woody and herbaceous growth forms in consumer-regulated ecosystems. However, these ecosystems are highly resilient to disturbance, an essential process that maintains diversity especially among the species-rich herbaceous component that is vulnerable to shading when consumer behaviour is altered.
Collapse
Affiliation(s)
- Hylton Adie
- School of Life Sciences, University of KwaZulu-Natal, P/Bag X01, Scottsville, 3209, South Africa
| | - Michael J Lawes
- School of Life Sciences, University of KwaZulu-Natal, P/Bag X01, Scottsville, 3209, South Africa
- Institute of Biodiversity and Environmental Conservation (IBEC), Universiti Malaysia Sarawak, 94300, Kota Samarahan, Sarawak, Malaysia
| |
Collapse
|
10
|
Steel ZL, Jones GM, Collins BM, Green R, Koltunov A, Purcell KL, Sawyer SC, Slaton MR, Stephens SL, Stine P, Thompson C. Mega-disturbances cause rapid decline of mature conifer forest habitat in California. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2763. [PMID: 36264047 DOI: 10.1002/eap.2763] [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: 07/28/2022] [Revised: 08/25/2022] [Accepted: 08/30/2022] [Indexed: 06/16/2023]
Abstract
Mature forests provide important wildlife habitat and support critical ecosystem functions globally. Within the dry conifer forests of the western United States, past management and fire exclusion have contributed to forest conditions that are susceptible to increasingly severe wildfire and drought. We evaluated declines in conifer forest cover in the southern Sierra Nevada of California during a decade of record disturbance by using spatially comprehensive forest structure estimates, wildfire perimeter data, and the eDaRT forest disturbance tracking algorithm. Primarily due to the combination of wildfires, drought, and drought-associated beetle epidemics, 30% of the region's conifer forest extent transitioned to nonforest vegetation during 2011-2020. In total, 50% of mature forest habitat and 85% of high density mature forests either transitioned to lower density forest or nonforest vegetation types. California spotted owl protected activity centers (PAC) experienced greater canopy cover decline (49% of 2011 cover) than non-PAC areas (42% decline). Areas with high initial canopy cover and without tall trees were most vulnerable to canopy cover declines, likely explaining the disproportionate declines of mature forest habitat and within PACs. Drought and beetle attack caused greater cumulative declines than areas where drought and wildfire mortality overlapped, and both types of natural disturbance far outpaced declines attributable to mechanical activities. Drought mortality that disproportionately affects large conifers is particularly problematic to mature forest specialist species reliant on large trees. However, patches of degraded forests within wildfire perimeters were larger with greater core area than those outside burned areas, and remnant forest habitats were more fragmented within burned perimeters than those affected by drought and beetle mortality alone. The percentage of mature forest that survived and potentially benefited from lower severity wildfire increased over time as the total extent of mature forest declined. These areas provide some opportunity for improved resilience to future disturbances, but strategic management interventions are likely also necessary to mitigate worsening mega-disturbances. Remaining dry mature forest habitat in California may be susceptible to complete loss in the coming decades without a rapid transition from a conservation paradigm that attempts to maintain static conditions to one that manages for sustainable disturbance dynamics.
Collapse
Affiliation(s)
| | - Gavin M Jones
- USFS Rocky Mountain Research Station, Albuquerque, New Mexico, USA
- University of New Mexico, Albuquerque, New Mexico, USA
| | - Brandon M Collins
- University of California, Berkeley, California, USA
- USFS Pacific Southwest Research Station, Davis, California, USA
| | - Rebecca Green
- Sequoia & Kings Canyon National Park, Three Rivers, California, USA
| | - Alexander Koltunov
- USFS Pacific Southwest Region, McClellan, California, USA
- University of California, Davis, California, USA
| | - Kathryn L Purcell
- USFS Pacific Southwest Research Station, Coarsegold, California, USA
| | | | | | | | - Peter Stine
- Stine Wildland Resources Science, Sacramento, California, USA
| | - Craig Thompson
- USFS Pacific Southwest Research Station, Fresno, California, USA
| |
Collapse
|
11
|
Too hot, too cold, or just right: Can wildfire restore dry forests of the interior Pacific Northwest? PLoS One 2023; 18:e0281927. [PMID: 36848330 PMCID: PMC9970105 DOI: 10.1371/journal.pone.0281927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 02/03/2023] [Indexed: 03/01/2023] Open
Abstract
As contemporary wildfire activity intensifies across the western United States, there is increasing recognition that a variety of forest management activities are necessary to restore ecosystem function and reduce wildfire hazard in dry forests. However, the pace and scale of current, active forest management is insufficient to address restoration needs. Managed wildfire and landscape-scale prescribed burns hold potential to achieve broad-scale goals but may not achieve desired outcomes where fire severity is too high or too low. To explore the potential for fire alone to restore dry forests, we developed a novel method to predict the range of fire severities most likely to restore historical forest basal area, density, and species composition in forests across eastern Oregon. First, we developed probabilistic tree mortality models for 24 species based on tree characteristics and remotely sensed fire severity from burned field plots. We applied these estimates to unburned stands in four national forests to predict post-fire conditions using multi-scale modeling in a Monte Carlo framework. We compared these results to historical reconstructions to identify fire severities with the highest restoration potential. Generally, we found basal area and density targets could be achieved by a relatively narrow range of moderate-severity fire (roughly 365-560 RdNBR). However, single fire events did not restore species composition in forests that were historically maintained by frequent, low-severity fire. Restorative fire severity ranges for stand basal area and density were strikingly similar for ponderosa pine (Pinus ponderosa) and dry mixed-conifer forests across a broad geographic range, in part due to relatively high fire tolerance of large grand (Abies grandis) and white fir (Abies concolor). Our results suggest historical forest conditions created by recurrent fire are not readily restored by single fires and landscapes have likely passed thresholds that preclude the effectiveness of managed wildfire alone as a restoration tool.
Collapse
|
12
|
Schmeller DS, Urbach D, Bates K, Catalan J, Cogălniceanu D, Fisher MC, Friesen J, Füreder L, Gaube V, Haver M, Jacobsen D, Le Roux G, Lin YP, Loyau A, Machate O, Mayer A, Palomo I, Plutzar C, Sentenac H, Sommaruga R, Tiberti R, Ripple WJ. Scientists' warning of threats to mountains. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 853:158611. [PMID: 36087665 DOI: 10.1016/j.scitotenv.2022.158611] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 09/04/2022] [Accepted: 09/04/2022] [Indexed: 06/15/2023]
Abstract
Mountains are an essential component of the global life-support system. They are characterized by a rugged, heterogenous landscape with rapidly changing environmental conditions providing myriad ecological niches over relatively small spatial scales. Although montane species are well adapted to life at extremes, they are highly vulnerable to human derived ecosystem threats. Here we build on the manifesto 'World Scientists' Warning to Humanity', issued by the Alliance of World Scientists, to outline the major threats to mountain ecosystems. We highlight climate change as the greatest threat to mountain ecosystems, which are more impacted than their lowland counterparts. We further discuss the cascade of "knock-on" effects of climate change such as increased UV radiation, altered hydrological cycles, and altered pollution profiles; highlighting the biological and socio-economic consequences. Finally, we present how intensified use of mountains leads to overexploitation and abstraction of water, driving changes in carbon stock, reducing biodiversity, and impacting ecosystem functioning. These perturbations can provide opportunities for invasive species, parasites and pathogens to colonize these fragile habitats, driving further changes and losses of micro- and macro-biodiversity, as well further impacting ecosystem services. Ultimately, imbalances in the normal functioning of mountain ecosystems will lead to changes in vital biological, biochemical, and chemical processes, critically reducing ecosystem health with widespread repercussions for animal and human wellbeing. Developing tools in species/habitat conservation and future restoration is therefore essential if we are to effectively mitigate against the declining health of mountains.
Collapse
Affiliation(s)
| | - Davnah Urbach
- Global Mountain Biodiversity Assessment, Institute of Plant Sciences, University of Bern, Bern, Switzerland.
| | - Kieran Bates
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK; MRC Centre for GlobaI Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK; Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK.
| | - Jordi Catalan
- CREAF Campus UAB, Edifici C, Cerdanyola Del Valles, Spain; CSIC, Campus UAB, Cerdanyola Del Valles, Spain.
| | - Dan Cogălniceanu
- Ovidius University Constanţa, Faculty of Natural Sciences and Agricultural Sciences, Al. Universităţii 1, 900470 Constanţa, Romania
| | - Matthew C Fisher
- MRC Centre for GlobaI Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK.
| | - Jan Friesen
- Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.
| | - Leopold Füreder
- Department of Ecology, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.
| | - Veronika Gaube
- University of Natural Resources and Life Sciences, Vienna, Department of Economics and Social Sciences, Institute of Social Ecology (SEC), Schottenfeldgasse 29, Austria.
| | - Marilen Haver
- LEFE, Université de Toulouse, INPT, UPS, Toulouse, France.
| | - Dean Jacobsen
- Freshwater Biological Section, Dept. Biology, University of Copenhagen, Denmark.
| | - Gael Le Roux
- LEFE, Université de Toulouse, INPT, UPS, Toulouse, France.
| | - Yu-Pin Lin
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taiwan.
| | - Adeline Loyau
- LEFE, Université de Toulouse, INPT, UPS, Toulouse, France.
| | - Oliver Machate
- Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Andreas Mayer
- University of Natural Resources and Life Sciences, Vienna, Department of Economics and Social Sciences, Institute of Social Ecology (SEC), Schottenfeldgasse 29, Austria.
| | - Ignacio Palomo
- Univ. Grenoble-Alpes, IRD, CNRS, Grenoble INP*, IGE, 38000 Grenoble, France.
| | - Christoph Plutzar
- University of Natural Resources and Life Sciences, Vienna, Department of Economics and Social Sciences, Institute of Social Ecology (SEC), Schottenfeldgasse 29, Austria.
| | - Hugo Sentenac
- LEFE, Université de Toulouse, INPT, UPS, Toulouse, France.
| | - Ruben Sommaruga
- Department of Ecology, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.
| | - Rocco Tiberti
- Department of Earth and Environmental Sciences - DSTA, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy.
| | - William J Ripple
- Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR, USA.
| |
Collapse
|
13
|
Shaw DC, Beedlow PA, Lee EH, Woodruff DR, Meigs GW, Calkins SJ, Reilly MJ, Merschel AG, Cline SP, Comeleo RL. The complexity of biological disturbance agents, fuels heterogeneity, and fire in coniferous forests of the western United States. FOREST ECOLOGY AND MANAGEMENT 2022; 525:1-27. [PMID: 36968296 PMCID: PMC10031511 DOI: 10.1016/j.foreco.2022.120572] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Forest biological disturbance agents (BDAs) are insects, pathogens, and parasitic plants that affect tree decline, mortality, and forest ecosystems processes. BDAs are commonly thought to increase the likelihood and severity of fire by converting live standing trees to more flammable, dead and downed fuel. However, recent research indicates that BDAs do not necessarily increase, and can reduce, the likelihood or severity of fire. This has led to confusion regarding the role of BDAs in influencing fuels and fire in fire-prone western United States forests. Here, we review the existing literature on BDAs and their effects on fuels and fire in the western US and develop a conceptual framework to better understand the complex relationships between BDAs, fuels and fire. We ask: 1) What are the major BDA groups in western US forests that affect fuels? and 2) How do BDA-affected fuels influence fire risk and outcomes? The conceptual framework is rooted in the spatiotemporal aspects of BDA life histories, which drive forest impacts, fuel characteristics and if ignited, fire outcomes. Life histories vary among BDAs from episodic, landscape-scale outbreaks (bark beetles, defoliators), to chronic, localized disturbance effects (dwarf mistletoes, root rots). Generally, BDAs convert aboveground live biomass to dead biomass, decreasing canopy fuels and increasing surface fuels. However, the rate of conversion varies with time-since-event and among BDAs and forest types, resulting in a wide range of effects on the amount of dead fuels at any given time and place, which interacts with the structure and composition of the stand before and subsequent to BDA events. A major influence on fuels may be that BDAs have emerged as dominant agents of forest heterogeneity creation. Because BDAs play complex roles in fuels and fire heterogeneity across the western US which are further complicated by interactions with climate change, drought, and forest management (fire suppression), their impacts on fuels, fire and ecological consequences cannot be categorized simply as positive or negative but need to be evaluated within the context of BDA life histories and ecosystem dynamics.
Collapse
Affiliation(s)
- David C. Shaw
- Department of Forest Engineering, Resources, and Management, Oregon State University, 216 Peavy Forest Science Complex, 3100 SW Jefferson Way, Corvallis, OR 97331, USA
| | - Peter A. Beedlow
- U.S. Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR 97333, USA
| | - E. Henry Lee
- U.S. Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR 97333, USA
| | - David R. Woodruff
- USDA Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, OR 97333, USA
| | - Garrett W. Meigs
- Washington State Department of Natural Resources, 1111 Washington St. SE, Olympia, WA 98504, USA
- Department of Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, 3180 SW Jefferson Way, Corvallis, OR 97331, USA
| | - Stephen J. Calkins
- Department of Forest Engineering, Resources, and Management, Oregon State University, 216 Peavy Forest Science Complex, 3100 SW Jefferson Way, Corvallis, OR 97331, USA
| | - Matthew J. Reilly
- USDA Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, OR 97333, USA
| | - Andrew G. Merschel
- Department of Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, 3180 SW Jefferson Way, Corvallis, OR 97331, USA
| | - Steven P. Cline
- U.S. Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR 97333, USA
| | - Randy L. Comeleo
- U.S. Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR 97333, USA
| |
Collapse
|
14
|
Keeley JE, Brennan TJ, Syphard AD. The effects of prolonged drought on vegetation dieback and megafires in southern California chaparral. Ecosphere 2022. [DOI: 10.1002/ecs2.4203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Jon E. Keeley
- U.S. Geological Survey, Western Ecological Research Center, Sequoia‐Kings Canyon Field Station Three Rivers California USA
- Department of Ecology and Evolutionary Biology University of California Los Angeles California USA
| | - Teresa J. Brennan
- U.S. Geological Survey, Western Ecological Research Center, Sequoia‐Kings Canyon Field Station Three Rivers California USA
| | | |
Collapse
|
15
|
High and Low Air Temperatures and Natural Wildfire Ignitions in the Sierra Nevada Region. ENVIRONMENTS 2022. [DOI: 10.3390/environments9080096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The Sierra Nevada region has experienced substantial wildfire impacts. Uncertainty pertaining to fire risk may be reduced by better understanding how air temperature (Ta: °C) influences wildfire ignitions independently of other factors. We linked lightning-ignited wildfires to Ta patterns across the region from 1992 to 2015 and compared monthly high- and low-air-temperature patterns between ignition and non-ignition locations at local scales (4 km). Regionally, more ignitions occurred in springs with a greater number of high-Ta months and fewer cool Ta months (analyzed separately) and in summers with fewer cool Ta months. Locally, summer ignition locations experienced warmer summer months on a normalized scale than non-ignition locations. The probability of a wildfire ignition was positively associated with a greater number of high-Ta months during and prior to fire seasons. Regionally, springs with a greater number of high-Ta months had more wildfire ignitions. Locally, as individual locations in the region experienced a greater number of high-Ta months preceding and including the fire season, they exhibited substantial increases in spring (+1446%), summer (+365%), and fall (+248%) ignitions. Thus, the frequent occurrence of high-Ta months is positively associated with lightning-ignited wildfires in the Sierra Nevada region.
Collapse
|
16
|
Christopoulou A, Sazeides CI, Fyllas NM. Size-mediated effects of climate on tree growth and mortality in Mediterranean Brutia pine forests. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 812:151463. [PMID: 34742797 DOI: 10.1016/j.scitotenv.2021.151463] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/01/2021] [Accepted: 11/01/2021] [Indexed: 06/13/2023]
Abstract
The Eastern Mediterranean Basin is experiencing long-term drought conditions that affect the growth and mortality of many forest tree species. We analysed tree rings from 113 Pinus brutia (living and dead) trees of different age (<50, 50-85, >85 years old) and size to study how climatic variation during the 20th century has shaped their radial-growth and mortality patterns. We selected the pine forest on the island of Lesvos (Greece) representing the largest continuous P. brutia forest on the Aegean islands, to develop a chronology that could provide a bridge between the available tree-ring data sets from the Western and Eastern Mediterranean region. The analysis of the novel chronology captured well-known drought events during the 20th century, such as those in 1949, 1990 and 2007, and provided an equation to reconstruct the intensity of droughts (10 month time scale). P. brutia tree-growth indicated a positive trend from the beginning until the 3rd quarter of the 21st century and then flattened for living trees. Trees that eventually died between 2010 and 2019, were characterized by a much lower growth than surviving trees and also illustrated a long-lasting negative growth trend. Precipitation and water availability (inferred from the SPEI drought index) were positively related to the growth of living and dead trees, mainly in the middle and old age classes. Temperature effect on tree growth shifted from negative to positive with increasing age of living trees, but remained always negative across all age classes in trees that eventually died. Our findings verify the positive effect of water availability on tree growth and survival of Mediterranean pines and highlight a size-mediated effect of temperature on tree growth, probably coupled with individual-tree access to underground water resources. Increased air temperatures during various time periods related to tree physiological activity seem to negatively affect tree survival across all age classes, in Mediterranean P. brutia forests, highlighting their potential vulnerability to global warming conditions.
Collapse
Affiliation(s)
- A Christopoulou
- Biodiversity Conservation Lab, Department of Environment, University of the Aegean, 81100 Mytilene, Greece; Centre for Research and Conservation of Cultural Heritage, Faculty of Fine Arts, Nicolaus Copernicus University, 87-100 Toruń, Poland.
| | - C I Sazeides
- Biodiversity Conservation Lab, Department of Environment, University of the Aegean, 81100 Mytilene, Greece
| | - N M Fyllas
- Biodiversity Conservation Lab, Department of Environment, University of the Aegean, 81100 Mytilene, Greece
| |
Collapse
|
17
|
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.
Collapse
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
| |
Collapse
|
18
|
Das AJ, Slaton MR, Mallory J, Asner GP, Martin RE, Hardwick P. Empirically validated drought vulnerability mapping in the mixed conifer forests of the Sierra Nevada. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2514. [PMID: 35094444 DOI: 10.1002/eap.2514] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/30/2021] [Accepted: 08/26/2021] [Indexed: 06/14/2023]
Abstract
Severe droughts are predicted to become more frequent in the future, and the consequences of such droughts on forests can be dramatic, resulting in massive tree mortality, rapid change in forest structure and composition, and substantially increased risk of catastrophic fire. Forest managers have tools at their disposal to try to mitigate these effects but are often faced with limited resources, forcing them to make choices about which parts of the landscape to target for treatment. Such planning can greatly benefit from landscape vulnerability assessments, but many existing vulnerability analyses are unvalidated and not grounded in robust empirical datasets. We combined robust sets of ground-based plot and remote sensing data, collected during the 2012-2016 California drought, to develop rigorously validated tools for assessing forest vulnerability to drought-related canopy tree mortality for the mixed conifer forests of the Sequoia and Kings Canyon national parks and potentially for mixed conifer forests in the Sierra Nevada as a whole. Validation was carried out using a large external dataset. The best models included normalized difference vegetation index (NDVI), elevation, and species identity. Models indicated that tree survival probability decreased with greenness (as measured by NDVI) and elevation, particularly if trees were growing slowly. Overall, models showed good calibration and validation, especially for Abies concolor, which comprise a large majority of the trees in many mixed conifer forests in the Sierra Nevada. Our models tended to overestimate mortality risk for Calocedrus decurrens and underestimate risk for pine species, in the latter case probably due to pine bark beetle outbreak dynamics. Validation results indicated dangers of overfitting, as well as showing that the inclusion of trees already under attack by bark beetles at the time of sampling can give false confidence in model strength, while also biasing predictions. These vulnerability tools should be useful to forest managers trying to assess which parts of their landscape were vulnerable during the 2012-2016 drought, and, with additional validation, may prove useful for ongoing assessments and predictions of future forest vulnerability.
Collapse
Affiliation(s)
- Adrian J Das
- U.S. Geological Survey, Western Ecological Research Center, Sequoia and Kings Canyon Field Station, Three Rivers, California, USA
| | - Michèle R Slaton
- USDA Forest Service, Pacific Southwest Region, Remote Sensing Laboratory, McClellan, California, USA
| | - Jeffrey Mallory
- USDA Forest Service, Pacific Southwest Region, Remote Sensing Laboratory, McClellan, California, USA
| | - Gregory P Asner
- Center for Global Discovery and Conservation Science, Arizona State University, Tempe, Arizona, USA
| | - Roberta E Martin
- Center for Global Discovery and Conservation Science, Arizona State University, Tempe, Arizona, USA
| | - Paul Hardwick
- Division of Resources Management and Science, Sequoia and Kings Canyon National Parks, Three Rivers, California, USA
| |
Collapse
|
19
|
Airey-Lauvaux C, Pierce AD, Skinner CN, Taylor AH. Changes in fire behavior caused by fire exclusion and fuel build-up vary with topography in California montane forests, USA. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 304:114255. [PMID: 34942550 DOI: 10.1016/j.jenvman.2021.114255] [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: 08/03/2021] [Revised: 12/02/2021] [Accepted: 12/05/2021] [Indexed: 06/14/2023]
Abstract
Wildfire sizes and proportions burned with high severity effects are increasing in seasonally dry forests, especially in the western USA. A critical need in efforts to restore or maintain these forest ecosystems is to determine where fuel build-up caused by fire exclusion reaches thresholds that compromise resilience to fire. Empirical studies identifying drivers of fire severity patterns in actual wildfires can be confounded by co-variation of vegetation and topography and the stochastic effects of weather and rarely consider long-term changes in fuel caused by fire exclusion. To overcome these limitations, we used a spatially explicit fire model (FlamMap) to compare potential fire behavior by topographic position in Lassen Volcanic National Park (LAVO), California, a large (43,000 ha), mountainous, unlogged landscape with extensive historical and contemporary fuels data. Fuel loads were uniformly distributed and incrementally increased across the landscape, meaning variation in fire behavior within each simulation was due to topography and among simulations, to fuels. We analyzed changes in fire line intensity (FLI) and crown fire potential as surface and canopy fuels increased from historical to contemporary levels and with percentile and actual wildfire weather conditions. Sensitivity to the influence of fuel build-up on fire behavior varied by topographic position. Steep slopes and ridges were most sensitive. At lower surface fuel loads, under pre-exclusion and contemporary canopy conditions, fire behavior was comparable and remained surface-type. As fuels increased, FLI and passive crown fire increased on steep slopes and ridgetops but remained largely unchanged on gentle slopes. Topographic variability in fire behavior was greatest with intermediate fuels. At higher surface fuel loads, under contemporary canopy fuels, passive crown fire dominated all topographic positions. With LAVO's current surface fuels, the area with potential for passive crown fire during actual fire weather increased from 6% pre-exclusion to 34% due to canopy fuel build-up. For topographically diverse landscapes, the results highlight where contemporary fire characteristics are most likely to deviate from historical patterns and may help managers prioritize locations for prescribed burning and managed wildfire to increase fire resilience in fuel rich landscapes.
Collapse
Affiliation(s)
- Catherine Airey-Lauvaux
- Department of Geography, The Pennsylvania State University, University Park, PA, 16802, United States.
| | - Andrew D Pierce
- Department of Geography, The Pennsylvania State University, University Park, PA, 16802, United States.
| | - Carl N Skinner
- Pacific Southwest Research Station, USDA Forest Service, Redding, CA, 96002, United States.
| | - Alan H Taylor
- Department of Geography, The Pennsylvania State University, University Park, PA, 16802, United States.
| |
Collapse
|
20
|
Rao K, Williams AP, Diffenbaugh NS, Yebra M, Konings AG. Plant-water sensitivity regulates wildfire vulnerability. Nat Ecol Evol 2022; 6:332-339. [PMID: 35132185 PMCID: PMC8913365 DOI: 10.1038/s41559-021-01654-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 12/17/2021] [Indexed: 11/16/2022]
Abstract
Extreme wildfires extensively impact human health and the environment. Increasing vapour pressure deficit (VPD) has led to a chronic increase in wildfire area in the western United States, yet some regions have been more affected than others. Here we show that for the same increase in VPD, burned area increases more in regions where vegetation moisture shows greater sensitivity to water limitation (plant-water sensitivity; R2 = 0.71). This has led to rapid increases in human exposure to wildfire risk, both because the population living in areas with high plant-water sensitivity grew 50% faster during 1990–2010 than in other wildland–urban interfaces and because VPD has risen most rapidly in these vulnerable areas. As plant-water sensitivity is strongly linked to wildfire vulnerability, accounting for ecophysiological controls should improve wildfire forecasts. If recent trends in VPD and demographic shifts continue, human wildfire risk will probably continue to increase. The authors show that an ecosystem’s sensitivity to drought, measured as the amount of change in vegetation moisture content for a given change in background moisture, predicts the fire hazard in that location.
Collapse
|
21
|
Knight CA, Tompkins RE, Wang JA, York R, Goulden ML, Battles JJ. Accurate tracking of forest activity key to multi-jurisdictional management goals: A case study in California. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 302:114083. [PMID: 34800763 DOI: 10.1016/j.jenvman.2021.114083] [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: 08/06/2021] [Revised: 11/06/2021] [Accepted: 11/07/2021] [Indexed: 06/13/2023]
Abstract
An essential component of sustainable forest management is accurate monitoring of forest activities. Although monitoring efforts have generally increased for many forests throughout the world, in practice, effective monitoring is complex. Determining the magnitude and location of progress towards sustainability targets can be challenging due to diverse forest operations across multiple jurisdictions, the lack of data standardization, and discrepancies between field inspections and remotely-sensed records. In this work, we used California as a multijurisdictional case study to explore these problems and develop an approach that broadly informs forest monitoring strategies. The State of California recently entered into a shared stewardship agreement with the US Forest Service (USFS) and set a goal to jointly treat one million acres of forest and rangeland annually by 2025. Currently, however, federal and state forest management datasets are disjoint. This work addresses three barriers stymying the use of federal and state archival records to assess management goals. These barriers are: 1) current databases from different jurisdictions have not been combined due to their distinct data collection processes and internal structures; 2) datasets have not been comprehensively analyzed, despite the need to understand the extent of previous treatments as well as the rate of current activity; and 3) the spatial accuracy of archival datasets has not been evaluated against remotely-sensed data. To reduce these barriers, we first aggregated existing archival forest management records between 1984 and 2019 from the USFS' Forest Activity Tracking System (FACTS) and the California Department of Forestry and Fire Protection (CAL FIRE) using a qualitative scalar of treatment intensity. Combined FACTS and CAL FIRE completed footprint acres - defined as unique areas of land where a treatment was completed at any time since 1984 - have decreased since a peak in 2008. At most, 300,000 footprint acres are completed each year, 30% of the million-acre goal. Prescribed fires - defined as direct burning operations - have risen over time, according to the FACTS hazardous fuels dataset but prescribed fire records in CAL FIRE's dataset have rapidly increased since 2016. We also refined the spatial and temporal detail of the aggregated management record using the Continuous Change Detection and Classification algorithm on satellite remote sensing data to produce a state-wide time series map of harvest disturbances. A comparison of the algorithm's refined data to the archival record potentially suggests over-reporting in both FACTS and CAL FIRE's archival datasets. Our integrated dataset provides a better assessment of current treatments and the path towards the 1-million-acre a year goal. The refined dataset leverages the strengths of complementary, albeit imperfect, monitoring strategies from archives and remotely-sensed detection.
Collapse
Affiliation(s)
- Clarke A Knight
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA, 94720, USA; California Center for Ecosystem Climate Solutions, University of California, Irvine, CA, 92697, USA.
| | - Ryan E Tompkins
- University of California Agriculture and Natural Resources Cooperative Extension, CA, 95971, USA
| | - Jonathan A Wang
- California Center for Ecosystem Climate Solutions, University of California, Irvine, CA, 92697, USA; Department of Earth System Science, University of California, Irvine, CA, 92697, USA
| | - Robert York
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA, 94720, USA; University of California Agriculture and Natural Resources Cooperative Extension, CA, 95971, USA
| | - Michael L Goulden
- California Center for Ecosystem Climate Solutions, University of California, Irvine, CA, 92697, USA; Department of Earth System Science, University of California, Irvine, CA, 92697, USA
| | - John J Battles
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA, 94720, USA; California Center for Ecosystem Climate Solutions, University of California, Irvine, CA, 92697, USA
| |
Collapse
|
22
|
Green DS, Martin ME, Powell RA, McGregor EL, Gabriel MW, Pilgrim KL, Schwartz MK, Matthews SM. Mixed‐severity wildfire and salvage logging affect the populations of a forest‐dependent carnivoran and a competitor. Ecosphere 2022. [DOI: 10.1002/ecs2.3877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- David S. Green
- Institute for Natural Resources Oregon State University Corvallis Oregon USA
| | - Marie E. Martin
- Institute for Natural Resources Oregon State University Corvallis Oregon USA
| | - Roger A. Powell
- Department of Applied Ecology North Carolina State University Raleigh North Carolina USA
| | - Eric L. McGregor
- Institute for Natural Resources Oregon State University Corvallis Oregon USA
| | - Mourad W. Gabriel
- USDA Forest Service Law Enforcement and Investigations Eureka California USA
| | - Kristine L. Pilgrim
- USDA Forest Service National Genomics Center for Wildlife and Fish Conservation Missoula Montana USA
| | - Michael K. Schwartz
- USDA Forest Service National Genomics Center for Wildlife and Fish Conservation Missoula Montana USA
| | - Sean M. Matthews
- Institute for Natural Resources Oregon State University Corvallis Oregon USA
| |
Collapse
|
23
|
Robbins ZJ, Xu C, Aukema BH, Buotte PC, Chitra-Tarak R, Fettig CJ, Goulden ML, Goodsman DW, Hall AD, Koven CD, Kueppers LM, Madakumbura GD, Mortenson LA, Powell JA, Scheller RM. Warming increased bark beetle-induced tree mortality by 30% during an extreme drought in California. GLOBAL CHANGE BIOLOGY 2022; 28:509-523. [PMID: 34713535 DOI: 10.1111/gcb.15927] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 06/13/2023]
Abstract
Quantifying the responses of forest disturbances to climate warming is critical to our understanding of carbon cycles and energy balances of the Earth system. The impact of warming on bark beetle outbreaks is complex as multiple drivers of these events may respond differently to warming. Using a novel model of bark beetle biology and host tree interactions, we assessed how contemporary warming affected western pine beetle (Dendroctonus brevicomis) populations and mortality of its host, ponderosa pine (Pinus ponderosa), during an extreme drought in the Sierra Nevada, California, United States. When compared with the field data, our model captured the western pine beetle flight timing and rates of ponderosa pine mortality observed during the drought. In assessing the influence of temperature on western pine beetles, we found that contemporary warming increased the development rate of the western pine beetle and decreased the overwinter mortality rate of western pine beetle larvae leading to increased population growth during periods of lowered tree defense. We attribute a 29.9% (95% CI: 29.4%-30.2%) increase in ponderosa pine mortality during drought directly to increases in western pine beetle voltinism (i.e., associated with increased development rates of western pine beetle) and, to a much lesser extent, reductions in overwintering mortality. These findings, along with other studies, suggest each degree (°C) increase in temperature may have increased the number of ponderosa pine killed by upwards of 35%-40% °C-1 if the effects of compromised tree defenses (15%-20%) and increased western pine beetle populations (20%) are additive. Due to the warming ability to considerably increase mortality through the mechanism of bark beetle populations, models need to consider climate's influence on both host tree stress and the bark beetle population dynamics when determining future levels of tree mortality.
Collapse
Affiliation(s)
- Zachary J Robbins
- Earth and Environmental Sciences Division (EES-14), Los Alamos National Laboratory, Los Alamos, New Mexico, USA
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina, USA
| | - Chonggang Xu
- Earth and Environmental Sciences Division (EES-14), Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - Brian H Aukema
- Department of Entomology, University of Minnesota, St. Paul, Minnesota, USA
| | - Polly C Buotte
- Energy and Resources Group, University of California Berkeley, Berkeley, California, USA
| | - Rutuja Chitra-Tarak
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina, USA
| | | | - Michael L Goulden
- Department of Earth System Science, University of California, Irvine, California, USA
| | - Devin W Goodsman
- Canadian Forest Service, Natural Resources Canada, Victoria, British Columbia, Canada
| | - Alexander D Hall
- Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA
| | - Charles D Koven
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Lara M Kueppers
- Energy and Resources Group, University of California Berkeley, Berkeley, California, USA
| | - Gavin D Madakumbura
- Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA
| | - Leif A Mortenson
- Pacific Southwest Research Station, USDA Forest Service, Davis, California, USA
| | - James A Powell
- Mathematics and Statistics Department, Utah State University, Logan, Utah, USA
| | - Robert M Scheller
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina, USA
| |
Collapse
|
24
|
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.
Collapse
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
| |
Collapse
|
25
|
Hessburg PF, Prichard SJ, Hagmann RK, Povak NA, Lake FK. Wildfire and climate change adaptation of western North American forests: a case for intentional management. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02432. [PMID: 34339086 PMCID: PMC9285088 DOI: 10.1002/eap.2432] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 02/17/2021] [Accepted: 03/03/2021] [Indexed: 05/05/2023]
Abstract
Forest landscapes across western North America (wNA) have experienced extensive changes over the last two centuries, while climatic warming has become a global reality over the last four decades. Resulting interactions between historical increases in forested area and density and recent rapid warming, increasing insect mortality, and wildfire burned areas, are now leading to substantial abrupt landscape alterations. These outcomes are forcing forest planners and managers to identify strategies that can modify future outcomes that are ecologically and/or socially undesirable. Past forest management, including widespread harvest of fire- and climate-tolerant large old trees and old forests, fire exclusion (both Indigenous and lightning ignitions), and highly effective wildfire suppression have contributed to the current state of wNA forests. These practices were successful at meeting short-term demands, but they match poorly to modern realities. Hagmann et al. review a century of observations and multi-scale, multi-proxy, research evidence that details widespread changes in forested landscapes and wildfire regimes since the influx of European colonists. Over the preceding 10 millennia, large areas of wNA were already settled and proactively managed with intentional burning by Indigenous tribes. Prichard et al. then review the research on management practices historically applied by Indigenous tribes and currently applied by some managers to intentionally manage forests for resilient conditions. They address 10 questions surrounding the application and relevance of these management practices. Here, we highlight the main findings of both papers and offer recommendations for management. We discuss progress paralysis that often occurs with strict adherence to the precautionary principle; offer insights for dealing with the common problem of irreducible uncertainty and suggestions for reframing management and policy direction; and identify key knowledge gaps and research needs.
Collapse
Affiliation(s)
- Paul F. Hessburg
- USDA‐FS, Pacific Northwest Research Station1133 N. Western AvenueWenatcheeWashington98801USA
- College of the Environment‐SEFSUniversity of WashingtonSeattleWashington98195USA
| | - Susan J. Prichard
- College of the Environment‐SEFSUniversity of WashingtonSeattleWashington98195USA
| | - R. Keala Hagmann
- College of the Environment‐SEFSUniversity of WashingtonSeattleWashington98195USA
- Applegate Forestry LLCCorvallisOregon97330USA
| | - Nicholas A. Povak
- USDA‐FS, Pacific Northwest Research Station1133 N. Western AvenueWenatcheeWashington98801USA
- USDA‐FS, Pacific Southwest Research Station2480 Carson RoadPlacervilleCalifornia95667USA
| | - Frank K. Lake
- USDA‐FS, Pacific Southwest Research Station1700 Bayview DriveArcataCalifornia95521USA
| |
Collapse
|
26
|
Abstract
The California Spotted Owl is an imperiled species that selects mature conifer forests for nesting and roosting while actively foraging in the “snag forest habitat” created when fire or drought kills most of the trees in patches. Federal agencies believe there are excess surface fuels in both of these habitat conditions in many of California’s forests due to fuel accumulation from decades of fire suppression and recent drought-related tree mortality. Accordingly, agencies such as the U.S. Forest Service are implementing widespread logging in Spotted Owl territories. While they acknowledge habitat degradation from such logging, and risks to the conservation of declining Spotted Owl populations, agencies hypothesize that such active forest management equates to effective fuel reduction that is needed to curb fire severity for the overall benefit of this at-risk species. In an initial investigation, I analyzed this issue in a large 2020 fire, the Creek Fire (153,738 ha), in the southern Sierra Nevada mountains of California. I found that pre-fire snag density was not correlated with burn severity. I also found that more intensive forest management was correlated to higher fire severity. My results suggest the fuel reduction approach is not justified and provide indirect evidence that such management represents a threat to Spotted Owls.
Collapse
|
27
|
Jager HI, Long JW, Malison RL, Murphy BP, Rust A, Silva LGM, Sollmann R, Steel ZL, Bowen MD, Dunham JB, Ebersole JL, Flitcroft RL. Resilience of terrestrial and aquatic fauna to historical and future wildfire regimes in western North America. Ecol Evol 2021; 11:12259-12284. [PMID: 34594498 PMCID: PMC8462151 DOI: 10.1002/ece3.8026] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/12/2021] [Accepted: 07/24/2021] [Indexed: 01/08/2023] Open
Abstract
Wildfires in many western North American forests are becoming more frequent, larger, and severe, with changed seasonal patterns. In response, coniferous forest ecosystems will transition toward dominance by fire-adapted hardwoods, shrubs, meadows, and grasslands, which may benefit some faunal communities, but not others. We describe factors that limit and promote faunal resilience to shifting wildfire regimes for terrestrial and aquatic ecosystems. We highlight the potential value of interspersed nonforest patches to terrestrial wildlife. Similarly, we review watershed thresholds and factors that control the resilience of aquatic ecosystems to wildfire, mediated by thermal changes and chemical, debris, and sediment loadings. We present a 2-dimensional life history framework to describe temporal and spatial life history traits that species use to resist wildfire effects or to recover after wildfire disturbance at a metapopulation scale. The role of fire refuge is explored for metapopulations of species. In aquatic systems, recovery of assemblages postfire may be faster for smaller fires where unburned tributary basins or instream structures provide refuge from debris and sediment flows. We envision that more-frequent, lower-severity fires will favor opportunistic species and that less-frequent high-severity fires will favor better competitors. Along the spatial dimension, we hypothesize that fire regimes that are predictable and generate burned patches in close proximity to refuge will favor species that move to refuges and later recolonize, whereas fire regimes that tend to generate less-severely burned patches may favor species that shelter in place. Looking beyond the trees to forest fauna, we consider mitigation options to enhance resilience and buy time for species facing a no-analog future.
Collapse
Affiliation(s)
- Henriette I. Jager
- Environmental Sciences DivisionOak Ridge National Laboratory (ORNL)Oak RidgeTNUSA
| | - Jonathan W. Long
- U.S. Department of AgriculturePacific Southwest Research StationDavisCAUSA
| | - Rachel L. Malison
- Flathead Lake Biological StationThe University of MontanaPolsonMTUSA
| | - Brendan P. Murphy
- School of Environmental ScienceSimon Fraser UniversityBurnabyBCCanada
| | - Ashley Rust
- Civil and Environmental Engineering DepartmentColorado School of MinesGoldenCOUSA
| | - Luiz G. M. Silva
- Institute for Land, Water and SocietyCharles Sturt UniversityAlburyNSWAustralia
- Department of CivilEnvironmental and Geomatic EngineeringStocker LabInstitute of Environmental EngineeringETH ZurichZürichSwitzerland
| | - Rahel Sollmann
- Department of Wildlife, Fish, and Conservation BiologyUniversity of California DavisDavisCAUSA
| | - Zachary L. Steel
- Department of Environmental Science, Policy and ManagementUniversity of CaliforniaBerkeleyCAUSA
| | - Mark D. Bowen
- Thomas Gast & Associates Environmental ConsultantsArcataCAUSA
| | - Jason B. Dunham
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science CenterCorvallisORUSA
| | - Joseph L. Ebersole
- Center for Public Health and Environmental AssessmentPacific Ecological Systems DivisionU.S. Environmental Protection AgencyCorvallisORUSA
| | | |
Collapse
|
28
|
Intermediate fire severity diversity promotes richness of forest carnivores in California. DIVERS DISTRIB 2021. [DOI: 10.1111/ddi.13374] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
|
29
|
Burned Area Mapping over the Southern Cape Forestry Region, South Africa Using Sentinel Data within GEE Cloud Platform. ISPRS INTERNATIONAL JOURNAL OF GEO-INFORMATION 2021. [DOI: 10.3390/ijgi10080511] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Planted forests in South Africa have been affected by an increasing number of economically damaging fires over the past four decades. They constitute a major threat to the forestry industry and account for over 80% of the country’s commercial timber losses. Forest fires are more frequent and severe during the drier drought conditions that are typical in South Africa. For proper forest management, accurate detection and mapping of burned areas are required, yet the exercise is difficult to perform in the field because of time and expense. Now that ready-to-use satellite data are freely accessible in the cloud-based Google Earth Engine (GEE), in this study, we exploit the Sentinel-2-derived differenced normalized burned ratio (dNBR) to characterize burn severity areas, and also track carbon monoxide (CO) plumes using Sentinel-5 following a wildfire that broke over the southeastern coast of the Western Cape province in late October 2018. The results showed that 37.4% of the area was severely burned, and much of it occurred in forested land in the studied area. This was followed by 24.7% of the area that was burned at a moderate-high level. About 15.9% had moderate-low burned severity, whereas 21.9% was slightly burned. Random forests classifier was adopted to separate burned class from unburned and achieved an overall accuracy of over 97%. The most important variables in the classification included texture, NBR, and the NIR bands. The CO signal sharply increased during fire outbreaks and marked the intensity of black carbon over the affected area. Our study contributes to the understanding of forest fire in the dynamics over the Southern Cape forestry landscape. Furthermore, it also demonstrates the usefulness of Sentinel-5 for monitoring CO. Taken together, the Sentinel satellites and GEE offer an effective tool for mapping fires, even in data-poor countries.
Collapse
|
30
|
Affiliation(s)
- Jonathan T Overpeck
- School for Environment and Sustainability, University of Michigan, Ann Arbor, MI, USA.
| | - David D Breshears
- School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, USA.
| |
Collapse
|
31
|
Cao S, Liu Z, Li W, Xian J. Balancing ecological conservation with socioeconomic development. AMBIO 2021; 50:1117-1122. [PMID: 33454911 PMCID: PMC8035341 DOI: 10.1007/s13280-020-01448-z] [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: 09/15/2020] [Revised: 11/01/2020] [Accepted: 11/18/2020] [Indexed: 06/12/2023]
Abstract
Ecological restoration and conservation are primary components of sustainable development around the world, particularly during the contemporary era of climate change. However, restoration and conservation are not free; they consume huge amounts of resources that would otherwise support social and economic development. Therefore, excessive conservation creates a risk of creating rather than eliminating poverty. Unfortunately, scientists have largely ignored the balance between these contrasting goals. Here, we discuss the concept of finding the threshold that represents a suitable balance between ecological conservation and economic development, thereby maximizing the benefits for both humans and the environment and promoting sustainable development. To demonstrate the concept, we examined China's ecological restoration achievements and discussed some of the unforeseen negative consequences that accompanied these achievements to discuss how future policies could better balance ecological and socioeconomic goals.
Collapse
Affiliation(s)
- Shixiong Cao
- School of Economics, Minzu University of China, No. 27 Zhongguancun South Street, Haidian District, Beijing, 100081 People’s Republic of China
| | - Zhexi Liu
- Academy of Social Sciences, Tsinghua University, No. 30 Shuangqing Road, Haidian District, Beijing, 100084 People’s Republic of China
| | - Weiming Li
- School of Economics, Minzu University of China, No. 27 Zhongguancun South Street, Haidian District, Beijing, 100081 People’s Republic of China
| | - Junli Xian
- School of Economics, Minzu University of China, No. 27 Zhongguancun South Street, Haidian District, Beijing, 100081 People’s Republic of China
| |
Collapse
|
32
|
Maringer J, Hacket‐Pain A, Ascoli D, Garbarino M, Conedera M. A new approach for modeling delayed fire‐induced tree mortality. Ecosphere 2021. [DOI: 10.1002/ecs2.3458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Janet Maringer
- Insubric Ecosystems Swiss Federal Institute for Forest, Snow and Landscape Research WSL A Ramél 18 CadenazzoCH‐6593Switzerland
| | - Andrew Hacket‐Pain
- Department of Geography and Planning School of Environmental Science University of Liverpool LiverpoolL69 7ZTUK
| | - Davide Ascoli
- Department of Agriculture, Forest and Food Sciences University of Turin Largo Paolo Braccini 2 Grugliasco10095Italy
| | - Matteo Garbarino
- Department of Agriculture, Forest and Food Sciences University of Turin Largo Paolo Braccini 2 Grugliasco10095Italy
| | - Marco Conedera
- Insubric Ecosystems Swiss Federal Institute for Forest, Snow and Landscape Research WSL A Ramél 18 CadenazzoCH‐6593Switzerland
| |
Collapse
|
33
|
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.
Collapse
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
| | | |
Collapse
|
34
|
Maher CT, Millar CI, Affleck DLR, Keane RE, Sala A, Tobalske C, Larson AJ, Nelson CR. Alpine treeline ecotones are potential refugia for a montane pine species threatened by bark beetle outbreaks. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e2274. [PMID: 33617144 DOI: 10.1002/eap.2274] [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: 09/09/2020] [Accepted: 10/05/2020] [Indexed: 06/12/2023]
Abstract
Warming-induced mountain pine beetle (Dendroctonus ponderosae; MPB) outbreaks have caused extensive mortality of whitebark pine (Pinus albicaulis; WBP) throughout the species' range. In the highest mountains where WBP occur, they cross alpine treeline ecotones (ATEs) where growth forms transition from trees to shrub-like krummholz, some of which survived recent MPB outbreaks. This observation motivated the hypothesis that ATEs are refugia for WBP because krummholz growth forms escape MPB attack and have the potential to produce viable seed. To test this hypothesis, we surveyed WBP mortality along transects from the ATE edge (locally highest krummholz WBP) downslope into the forest and, to distinguish if survival mechanisms are unique to ATEs, across other forest ecotones (OFEs) from the edge of WBP occurrence into the forest. We replicated this design at 10 randomly selected sites in the U.S. Northern Rocky Mountains. We also surveyed reproduction in a subset of ATE sites. Mortality was nearly absent in upper ATEs (mean ± SE percent dead across all sites of 0.03% ± 0.03% 0-100 m from the edge and 14.1% ± 1.7% 100-500 m from the edge) but was above 20% along OFEs (21.4 ± 5.2% 0-100 m and 32.4 ± 2.7% 100-500 m from the edge). We observed lower reproduction in upper ATEs (16 ± 9.9 cones/ha and 12.9 ± 5.3 viable seeds/cone 0-100 m from the edge) compared to forests below (317.1 ± 64.4 cones/ha and 32.5 ± 2.5 viable seeds/cone 100-500 m from the edge). Uniquely high WBP survival supports the hypothesis that ATEs serve as refugia because krummholz growth forms escape MPB attack. However, low reproduction suggests ATE refugia function over longer time periods. Beyond our WBP system, we propose that plant populations in marginal environments are candidate refugia if distinct phenotypes result in reduced disturbance impacts.
Collapse
Affiliation(s)
- Colin T Maher
- WA Franke College of Forestry and Conservation, The University of Montana, 32 Campus Drive, Missoula, Montana, 59812, USA
| | - Constance I Millar
- Pacific Southwest Research Station, USDA Forest Service, 800 Buchanan Street, Albany, California, 94710, USA
| | - David L R Affleck
- WA Franke College of Forestry and Conservation, The University of Montana, 32 Campus Drive, Missoula, Montana, 59812, USA
| | - Robert E Keane
- Rocky Mountain Research Station, Missoula Fire Science Laboratory, USDA Forest Service, 5775 Highway 10 West, Missoula, Montana, 59808, USA
| | - Anna Sala
- Division of Biological Sciences, The University of Montana, 32 Campus Drive, Missoula, Montana, 59812, USA
| | - Claudine Tobalske
- Spatial Analysis Lab, Montana Natural Heritage Program, The University of Montana, 32 Campus Drive, Missoula, Montana, 59812, USA
| | - Andrew J Larson
- WA Franke College of Forestry and Conservation, Wilderness Institute, The University of Montana, 32 Campus Drive, Missoula, Montana, 59812, USA
| | - Cara R Nelson
- WA Franke College of Forestry and Conservation, The University of Montana, 32 Campus Drive, Missoula, Montana, 59812, USA
| |
Collapse
|
35
|
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.
Collapse
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
| |
Collapse
|
36
|
Parker L, Pathak T, Ostoja S. Climate change reduces frost exposure for high-value California orchard crops. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 762:143971. [PMID: 33373749 DOI: 10.1016/j.scitotenv.2020.143971] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 11/13/2020] [Accepted: 11/14/2020] [Indexed: 06/12/2023]
Abstract
Frost exposure is a particular challenge for cultivating perennial crops, whose adaptive capacity to weather and climate impacts is limited. Irrigation is a common means of mitigating damage, but draws on limited water resources, is costly, and energy intensive. Here we examined the projected impact of climate change on the incidence of frost temperatures during the coldest winters, defined by the 98th percentile of cool season (November-April) frost hours, under both early- and mid-21st century time periods, as compared to contemporary conditions, across a range of threshold temperatures. We focused on three high-value perennial orchard crops - almonds, avocados, and oranges - to assess the effects of climate change on the incidence of temperatures below crop-specific threshold temperatures and for crop-specific critical development phases, and what these temporal changes in frost exposure may mean for the water and energy requirements for mitigating damages. Across time periods and temperature thresholds, frost exposure declines in California's agricultural regions, with an average of reduction in frost exposure of 63% by the mid-21st century. The majority of almond and orange acreage saw 50-75% reductions in frost exposure by mid-century, while avocado acreage experienced >75% fewer frost hours. This yielded attendant reductions in water use and energy costs, and growers in the highest acreage counties may save more than 50,000 acre feet of water and $4.2 million in electricity costs for water pumping per year, collectively. Although climate change is projected to increase growing season crop water demands, pest pressures, and have an overall net-negative impact on agriculture, the potential reduction in frost exposure and the accompanying water and energy costs to mitigate frost damages may allow growers to reprioritize some of their long-term decisions around farm management.
Collapse
Affiliation(s)
- Lauren Parker
- USDA California Climate Hub, Davis, CA 95616, United States of America; John Muir Institute of the Environment, University of California, Davis, CA 95616, United States of America.
| | - Tapan Pathak
- Division of Agriculture and Natural Resources, University of California, Merced, CA 95343, United States of America
| | - Steven Ostoja
- USDA California Climate Hub, Davis, CA 95616, United States of America; John Muir Institute of the Environment, University of California, Davis, CA 95616, United States of America; USDA-ARS Crops Pathology and Genetics Research Unit, Davis, CA 95616, United States of America
| |
Collapse
|
37
|
Steel ZL, Goodwin MJ, Meyer MD, Fricker GA, Zald HSJ, Hurteau MD, North MP. Do forest fuel reduction treatments confer resistance to beetle infestation and drought mortality? Ecosphere 2021. [DOI: 10.1002/ecs2.3344] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Affiliation(s)
- Z. L. Steel
- John Muir Institute University of California Davis California95616USA
- Department of Environmental Science, Policy and Management University of California Berkeley California94720USA
| | - M. J. Goodwin
- Department of Biology University of New Mexico Albuquerque New Mexico87131USA
| | - M. D. Meyer
- Pacific Southwest Region USDA Forest Service Southern Sierra Province Bishop California93514USA
| | - G. A. Fricker
- Social Sciences Department California Polytechnic University San Luis Obispo California93407USA
| | - H. S. J. Zald
- Department of Forestry and Wildland Resources Humboldt State University Arcata California95521USA
| | - M. D. Hurteau
- Department of Biology University of New Mexico Albuquerque New Mexico87131USA
| | - M. P. North
- John Muir Institute University of California Davis California95616USA
- Pacific Southwest Research Station USDA Forest Service Mammoth Lakes California93546USA
| |
Collapse
|
38
|
Merrick MJ, Morandini M, Greer VL, Koprowski JL. Endemic Population Response to Increasingly Severe Fire: A Cascade of Endangerment for the Mt. Graham Red Squirrel. Bioscience 2021. [DOI: 10.1093/biosci/biaa153] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Abstract
Drought, past fire suppression, insect invasion, and high-severity fire represent a disturbance cascade characteristic of forests in the western United States. The result is altered forest ecosystems diminished in their function and capacity to support biodiversity. Small habitat specialists are particularly vulnerable to the impacts of disturbances because of their limited movement capacity and high site fidelity. Research suggests that small mammals suffer limited direct mortality from fire but are increasingly vulnerable to local extirpation because of secondary impacts that include habitat loss and reduced food availability, survival, and reproduction. We examine the direct and secondary impacts of increasingly severe fire events on the endangered Mt. Graham red squirrel—a model system to demonstrate how disturbances can threaten the persistence of range-limited species. We document survival, space use, and displacement prior to and following fires and discuss implications for conservation. We suggest that management plans address future threats, including disturbance-related habitat loss.
Collapse
Affiliation(s)
| | | | | | - John L Koprowski
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, United States
- JK is also a dean, professor, and the Wyoming Excellence Chair of at the Haub School of Environment and Natural Resources, University of Wyoming
| |
Collapse
|
39
|
Stephens SL, Battaglia MA, Churchill DJ, Collins BM, Coppoletta M, Hoffman CM, Lydersen JM, North MP, Parsons RA, Ritter SM, Stevens JT. Forest Restoration and Fuels Reduction: Convergent or Divergent? Bioscience 2020. [DOI: 10.1093/biosci/biaa134] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
For over 20 years, forest fuel reduction has been the dominant management action in western US forests. These same actions have also been associated with the restoration of highly altered frequent-fire forests. Perhaps the vital element in the compatibility of these treatments is that both need to incorporate the salient characteristics that frequent fire produced—variability in vegetation structure and composition across landscapes and the inability to support large patches of high-severity fire. These characteristics can be achieved with both fire and mechanical treatments. The possible key to convergence of fuel reduction and forest restoration strategies is integrated planning that permits treatment design flexibility and a longer-term focus on fire reintroduction for maintenance. With changing climate conditions, long-term forest conservation will probably need to be focused on keeping tree density low enough (i.e., in the lower range of historic variation) for forest conditions to adapt to emerging disturbance patterns and novel ecological processes.
Collapse
Affiliation(s)
- Scott L Stephens
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, in Berkeley, California
| | - Mike A Battaglia
- US Department of Agriculture (USDA), Forest Service, Rocky Mountain Research Station, Fort Collins, Colorado
| | - Derek J Churchill
- Forest Health and Resiliency Division of the Washington Department of Natural Resources, Olympia, Washington
| | - Brandon M Collins
- Fire Research and Outreach at the University of California, Berkeley, Berkeley, California, and with the USDA Forest Service, Pacific Southwest Research Station, Davis, California
| | - Michelle Coppoletta
- USDA Forest Service, Sierra Cascade Province Ecology Program, Quincy, California
| | - Chad M Hoffman
- Department of Forest and Rangeland Stewardship, Colorado State University, Fort Collins, Colorado
| | - Jamie M Lydersen
- California Department of Forestry and Fire Protection, Fire and Resource Assessment Program, Sacramento, California
| | - Malcolm P North
- USDA Forest Service, PSW Research Station, Mammoth Lakes, California, and with the Department of Plant Sciences, University of California, Davis, Davis, California
| | | | - Scott M Ritter
- Department of Forest and Rangeland Stewardship, Colorado State University, Fort Collins, Colorado
| | - Jens T Stevens
- US Geological Survey, New Mexico Landscapes Field Station, Santa Fe, New Mexico
| |
Collapse
|
40
|
Goodwin MJ, North MP, Zald HSJ, Hurteau MD. Changing climate reallocates the carbon debt of frequent-fire forests. GLOBAL CHANGE BIOLOGY 2020; 26:6180-6189. [PMID: 32810926 DOI: 10.1111/gcb.15318] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 07/24/2020] [Indexed: 06/11/2023]
Abstract
Ongoing climate change will alter the carbon carrying capacity of forests as they adjust to climatic extremes and changing disturbance regimes. In frequent-fire forests, increasing drought frequency and severity are already causing widespread tree mortality events, which can exacerbate the carbon debt that has developed as a result of fire exclusion. Forest management techniques that reduce tree density and surface fuels decrease the risk of high-severity wildfire and may also limit drought-induced mortality by reducing competition. We used a long-term thinning and burning experiment in a mixed-conifer forest to investigate the effects of the 2012-2015 California drought on forest carbon dynamics in each treatment, including the carbon emissions from a second-entry prescribed fire that followed the drought. We assessed differences in carbon stability and tree survival across treatments, expecting that both carbon stability and survival probability would increase with increasing treatment intensity (decreasing basal area). Additionally, we analyzed the effects of drought- mortality on second-entry burn emissions and compared emissions for the first- and second-entry burns. We found a non-linear relationship between treatment intensity and carbon stability, which was in part driven by varying relationships between individual tree growing space and survival across treatments. Drought mortality increased dead tree and surface fuel carbon in all treatments, which contributed to higher second-entry burn emissions for two of the three burn treatments when compared to the first burn. Our findings suggest that restoration treatments will not serve as a panacea for ongoing climate change and that the carbon debt of these forests will become increasingly unstable as the carbon carrying capacity adjusts to severe drought events. Managing the carbon debt with prescribed fire will help reduce the risk of additional mortality from wildfire, but at an increasing carbon cost for forest management.
Collapse
Affiliation(s)
- Marissa J Goodwin
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Malcolm P North
- Pacific Southwest Research Station, USDA Forest Service, Mammoth Lakes, CA, USA
- Department of Plant Sciences, University of California, Davis, CA, USA
| | - Harold S J Zald
- Department of Forestry and Wildland Resources, Humboldt State University, Arcata, CA, USA
| | - Matthew D Hurteau
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| |
Collapse
|
41
|
Xu X, Jia G, Zhang X, Riley WJ, Xue Y. Climate regime shift and forest loss amplify fire in Amazonian forests. GLOBAL CHANGE BIOLOGY 2020; 26:5874-5885. [PMID: 32662146 DOI: 10.1111/gcb.15279] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 07/07/2020] [Indexed: 06/11/2023]
Abstract
Frequent Amazonian fires over the last decade have raised the alarm about the fate of the Earth's most biodiverse forest. The increased fire frequency has been attributed to altered hydrological cycles. However, observations over the past few decades have demonstrated hydrological changes that may have opposing impacts on fire, including higher basin-wide precipitation and increased drought frequency and severity. Here, we use multiple satellite observations and climate reanalysis datasets to demonstrate compelling evidence of increased fire susceptibility in response to climate regime shifts across Amazonia. We show that accumulated forest loss since 2000 warmed and dried the lower atmosphere, which reduced moisture recycling and resulted in increased drought extent and severity, and subsequent fire. Extremely dry and wet events accompanied with hot days have been more frequent in Amazonia due to climate shift and forest loss. Simultaneously, intensified water vapor transport from the tropical Pacific and Atlantic increased high-altitude atmospheric humidity and heavy rainfall events, but those events did not alleviate severe and long-lasting droughts. Amazonia fire risk is most significant in the southeastern region where tropical savannas undergo long seasonally dry periods. We also find that fires have been expanding through the wet-dry transition season and northward to savanna-forest transition and tropical seasonal forest regions in response to increased forest loss at the "Arc of Deforestation." Tropical forests, which have adapted to historically moist conditions, are less resilient and easily tip into an alternative state. Our results imply forest conservation and fire protection options to reduce the stress from positive feedback between forest loss, climate change, and fire.
Collapse
Affiliation(s)
- Xiyan Xu
- Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Gensuo Jia
- Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Xiaoyan Zhang
- School of Atmospheric Science, Nanjing University of Information Science and Technology, Nanjing, China
| | - William J Riley
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Ying Xue
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, China
| |
Collapse
|
42
|
Effect of Silviculture on Carbon Pools during Development of a Ponderosa Pine Plantation. FORESTS 2020. [DOI: 10.3390/f11090997] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Forest stands can be considered as dynamic carbon pools throughout their developmental stages. Silvicultural thinning and initial planting densities for reforestation not only manipulate the structure or composition of vegetation, but also disturb forest floor and soils, which, in turn, influences the dynamics of carbon pools. Understanding these carbon pools both spatially and temporally can provide useful information for land managers to achieve their management goals. Here, we estimated five major carbon pools in experimental ponderosa pine (Pinus ponderosa) plots that were planted to three levels of spacing and where competing vegetation was either controlled (VC) or not controlled (NVC). The objectives were to determine how an early competing vegetation control influences the long-term carbon dynamics and how stand density affects the maximum carbon (C) sequestration for these plantations. We found that planting density did not affect total ecosystem C at either sampling age 28 or 54. Because of competing vegetation ingrowth, the NVC (85 ± 14 Mg ha−1) accumulated greater C than the VC (61 ± 6 Mg ha−1) at age 28. By age 54, the differences between treatments narrow with the NVC (114 ± 11 Mg ha−1) and the VC (106 ± 11 Mg ha−1) as the pines continue to grow relatively faster in the VC when compared to NVC and C of ingrowth vegetation decreased in NVC, presumably due to shading by the overstory pines. The detritus was not significantly different among treatments in either years, although the mean forest floor and soil C was slightly greater in NVC. While NVC appears to sequester more C early on, the differences from the VC were rather subtle. Clearly, as the stands continue to grow, the C of the larger pines of the VC may overtake the total C of the NVC. We conclude that, to manage forests for carbon, we must pay more attention to promoting growth of overstory trees by controlling competing vegetation early, which will provide more opportunities for foresters to create resilient forests to disturbances and store C longer in a changing climate.
Collapse
|
43
|
Weiskopf SR, Rubenstein MA, Crozier LG, Gaichas S, Griffis R, Halofsky JE, Hyde KJW, Morelli TL, Morisette JT, Muñoz RC, Pershing AJ, Peterson DL, Poudel R, Staudinger MD, Sutton-Grier AE, Thompson L, Vose J, Weltzin JF, Whyte KP. Climate change effects on biodiversity, ecosystems, ecosystem services, and natural resource management in the United States. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 733:137782. [PMID: 32209235 DOI: 10.1016/j.scitotenv.2020.137782] [Citation(s) in RCA: 114] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 02/28/2020] [Accepted: 03/05/2020] [Indexed: 05/22/2023]
Abstract
Climate change is a pervasive and growing global threat to biodiversity and ecosystems. Here, we present the most up-to-date assessment of climate change impacts on biodiversity, ecosystems, and ecosystem services in the U.S. and implications for natural resource management. We draw from the 4th National Climate Assessment to summarize observed and projected changes to ecosystems and biodiversity, explore linkages to important ecosystem services, and discuss associated challenges and opportunities for natural resource management. We find that species are responding to climate change through changes in morphology and behavior, phenology, and geographic range shifts, and these changes are mediated by plastic and evolutionary responses. Responses by species and populations, combined with direct effects of climate change on ecosystems (including more extreme events), are resulting in widespread changes in productivity, species interactions, vulnerability to biological invasions, and other emergent properties. Collectively, these impacts alter the benefits and services that natural ecosystems can provide to society. Although not all impacts are negative, even positive changes can require costly societal adjustments. Natural resource managers need proactive, flexible adaptation strategies that consider historical and future outlooks to minimize costs over the long term. Many organizations are beginning to explore these approaches, but implementation is not yet prevalent or systematic across the nation.
Collapse
Affiliation(s)
- Sarah R Weiskopf
- U.S. Geological Survey National Climate Adaptation Science Center, Reston, VA, USA.
| | | | - Lisa G Crozier
- NOAA Northwest Fisheries Science Center, Seattle, WA, USA
| | - Sarah Gaichas
- NOAA Northeast Fisheries Science Center, Woods Hole, MA, USA
| | - Roger Griffis
- NOAA National Marine Fisheries Service, Silver Spring, MD, USA
| | - Jessica E Halofsky
- University of Washington, School of Environmental and Forest Sciences, Seattle, WA, USA
| | | | - Toni Lyn Morelli
- U.S. Geological Survey Northeast Climate Adaptation Science Center, Amherst, MA, USA
| | - Jeffrey T Morisette
- U.S. Department of the Interior, National Invasive Species Council Secretariat, Fort Collins, CO, USA
| | - Roldan C Muñoz
- NOAA Southeast Fisheries Science Center, Beaufort, NC, USA
| | | | - David L Peterson
- University of Washington, School of Environmental and Forest Sciences, Seattle, WA, USA
| | | | - Michelle D Staudinger
- U.S. Geological Survey Northeast Climate Adaptation Science Center, Amherst, MA, USA
| | - Ariana E Sutton-Grier
- University of Maryland Earth System Science Interdisciplinary Center, College Park, MD, USA
| | - Laura Thompson
- U.S. Geological Survey National Climate Adaptation Science Center, Reston, VA, USA
| | - James Vose
- U.S. Forest Service Southern Research Station, Raleigh, NC, USA
| | | | | |
Collapse
|
44
|
|
45
|
Abstract
Wildland fire managers are increasingly embracing risk management principles by being more anticipatory, proactive, and “engaging the fire before it starts”. This entails investing in pre-season, cross-boundary, strategic fire response planning with partners and stakeholders to build a shared understanding of wildfire risks and management opportunities. A key innovation in planning is the development of potential operational delineations (PODs), i.e., spatial management units whose boundaries are relevant to fire containment operations (e.g., roads, ridgetops, and fuel transitions), and within which potential fire consequences, suppression opportunities/challenges, and strategic response objectives can be analyzed to inform fire management decision making. As of the summer of 2020, PODs have been developed on more than forty landscapes encompassing National Forest System lands across the western USA, providing utility for planning, communication, mitigation prioritization, and incident response strategy development. Here, we review development of a decision support tool—a POD Atlas—intended to facilitate cross-boundary, collaborative strategic wildfire planning and management by providing high-resolution information on landscape conditions, values at risk, and fire management resource needs for individual PODs. With the atlas, users can rapidly access and assimilate multiple forms of pre-loaded data and analytics in a customizable manner. We prototyped and operationalized this tool in concert with, and for use by, fire managers on several National Forests in the Southern Rocky Mountains of the USA. We present examples, discuss real-world use cases, and highlight opportunities for continued decision support improvement.
Collapse
|
46
|
Furniss TJ, Larson AJ, Kane VR, Lutz JA. Wildfire and drought moderate the spatial elements of tree mortality. Ecosphere 2020. [DOI: 10.1002/ecs2.3214] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- Tucker J. Furniss
- Wildland Resources Department and Ecology Center Utah State University Logan Utah84322USA
| | - Andrew J. Larson
- Wilderness Institute and Department of Forest Management University of Montana Missoula Montana59812USA
| | - Van R. Kane
- School of Environmental and Forest Sciences University of Washington Seattle Washington98195USA
| | - James A. Lutz
- Wildland Resources Department and Ecology Center Utah State University Logan Utah84322USA
| |
Collapse
|
47
|
Rouzitalab Z, Maklavany DM, Jafarinejad S, Rashidi A. Lignocellulose-based adsorbents: A spotlight review of the effective parameters on carbon dioxide capture process. CHEMOSPHERE 2020; 246:125756. [PMID: 31918088 DOI: 10.1016/j.chemosphere.2019.125756] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/21/2019] [Accepted: 12/24/2019] [Indexed: 06/10/2023]
Abstract
The increasing demand for energy all around the world has led to a rise in greenhouse gases (GHGs), of which carbon dioxide (CO2) is the most important. CO2 is largely responsible for global warming and climate change. Processes such as carbon dioxide capture and storage (CCS), which have an effective role in climate mitigation, seem to be promising. In recent years, porous carbons, particularly activated carbons (ACs), have rapidly emerged as one of the most effective adsorbents of CO2. However, the implementation of pristine ACs in the real world is still hindered due to their physical and weak adsorption, which makes these adsorbents sensitive to temperature and relatively poor in selectivity. Hence, the surface modification of ACs is essential in order to improve their surface area, pore structure and alkalinity. Numerous studies have reported lignocellulose-based ACs as very promising adsorbents of CO2. In this review, the sources, health and environmental effects of CO2, and the abatement methods of GHGs are described. In addition, the capture and separation of CO2 from gas stream using various types of lignocellulose-based ACs are summarized. Furthermore, the key factors controlling the adsorption of CO2 by ACs (characteristics of adsorbents, preparation conditions, as well as adsorption conditions) are comprehensively and critically discussed. Finally, future research needs and prospective research challenges are summarized.
Collapse
Affiliation(s)
- Zahra Rouzitalab
- Civil Engineering Division, College of Environment, Karaj, P.O. Box 31746-74761, Alborz, Iran
| | - Davood Mohammady Maklavany
- Carbon & Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), Tehran, P.O. Box 31746-74761, Tehran, Iran
| | - Shahryar Jafarinejad
- Department of Chemical Engineering, College of Engineering, Tuskegee University, Tuskegee, P.O. Box 5899, Alabama, 36088, USA
| | - Alimorad Rashidi
- Carbon & Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), Tehran, P.O. Box 31746-74761, Tehran, Iran.
| |
Collapse
|
48
|
Mazzamuto MV, Mazzella MN, Merrick MJ, Koprowski JL. Fire impacts on a forest obligate: western gray squirrel response to burn severity. Mamm Biol 2020. [DOI: 10.1007/s42991-020-00024-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
49
|
Sarricolea P, Serrano-Notivoli R, Fuentealba M, Hernández-Mora M, de la Barrera F, Smith P, Meseguer-Ruiz Ó. Recent wildfires in Central Chile: Detecting links between burned areas and population exposure in the wildland urban interface. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 706:135894. [PMID: 31841846 DOI: 10.1016/j.scitotenv.2019.135894] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 11/21/2019] [Accepted: 12/01/2019] [Indexed: 06/10/2023]
Abstract
Wildfires are gaining importance in the Mediterranean regions owing to climate change and landscape changes due to the increasing closeness between urban areas and forests prone to wildfires. We analysed the dry season wildfire occurrences in the Mediterranean region of Central Chile (32°S-39°30' S) between 2000 and 2017, using satellite images to detect burned areas, their landscape metrics and the land use and covers (vegetal) pre-wildfire, in order to determine the population living in areas that may be affected by wildfires. The existing regulations in western Mediterranean countries (Portugal, Spain, France, and Italy) were used to identify and define the wildland-urban interface (WUI) areas, quantifying the people inhabiting them and estimating the population affected by burned areas from 2001 to 2017. We used the Google Earth Engine to process MODIS products and extract both burned areas and land covers. We detected that 25% of the urban population inhabits WUI areas (i.e. Biobío, Araucanía and Valparaíso regions) where the urban population exposed to burned areas exceeds 40%. Most of the land use and land covers affected by wildfires are anthropogenic land covers, classified as savannas, croplands, evergreen broadleaf forests and woody savannas, representing >70% of the burned areas. Urban areas show only 0.6% of the burned surface from 2001 to 2017. We estimate that 55,680 people are potentially affected by wildfires, and 50% of them are in just one administrative region. These results show the imperative need for public policies as a regulating force for establishing WUI areas with the purpose of identifying wildfire risk in urban areas, such as establishing prevention methods as firewalls and prescribed fires.
Collapse
Affiliation(s)
| | - Roberto Serrano-Notivoli
- Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (EEAD-CSIC), Zaragoza, Spain
| | - Magdalena Fuentealba
- Departamento de Ecología, Pontificia Universidad Católica de Chile, Alameda, Santiago, Chile; Institute of Ecology and Biodiversity (IEB), Santiago, Chile; Laboratorio Internacional de Cambio Global, LINCGlobal PUC-CSIC, Spain
| | - Marina Hernández-Mora
- Instituto de Geografía de la Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Francisco de la Barrera
- Departamento de Geografía, Universidad de Concepción, Concepción, Chile; Centro del Desarrollo Urbano Sustentable, Concepción, Chile
| | - Pamela Smith
- Department of Geography, University of Chile, Santiago, Chile; Center for Climate and Resilience Research (CR)2, Santiago, Chile
| | - Óliver Meseguer-Ruiz
- Departamento de Ciencias Históricas y Geográficas, Universidad de Tarapacá, Arica, Chile
| |
Collapse
|
50
|
Crotteau JS, Keyes CR, Hood SM, Larson AJ. Vegetation dynamics following compound disturbance in a dry pine forest: fuel treatment then bark beetle outbreak. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e02023. [PMID: 31628705 DOI: 10.1002/eap.2023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 07/26/2019] [Accepted: 08/27/2019] [Indexed: 06/10/2023]
Abstract
In the western United States, restoration of forests with historically frequent, low-severity fire regimes often includes fuel reduction that reestablish open, early-seral conditions while reducing fuel continuity and loading. Between 2001 and 2016, fuel reduction (e.g., thinning, prescribed burning, etc.) was implemented on over 26 million hectares of federal lands alone in the United States, reflecting the urgency to mitigate risk from high-severity wildfire. However, between 2001 and 2012, nearly 20 million hectares in the United States were impacted by mountain pine beetle (MPB; Dendroctonus ponderosae), compounding restoration effects in wildfire-hazard-treated stands. Knowledge of the effects of treatments followed by natural disturbance on long-term forest structure and communities is needed, especially considering that fuel treatments are increasingly being implemented and warming climate is predicted to exacerbate disturbance frequency and severity. We tested the interacting effects of treatments designed to reduce high-severity wildfire hazard in stands subsequently challenged by MPB outbreak on vegetation dynamics using a factorial experimental design (control, thin only, burn only, thin + burn) in a ponderosa pine (Pinus ponderosa)-dominated forest. Stands were treated by 2002, then impacted by MPB outbreak from 2005 to 2012. We assessed change in overstory and understory forest community structure, composition, and diversity over time. There were distinct thinning, burning, and year effects. Thinning immediately reduced overstory density; pine density then declined 4.5 times more in unthinned than thinned treatments due to MPB. Burning immediately reduced graminoid, shrub, and total understory cover by as much as 52%, resulting in greater species evenness than unburned treatments, but differences disappeared by 2016 due to growth and MPB outbreak. Similarly, multivariate analyses indicated forest communities were starkly different after treatment but became more similar over time, though key understory and overstory attributes still distinguish control and thin + burn. This study shows the value of long-term silvicultural experiments to evaluate treatment longevity and the compounded effects of treatment and natural disturbance. We demonstrate the homogenizing effects of treatment-induced growth coupled with MPB-caused tree mortality on management strategies that just treat the overstory (thinning) or understory (burning), showing that only combined treatments can provide the unique structural and compositional outcomes expected of restoration.
Collapse
Affiliation(s)
- Justin S Crotteau
- Pacific Northwest Research Station, USDA Forest Service, 11175 Auke Lake Way, Juneau, Alaska, 99801, USA
| | - Christopher R Keyes
- WA Franke College of Forestry and Conservation, University of Montana, 32 Campus Drive, Missoula, Montana, 59812, USA
| | - Sharon M Hood
- Rocky Mountain Research Station, Fire, Fuel, and Smoke Science Program, USDA Forest Service, 5775 Highway 10 W., Missoula, Montana, 59808, USA
| | - Andrew J Larson
- WA Franke College of Forestry and Conservation, University of Montana, 32 Campus Drive, Missoula, Montana, 59812, USA
| |
Collapse
|