1
|
Zhang Z, Ju W, Zhou Y, Li X. Revisiting the cumulative effects of drought on global gross primary productivity based on new long-term series data (1982-2018). GLOBAL CHANGE BIOLOGY 2022; 28:3620-3635. [PMID: 35343026 DOI: 10.1111/gcb.16178] [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: 01/29/2022] [Revised: 03/05/2022] [Accepted: 03/05/2022] [Indexed: 06/14/2023]
Abstract
Drought has broad and deep impacts on vegetation. Studies on the effects of drought on vegetation have been conducted over years. Recently, the cumulative effect of drought is recognized as another key factor affecting plant growth. However, global-scale studies on this phenomenon are still lacking. Thus, based on new satellite based gross primary productivity (GPP) and multi-temporal scale Standardized Precipitation Evapotranspiration Index data sets, we explored the cumulative effect duration (CED) of drought on global vegetation GPP and analyzed its variability across elevations and climatic zones. The main findings were as follows: (1) The cumulative effect of drought on GPP was widespread, with an average CED of 4.89 months. (2) CED of drought on GPP varied among vegetation types. Specifically, grasslands showed the longest duration, with an average value of 5.28 months, followed by shrublands (5.09 months), wetlands (5.03 months), croplands (4.85 months), savannas (4.58 months), and forestlands (4.57 months). (3) CED of drought on GPP changes with climate conditions. It decreased with the decrease of precipitation in the driest month (Pdry ) and mean annual precipitation in tropical and arid climate zones, respectively. In both temperate and cold climate zones, CED of drought on GPP was shorter in areas with dry winter than that in areas with dry summer. It increased with the decrease of mean annual air temperature in tropical climate zones and decreased with the increase of summer temperature in temperate and cold climatic zones. (4) With increasing elevation, CED of drought on GPP showed a pattern of increasing (0-3000 m), then decreasing (3000-5000 m), and increasing again (>5000 m). Our findings highlight the heterogeneity of CED of drought on GPP, owing to differences in vegetation types, long-term hydrothermal conditions, elevation, etc. The results could deepen our understanding of the effects of drought on global vegetation.
Collapse
Affiliation(s)
- Zhenyu Zhang
- International Institute of Earth System Science, Nanjing University, Nanjing, China
- School of Geography and Ocean Science, Nanjing University, Nanjing, China
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, Zhejiang, China
| | - Weimin Ju
- International Institute of Earth System Science, Nanjing University, Nanjing, China
- Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China
| | - Yanlian Zhou
- School of Geography and Ocean Science, Nanjing University, Nanjing, China
| | - Xiaoyu Li
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, Zhejiang, China
| |
Collapse
|
2
|
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
|
3
|
Kirchhoff C, Callaghan CT, Keith DA, Indiarto D, Taseski G, Ooi MKJ, Le Breton TD, Mesaglio T, Kingsford RT, Cornwell WK. Rapidly mapping fire effects on biodiversity at a large-scale using citizen science. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 755:142348. [PMID: 33045599 DOI: 10.1016/j.scitotenv.2020.142348] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/09/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
The unprecedented scale of the 2019-2020 eastern Australian bushfires exemplifies the challenges that scientists and conservation biologists face monitoring the effects on biodiversity in the aftermath of large-scale environmental disturbances. After a large-scale disturbance, conservation policy and management actions need to be both timely and informed by data. By working with the public, often widely spread out over such disturbed areas, citizen science offers a unique opportunity to collect data on biodiversity responses at the appropriate scale. We detail a citizen science project, hosted through iNaturalist, launched shortly after the 2019-2020 bushfire season in eastern Australia. It rapidly (1) provided accurate data on fire severity, relevant to future recovery; and (2) delivered data on a wide range (mosses to mammals) of biodiversity responses at a scale that matched the geographic extent of these fires.
Collapse
Affiliation(s)
- Casey Kirchhoff
- Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW 2052, Australia.
| | - Corey T Callaghan
- Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW 2052, Australia; Ecology & Evolution Research Centre, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - David A Keith
- Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW 2052, Australia; NSW Department of Planning, Industry, and Environment, Sydney, NSW, Australia; Bushfire Risk Management Research Hub, Wollongong, NSW, Australia
| | - Dony Indiarto
- Ecology & Evolution Research Centre, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Guy Taseski
- Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Mark K J Ooi
- Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW 2052, Australia; Bushfire Risk Management Research Hub, Wollongong, NSW, Australia
| | - Tom D Le Breton
- Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW 2052, Australia; Bushfire Risk Management Research Hub, Wollongong, NSW, Australia
| | - Thomas Mesaglio
- Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Richard T Kingsford
- Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| | - William K Cornwell
- Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW 2052, Australia; Ecology & Evolution Research Centre, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW 2052, Australia
| |
Collapse
|
4
|
Zhou Y, Wigley BJ, Case MF, Coetsee C, Staver AC. Rooting depth as a key woody functional trait in savannas. THE NEW PHYTOLOGIST 2020; 227:1350-1361. [PMID: 32306404 DOI: 10.1111/nph.16613] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/08/2020] [Indexed: 05/17/2023]
Abstract
Dimensions of tree root systems in savannas are poorly understood, despite being essential in resource acquisition and post-disturbance recovery. We studied tree rooting patterns in Southern African savannas to ask: how tree rooting strategies affected species responses to severe drought; and how potential rooting depths varied across gradients in soil texture and rainfall. First, detailed excavations of eight species in Kruger National Park suggest that the ratio of deep to shallow taproot diameters provides a reasonable proxy for potential rooting depth, facilitating extensive interspecific comparison. Detailed excavations also suggest that allocation to deep roots traded off with shallow lateral root investment, and that drought-sensitive species rooted more shallowly than drought-resistant ones. More broadly across 57 species in Southern Africa, potential rooting depths were phylogenetically constrained, with investment to deep roots evident among miombo Detarioids, consistent with results suggesting they green up before onset of seasonal rains. Soil substrate explained variation, with deeper roots on sandy, nutrient-poor soils relative to clayey, nutrient-rich ones. Although potential rooting depth decreased with increasing wet season length, mean annual rainfall had no systematic effect on rooting depth. Overall, our results suggest that rooting depth systematically structures the ecology of savanna trees. Further work examining other anatomical and physiological root traits should be a priority for understanding savanna responses to changing climate and disturbances.
Collapse
Affiliation(s)
- Yong Zhou
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06511, USA
| | - Benjamin J Wigley
- Department of Environmental Biology, Sapienza University of Rome, Ple A. Moro 5, Rome, Italy
- School of Natural Resource Management, Nelson Mandela University, George, 6529, South Africa
| | - Madelon F Case
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06511, USA
| | - Corli Coetsee
- School of Natural Resource Management, Nelson Mandela University, George, 6529, South Africa
- Scientific Services, Kruger National Park, Private Bag X402, Skukuza, 1350, South Africa
| | - Ann Carla Staver
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, 06511, USA
| |
Collapse
|
5
|
Case MF, Wigley‐Coetsee C, Nzima N, Scogings PF, Staver AC. Severe drought limits trees in a semi‐arid savanna. Ecology 2019; 100:e02842. [DOI: 10.1002/ecy.2842] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 05/20/2019] [Accepted: 06/25/2019] [Indexed: 11/09/2022]
Affiliation(s)
- Madelon F. Case
- Department of Ecology and Evolutionary Biology Yale University P. O. Box 208106 New Haven Connecticut 06520‐8106 USA
| | - Corli Wigley‐Coetsee
- South African National Parks, Scientific Services Private Bag x 402 Skukuza 1350 South Africa
- School of Natural Resource Management Nelson Mandela University George Campus George 6560 South Africa
| | - Noel Nzima
- South African National Parks, Scientific Services Private Bag x 402 Skukuza 1350 South Africa
| | - Peter F. Scogings
- University of KwaZulu‐Natal School of Life Sciences Private Bag X01 Scottsville 3209 South Africa
| | - A. Carla Staver
- Department of Ecology and Evolutionary Biology Yale University P. O. Box 208106 New Haven Connecticut 06520‐8106 USA
| |
Collapse
|
6
|
Aspinwall MJ, Pfautsch S, Tjoelker MG, Vårhammar A, Possell M, Drake JE, Reich PB, Tissue DT, Atkin OK, Rymer PD, Dennison S, Van Sluyter SC. Range size and growth temperature influence Eucalyptus species responses to an experimental heatwave. GLOBAL CHANGE BIOLOGY 2019; 25:1665-1684. [PMID: 30746837 DOI: 10.1111/gcb.14590] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 02/03/2019] [Accepted: 02/04/2019] [Indexed: 05/24/2023]
Abstract
Understanding forest tree responses to climate warming and heatwaves is important for predicting changes in tree species diversity, forest C uptake, and vegetation-climate interactions. Yet, tree species differences in heatwave tolerance and their plasticity to growth temperature remain poorly understood. In this study, populations of four Eucalyptus species, two with large range sizes and two with comparatively small range sizes, were grown under two temperature treatments (cool and warm) before being exposed to an equivalent experimental heatwave. We tested whether the species with large and small range sizes differed in heatwave tolerance, and whether trees grown under warmer temperatures were more tolerant of heatwave conditions than trees grown under cooler temperatures. Visible heatwave damage was more common and severe in the species with small rather than large range sizes. In general, species that showed less tissue damage maintained higher stomatal conductance, lower leaf temperatures, larger increases in isoprene emissions, and less photosynthetic inhibition than species that showed more damage. Species exhibiting more severe visible damage had larger increases in heat shock proteins (HSPs) and respiratory thermotolerance (Tmax ). Thus, across species, increases in HSPs and Tmax were positively correlated, but inversely related to increases in isoprene emissions. Integration of leaf gas-exchange, isoprene emissions, proteomics, and respiratory thermotolerance measurements provided new insight into mechanisms underlying variability in tree species heatwave tolerance. Importantly, warm-grown seedlings were, surprisingly, more susceptible to heatwave damage than cool-grown seedlings, which could be associated with reduced enzyme concentrations in leaves. We conclude that species with restricted range sizes, along with trees growing under climate warming, may be more vulnerable to heatwaves of the future.
Collapse
Affiliation(s)
- Michael J Aspinwall
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
- Department of Biology, University of North Florida, Jacksonville, Florida
| | - Sebastian Pfautsch
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Mark G Tjoelker
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Angelica Vårhammar
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Malcolm Possell
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - John E Drake
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
- Forest and Natural Resources Management, SUNY-ESF, Syracuse, New York
| | - Peter B Reich
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
- Department of Forest Resources, University of Minnesota, Minnesota
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Owen K Atkin
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Paul D Rymer
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Siobhan Dennison
- Department of Biological Science, Macquarie University, North Ryde, NSW, Australia
| | - Steven C Van Sluyter
- Department of Biological Science, Macquarie University, North Ryde, NSW, Australia
| |
Collapse
|
7
|
Hagger V, Dwyer J, Shoo L, Wilson K. Use of seasonal forecasting to manage weather risk in ecological restoration. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2018; 28:1797-1807. [PMID: 30024642 DOI: 10.1002/eap.1769] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 04/30/2018] [Accepted: 05/15/2018] [Indexed: 06/08/2023]
Abstract
Ecological restoration has widely variable outcomes from successes to partial or complete failures, and there are diverse perspectives on the factors that influence the likelihood of success. However, not much is known about how these factors are perceived, and whether people's perceptions match realities. We surveyed 307 people involved in the restoration of native vegetation across Australia to identify their perceptions on the factors influencing the success of restoration projects. We found that weather (particularly drought and flooding) has realized impacts on the success of restoration projects, but is not perceived to be an important risk when planning new projects. This highlights the need for better recognition and management of weather risk in restoration and a potential role of seasonal forecasting. We used restoration case studies across Australia to assess the ability of seasonal forecasts provided by the Predictive Ocean Atmosphere Model for Australia, version M24 (POAMA-2) to detect unfavorable weather with sufficient skill and lead time to be useful for restoration projects. We found that rainfall and temperature variables in POAMA-2 predicted 88% of the weather issues encountered in restoration case studies apart from strong winds and cyclones. Of those restoration case studies with predictable weather issues, POAMA-2 had the forecast skill to predict the dominant or first-encountered issue in 67% of cases. We explored the challenges associated with uptake of forecast products through consultation with restoration practitioners and developed a prototype forecast product using a local case study. Integrating seasonal forecasting into decision making through (1) identifying risk management strategies during restoration planning, (2) accessing the forecast a month prior to revegetation activities, and (3) adapting decisions if extreme weather is forecasted, is expected to improve the establishment success of restoration.
Collapse
Affiliation(s)
- Valerie Hagger
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
- Australian Research Council Centre of Excellence for Environmental Decisions, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - John Dwyer
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
- CSIRO, Land and Water Flagship, Dutton Park, Queensland, 4102, Australia
| | - Luke Shoo
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
- Australian Research Council Centre of Excellence for Environmental Decisions, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Kerrie Wilson
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
- Australian Research Council Centre of Excellence for Environmental Decisions, The University of Queensland, Brisbane, Queensland, 4072, Australia
| |
Collapse
|
8
|
Palmquist KA, Bradford JB, Martyn TE, Schlaepfer DR, Lauenroth WK. STEPWAT
2: an individual‐based model for exploring the impact of climate and disturbance on dryland plant communities. Ecosphere 2018. [DOI: 10.1002/ecs2.2394] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Kyle A. Palmquist
- Department of Botany University of Wyoming Laramie Wyoming 82071 USA
| | - John B. Bradford
- U.S. Geological Survey, Southwest Biological Science Center Flagstaff Arizona 86001 USA
| | - Trace E. Martyn
- School of Biological Sciences The University of Queensland St. Lucia Queensland 4072 Australia
| | - Daniel R. Schlaepfer
- School of Forestry and Environmental Studies Yale University New Haven Connecticut 06511 USA
| | - William K. Lauenroth
- Department of Botany University of Wyoming Laramie Wyoming 82071 USA
- School of Forestry and Environmental Studies Yale University New Haven Connecticut 06511 USA
| |
Collapse
|
9
|
Lloret F, Kitzberger T. Historical and event-based bioclimatic suitability predicts regional forest vulnerability to compound effects of severe drought and bark beetle infestation. GLOBAL CHANGE BIOLOGY 2018; 24:1952-1964. [PMID: 29316042 DOI: 10.1111/gcb.14039] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 11/30/2017] [Accepted: 12/13/2017] [Indexed: 06/07/2023]
Abstract
Vulnerability to climate change, and particularly to climate extreme events, is expected to vary across species ranges. Thus, we need tools to standardize the variability in regional climatic legacy and extreme climate across populations and species. Extreme climate events (e.g., droughts) can erode populations close to the limits of species' climatic tolerance. Populations in climatic-core locations may also become vulnerable because they have developed a greater demand for resources (i.e., water) that cannot be enough satisfied during the periods of scarcity. These mechanisms can become exacerbated in tree populations when combined with antagonistic biotic interactions, such as insect infestation. We used climatic suitability indices derived from Species Distribution Models (SDMs) to standardize the climatic conditions experienced across Pinus edulis populations in southwestern North America, during a historical period (1972-2000) and during an extreme event (2001-2007), when the compound effect of hot drought and bark beetle infestation caused widespread die-off and mortality. Pinus edulis climatic suitability diminished dramatically during the die-off period, with remarkable variation between years. P. edulis die-off occurred mainly not just in sites that experienced lower climatic suitability during the drought but also where climatic suitability was higher during the historical period. The combined effect of historically high climatic suitability and a marked decrease in the climatic suitability during the drought best explained the range-wide mortality. Lagged effects of climatic suitability loss in previous years and co-occurrence of Juniperus monosperma also explained P. edulis die-off in particular years. Overall, the study shows that past climatic legacy, likely determining acclimation, together with competitive interactions plays a major role in responses to extreme drought. It also provides a new approach to standardize the magnitude of climatic variability across populations using SDMs, improving our capacity to predict population's or species' vulnerability to climatic change.
Collapse
Affiliation(s)
- Francisco Lloret
- CREAF Cerdanyola del Vallès, Bellaterra, Spain
- Univ Autònoma Barcelona, Cerdanyola del Vallès, Spain
| | - Thomas Kitzberger
- Laboratorio Ecotono, INIBIOMA-CONICET, Universidad Nacional del Comahue, Bariloche, Argentina
| |
Collapse
|
10
|
Synodinos AD, Tietjen B, Lohmann D, Jeltsch F. The impact of inter-annual rainfall variability on African savannas changes with mean rainfall. J Theor Biol 2017; 437:92-100. [PMID: 29054812 DOI: 10.1016/j.jtbi.2017.10.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 09/29/2017] [Accepted: 10/16/2017] [Indexed: 11/17/2022]
Abstract
Savannas are mixed tree-grass ecosystems whose dynamics are predominantly regulated by resource competition and the temporal variability in climatic and environmental factors such as rainfall and fire. Hence, increasing inter-annual rainfall variability due to climate change could have a significant impact on savannas. To investigate this, we used an ecohydrological model of stochastic differential equations and simulated African savanna dynamics along a gradient of mean annual rainfall (520-780 mm/year) for a range of inter-annual rainfall variabilities. Our simulations produced alternative states of grassland and savanna across the mean rainfall gradient. Increasing inter-annual variability had a negative effect on the savanna state under dry conditions (520 mm/year), and a positive effect under moister conditions (580-780 mm/year). The former resulted from the net negative effect of dry and wet extremes on trees. In semi-arid conditions (520 mm/year), dry extremes caused a loss of tree cover, which could not be recovered during wet extremes because of strong resource competition and the increased frequency of fires. At high mean rainfall (780 mm/year), increased variability enhanced savanna resilience. Here, resources were no longer limiting and the slow tree dynamics buffered against variability by maintaining a stable population during 'dry' extremes, providing the basis for growth during wet extremes. Simultaneously, high rainfall years had a weak marginal benefit on grass cover due to density-regulation and grazing. Our results suggest that the effects of the slow tree and fast grass dynamics on tree-grass interactions will become a major determinant of the savanna vegetation composition with increasing rainfall variability.
Collapse
Affiliation(s)
- Alexis D Synodinos
- Department of Plant Ecology and Nature Conservation, Institute of Biochemistry and Biology, University of Potsdam, Am Mühlenberg, 314476 Golm-Potsdam, Germany.
| | - Britta Tietjen
- Biodiversity/Theoretical Ecology, Institute of Biology, Freie Universität Berlin, Altensteinstr. 34, Berlin 14195, Germany; Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin D-14195, Germany
| | - Dirk Lohmann
- Department of Plant Ecology and Nature Conservation, Institute of Biochemistry and Biology, University of Potsdam, Am Mühlenberg, 314476 Golm-Potsdam, Germany
| | - Florian Jeltsch
- Department of Plant Ecology and Nature Conservation, Institute of Biochemistry and Biology, University of Potsdam, Am Mühlenberg, 314476 Golm-Potsdam, Germany
| |
Collapse
|
11
|
Jump AS, Ruiz-Benito P, Greenwood S, Allen CD, Kitzberger T, Fensham R, Martínez-Vilalta J, Lloret F. Structural overshoot of tree growth with climate variability and the global spectrum of drought-induced forest dieback. GLOBAL CHANGE BIOLOGY 2017; 23:3742-3757. [PMID: 28135022 DOI: 10.1111/gcb.13636] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 12/26/2016] [Indexed: 05/25/2023]
Abstract
Ongoing climate change poses significant threats to plant function and distribution. Increased temperatures and altered precipitation regimes amplify drought frequency and intensity, elevating plant stress and mortality. Large-scale forest mortality events will have far-reaching impacts on carbon and hydrological cycling, biodiversity, and ecosystem services. However, biogeographical theory and global vegetation models poorly represent recent forest die-off patterns. Furthermore, as trees are sessile and long-lived, their responses to climate extremes are substantially dependent on historical factors. We show that periods of favourable climatic and management conditions that facilitate abundant tree growth can lead to structural overshoot of aboveground tree biomass due to a subsequent temporal mismatch between water demand and availability. When environmental favourability declines, increases in water and temperature stress that are protracted, rapid, or both, drive a gradient of tree structural responses that can modify forest self-thinning relationships. Responses ranging from premature leaf senescence and partial canopy dieback to whole-tree mortality reduce canopy leaf area during the stress period and for a lagged recovery window thereafter. Such temporal mismatches of water requirements from availability can occur at local to regional scales throughout a species geographical range. As climate change projections predict large future fluctuations in both wet and dry conditions, we expect forests to become increasingly structurally mismatched to water availability and thus overbuilt during more stressful episodes. By accounting for the historical context of biomass development, our approach can explain previously problematic aspects of large-scale forest mortality, such as why it can occur throughout the range of a species and yet still be locally highly variable, and why some events seem readily attributable to an ongoing drought while others do not. This refined understanding can facilitate better projections of structural overshoot responses, enabling improved prediction of changes in forest distribution and function from regional to global scales.
Collapse
Affiliation(s)
- Alistair S Jump
- Biological and Environmental Sciences, University of Stirling, Scotland, FK9 4LA, UK
- CREAF, Campus de Bellaterra (UAB), Edifici C, Cerdanyola del Vallès 08193, Catalonia, Spain
| | - Paloma Ruiz-Benito
- Biological and Environmental Sciences, University of Stirling, Scotland, FK9 4LA, UK
- Forest Ecology and Restoration Group, Department of Life Sciences, Science Building, Universidad de Alcalá, Campus Universitario, 28805 Alcalá de Henares, Madrid, Spain
| | - Sarah Greenwood
- Biological and Environmental Sciences, University of Stirling, Scotland, FK9 4LA, UK
| | - Craig D Allen
- U.S. Geological Survey, Fort Collins Science Center, New Mexico Landscapes Field Station, Los Alamos, NM, 87544, USA
| | - Thomas Kitzberger
- Laboratorio Ecotono, INIBIOMA, CONICET-Universidad Nacional del Comahue, Bariloche, 8400, Río Negro, Argentina
| | - Rod Fensham
- Queensland Herbarium, Environmental Protection Agency, Mt Coot-tha Road, Toowong, Qld, 4066, Australia
- School of Biological Sciences, University of Queensland, St Lucia, Qld, 4072, Australia
| | - Jordi Martínez-Vilalta
- CREAF, Campus de Bellaterra (UAB), Edifici C, Cerdanyola del Vallès 08193, Catalonia, Spain
- Autonomous University of Barcelona, Cerdanyola del Vallès 08193, Catalonia, Spain
| | - Francisco Lloret
- CREAF, Campus de Bellaterra (UAB), Edifici C, Cerdanyola del Vallès 08193, Catalonia, Spain
- Autonomous University of Barcelona, Cerdanyola del Vallès 08193, Catalonia, Spain
| |
Collapse
|
12
|
Fensham RJ, Freeman ME, Laffineur B, Macdermott H, Prior LD, Werner PA. Variable rainfall has a greater effect than fire on the demography of the dominant tree in a semi-aridEucalyptus savanna. AUSTRAL ECOL 2017. [DOI: 10.1111/aec.12495] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Roderick J. Fensham
- Queensland Herbarium; Department of Science, Information Technology and Innovation; Brisbane Botanic Gardens; Mt Coot-tha Road Toowong Queensland 4066 Australia
- School of Biological Sciences; University of Queensland; St Lucia Queensland Australia
| | | | - Boris Laffineur
- Queensland Herbarium; Department of Science, Information Technology and Innovation; Brisbane Botanic Gardens; Mt Coot-tha Road Toowong Queensland 4066 Australia
- School of Biological Sciences; University of Queensland; St Lucia Queensland Australia
| | - Harry Macdermott
- Queensland Herbarium; Department of Science, Information Technology and Innovation; Brisbane Botanic Gardens; Mt Coot-tha Road Toowong Queensland 4066 Australia
- School of Biological Sciences; University of Queensland; St Lucia Queensland Australia
| | - Lynda D. Prior
- School of Biological Sciences; University of Tasmania; Hobart Tasmania Australia
| | - Patricia A. Werner
- Fenner School of Environment and Society; Australian National University; Canberra Australian Capital Territory Australia
| |
Collapse
|
13
|
O'Brien MJ, Engelbrecht BMJ, Joswig J, Pereyra G, Schuldt B, Jansen S, Kattge J, Landhäusser SM, Levick SR, Preisler Y, Väänänen P, Macinnis-Ng C. A synthesis of tree functional traits related to drought-induced mortality in forests across climatic zones. J Appl Ecol 2017. [DOI: 10.1111/1365-2664.12874] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Michael J. O'Brien
- Estación Experimental de Zonas Áridas; Consejo Superior de Investigaciones Científicas; Carretera de Sacramento s/n E-04120 La Cañada Almería Spain
- Department of Evolutionary Biology and Environmental Studies; University of Zurich; Winterthurerstrasse 190 CH-8057 Zurich Switzerland
| | - Bettina M. J. Engelbrecht
- Department of Plant Ecology; Bayreuth Center for Ecology and Environmental Research; University of Bayreuth; 95440 Bayreuth Germany
- Smithsonian Tropical Research Institute; Apartado 0843-03092 Balboa Ancon Republic of Panama
| | - Julia Joswig
- Max-Plank Institute for Biogeochemistry; Hans-Knöll-Str. 10 07745 Jena Germany
| | - Gabriela Pereyra
- Max-Plank Institute for Biogeochemistry; Hans-Knöll-Str. 10 07745 Jena Germany
| | - Bernhard Schuldt
- Plant Ecology; Albrecht von Haller Institute for Plant Sciences; University of Göttingen; UntereKarspüle 2 37073 Göttingen Germany
| | - Steven Jansen
- Institute of Systematic Botany and Ecology; Ulm University; Albert-Einstein-Allee 11 89081 Ulm Germany
| | - Jens Kattge
- Max-Plank Institute for Biogeochemistry; Hans-Knöll-Str. 10 07745 Jena Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; Deutscher Platz 5e 04103 Leipzig Germany
| | - Simon M. Landhäusser
- Department of Renewable Resources; University of Alberta; Edmonton AB T6G 2E3 Canada
| | - Shaun R. Levick
- Max-Plank Institute for Biogeochemistry; Hans-Knöll-Str. 10 07745 Jena Germany
| | - Yakir Preisler
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture; The Hebrew University of Jerusalem; PO Box 12 Rehovot 76100 Israel
- Department of Earth and Planetary Science; Weizmann Institute of Science; Rehovot Israel
| | - Päivi Väänänen
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture; The Hebrew University of Jerusalem; PO Box 12 Rehovot 76100 Israel
| | - Cate Macinnis-Ng
- School of Biological Sciences; University of Auckland; Private Bag 92019 Auckland 1142 New Zealand
| |
Collapse
|
14
|
Mitchell PJ, O'Grady AP, Pinkard EA, Brodribb TJ, Arndt SK, Blackman CJ, Duursma RA, Fensham RJ, Hilbert DW, Nitschke CR, Norris J, Roxburgh SH, Ruthrof KX, Tissue DT. An ecoclimatic framework for evaluating the resilience of vegetation to water deficit. GLOBAL CHANGE BIOLOGY 2016; 22:1677-1689. [PMID: 26643922 DOI: 10.1111/gcb.13177] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 11/18/2015] [Indexed: 06/05/2023]
Abstract
The surge in global efforts to understand the causes and consequences of drought on forest ecosystems has tended to focus on specific impacts such as mortality. We propose an ecoclimatic framework that takes a broader view of the ecological relevance of water deficits, linking elements of exposure and resilience to cumulative impacts on a range of ecosystem processes. This ecoclimatic framework is underpinned by two hypotheses: (i) exposure to water deficit can be represented probabilistically and used to estimate exposure thresholds across different vegetation types or ecosystems; and (ii) the cumulative impact of a series of water deficit events is defined by attributes governing the resistance and recovery of the affected processes. We present case studies comprising Pinus edulis and Eucalyptus globulus, tree species with contrasting ecological strategies, which demonstrate how links between exposure and resilience can be examined within our proposed framework. These examples reveal how climatic thresholds can be defined along a continuum of vegetation functional responses to water deficit regimes. The strength of this framework lies in identifying climatic thresholds on vegetation function in the absence of more complete mechanistic understanding, thereby guiding the formulation, application and benchmarking of more detailed modelling.
Collapse
Affiliation(s)
| | - Anthony P O'Grady
- CSIRO Land and Water, 15 College Rd, Sandy Bay, TAS, 7005, Australia
| | | | - Timothy J Brodribb
- School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, TAS, 7005, Australia
| | - Stefan K Arndt
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, VIC, 3121, Australia
| | - Chris J Blackman
- Hawkesbury Institute for the Environment, Western Sydney University, Science Rd, Richmond, NSW, 2753, Australia
| | - Remko A Duursma
- Hawkesbury Institute for the Environment, Western Sydney University, Science Rd, Richmond, NSW, 2753, Australia
| | - Rod J Fensham
- Queensland Herbarium, Environmental Protection Agency, Mount Coot-tha Road, Toowong, QLD, 4066, Australia
- School of Biological Sciences, University of Queensland, Chancellors Pl., St Lucia, QLD, 4072, Australia
| | - David W Hilbert
- CSIRO Ecosystem Sciences, Tropical Forest Research Centre, Atherton, QLD, 4883, Australia
| | - Craig R Nitschke
- School of Ecosystem and Forest Sciences, The University of Melbourne, 500 Yarra Boulevard, Richmond, VIC, 3121, Australia
| | - Jaymie Norris
- Department of Environment, Land, Water and Planning, Victorian Government, Melbourne, VIC, 3000, Australia
| | - Stephen H Roxburgh
- CSIRO Land and Water, Clunies Ross St, Black Mountain, ACT, 2601, Australia
| | - Katinka X Ruthrof
- Centre of Excellence for Climate Change, Woodland and Forest Health, School of Veterinary and Life Sciences Murdoch University, 90 South St, Murdoch, WA, 6150, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Science Rd, Richmond, NSW, 2753, Australia
| |
Collapse
|
15
|
Meta-analysis reveals that hydraulic traits explain cross-species patterns of drought-induced tree mortality across the globe. Proc Natl Acad Sci U S A 2016; 113:5024-9. [PMID: 27091965 DOI: 10.1073/pnas.1525678113] [Citation(s) in RCA: 325] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Drought-induced tree mortality has been observed globally and is expected to increase under climate change scenarios, with large potential consequences for the terrestrial carbon sink. Predicting mortality across species is crucial for assessing the effects of climate extremes on forest community biodiversity, composition, and carbon sequestration. However, the physiological traits associated with elevated risk of mortality in diverse ecosystems remain unknown, although these traits could greatly improve understanding and prediction of tree mortality in forests. We performed a meta-analysis on species' mortality rates across 475 species from 33 studies around the globe to assess which traits determine a species' mortality risk. We found that species-specific mortality anomalies from community mortality rate in a given drought were associated with plant hydraulic traits. Across all species, mortality was best predicted by a low hydraulic safety margin-the difference between typical minimum xylem water potential and that causing xylem dysfunction-and xylem vulnerability to embolism. Angiosperms and gymnosperms experienced roughly equal mortality risks. Our results provide broad support for the hypothesis that hydraulic traits capture key mechanisms determining tree death and highlight that physiological traits can improve vegetation model prediction of tree mortality during climate extremes.
Collapse
|
16
|
Allen CD, Breshears DD, McDowell NG. On underestimation of global vulnerability to tree mortality and forest die-off from hotter drought in the Anthropocene. Ecosphere 2015. [DOI: 10.1890/es15-00203.1] [Citation(s) in RCA: 1345] [Impact Index Per Article: 149.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
|
17
|
O'Grady AP, Mitchell PJ. Looking forward, looking back: capturing drought in flagrante delicto and uncovering its broader consequences for forest ecosystems. TREE PHYSIOLOGY 2015; 35:803-805. [PMID: 26311305 DOI: 10.1093/treephys/tpv072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Affiliation(s)
- A P O'Grady
- CSIRO Land and Water Flagship, Private Bag 12, Hobart, Tasmania 7001, Australia
| | - P J Mitchell
- CSIRO Land and Water Flagship, Private Bag 12, Hobart, Tasmania 7001, Australia
| |
Collapse
|