Hanging by a thread? Forests and drought

Science, Journal Year: 2020, Volume and Issue: 368(6488), P. 261 - 266

Published: April 16, 2020

Trees are the living foundations on which most terrestrial biodiversity is built. Central to success of trees their woody bodies, connect elevated photosynthetic canopies with essential belowground activities water and nutrient acquisition. The slow construction these carbon-dense, skeletons leads a generation time, leaving forests highly susceptible rapid changes in climate. Other long-lived, sessile organisms such as corals appear be poorly equipped survive changes, raises questions about vulnerability contemporary future climate change. emerging view that, similar corals, tree species have rather inflexible damage thresholds, particularly terms stress, especially concerning. This Review examines recent progress our understanding how looks for growing hotter drier atmosphere.

Language: Английский

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Changing wildfire, changing forests: the effects of climate change on fire regimes and vegetation in the Pacific Northwest, USA

Fire Ecology, Journal Year: 2020, Volume and Issue: 16(1)

Published: Jan. 27, 2020

Abstract Background Wildfires in the Pacific Northwest (Washington, Oregon, Idaho, and western Montana, USA) have been immense recent years, capturing attention of resource managers, fire scientists, general public. This paper synthesizes understanding potential effects changing climate regimes on forests, including disturbance stress interactions, forest structure composition, post-fire ecological processes. We frame this information a risk assessment context, conclude with management implications future research needs. Results Large severe fires are associated warm dry conditions, such conditions will likely occur increasing frequency warming climate. According to projections based historical records, current trends, simulation modeling, protracted warmer drier drive lower fuel moisture longer seasons future, extent compared twentieth century. Interactions between other disturbances, as drought insect outbreaks, be primary drivers ecosystem change Reburns also more frequently drought, tree regeneration species composition. Hotter, sites may particularly at for failures. Conclusion Resource managers unable affect total area burned by fire, trend is driven strongly However, treatments, when implemented spatially strategic manner, can help decrease intensity severity improve resilience insects, drought. Where treatments less effective (wetter, high-elevation, coastal forests), consider implementing breaks around high-value resources. When where planting an option, different genetic stock than has used past increase seedling survival. Planting seedlings cooler, wetter microsites In driest topographic locations, need they try forestall allow conversions vegetation what currently dominant.

Language: Английский

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Drought, Tree Mortality, and Wildfire in Forests Adapted to Frequent Fire

BioScience, Journal Year: 2017, Volume and Issue: 68(2), P. 77 - 88

Published: Nov. 20, 2017

Massive tree mortality has occurred rapidly in frequent-fire-adapted forests of the Sierra Nevada, California. This is a product acute drought compounded by long-established removal key ecosystem process: frequent, low- to moderate-intensity fire. The recent many implications for future these and ecological goods services they provide society. Future wildfire hazard following this can be generally characterized decreased crown fire potential increased surface intensity short intermediate term. scale present so large that greater "mass fire" exists coming decades, driven amount continuity dry, combustible, woody material could produce large, severe fires. For long-term adaptation climate change, we highlight importance moving beyond triage dead dying trees making "green" (live) more resilient.

Language: Английский

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Structural overshoot of tree growth with climate variability and the global spectrum of drought‐induced forest dieback

Global Change Biology, Journal Year: 2017, Volume and Issue: 23(9), P. 3742 - 3757

Published: Jan. 30, 2017

Abstract Ongoing climate change poses significant threats to plant function and distribution. Increased temperatures altered precipitation regimes amplify drought frequency intensity, elevating stress mortality. Large‐scale forest mortality events will have far‐reaching impacts on carbon hydrological cycling, biodiversity, ecosystem services. However, biogeographical theory global vegetation models poorly represent recent die‐off patterns. Furthermore, as trees are sessile long‐lived, their responses extremes substantially dependent historical factors. We show that periods of favourable climatic management conditions facilitate abundant tree growth can lead structural overshoot aboveground biomass due a subsequent temporal mismatch between water demand availability. When environmental favourability declines, increases in temperature protracted, rapid, or both, drive gradient modify self‐thinning relationships. Responses ranging from premature leaf senescence partial canopy dieback whole‐tree reduce area during the period for lagged recovery window thereafter. Such mismatches requirements availability occur at local regional scales throughout species geographical range. As projections predict large future fluctuations both wet dry conditions, we expect forests become increasingly structurally mismatched thus overbuilt more stressful episodes. By accounting context development, our approach explain previously problematic aspects large‐scale mortality, such why it range yet still be locally highly variable, some seem readily attributable an ongoing while others do not. This refined understanding better responses, enabling improved prediction changes distribution scales.

Language: Английский

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Tree height explains mortality risk during an intense drought

Nature Communications, Journal Year: 2019, Volume and Issue: 10(1)

Published: Sept. 26, 2019

Forest mortality is accelerating due to climate change and the largest trees may be at greatest risk, threatening critical ecological, economic, social benefits. Here, we combine high-resolution airborne LiDAR optical data track tree-level rates for ~2 million in California over 8 years, showing that tree height strongest predictor of during extreme drought. Large die twice rate small environmental gradients temperature, water, competition control intensity height-mortality relationship. These findings suggest future persistent drought cause widespread on Earth.

Language: Английский

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Tree mortality following drought in the central and southern Sierra Nevada, California, U.S.

Forest Ecology and Management, Journal Year: 2018, Volume and Issue: 432, P. 164 - 178

Published: Sept. 20, 2018

Language: Английский

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Lessons from California’s 2012–2016 Drought

Journal of Water Resources Planning and Management, Journal Year: 2018, Volume and Issue: 144(10)

Published: July 31, 2018

California’s 5-year drought has ended, even as its aftermath lingers. From 2012–2016 much or all of California was under severe conditions, with greatly diminished precipitation, snowpack, and streamflow higher temperatures. Water shortages to forests, aquatic ecosystems, hydroelectric power plants, rural drinking water supplies, agriculture, cities caused billions dollars in economic losses, killed millions forest trees, brought several fish species closer extinction, inconvenience some expense households businesses. The also innovations improvements management, which will better prepare for future droughts. This paper summarizes the magnitude impacts drought. then reviews arising from larger historical context management California. Lessons modern are discussed. Droughts modern, well-managed systems serving globalized economies need not be economically catastrophic, but always have challenges, particularly native ecosystems. In every other system, droughts usefully expose weaknesses inadequate preparation management. this regard California, managers ecosystems small supplies had most learn.

Language: Английский

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Climate, Environment, and Disturbance History Govern Resilience of Western North American Forests

Frontiers in Ecology and Evolution, Journal Year: 2019, Volume and Issue: 7

Published: July 10, 2019

Resilience and resistance concepts have broad application to ecology society. is an emergent property that reflects the amount of disruption a system can withstand before its structure or organization uncharacteristically shift. Resistance component resilience. Before advent intensive forest management fire suppression, western North American forests exhibited naturally occurring resilience wildfires other disturbances. Using evidence from ten ecoregions, spanning Canada Mexico, we review properties these reinforced those qualities. We show examples multi-level landscape resilience, feedbacks within among levels, how conditions changed under climatic influences. highlight geographic similarities differences in historical landscapes, their types, abrupt large-scale disruptions. discuss regional climates’ role episodically abruptly reorganizing plant animal biogeography, give clear changes suggest managing for resilient construct strongly dependent on scale social values. It involves human community adaptations work with ecosystems they depend processes shape them. entails actively factors exploiting mechanisms drive dynamics at each level as means adapting species, communities climate change, maintaining core ecosystem functions, processes, services. Finally, it compels us prioritize incorporates ongoing disturbances anticipated effects changes, support dynamically shifting patchworks nonforest. Doing so will make wildfire regimes more gradual less disruptive individuals

Language: Английский

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Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests

Ecological Applications, Journal Year: 2021, Volume and Issue: 31(8)

Published: Aug. 2, 2021

Implementation of wildfire- and climate-adaptation strategies in seasonally dry forests western North America is impeded by numerous constraints uncertainties. After more than a century resource land use change, some question the need for proactive management, particularly given novel social, ecological, climatic conditions. To address this question, we first provide framework assessing changes landscape conditions fire regimes. Using framework, then evaluate evidence change contemporary relative to those maintained active regimes, i.e., uninterrupted or human-induced exclusion. The cumulative results research document persistent substantial deficit widespread alterations ecological structures functions. These are not necessarily apparent at all spatial scales dimensions regimes forest nonforest Nonetheless, loss once abundant influence low- moderate-severity fires suggests that even least fire-prone ecosystems may be affected alteration surrounding and, consequently, ecosystem Vegetation patterns fire-excluded forested landscapes no longer reflect heterogeneity interacting Live dead vegetation (surface canopy fuels) generally continuous before European colonization. As result, current vulnerable direct indirect effects seasonal episodic increases drought fire, especially under rapidly warming climate. Long-term exclusion contemporaneous social-ecological influences continue extensively modify landscapes. Management realigns adapts can moderate transitions as human communities adapt changing disturbance adaptation developed, evaluated, implemented, objective scientific evaluation ongoing monitoring aid differentiation warranted unwarranted

Language: Английский

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A reconstruction of global hydroclimate and dynamical variables over the Common Era

Scientific Data, Journal Year: 2018, Volume and Issue: 5(1)

Published: May 22, 2018

Abstract Hydroclimate extremes critically affect human and natural systems, but there remain many unanswered questions about their causes how to interpret dynamics in the past climate change projections. These uncertainties are due, part, lack of long-term, spatially resolved hydroclimate reconstructions information on underlying physical drivers for regions. Here we present first global associated dynamical variables over two thousand years. We use a data assimilation approach tailored reconstruct that optimally combines 2,978 paleoclimate proxy-data time series with constraints an atmosphere—ocean model. The annually or seasonally include spatiotemporal drought indices, near-surface air temperature, index North Atlantic variability, location intertropical convergence zone, monthly Niño indices. This database, called Paleo Hydrodynamics Data Assimilation product (PHYDA), will provide critical new platform investigating variability extremes, while informing interpretations future

Language: Английский

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