The impact of rising CO₂and acclimation on the response of US forests to global warming

Proceedings of the National Academy of Sciences, Journal Year: 2019, Volume and Issue: 116(51), P. 25734 - 25744

Published: Nov. 25, 2019

The response of forests to climate change depends in part on whether the photosynthetic benefit from increased atmospheric CO 2 (∆C a = future minus historic ) compensates for physiological stresses higher temperature (∆T). We predicted outcome these competing responses by using optimization theory and mechanistic model tree water transport photosynthesis. simulated current productivity, stress, mortality mature monospecific stands with soil, species, sampled 20 continental US locations. modeled without acclimation ∆C ∆T, where acclimated adjusted leaf area, capacity, stand density maximize productivity while avoiding stress. Without acclimation, -driven boost net primary (NPP) was compromised ∆T-driven stress associated vascular failure. With NPP biomass (C storage) accentuated cooler futures but negated warmer reduction biomass. Thus, hotter reduced forest through either or acclimation. Forest outcomes depended projected climatic /∆T ratios were above below thresholds that neutralized negative impacts warming. Critically, if do not acclimate, must be ca . 89 ppm⋅°C −1 avoid chronic threshold met 55% projections. If rise 67 increase, lower 71%

Language: Английский

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Sampling bias overestimates climate change impacts on forest growth in the southwestern United States

Nature Communications, Journal Year: 2018, Volume and Issue: 9(1)

Published: Dec. 11, 2018

Abstract Climate−tree growth relationships recorded in annual rings have recently been the basis for projecting climate change impacts on forests. However, most trees and sample sites represented International Tree-Ring Data Bank (ITRDB) were chosen to maximize signal are characterized by marginal growing conditions not representative of larger forest ecosystem. We evaluate magnitude this potential bias using a spatially unbiased tree-ring network collected USFS Forest Inventory Analysis (FIA) program. show that U.S. Southwest ITRDB samples overestimate regional sensitivity 41–59%, because sampled at warmer drier locations, both macro- micro-site scale, systematically older compared FIA collection. Although there uncertainties associated with our statistical approach, projection based suggests 29% less change-induced decrease climate-sensitive samples.

Language: Английский

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Climate change‐associated trends in net biomass change are age dependent in western boreal forests of Canada

Ecology Letters, Journal Year: 2016, Volume and Issue: 19(9), P. 1150 - 1158

Published: July 28, 2016

Abstract The impacts of climate change on forest net biomass are poorly understood but critical for predicting forest's contribution to the global carbon cycle. Recent studies show change‐associated declines in mature plots. representativeness these plots regional forests, however, remains uncertain because we lack an assessment whether differ with age. Using data from varying ages 17 210 years, monitored 1958 2011 western Canada, found that has little effect forests ≤ 40 years age due increased growth offsetting mortality, led large decreases older mortality accompanying gain. Our analysis highlights need incorporate profiles examining past and projecting future responses change.

Language: Английский

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Detecting early warning signals of tree mortality in boreal North America using multiscale satellite data

Global Change Biology, Journal Year: 2018, Volume and Issue: 24(6), P. 2284 - 2304

Published: Feb. 26, 2018

Abstract Increasing tree mortality from global change drivers such as drought and biotic infestations is a widespread phenomenon, including in the boreal zone where climate changes feedbacks to Earth system are relatively large. Despite importance for science management communities, our ability forecast at landscape continental scales limited. However, two independent information streams have potential inform improve forecasts: repeat forest inventories satellite remote sensing. Time series of tree‐level growth patterns indicate that productivity declines related temporal dynamics often precede years decades before death. Plot‐level productivity, turn, has been satellite‐based indices Normalized difference vegetation index ( NDVI ). Here we link these data sources show early warning signals evident several ‐based metrics up 24 We focus on three products across western North America influenced by periodic drought. These capture range conditions spatial resolution highlight sensitivity limitations approach. Overall, results use mortality. Relationships broadly consistent inventories, species, resolutions, although utility coarse‐scale imagery heterogeneous aspen parkland was Longer‐term annually remeasured sites with high levels generate strongest signals, still found robust relationships typical 5 year frequency. The approach developed here can be used basis improving models monitoring systems.

Language: Английский

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Northern forest tree populations are physiologically maladapted to drought

Nature Communications, Journal Year: 2018, Volume and Issue: 9(1)

Published: Dec. 4, 2018

Abstract Northern forests at the leading edge of their distributions may not show increased primary productivity under climate warming, being limited by climatic extremes such as drought. Looking beyond tree growth to underlying physiological mechanisms is fundamental for accurate predictions forest responses warming and drought stress. Within a 32-year genetic field trial, we analyze relative contributions xylem plasticity inferred stomatal response tolerance in regional populations widespread conifer. Genetic adaptation leads varying Trailing-edge produce fewer tracheids with thicker cell walls, characteristic drought-tolerance. Stomatal explains moderate central areas species range. Growth loss northern population linked low responsiveness combined production thinner walls. Forests western boreal therefore lack adaptations necessary tolerate drier conditions.

Language: Английский

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Assessing the response of forest productivity to climate extremes in Switzerland using model–data fusion

Global Change Biology, Journal Year: 2020, Volume and Issue: 26(4), P. 2463 - 2476

Published: Jan. 22, 2020

The response of forest productivity to climate extremes strongly depends on ambient environmental and site conditions. To better understand these relationships at a regional scale, we used nearly 800 observation years from 271 permanent long-term monitoring plots across Switzerland, obtained between 1980 2017. We assimilated data into the 3-PG ecosystem model using Bayesian inference, reducing bias predictions 14% 5% for stem carbon stocks 45% 9% stock changes. then estimated forests dominated by Picea abies Fagus sylvatica period 1960-2018, tested shifts in along elevational gradient extreme years. Simulated net primary (NPP) decreased with elevation (2.86 ± 0.006 Mg C ha-1 year-1 km-1 P. 0.93 0.010 F. sylvatica). During warm-dry extremes, simulated NPP both species increased higher lower elevations, reductions more than 25% up 21% potential distribution range Switzerland. Reduced plant water availability had stronger effect temperature during extremes. Importantly, cold-dry negative impacts comparable Overall, our calibrated suggests that is complex simple shift toward elevation. Such robust estimates are key increasing understanding ecosystems dynamics under

Language: Английский

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Rapid 21st century climate change projected to shift composition and growth of Canada’s Acadian Forest Region

Forest Ecology and Management, Journal Year: 2017, Volume and Issue: 405, P. 284 - 294

Published: Sept. 27, 2017

Language: Английский

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Improved tree-ring archives will support earth-system science

Nature Ecology & Evolution, Journal Year: 2017, Volume and Issue: 1(2)

Published: Jan. 24, 2017

Language: Английский

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Climate change impacts on boreal forest timber supply

Forest Policy and Economics, Journal Year: 2018, Volume and Issue: 92, P. 11 - 21

Published: April 7, 2018

Language: Английский

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Seasonal variability of forest sensitivity to heat and drought stresses: A synthesis based on carbon fluxes from North American forest ecosystems

Global Change Biology, Journal Year: 2019, Volume and Issue: 26(2), P. 901 - 918

Published: Sept. 17, 2019

Climate extremes such as heat waves and droughts are projected to occur more frequently with increasing temperature an intensified hydrological cycle. It is important understand quantify how forest carbon fluxes respond drought stress. In this study, we developed a series of daily indices sensitivity stress indicated by air (Ta ) evaporative fraction (EF). Using normalized from the FLUXNET Network for 34 sites in North America, seasonal pattern sensitivities net ecosystem productivity (NEP), gross (GEP) respiration (RE) response Ta EF anomalies were compared different types. The results showed that warm temperatures spring had positive effect on NEP conifer forests but negative impact deciduous forests. GEP increased higher decreased summer. drought-induced decrease NEP, which mostly occurred forests, was driven reduction GEP. similar dampening both RE, therefore leading neutral response. mean annual temperature. Drier less sensitive Natural older stand age tended be resilient climate stresses managed younger Classification Regression Tree analysis seasons most powerful variables explaining variation Our implied magnitude direction flux changes highly dependent dynamics timing extremes.

Language: Английский

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