Nonstructural leaf carbohydrate dynamics of <i><scp>P</scp>inus edulis</i> during drought‐induced tree mortality reveal role for carbon metabolism in mortality mechanism

Adams, Henry D.; Germino, Matthew J.; Breshears, David D.; Barron‐Gafford, Greg A.; Guardiola‐Claramonte, Maite; Zou, Chris B.; Huxman, Travis E.

doi:10.1111/nph.12102

Cited by 230 publications

(182 citation statements)

References 88 publications

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“…Some of the unexplained variation may be caused by our inability to include topoedaphic and plant community effects as well as other potentially useful traits because of lack of data. In particular, it would be valuable to examine the level and utility of carbon reserves during drought, which were related to mortality in some studies (28,29) but not in others (14,30). Currently, however, enormous methodological uncertainty with nonstructural carbohydrates measurements prohibits cross-study comparison (31).…”

Section: Resultsmentioning

confidence: 99%

Meta-analysis reveals that hydraulic traits explain cross-species patterns of drought-induced tree mortality across the globe

Anderegg

Klein

Bartlett

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

622

546

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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.meta-analysis | climate change | carbon cycle | climate extremes | biodiversity F orests assimilate and sequester ∼2.4 Pg carbon per year (1), equivalent to 25% of anthropogenic emissions, and provide manifold goods and services to society (2). Climate extremes, such as severe drought, could trigger abrupt and irreversible changes in Earth's forests (3, 4), which would have profound implications for their biodiversity, ecosystem services, and carbon storage (5). Episodes of widespread tree mortality in response to drought and/or heat stress have been observed across the globe in the past few decades (4). In addition, drought severity and frequency are projected to increase with temperature-driven rises in evaporative demand (6). There is fundamental concern that increased climate-induced mortality of trees (7) could offset carbon sinks currently yielded in old growth and regrowth forests alike (8).Predicting plant demographic rates, such as mortality, using physiological traits is a central aim of ecology with critical importance for modeling climate change impacts and the carbon cycle (9). Drought-induced tree mortality has been particularly challenging to model and predict because of uncertainty in traits and mechanisms underlying the physiology of tree death (10, 11). Despite this uncertainty (12, 13), the failure of the plant vascular hydraulic transport system is considered to be a central pathway to mortality (7,(14)(15)(16)(17). This failure happens through embolism of a tree's water transport elements by air bubbles during high xylem tensions induced by low soil moisture and/or high atmospheric evaporative demand during...

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Section: Resultsmentioning

confidence: 99%

Meta-analysis reveals that hydraulic traits explain cross-species patterns of drought-induced tree mortality across the globe

Anderegg

Klein

Bartlett

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

622

546

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“…2009; Adams et al. 2013). On the other hand, drought could decrease a tree's carbon demand by downregulating growth, leading to a sink limitation, and in some cases, increased allocation to storage (Sala et al.…”

Section: Introductionmentioning

confidence: 99%

Drought and shade deplete nonstructural carbohydrate reserves in seedlings of five temperate tree species

Maguire

Kobe

2015

Ecology and Evolution

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Plants that store nonstructural carbohydrates (NSC) may rely on carbon reserves to survive carbon‐limiting stress, assuming that reserves can be mobilized. We asked whether carbon reserves decrease in resource stressed seedlings, and if NSC allocation is related to species' relative stress tolerances. We tested the effects of stress (shade, drought, and defoliation) on NSC in seedlings of five temperate tree species (Acer rubrum Marsh., Betula papyrifera Marsh., Fraxinus americana L ., Quercus rubra L., and Quercus velutina Lam.). In a greenhouse experiment, seedlings were subjected to combinations of shade, drought, and defoliation. We harvested seedlings over 32–97 days and measured biomass and NSC concentrations in stems and roots to estimate depletion rates. For all species and treatments, except for defoliation, seedling growth and NSC accumulation ceased. Shade and drought combined caused total NSC decreases in all species. For shade or drought alone, only some species experienced decreases. Starch followed similar patterns as total NSC, but soluble sugars increased under drought for drought‐tolerant species. These results provide evidence that species deplete stored carbon in response to carbon limiting stress and that species differences in NSC response may be important for understanding carbon depletion as a buffer against shade‐ and drought‐induced mortality.

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“…Most of these studies reported widespread reductions of growth and increased mortality worldwide, which affect several tree species and biomes, including tropical forests (Fisher et al 2007), temperate mountain conifer and hardwood forests (Linares & Camarero 2012, Anderegg et al 2013, drought-prone mountain conifer forests (Adams et al 2013), Mediterranean conifer forests (Linares et al 2009) and Mediterranean oak forests (Lloret et al 2004, Camarero et al 2015a, 2015b.…”

Section: Introductionmentioning

confidence: 99%

Drought-induced oak decline in the western Mediterranean region: an overview on current evidences, mechanisms and management options to improve forest resilience

Gentilesca¹,

Camarero²,

Colangelo³

et al. 2017

iForest

120

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Increased forest vulnerability is being reflected as more widespread and severe drought-induced decline episodes. In particular, the Mediterranean area is revealing a high susceptibility to phenomena of loss in tree vitality across species. Within tree species, oaks (Quercus spp.) are experiencing extensive decline in many countries. However, in the wake of the so-called "oak decline phenomenon", the attention on these species has generally been limited. In this paper, we review the current available literature on oakdecline cases reported within the Mediterranean Basin, with particular remark for those occurred in Italy and Spain. More specifically our main aims were to: (i) provide an update on the patterns and mechanisms of decline by focusing on tree-ring and wood-anatomical variables; (ii) provide some hints for improving the resistance and resilience of oak stands experiencing decline. Our review reveals that drought is reported as the main driver triggering oak decline within the Mediterranean Basin, although other causes (i.e., increasing temperature, pathogens attack or excessive stand density) could exacerbate decline. In most reported cases, drought induced a substantial reduction of growth and changes in some wood anatomical properties. Indeed, growth decline prior death is also indicated as an early-warning signal of impending death. In ring-porous oak species, declining trees were often characterized by a very low production of latewood and a decrease in lumen area of the widest earlywood vessels, suggesting a potential reduction of hydraulic conductivity. Moreover, hydraulic dysfunction is reported as the main cause of decline. Finally, regarding management actions that should be considered for improving the resilience of declining stands and preserve the species-specific stand composition, it could be useful to shorten the rotation period of coppice stands or promoting their gradual conversion towards high forests, and favoring more drought-resistant species should also be considered. In addition, regeneration prior to regeneration cuts should be improved by anticipating seed dispersal or by planting oak seedlings obtained from local germoplasm.

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Nonstructural leaf carbohydrate dynamics of Pinus edulis during drought‐induced tree mortality reveal role for carbon metabolism in mortality mechanism

Cited by 230 publications

References 88 publications

Meta-analysis reveals that hydraulic traits explain cross-species patterns of drought-induced tree mortality across the globe

Meta-analysis reveals that hydraulic traits explain cross-species patterns of drought-induced tree mortality across the globe

Drought and shade deplete nonstructural carbohydrate reserves in seedlings of five temperate tree species

Drought-induced oak decline in the western Mediterranean region: an overview on current evidences, mechanisms and management options to improve forest resilience

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