Drought induced tree mortality – a tree‐ring isotope based conceptual model to assess mechanisms and predispositions

Geßler, Arthur; Cailleret, Maxime; Joseph, Jobin; Schönbeck, Leonie; Schaub, Marcus; Lehmann, Marco M.; Treydte, Kerstin; Rigling, Andreas; Timofeeva, Galina; Saurer, Matthias

doi:10.1111/nph.15154

Cited by 96 publications

(75 citation statements)

References 47 publications

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“…This implies that the high iWUE did not result in an enhancement but rather a decrease in tree growth. Trees are likely switched to a more conservative water-use strategy by enhancing stomatal control during the continuous drying trend, resulting in tree growth decline, even though iWUE increases [22,26].…”

Section: Implications Of Iwue For Tree-ring Growthmentioning

confidence: 99%

“…The reasons for this may be that climate and other exogenous factors, such as drought [18,[22][23][24], mistletoe infection, and nutrient availability [20,22,25], can concurrently affect tree growth by causing stress that counteracts the effect of changes in CO 2atm . The relationships between iWUE, climate, and tree growth are not always linear [3,17,25,26]. Thus, to disentangle the contributions of CO 2atm and climate to an increase in iWUE, it is important to determine the drivers of iWUE variability in trees or forests [9,10].…”

Section: Introductionmentioning

confidence: 99%

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Disentangling Contributions of CO2 Concentration and Climate to Changes in Intrinsic Water-Use Efficiency in the Arid Boreal Forest in China’s Altay Mountains

Xu¹,

Liu²,

Belmecheri³

et al. 2018

Forests

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Intrinsic water-use efficiency (iWUE) is affected by the balance of photosynthetic rate, stomatal conductance, and climate, along with many other exogenous factors, such as the CO2 concentration in the atmosphere (CO2atm), nutrients, and water holding capacity of the soil. The relative contributions of CO2atm and climate to iWUE are still incompletely understood, particularly for boreal forests where the climate is undergoing unprecedented warming. We combined δ13C and δ18O in tree rings from the Siberian larch (Larix sibirica Ledeb.) in Northwestern China’s Altay Mountains, which receives 190 mm in annual precipitation, to detect the drivers of long-term iWUE changes and their time-varying contributions over the past 222 years. A climate optimization approach was used to isolate the influence of climate from CO2atm influence on iWUE. We found that iWUE increased about 33.6% from 1790 to 2011, and rising CO2atm contributed 48.8% to this iWUE increase. The contributions of CO2atm and climate (drought conditions) varied during the study period 1790–2011. From 1790 to 1876, the climate was the most important factor contributing to the changes in iWUE. From 1877 to 1972, CO2atm was the main contributor; however, after 1973, the climate was again the dominant contributor to the increase in iWUE, especially during 1996–2011. During the period 1996–2011, climate substantially (83%) contributed to the iWUE increase. Our findings imply that, in the boreal forest in Northwestern China’s arid region, iWUE experienced three changes: (1) the climate dominating from 1790 to 1876; (2) CO2atm dominating from 1877 to 1972, and (3) climate dominating again during the past four decades. We observed that the relationships between iWUE and tree-ring width shifted from positive to negative from 1996 onwards. These relationship changes indicate that CO2atm-mediated effects of increasing iWUE on tree growth are counteracted by climatic drought stress and iWUE increase cannot counter the stress from drought on tree growth in China’s arid boreal forest.

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Section: Implications Of Iwue For Tree-ring Growthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Disentangling Contributions of CO2 Concentration and Climate to Changes in Intrinsic Water-Use Efficiency in the Arid Boreal Forest in China’s Altay Mountains

Xu¹,

Liu²,

Belmecheri³

et al. 2018

Forests

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“…In several cases, tree mortality is preceded, from a few years to decades, by reductions in growth [5,6]. Since many factors are involved in mortality process, it remains difficult to understand why some individuals die and others stay alive within the same stand [1,3,[7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Radial Growth Patterns Associated with Tree Mortality in Nothofagus pumilio Forest

Rodríguez‐Catón

Villalba

Srur

et al. 2019

Forests

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Tree mortality is a key process in forest dynamics. Despite decades of effort to understand this process, many uncertainties remain. South American broadleaf species are particularly under-represented in global studies on mortality and forest dynamics. We sampled monospecific broadleaf Nothofagus pumilio forests in northern Patagonia to predict tree mortality based on stem growth. Live or dead conditions in N. pumilio trees can be predicted with high accuracy using growth rate as an explanatory variable in logistic models. In Paso Córdova (CO), Argentina, where the models were calibrated, the probability of death was a strong negative function of radial growth, particularly during the six years prior to death. In addition, negative growth trends during 30 to 45 years prior to death increased the accuracy of the models. The CO site was affected by an extreme drought during the summer 1978-1979, triggering negative trends in radial growth of many trees. Individuals showing below-average and persistent negative trends in radial growth are more likely to die than those showing high growth rates and positive growth trends in recent decades, indicating the key role of droughts in inducing mortality. The models calibrated at the CO site showed high verification skill by accurately predicting tree mortality at two independent sites 76 and 141 km away. Models based on relative growth rates showed the highest and most balanced accuracy for both live and dead individuals. Thus, the death of individuals across different N. pumilio sites was largely determined by the growth rate relative to the total size of the individuals. Our findings highlight episodic severe drought as a triggering mechanism for growth decline and eventual death for N. pumilio, similar to results found previously for several other species around the globe. In the coming decades, many forests globally will be exposed to more frequent and/or severe episodes of reduced warm-season soil moisture. Tree-ring studies such as this one can aid prediction of future changes in forest productivity, mortality, and composition. Author Contributions: R.V., M.R.-C., and A.S. planned and designed plot setup and collected samples for the research with the help of people mention in Acknowledgments; methodology, R.V., M.R.-C.; dendrochronological processing and formal analysis, M.R.-C.; resources and funding acquisition, R.V., M.R.-C., A.S., and A.P.W.; data curation, M.R.-C.; writing-original draft preparation, M.R.-C.; writing-review and editing, M.R.-C., R.V., A.S., and A.P.W.; supervision, R.V. and A.S. Funding:We are grateful for support from Consejo Nacional de Investigaciones Científicas y Técnicas for providing the postdoctoral fellowship (CONICET), Argentina and BNP-PARIBAS Foundation through THEMES Project. APW was supported by NSF awards 1602581 and 1743738.

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“…[17][18][19][20][21][22] ). An important factor to consider is that, while severe drought may trigger tree mortality within a population, some trees can be less vulnerable to dry conditions than others and survive 14,[23][24][25] . Since most trees face several drought events during their lives, high resilience to drought might determine long-term tree survival.…”

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confidence: 99%

Low growth resilience to drought is related to future mortality risk in trees

et al. 2020

Self Cite

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Severe droughts have the potential to reduce forest productivity and trigger tree mortality. Most trees face several drought events during their life and therefore resilience to dry conditions may be crucial to long-term survival. We assessed how growth resilience to severe droughts, including its components resistance and recovery, is related to the ability to survive future droughts by using a tree-ring database of surviving and now-dead trees from 118 sites (22 species, >3,500 trees). We found that, across the variety of regions and species sampled, trees that died during water shortages were less resilient to previous non-lethal droughts, relative to coexisting surviving trees of the same species. In angiosperms, drought-related mortality risk is associated with lower resistance (low capacity to reduce impact of the initial drought), while it is related to reduced recovery (low capacity to attain pre-drought growth rates) in gymnosperms. The different resilience strategies in these two taxonomic groups open new avenues to improve our understanding and prediction of drought-induced mortality.

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Drought induced tree mortality – a tree‐ring isotope based conceptual model to assess mechanisms and predispositions

Cited by 96 publications

References 47 publications

Disentangling Contributions of CO2 Concentration and Climate to Changes in Intrinsic Water-Use Efficiency in the Arid Boreal Forest in China’s Altay Mountains

Disentangling Contributions of CO2 Concentration and Climate to Changes in Intrinsic Water-Use Efficiency in the Arid Boreal Forest in China’s Altay Mountains

Radial Growth Patterns Associated with Tree Mortality in Nothofagus pumilio Forest

Low growth resilience to drought is related to future mortality risk in trees

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