Climate change impact on tree mortality differs with tree social status

The high tree mortality during the dry and hot years of 2018–2019 in Europe has triggered concerns on the future of European beech (Fagus sylvatica L.) forests under climate change and raised questions as to whether forest management may increase tree mortality. We compared long‐term mortality rates of beech between managed and unmanaged stands including the years 2018‐2019 at 11 sites in Hesse, Germany. We hypothesized that mortality would increase with climate water deficits during the growing season, initial stand density, decreasing dominance of trees, and decreasing intensity of tree removals. Initial stand density, tree removals, the climate water balance and the competitive status of trees were used as predictor variables. Mean annual natural mortality rates ranged between 0.5% and 2.1%. Even in the drought years, we observed no signs of striking canopy disintegration. The significantly higher mortality (1.6–2.1%) in unmanaged stands during the drought years 2018 and 2019 was largely confined to suppressed trees. There was no significant increase of mortality in managed stands during the drought years, but a shift in mortality towards larger canopy trees. Our study did not confirm a general influence of management, in the form of tree removals, on mortality rates. Yet, we found that during drought years, management changed the distribution of mortality within the tree community. To analyse the effects of management on mortality rates more comprehensively, a wider gradient in site moisture conditions, including sites drier than in this study, and longer post‐drought periods should be employed.

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“…Comparable to our study also Taccoen et al . (2021) have found over‐mortality of suppressed trees as a consequence of drought.…”

Section: Discussionmentioning

confidence: 99%

Management alters drought‐induced mortality patterns in European beech (Fagus sylvaticaL.) forests

et al. 2022

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“…Mortality data in tree ecology is often treated as a binary variable that can be best accomodated by logistic regression analysis 14 , 42 , 43 . However, when the cause of death is primarily caused by a pathogen which resembles a mortality pattern close to a pandemic situation (i.e.…”

Section: Methodsmentioning

confidence: 99%

European-wide forest monitoring substantiate the neccessity for a joint conservation strategy to rescue European ash species (Fraxinus spp.)

George

Sanders

Timmermann

et al. 2022

Sci Rep

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European ash (Fraxinus excelsior) and narrow-leafed ash (F. angustifolia) are keystone forest tree species with a broad ecological amplitude and significant economic importance. Besides global warming both species are currently under significant threat by an invasive fungal pathogen that has been spreading progressively throughout the continent for almost three decades. Ash dieback caused by the ascomycete Hymenoscyphus fraxineus is capable of damaging ash trees of all age classes and often ultimately leads to the death of a tree after years of progressively developing crown defoliation. While studies at national and regional level already suggested rapid decline of ash populations as a result of ash dieback, a comprehensive survey at European level with harmonized crown assessment data across countries could shed more light into the population decline from a pan-European perspective and could also pave the way for a new conservation strategy beyond national boarders. Here we present data from the ICP Forests Level I crown condition monitoring from 27 countries resulting in > 36,000 observations. We found a substantial increase in defoliation and mortality over time indicating that crown defoliation has almost doubled during the last three decades. Hotspots of mortality are currently situated in southern Scandinavia and north-eastern Europe. Overall survival probability after nearly 30 years of infection has already reached a critical value of 0.51, but with large differences among regions (0.20–0.86). Both a Cox proportional hazard model as well as an Aalen additive regression model strongly suggest that survival of ash is significantly lower in locations with excessive water regime and which experienced more extreme precipitation events during the last two decades. Our results underpin the necessity for fast governmental action and joint rescue efforts beyond national borders since overall mean defoliation will likely reach 50% as early as 2030 as suggested by time series forecasting.

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“…The global average temperature has reportedly increased by 0.85 • C compared with the pre-industrial levels (IPCC, 2018), and this has raised widespread attention. Current research shows that increasing temperatures have positive (Day et al, 2008;Wu et al, 2020), neutral (Mao et al, 2016;Peng et al, 2020), or negative (Herguido et al, 2016;Taccoen et al, 2021) effects on plant growth. These discrepancies may be related to the differences in soil nutrient availability and plant nutrient requirements.…”

Section: Introductionmentioning

confidence: 99%

Variations in Rainfall Affect the Responses of Foliar Chemical Properties of Cunninghamia lanceolata Seedlings to Soil Warming

et al. 2021

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Climate warming is becoming an increasingly serious threat. Understanding plant stoichiometry changes under climate warming is crucial for predicting the effects of future warming on terrestrial ecosystem productivity. Nevertheless, how plant stoichiometry responds to warming when interannual rainfall variation is considered, remains poorly understood. We performed a field soil warming experiment (+5°C) using buried heating cables in subtropical areas of China from 2015 to 2018. Stoichiometric patterns of foliar C:N:P:K:Ca:Mg, non-structural carbohydrate, and stable isotope of Cunninghamia lanceolata seedlings were studied. Our results showed that soil warming decreased foliar P and K concentrations, C:Ca, P:Ca, and P:Mg ratios. However, soil warming increased foliar Ca concentration, δ15N value, C:P and N:P ratios. The response ratios of foliar N, C:N, and δ15N to soil warming were correlated with rainfall. Our findings indicate that there was non-homeostasis of N and C:N under warming conditions. Three possible reasons for this result are considered and include interannual variations in rainfall, increased loss of N, and N limitation in leaves. Piecewise structural equation models showed that stoichiometric non-homeostasis indirectly affected the growth of C. lanceolata seedlings in response to soil warming. Consequently, the growth of C. lanceolata seedlings remained unchanged under the warming treatment. Taken together, our results advance the understanding of how altered foliar stoichiometry relates to changes in plant growth in response to climate warming. Our results emphasize the importance of rainfall variations for modulating the responses of plant chemical properties to warming. This study provides a useful method for predicting the effects of climate warming on economically important timber species.

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Climate change impact on tree mortality differs with tree social status

Cited by 23 publications

References 83 publications

Management alters drought‐induced mortality patterns in European beech (Fagus sylvaticaL.) forests

Management alters drought‐induced mortality patterns in European beech (Fagus sylvaticaL.) forests

European-wide forest monitoring substantiate the neccessity for a joint conservation strategy to rescue European ash species (Fraxinus spp.)

Variations in Rainfall Affect the Responses of Foliar Chemical Properties of Cunninghamia lanceolata Seedlings to Soil Warming

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