Varying growth response of Central European tree species to the extraordinary drought period of 2018 – 2020

Thom, Dominik; Buras, Allan; Heym, Michael; Klemmt, Hans-Joachim; Wauer, Alexandra

doi:10.1016/j.agrformet.2023.109506

Cited by 26 publications

(5 citation statements)

References 59 publications

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“…Other studies that assessed the impact of the 2018-2020 drought on forests have consistently reported signs of tree drought stress, reduced growth and increased tree mortality, both during and after the drought period (Buras et al, 2020;Obladen et al, 2021;Pohl et al, 2023;Schnabel et al, 2022;Schuldt et al, 2020;Senf et al, 2020). While our reported growth reduction by 36.8 % lines up with the finding of an earlier study by Thom et al, 2023, that reported a 41.3% reduction during the 2018-2020 drought, it should be kept in mind that our reductions are biologically even higher, because we expect an ontogenetic increase (Pretzsch, 2020). While a generally favourable nutrient supply can alleviate drought impacts on trees (Schmied et al, 2023), our initial anticipation of less pronounced growth reductions, based on the consideration of the soil characteristics at the site (Altermann et al, 2005) -particularly its high fertility and favourable water relations (see Methods) -did not align with the observed outcomes.…”

Section: Discussionsupporting

confidence: 90%

Forest growth resistance and resilience to the 2018-2020 drought depend on tree diversity and mycorrhizal type

Sachsenmaier,

Schnabel,

Dietrich

et al. 2024

Preprint

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1. The frequency of consecutive drought years is predicted to increase due to climate change. These droughts have strong negative impacts on forest ecosystems. Mixing tree species is proposed to increase the drought resistance and resilience of tree communities. However, this promising diversity effect has not yet been investigated under extreme drought conditions and in the context of complementary mycorrhizal associations and their potential role in enhancing water uptake. 2. Here, we investigate whether tree diversity promotes growth resistance and resilience to extreme drought and whether drought responses are modulated by mycorrhizal associations. We used inventory data (2015 - 2021) of a young tree diversity experiment in Germany, manipulating tree species richness (1, 2, 4 species) and mycorrhizal type (communities containing arbuscular mycorrhizal (AM) or ectomycorrhizal (EM) tree species, or both). For all tree communities, we calculated basal area increment (BAI) in the periods before, during, and after the drought and used the concepts of resistance and resilience to quantify growth responses to drought. 3. We found strong growth declines during the extreme 2018-2020 drought for most of the tree communities. Contrary to our hypothesis, we did not find that tree species richness per se can buffer the negative impacts of extreme drought on tree growth. However, while for EM communities, drought resistance, and resilience decreased with tree species richness, they increased for AM communities and communities comprising both mycorrhizal types. We highlight that among various tree species mixtures, only those with mixed mycorrhizal types outperformed their respective monocultures during and after drought. Further, under extreme drought, the community tends to segregate into 'winner' and 'loser' tree species in terms of diversity, indicating a potential intensification of competition. 4. While we cannot disentangle the underlying mechanisms, or clarify the role of mycorrhiza during drought, our findings suggest that mixtures of mycorrhizal types within tree communities could help safeguard forests against increasing drought frequency. 5. Synthesis: Drought resistance and resilience of tree communities depend on tree diversity and mycorrhizal association types. Mixing tree species with diverse mycorrhizal types holds promise for forest restoration in the face of climate change.

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Section: Discussionsupporting

confidence: 90%

Forest growth resistance and resilience to the 2018-2020 drought depend on tree diversity and mycorrhizal type

Sachsenmaier,

Schnabel,

Dietrich

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…Other studies that assessed the impact of the 2018-2020 drought on forests have consistently reported signs of tree drought stress, reduced growth and increased tree mortality, both during and after the drought period (Buras et al, 2020;Obladen et al, 2021;Pohl et al, 2023;Schnabel et al, 2022;Schuldt et al, 2020;Senf et al, 2020). Although our reported growth reduction by 36.8% lines up with the finding of an earlier study by Thom et al, 2023, that reported a 41.3% reduction during the 2018-2020 drought, it should be kept in mind that our reductions are biologically even higher, because we expect an ontogenetic increase (Pretzsch, 2020). Although a generally favourable nutrient supply can alleviate drought impacts on trees (Schmied et al, 2023), our initial anticipation of less pronounced growth reductions, based on the consideration of the soil characteristics at the site (Altermann et al, 2005)-particularly its high fertility and favourable water relations (see Section 2.1)-did not align with the observed outcomes.…”

Section: Strong Growth Reductions During Extreme Droughtsupporting

confidence: 89%

Forest growth resistance and resilience to the 2018–2020 drought depend on tree diversity and mycorrhizal type

Sachsenmaier,

Schnabel,

Dietrich

et al. 2024

Journal of Ecology

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The frequency of consecutive drought years is predicted to increase due to climate change. These droughts have strong negative impacts on forest ecosystems. Mixing tree species is proposed to increase the drought resistance and resilience of tree communities. However, this promising diversity effect has not yet been investigated under extreme drought conditions and in the context of complementary mycorrhizal associations and their potential role in improving water uptake. Here, we investigate whether tree diversity promotes growth resistance and resilience to extreme drought and whether drought responses are modulated by mycorrhizal associations. We used inventory data (2015–2021) from a young tree diversity experiment in Germany, manipulating tree species richness (1, 2 and 4 species) and mycorrhizal type (communities containing arbuscular mycorrhizal [AM] or ectomycorrhizal [EM] tree species, or both). For all tree communities, we calculated basal area increment in the periods before, during and after drought and used the concepts of resistance and resilience to quantify growth responses to drought. We found strong growth declines during the extreme 2018–2020 drought for most tree communities. Contrary to our hypothesis, we did not find that tree species richness per se can buffer the negative impacts of extreme drought on tree growth. However, while for EM communities, drought resistance and resilience decreased with tree species richness, they increased for AM communities and communities comprising both mycorrhizal types. We highlight that among various mixtures of tree species, only those with mixed mycorrhizal types outperformed their respective monocultures during and after drought. Furthermore, under extreme drought, the community tends to segregate into ‘winner’ and ‘loser’ tree species in terms of diversity, indicating a possible intensification of competition. While we cannot disentangle the underlying mechanisms or clarify the role of mycorrhiza during drought, our findings suggest that mixtures of mycorrhizal types within tree communities could help safeguard forests against increasing drought frequency. Synthesis. Drought resistance and resilience of tree communities depend on tree diversity and mycorrhizal association types. Mixing tree species with diverse mycorrhizal types holds promise for forest restoration in the face of climate change.

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“…There are many studies on the role of intraspecific variation, which captures the diversity of phenotypes, in tree responses to drought (e.g. F. sylvatica; Baudis et al, 2014;Carsjens et al, 2014;Cocozza et al, 2016;Dounavi et al, 2016;González De Andrés et al, 2021;Leuschner, 2020;Thom et al, 2023;Wang et al, 2021), with the aim to improve decisionmaking in forest management and enhance forest resilience to climate change. Our experiment demonstrated a variety of physiological responses to decreased water availability.…”

Section: Intraspecific Variation In Drought Stress Responses Across G...mentioning

confidence: 99%

Leaf spectroscopy reveals drought response variation inFagus sylvaticasaplings from across the species’ range

Kurath,

van Moorsel,

Klaver

et al. 2024

Preprint

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The common European beech (F. sylvatica) is sensitive to prolonged droughts, and its natural distribution is expected to shift with climate change. To persist in novel environments, young trees rely on the capacity to express diverse response phenotypes. Several methods exist to study drought effects on trees and their diverse adaptive mechanisms, but these are usually destructive, and challenging to scale to the large sample numbers needed to investigate biological variation. We conducted a common garden experiment outdoors, but under controlled watering conditions, with 180 potted two-year-old saplings from 16 beech provenances across the species range, representing three distinct genetic clusters. Drought stress was simulated by interrupting irrigation. We measured leaf reflectance of visible to short-wave infrared electromagnetic radiation. We determined drought-induced changes in biochemical and structural traits derived from spectral indices and a model of leaf optical properties, and assessed intraspecific response diversity. We quantified changes in pigmentation, water balance, nitrogen, lignin, epicuticular wax, and leaf mass per area in drought-treated saplings from different genetic clusters, revealing differences in likely adaptive responses to drought.F. sylvaticasaplings from the Iberian Peninsula showed signatures of greater drought resistance, i.e., the least trait change in response to the drought treatment. Stomatal conductance and soil moisture were used to assess drought severity. We demonstrate that high-resolution, broad-range leaf spectroscopy is an effective and non-destructive tool to assess individual drought responses that can characterize functional intraspecific variation among young beech trees.

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Varying growth response of Central European tree species to the extraordinary drought period of 2018 – 2020

Cited by 26 publications

References 59 publications

Forest growth resistance and resilience to the 2018-2020 drought depend on tree diversity and mycorrhizal type

Forest growth resistance and resilience to the 2018-2020 drought depend on tree diversity and mycorrhizal type

Forest growth resistance and resilience to the 2018–2020 drought depend on tree diversity and mycorrhizal type

Leaf spectroscopy reveals drought response variation inFagus sylvaticasaplings from across the species’ range

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