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Changing climate sensitivity of secondary growth following extreme drought events in forest ecosystems: a global analysis

Leifsson, C.; Buras, A.; Rammig, A.; Zang, C. (2023)

Environmental Research Letters 18, 014021.
DOI: 10.1088/1748-9326/aca9e5


Open Access Peer Reviewed
 

Understanding tree-response to extreme drought events is imperative for maintaining forest ecosystem services under climate change. While tree-ring derived secondary growth measurements are often used to estimate direct and lagging drought impacts, so-called drought legacies, underlying physiological responses remain difficult to constrain across species and site conditions. As extreme droughts may alter the functioning of plants in terms of resource allocation being shifted towards repair and physiological adjustments, climate control on growth may consequently be altered until physiological recovery is completed. In this context, we here advance the concept of drought legacy effects by quantifying 'functional legacies' as climate sensitivity deviations (CSD) of secondary growth after droughts, i.e. temporary alterations of climate-growth relations. We quantified climate sensitivity deviations after extreme drought events by applying linear mixed-effects models to a global-scale, multi-species tree-ring dataset and differentiated responses by clades, site aridity and hydraulic safety margins (HSMs). We found that while direct secondary growth legacies were common across these groups, responses in post-drought climate sensitivity deviations were nuanced. Gymnosperms showed weaker coupling between secondary growth and the dominant climatic driver after droughts, a response that was narrowed down to gymnosperms with a small HSM, i.e. risky hydraulic strategy. In comparison, angiosperms instead showed stronger coupling between secondary growth and the dominant climatic driver following droughts, which was narrowed down to the angiosperms growing in arid sites. These results are consistent with current understanding of physiological impairment and carbon reallocation mechanisms, and the distinct functional responses suggest functional legacies quantified by climate sensitivity deviations is a promising avenue for detecting and thus studying physiological mechanisms underlying drought-responses in tree growth on large scales.

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Tuesday Discussion with Jörg Ewald

Medienbeitrag, .; Ewald, J. (2022)

Youtube-Presentation about BAYSICS at the Rachel Carson Center.


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Die Stechpalme im Gebiet der Bayerischen Voralpen: Vorkommen und Genetik

Ewald, J.; Schäfer, H.; Olleck, M.; Rösler, S.; Gibis, F.; Kastner, T.; Höwener, A....

Forstliche Forschungsberichte München. Schriftenreihe des Zentrums Wald-Forst-Holz Weihenstephan 223.



Die Stechpalme im Gebiet der Bayerischen Voralpen: Vorkommen und Genetik

Ewald, J.; Schäfer, H. (2022)

Forstliche Forschungsberichte. Schriftenreihe des Zentrums Wald-Forst-Holz Weihenstephan 223, S. 5-14.



Aktuelle Verbreitung und Standortansprüche der Stechpalme im bayerischen Voralpenraum

Olleck, M.; Ewald, J. (2022)

Forstliche Forschungsberichte. Schriftenreihe des Zentrums Wald-Forst-Holz Weihenstephan 223, S. 15-46.



Entspricht das „Höherwandern“ der Stechpalme (Ilex aquifolium L.) in den Bayerischen Alpen seit Sendtner (1854) der Erwärmung in diesem Zeitraum?

Rösler, S.; Olleck, M.; Ewald, J. (2022)

Forstliche Forschungsberichte. Schriftenreihe des Zentrums Wald-Forst-Holz Weihenstephan 223, S. 47-64.



Earlier flowering of winter oilseed rape compensates for higher pest pressure in warmer climates

Fricke, U.; Redlich, S.; Zhang, J.; Benjamin, C.; Englmeier, J.; Ganuza, C....

Journal of Applied Ecology1-11 00, S. 1-11.
DOI: 10.1111/1365-2664.14335


Open Access Peer Reviewed
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Tuesday Discussion with Jörg Ewald (Hochschule Weihenstephan-Triesdorf) - Guest Lecture at Rachel Carson Center for Environment and Society der LMU München

Ewald, J. (2022)



Quantifying the impacts of land cover change on gross primary productivity globally

Krause, A.; Papastefanou, P.; Gregor, K.; Layritz, L.; Zang, C.; Buras, A.; Li, X....

Scientific Reports 12, 18398.
DOI: 10.1038/s41598-022-23120-0


Open Access Peer Reviewed
 

Historically, humans have cleared many forests for agriculture. While this substantially reduced ecosystem carbon storage, the impacts of these land cover changes on terrestrial gross primary productivity (GPP) have not been adequately resolved yet. Here, we combine high-resolution datasets of satellite-derived GPP and environmental predictor variables to estimate the potential GPP of forests, grasslands, and croplands around the globe. With a mean GPP of 2.0 kg C m−2 yr−1 forests represent the most productive land cover on two thirds of the total area suitable for any of these land cover types, while grasslands and croplands on average reach 1.5 and 1.8 kg C m−2 yr−1, respectively. Combining our potential GPP maps with a historical land-use reconstruction indicates a 4.4% reduction in global GPP from agricultural expansion. This land-use-induced GPP reduction is amplified in some future scenarios as a result of ongoing deforestation (e.g., the large-scale bioenergy scenario SSP4-3.4) but partly reversed in other scenarios (e.g., the sustainability scenario SSP1-1.9) due to agricultural abandonment. Comparing our results to simulations from state-of-the-art Earth System Models, we find that all investigated models deviate substantially from our estimates and from each other. Our maps could be used as a benchmark to reduce this inconsistency, thereby improving projections of land-based climate mitigation potentials.

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Dynamik und Anpassung der Naturwälder an den Klimawandel- Verbundprojekt vergleicht Reaktion von unbewirtschafteten und bewirtschafteten Wäldern auf Dürreperioden

Ewald, J.; Ammer, C.; Blaschke, M.; Hagge, J.; Henkel, A.; Hese, S.; Klamm, A....

Posterpräsentation zum Projektauftakt auf dem Waldklimafonds-Kongress 2022 in Göttingen.


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Dung-visiting beetle diversity is mainly affected by land use, while community specialization is driven by climate

Englmeier, J.; von Hoermann, C.; Rieker, D.; Benbow, M.; Benjamin, C.; Fricke, U....

Ecology and Evolution 12, e9386 (10).
DOI: 10.1002/ece3.9386


Open Access Peer Reviewed
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Höhengrenzen von Baumarten selbst erkunden - BAYSICS, Teilprojekt 6

Rösler, S.; Olleck, M.; Reger, B.; Ewald, J. (2022)

Poster beim IÖL-Science Day am 29.09.2022.



Für die Streuobstwiesen

Honecker, R.; Wölfl, S.; Gruber, P. (2022)

LandInForm-Magazin für Ländliche Räume (3.22), S. 40-41.


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Recent extreme drought events in the Amazon rainforest: assessment of different precipitation and evapotranspiration datasets and drought indicators

Papastefanou, P.; Zang, C.; Angelov, Z.; Anderson de Castro, A.; Jimenez, J....

Biogeosciences 19, S. 3843–3861.
DOI: 10.5194/bg-19-3843-2022


Open Access Peer Reviewed
 

Over the last decades, the Amazon rainforest has been hit by multiple severe drought events. Here, we assess the severity and spatial extent of the extreme drought years 2005, 2010 and 2015/16 in the Amazon region and their impacts on the regional carbon cycle. As an indicator of drought stress in the Amazon rainforest, we use the widely applied maximum cumulative water deficit (MCWD). Evaluating nine state-of-the-art precipitation datasets for the Amazon region, we find that the spatial extent of the drought in 2005 ranges from 2.2 to 3.0 (mean =2.7) ×106 km2 (37 %–51 % of the Amazon basin, mean =45 %), where MCWD indicates at least moderate drought conditions (relative MCWD anomaly ). In 2010, the affected area was about 16 % larger, ranging from 3.0 up to 4.4 (mean =3.6) ×106 km2 (51 %–74 %, mean =61 %). In 2016, the mean area affected by drought stress was between 2005 and 2010 (mean  km2; 55 % of the Amazon basin), but the general disagreement between datasets was larger, ranging from 2.4 up to 4.1×106 km2 (40 %–69 %). In addition, we compare differences and similarities among datasets using the self-calibrating Palmer Drought Severity Index (scPDSI) and a dry-season rainfall anomaly index (RAI). We find that scPDSI shows a stronger and RAI a much weaker drought impact in terms of extent and severity for the year 2016 compared to MCWD. We further investigate the impact of varying evapotranspiration on the drought indicators using two state-of-the-art evapotranspiration datasets. Generally, the variability in drought stress is most dependent on the drought indicator (60 %), followed by the choice of the precipitation dataset (20 %) and the evapotranspiration dataset (20 %). Using a fixed, constant evapotranspiration rate instead of variable evapotranspiration can lead to an overestimation of drought stress in the parts of Amazon basin that have a more pronounced dry season (for example in 2010). We highlight that even for well-known drought events the spatial extent and intensity can strongly depend upon the drought indicator and the data sources it is calculated with. Using only one data source and drought indicator has the potential danger of under- or overestimating drought stress in regions with high measurement uncertainty, such as the Amazon basin.

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Bäume wandern himmelwärts

Rösler, S. (2022)

alpinwelt - Das Bergmagazin für München und Oberland 2022 (03), S. 28-29.


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Einheitliche Orientierungswerte für öffentliches Grün

Blum, P.; Böhme, C.; Kühnau, C.; Reinke, M.; Willen, L. (2022)

Stadt + Grün 71 (8), S. 19-23.


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Alpengärten - in neuer Blüte

Rösler, S. (2022)

Panorama - Das Magazin des Deutschen Alpenvereins 74 (4), S. 24.



Klimawandel im Wettersteinwald - Wissenschaftliche Analysen in einem Naturwaldreservat

Medienbeitrag, . (2022)

Beitrag des BR vom 16.07.2022.


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Combustion behaviour and slagging tendencies of pure, blended and kaolin additivated biomass pellets from fen paludicultures in two small-scale boilers < 30 kW

Kuptz, D.; Kuchler, C.; Rist, E.; Eickenscheidt, T.; Mack, R.; Schön, C.; Drösler, M....

Biomass and Bioenergy (accepted and in print).


Peer Reviewed

Klimawandel vor der Haustür: BAYSICS - Bayerisches Synthese-Informations-Citizen Science Portal für Klimaforschung und Wissenschaftskommunikation

Menzel, A.; Lüpke, A.; Kloos, S. (2022)

Umwelt-Technologie und Energie in Bayern 2022/2023, S. 30-33.



Institut für Ökologie und Landschaft (IÖL)

Hochschule Weihenstephan-Triesdorf

Institut für Ökologie und Landschaft (IÖL)
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85354 Freising

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