Waldinventur und Klimawandel

Experten dreier deutscher Hochschulen entwickelten gemeinsam mit der Ostdeutschen Gesellschaft für Forstplanung mbH ein neues, forstliches Monitoringsystem. Das Verbundprojekt „Entwicklung eines forstlichen Monitoringsystems unter Berücksichtigung von Kohlenstoffspeicherung und Klimaanpassung“ (FOMOSY-KK) wird vorgestellt

Potential Analysis for Further Nature Conservation in Azerbaijan: A Spatial and Political Investment Strategy

Financed by the MAVA Foundation (Switzerland), the Michael Succow Foundation (MSF), in cooperation with various experts from Azerbaijan, conducted a detailed gap analysis of potential future protected areas in Azerbaijan. This report presents the results of this project and constitutes a part of the strategy of the MSF: to provide sound background information on the biological value and its further potential for protection in Azerbaijan. From the very beginning of the foundation’s engagement in Azerbaijan nine years ago, the sciencebased protection of landscapes and species has been the main focus of our work in the country.researc

Climate-change-driven growth decline of European beech forests

The growth of past, present, and future forests was, is and will be affected by climate variability. This multifaceted relationship has been assessed in several regional studies, but spatially resolved, large-scale analyses are largely missing so far. Here we estimate recent changes in growth of 5800 beech trees (Fagus sylvatica L.) from 324 sites, representing the full geographic and climatic range of species. Future growth trends were predicted considering state-of-the-art climate scenarios. The validated models indicate growth declines across large region of the distribution in recent decades, and project severe future growth declines ranging from -20% to more than -50% by 2090, depending on the region and climate change scenario (i.e. CMIP6 SSP1-2.6 and SSP5-8.5). Forecasted forest productivity losses are most striking towards the southern distribution limit of Fagus sylvatica, in regions where persisting atmospheric high-pressure systems are expected to increase drought severity. The projected 21st century growth changes across Europe indicate serious ecological and economic consequences that require immediate forest adaptation.Additional co-authors: Ernst van der Maaten, Sjepan Mikac, Bat-Enerel Banzragch, Wolfgang Beck, Hugues Claessens, Vojtěch Čada, Katarina Čufar, Choimaa Dulamsuren, Jozica Gričar, Eustaquio Gil-Pelegrín, Pavel Janda, Marko Kazimirovic, Juergen Kreyling, Nicolas Latte, Christoph Leuschner, Luis Alberto Longares, Annette Menzel, Maks Merela, Renzo Motta, Lena Muffler, Paola Nola, Any Mary Petritan, Ion Catalin Petritan, Peter Prislan, Álvaro Rubio-Cuadrado, Miloš Rydval, Branko Stajić, Miroslav Svoboda, Elvin Toromani, Volodymyr Trotsiuk, Martin Wilmking, Tzvetan Zlatanov & Martin de Lui

The 2018 European heatwave led to stem dehydration but not to consistent growth reductions in forests

Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-temporal resolution dendrometer data from 21 species across 53 sites. Relative to the two preceding years, annual stem growth was not consistently reduced by the 2018 heatwave but stems experienced twice the temporary shrinkage due to depletion of water reserves. Conifer species were less capable of rehydrating overnight than broadleaves across gradients of soil and atmospheric drought, suggesting less resilience toward transient stress. In particular, Norway spruce and Scots pine experienced extensive stem dehydration. Our high-resolution dendrometer network was suitable to disentangle the effects of a severe heatwave on tree growth and desiccation at large-spatial scales in situ, and provided insights on which species may be more vulnerable to climate extremes

The 2018 European heatwave led to stem dehydration but not to consistent growth reductions in forests

Publisher Copyright: © 2022, The Author(s).Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These impacts remain poorly understood at the tree and species level and across large spatial scales. Here, we investigate the effects of the record-breaking 2018 European heatwave on tree growth and tree water status using a collection of high-temporal resolution dendrometer data from 21 species across 53 sites. Relative to the two preceding years, annual stem growth was not consistently reduced by the 2018 heatwave but stems experienced twice the temporary shrinkage due to depletion of water reserves. Conifer species were less capable of rehydrating overnight than broadleaves across gradients of soil and atmospheric drought, suggesting less resilience toward transient stress. In particular, Norway spruce and Scots pine experienced extensive stem dehydration. Our high-resolution dendrometer network was suitable to disentangle the effects of a severe heatwave on tree growth and desiccation at large-spatial scales in situ, and provided insights on which species may be more vulnerable to climate extremes.Peer reviewe

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world\u27s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km² resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e., offset) between in-situ soil temperature measurements, based on time series from over 1200 1-km² pixels (summarized from 8500 unique temperature sensors) across all the world’s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in-situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Jet stream position explains regional anomalies in European beech forest productivity and tree growth.

The mechanistic pathways connecting ocean-atmosphere variability and terrestrial productivity are well-established theoretically, but remain challenging to quantify empirically. Such quantification will greatly improve the assessment and prediction of changes in terrestrial carbon sequestration in response to dynamically induced climatic extremes. The jet stream latitude (JSL) over the North Atlantic-European domain provides a synthetic and robust physical framework that integrates climate variability not accounted for by atmospheric circulation patterns alone. Surface climate impacts of north-south summer JSL displacements are not uniform across Europe, but rather create a northwestern-southeastern dipole in forest productivity and radial-growth anomalies. Summer JSL variability over the eastern North Atlantic-European domain (5-40E) exerts the strongest impact on European beech, inducing anomalies of up to 30% in modelled gross primary productivity and 50% in radial tree growth. The net effects of JSL movements on terrestrial carbon fluxes depend on forest density, carbon stocks, and productivity imbalances across biogeographic regions

Global maps of soil temperature.

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Dendroecology of Beech & Oak. Past growth and future development - how climate, site conditions and strong environmental shifts influence growth performance of Fagus sylvatica (L.) and Quercus robur (L.) in northern Central-Europe

Global change, amongst others characterized by increasing temperatures, altered precipitation patterns, an increase of extreme climatic events and continued atmospheric depositions of pollutants, is expected to severely impact forest ecosystems worldwide. The complex interplay between different factors acting upon tree growth, combined with regional patterns in climatic change calls for a region specific evaluation of the possible consequences on forest ecosystems. For northeastern Germany regional climate models identify a rise in temperatures and a change in precipitation patterns. Drier summers and wetter winters together with an increase in extreme weather events are seen as the most pronounced changes that will occur during the 21st century. In this thesis I analysed past growth rates and climate-growth relationships in different stands of beech (Fagus sylvatica L.) and oak (Quercus robur L.) along a gradient of decreasing precipitation in a space for time approach. Special attention was paid to the influence of summer drought, soil waterlogging and the importance of site conditions in modulating the reactions to these climatic stressors. Departing from these retrospective analyses, future growth trends are modelled for beech, oak and Scots pine (Pinus sylvestris L.), based on projections of a regional climate model until the year 2100. Furthermore, I studied the influence of sudden and extreme shifts in hydrological conditions on the growth of oaks in a drained peatland that was subject to catastrophic rewetting. All analyses of this thesis are based on ring-width and wood anatomical features applying a variety of dendrochronological methods. The gradient approach revealed similar climate-growth relationships for beech and oak on drought exposed, sandy sites, where water availability during early summer was the main growth-limiting factor for both species. Decreasing precipitation rates towards the East are associated with higher drought susceptibility, especially for beech. As a result, competitive superiority of beech over oak decreases. In a drier future the competitive balance between the two species may shift (rank reversal). During the past decades beech has shown larger interannual growth variability and a higher number of growth depressions. These changes might indicate that increasing temperatures and climatic variability are already affecting its growth patterns and climate sensitivity. This is in line with the prospective modelling approach. According to our models, growth trends will turn negative for beech and oak towards the end of the 21st century, with beech showing the highest growth reduction (23% compared to the reference period 1971-2000). For pine, modelled growth rates show only minor changes. Whereas beech and oak shared a high common signal on the dry sites, the two species differed in high frequency ring patterns on the wet sites. On poorly drained, loamy soils beech, with its superficial root system, suffered from summer droughts. In contrast, on these sites ring-width of pedunculate oak was not correlated to summer moisture conditions resulting in differing interannual ring patterns between dry and wet sites. Wet periods with high soil water saturation did not have a negative influence on the growth of either species. Such a lack of response is not surprising for oak, which is generally known as rather tolerant to soil waterlogging, but it indicates an unexpectedly high tolerance of beech to stagnating wetness. Using the natural laboratory of an oak forest that suffered a catastrophic flooding I could show that slower grown trees that had likely been suppressed displayed a higher adaptive capacity compared with bigger, dominant trees. Many of the previously dominant individuals died within 18 years after the event. Trees that survived the groundwater rise displayed a typical ring pattern: growth was suppressed for a few years, but afterwards recovered and even surpassed previous growth rates, most likely as a result of competition release. The sudden hydrological change left a clear imprint in ring patterns and wood anatomical features in both the dying and the surviving trees. This differentiated imprint may be helpful for a better interpretation of growth patterns found in subfossil bog oaks, an important climate proxy of the Holocene. The insights gained from this thesis support existing concerns about drought induced growth decline for oak, but especially for beech. Changes in precipitation patterns might lead to wetter conditions during winter, but these will likely have only little effect on growth. Both s show rather high resilience to stagnating wetness. More likely, it are extreme events like prolonged droughts or heavy rainfalls that might breach thresholds in the ability of the two species to cope with too much or too little water. Such extreme events thus pose a strong risk to the future growth performance of both oak and beech.Der globale Wandel, unter anderem gekennzeichnet durch steigende Temperaturen, veränderte Niederschlagsmuster, eine Zunahme von Extremereignissen sowie fortgesetzten hohen Depositionen von Luftschadstoffen, wird in starkem Maße die Waldökosysteme weltweit beeinflussen. Räumliche Unterschiede in den Mustern des Klimawandels und das komplexe Wechselspiel der Einwirkungen der unterschiedlichen Faktoren, erfordern eine regionalspezifische Evaluierung der möglichen Auswirkungen des globalen Wandels auf die Wälder. Für Nordostdeutschland werden von regionalen Klimamodellen ein weiterer Anstieg der Temperaturen sowie Veränderungen der Niederschlagsmuster hin zu trockeneren Sommern und feuchteren Wintern prognostiziert. In dieser Arbeit habe ich unter Zuhilfenahme eines „Raum für Zeit“- Ansatzes vergangene Wachstumsraten und Klima-Wachstumsbeziehungen von Rotbuche (Fagus sylvatica L.) und Stieleiche (Quercus robur L.) entlang eines Niederschlagsgradienten analysiert. Besondere Aufmerksamkeit wurde dabei auf die Einflüsse von Sommertrockenheit und Staunässe sowie die Bedeutung von Standortsfaktoren hinsichtlich Art und Stärke der Reaktionen der Bäume auf die klimatischen Stressfaktoren gelegt. In Fortführung dieser retrospektiven Analysen wurden die Wachstumstrends für Buche, Eiche und Kiefer (Pinus sylvestris L.) unter Zugrundelegung regionaler Klimaszenarien in die Zukunft modelliert. Den Einfluss plötzlicher und extremer Veränderungen der hydrologischen Bedingungen habe ich für die Baumart Eiche am Beispiel einer Wiedervernässung eines bewaldeten Moores getestet. Alle Analysen in dieser Arbeit basieren auf Jahrringbreiten und holzanatomischen Merkmalen unter Anwendung einer breiten Palette dendrochronologischer Methodik. Der Gradientenansatz enthüllte ähnliche Klima-Wachstumszusammenhänge für Buche und Eiche auf trockenheitsgefährdeten Sandstandorten. Wasserverfügbarkeit während des Frühsommers stellte sich als der wichtigste klimatische Faktor heraus. Abnehmende Niederschlagsraten von West nach Ost führen zu einer gesteigerten Trockenheitsempfindlichkeit beider Arten, besonders jedoch der Buche. Dies manifestiert sich in einer Abnahme der Konkurrenzüberlegenheit der Buche gegenüber der Eiche und könnte in der Fortführung unter zukünftig trockeneren Bedingungen zu Änderungen der Konkurrenzverhältnisse bis hin zu einer Rangumkehr führen. Eine beobachtete Steigerung der Wachstumsvariabilität sowie eine Zunahme der Wachstumsdepressionen deuten darauf hin, dass rezente Klimaänderungen bereits Einfluss auf Wachstumsmuster der Buche nehmen. Das wird von den Aussagen des prospektiven Modellansatzes bestätigt. Demnach sind sowohl für die Buche als auch für die Eiche künftig negative Wachstumstrends zu erwarten. Dabei zeigt die Buche die größten Abnahmen von bis zu -23% im Vergleich der Periode 1971-2000 mit dem Ende des einundzwanzigsten Jahrhunderts (2071-2100). Die modellierten künftigen Wachstumstrends der Kiefer zeigen nur geringe Veränderungen. Während die Buche, bedingt durch ihr oberflächliches Wurzelsystem, auch auf wechselfeuchten Böden unter Sommertrockenheit leidet, sind die Ringbreiten der Eiche hier nicht mit der Wasserversorgung korreliert. Im Gegensatz zu ähnlichen Ringmustern auf Sandstandorten zeigen Buche und Eiche auf hydromorphen Standorten unterschiedliche interannuelle Schwankungen. Darüber hinaus konnte ich keinen negativen Einfluss von besonders feuchten Perioden mit hoher Bodenwassersättigung auf das Wachstum beider Arten ausmachen. Das ist wenig überraschend für die gemeinhin als tolerant gegenüber wassergesättigten Böden bekannte Eiche, weist aber auf eine unerwartet hohe Toleranz der Buche gegenüber stagnierendem Bodenwasser hin. Ergebnisse aus dem natürlichen Labor eines überfluteten Eichenwaldes zeigten, dass vormals unterdrückte Individuen eine höhere Anpassungskapazität verglichen mit größeren und dominanten Bäumen aufweisen. Viele der vormals dominanten Bäume starben im Laufe von 18 Jahren nach dem Ereignis. Bäume welche den plötzlichen Grundwasseranstieg überlebten, zeigten nach einer kurzen Periode stark verringerten Wachstums eine anschließende Erholung. Die plötzliche Änderung der Hydrologie hat also ein charakteristisches Ringmuster hinterlassen, welches hilfreich bezüglich einer genaueren Interpretation von Wachstumsmustern subfossiler Mooreichenstämme sein kann. Meine Ergebnisse bestätigen frühere Besorgnisse bezüglich trockenheitsbedingter Wachstumseinbußen unter sich änderndem Klima, besonders bei der Buche. Die projizierten feuchteren Bedingungen im Winter lassen dahingegen nur geringe Auswirkungen auf das Wachstum beider Arten erwarten. Es sind stattdessen eher die klimatischen Extremereignisse wie Sommertrockenheiten oder Starkregenereignisse welche die Toleranzschwelle der beiden Arten gegenüber einem “zu viel“ oder “zu wenig“ an Wasser überschreiten könnten und daher ein starkes Risiko für künftige Ertragsleistungen darstellen