TY  - JOUR
A1  - Stiegler, Jonas
A1  - Pahl, Janice
A1  - Guillen, Rafael Arce
A1  - Ullmann, Wiebke
A1  - Blaum, Niels
T1  - The heat is on
BT  - impacts of rising temperature on the activity of a common European mammal
JF  - Frontiers in Ecology and Evolution
N2  - Climate conditions severely impact the activity and, consequently, the fitness of wildlife species across the globe. Wildlife can respond to new climatic conditions, but the pace of human-induced change limits opportunities for adaptation or migration. Thus, how these changes affect behavior, movement patterns, and activity levels remains unclear. In this study, we investigate how extreme weather conditions affect the activity of European hares (Lepus europaeus) during their peak reproduction period. When hares must additionally invest energy in mating, prevailing against competitors, or lactating, we investigated their sensitivities to rising temperatures, wind speed, and humidity. To quantify their activity, we used the overall dynamic body acceleration (ODBA) calculated from tri-axial acceleration measurements of 33 GPS-collared hares. Our analysis revealed that temperature, humidity, and wind speed are important in explaining changes in activity, with a strong response for high temperatures above 25 & DEG;C and the highest change in activity during temperature extremes of over 35 & DEG;C during their inactive period. Further, we found a non-linear relationship between temperature and activity and an interaction of activity changes between day and night. Activity increased at higher temperatures during the inactive period (day) and decreased during the active period (night). This decrease was strongest during hot tropical nights. At a stage of life when mammals such as hares must substantially invest in reproduction, the sensitivity of females to extreme temperatures was particularly pronounced. Similarly, both sexes increased their activity at high humidity levels during the day and low wind speeds, irrespective of the time of day, while the effect of humidity was stronger for males. Our findings highlight the importance of understanding the complex relationships between extreme weather conditions and mammal behavior, critical for conservation and management. With ongoing climate change, extreme weather events such as heat waves and heavy rainfall are predicted to occur more often and last longer. These events will directly impact the fitness of hares and other wildlife species and hence the population dynamics of already declining populations across Europe.
KW  - activity
KW  - ODBA
KW  - animal tracking
KW  - European hare
KW  - extreme weather events
KW  - climate change
Y1  - 2023
U6  - https://doi.org/10.3389/fevo.2023.1193861
SN  - 2296-701X
VL  - 11
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Veh, Georg
A1  - Lützow, Natalie
A1  - Kharlamova, Varvara
A1  - Petrakov, Dmitry
A1  - Hugonnet, Romain
A1  - Korup, Oliver
T1  - Trends, breaks, and biases in the frequency of reported glacier lake outburst floods
JF  - Earth's future
N2  - Thousands of glacier lakes have been forming behind natural dams in high mountains following glacier retreat since the early 20th century. Some of these lakes abruptly released pulses of water and sediment with disastrous downstream consequences. Yet it remains unclear whether the reported rise of these glacier lake outburst floods (GLOFs) has been fueled by a warming atmosphere and enhanced meltwater production, or simply a growing research effort. Here we estimate trends and biases in GLOF reporting based on the largest global catalog of 1,997 dated glacier-related floods in six major mountain ranges from 1901 to 2017. We find that the positive trend in the number of reported GLOFs has decayed distinctly after a break in the 1970s, coinciding with independently detected trend changes in annual air temperatures and in the annual number of field-based glacier surveys (a proxy of scientific reporting). We observe that GLOF reports and glacier surveys decelerated, while temperature rise accelerated in the past five decades. Enhanced warming alone can thus hardly explain the annual number of reported GLOFs, suggesting that temperature-driven glacier lake formation, growth, and failure are weakly coupled, or that outbursts have been overlooked. Indeed, our analysis emphasizes a distinct geographic and temporal bias in GLOF reporting, and we project that between two to four out of five GLOFs on average might have gone unnoticed in the early to mid-20th century. We recommend that such biases should be considered, or better corrected for, when attributing the frequency of reported GLOFs to atmospheric warming.
KW  - glaciers
KW  - climate change
KW  - hazard
KW  - mountains
KW  - cryosphere
KW  - frequency
Y1  - 2022
U6  - https://doi.org/10.1029/2021EF002426
SN  - 2328-4277
VL  - 10
IS  - 3
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Souto-Veiga, Rodrigo
A1  - Groeneveld, Juergen
A1  - Enright, Neal J.
A1  - Fontaine, Joseph B.
A1  - Jeltsch, Florian
T1  - Declining pollination success reinforces negative climate and fire change impacts in a serotinous, fire-killed plant
JF  - Plant ecology : an international journal
N2  - Climate change projections predict that Mediterranean-type ecosystems (MTEs) are becoming hotter and drier and that fires will become more frequent and severe. 
While most plant species in these important biodiversity hotspots are adapted to hot, dry summers and recurrent fire, the Interval Squeeze framework suggests that reduced seed production (demographic shift), reduced seedling establishment after fire (post fire recruitment shift), and reduction in the time between successive fires (fire interval shift) will threaten fire killed species under climate change. 

One additional potential driver of accelerated species decline, however, has not been considered so far: the decrease in pollination success observed in many ecosystems worldwide has the potential to further reduce seed accumulation and thus population persistence also in these already threatened systems. 
Using the well-studied fire-killed and serotinous shrub species Banksia hookeriana as an example, we apply a new spatially implicit population simulation model to explore population dynamics under past (1988-2002) and current (2003-2017) climate conditions, deterministic and stochastic fire regimes, and alternative scenarios of pollination decline. 

Overall, model results suggest that while B. hookeriana populations were stable under past climate conditions, they will not continue to persist under current (and prospective future) climate. 
Negative effects of climatic changes and more frequent fires are reinforced by the measured decline in seed set leading to further reduction in the mean persistence time by 12-17%. 
These findings clearly indicate that declining pollination rates can be a critical factor that increases further the pressure on the persistence of fire-killed plants. 
Future research needs to investigate whether other fire-killed species are similarly threatened, and if local population extinction may be compensated by recolonization events, facilitating persistence in spatially structured meta-communities.
KW  - climate change
KW  - fire frequency
KW  - interval squeeze
KW  - pollination
KW  - process-based simulation model
KW  - mediterranean-type ecosystem
Y1  - 2022
U6  - https://doi.org/10.1007/s11258-022-01244-7
SN  - 1385-0237
SN  - 1573-5052
VL  - 223
IS  - 7
SP  - 863
EP  - 881
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Ben Nsir, Siwar
A1  - Jomaa, Seifeddine
A1  - Yildirim, Umit
A1  - Zhou, Xiangqian
A1  - D'Oria, Marco
A1  - Rode, Michael
A1  - Khlifi, Slaheddine
T1  - Assessment of climate change impact on discharge of the lakhmass catchment (Northwest Tunisia)
JF  - Water
N2  - The Mediterranean region is increasingly recognized as a climate change hotspot but is highly underrepresented in hydrological climate change studies. This study aims to investigate the climate change effects on the hydrology of Lakhmass catchment in Tunisia. Lakhmass catchment is a part of the Medium Valley of Medjerda in northwestern Tunisia that drains an area of 126 km(2). First, the Hydrologiska Byrans Vattenbalansavdelning light (HBV-light) model was calibrated and validated successfully at a daily time step to simulate discharge during the 1981-1986 period. The Nash Sutcliffe Efficiency and Percent bias (NSE, PBIAS) were (0.80, +2.0%) and (0.53, -9.5%) for calibration (September 1982-August 1984) and validation (September 1984-August 1986) periods, respectively. Second, HBV-light model was considered as a predictive tool to simulate discharge in a baseline period (1981-2009) and future projections using data (precipitation and temperature) from thirteen combinations of General Circulation Models (GCMs) and Regional Climatic Models (RCMs). We used two trajectories of Representative Concentration Pathways, RCP4.5 and RCP8.5, suggested by the Intergovernmental Panel on Climate Change (IPCC). Each RCP is divided into three projection periods: near-term (2010-2039), mid-term (2040-2069) and long-term (2070-2099). For both scenarios, a decrease in precipitation and discharge will be expected with an increase in air temperature and a reduction in precipitation with almost 5% for every +1 degrees C of global warming. By long-term (2070-2099) projection period, results suggested an increase in temperature with about 2.7 degrees C and 4 degrees C, and a decrease in precipitation of approximately 7.5% and 15% under RCP4.5 and RCP8.5, respectively. This will likely result in a reduction of discharge of 12.5% and 36.6% under RCP4.5 and RCP8.5, respectively. This situation calls for early climate change adaptation measures under a participatory approach, including multiple stakeholders and water users.
KW  - hydrological modeling
KW  - HBV-light model
KW  - Mediterranean
KW  - discharge
KW  - climate change
KW  - RCP4,5 and 8,5
Y1  - 2022
U6  - https://doi.org/10.3390/w14142242
SN  - 2073-4441
VL  - 14
IS  - 14
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - McCool, Weston C.
A1  - Codding, Brian F.
A1  - Vernon, Kenneth B.
A1  - Wilson, Kurt M.
A1  - Yaworsky, Peter M.
A1  - Marwan, Norbert
A1  - Kennett, Douglas J.
T1  - Climate change-induced population pressure drives high rates of lethal violence in the Prehispanic central Andes
JF  - Proceedings of the National Academy of Sciences of the United States of America : PNAS
N2  - Understanding the influence of climate change and population pressure on human conflict remains a critically important topic in the social sciences. Long-term records that evaluate these dynamics across multiple centuries and outside the range of modern climatic variation are especially capable of elucidating the relative effect of-and the interaction between-climate and demography. This is crucial given that climate change may structure population growth and carrying capacity, while both climate and population influence per capita resource availability. This study couples paleoclimatic and demographic data with osteological evaluations of lethal trauma from 149 directly accelerator mass spectrometry C-14-dated individuals from the Nasca highland region of Peru. Multiple local and supraregional precipitation proxies are combined with a summed probability distribution of 149 C-14 dates to estimate population dynamics during a 700-y study window. Counter to previous findings, our analysis reveals a precipitous increase in violent deaths associated with a period of productive and stable climate, but volatile population dynamics. We conclude that favorable local climate conditions fostered population growth that put pressure on the marginal and highly circumscribed resource base, resulting in violent resource competition that manifested in over 450 y of internecine warfare. These findings help support a general theory of intergroup violence, indicating that relative resource scarcity-whether driven by reduced resource abundance or increased competition-can lead to violence in subsistence societies when the outcome is lower per capita resource availability.
KW  - climate change
KW  - population pressure
KW  - warfare
KW  - lethal violence
KW  - Andes
Y1  - 2022
U6  - https://doi.org/10.1073/pnas.2117556119
SN  - 0027-8424
SN  - 1091-6490
VL  - 119
IS  - 17
PB  - National Acad. of Sciences
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kong, Xiangzhen
A1  - Ghaffar, Salman
A1  - Determann, Maria
A1  - Friese, Kurt
A1  - Jomaa, Seifeddine
A1  - Mi, Chenxi
A1  - Shatwell, Tom
A1  - Rinke, Karsten
A1  - Rode, Michael
T1  - Reservoir water quality deterioration due to deforestation emphasizes the indirect effects of global change
JF  - Water research : a journal of the International Association on Water Quality (IAWQ)
N2  - Deforestation is currently a widespread phenomenon and a growing environmental concern in the era of rapid climate change. 
In temperate regions, it is challenging to quantify the impacts of deforestation on the catchment dynamics and downstream aquatic ecosystems such as reservoirs and disentangle these from direct climate change impacts, let alone project future changes to inform management. 
Here, we tackled this issue by investigating a unique catchment-reservoir system with two reservoirs in distinct trophic states (meso- and eutrophic), both of which drain into the largest drinking water reservoir in Germany. 
Due to the prolonged droughts in 2015-2018, the catchment of the mesotrophic reservoir lost an unprecedented area of forest (exponential increase since 2015 and ca. 17.1% loss in 2020 alone). 
We coupled catchment nutrient exports (HYPE) and reservoir ecosystem dynamics (GOTM-WET) models using a process-based modeling approach. The coupled model was validated with datasets spanning periods of rapid deforestation, which makes our future projections highly robust. 
Results show that in a short-term time scale (by 2035), increasing nutrient flux from the catchment due to vast deforestation (80% loss) can turn the mesotrophic reservoir into a eutrophic state as its counterpart. 
Our results emphasize the more prominent impacts of deforestation than the direct impact of climate warming in impairment of water quality and ecological services to downstream aquatic ecosystems. Therefore, we propose to evaluate the impact of climate change on temperate reservoirs by incorporating a time scale-dependent context, highlighting the indirect impact of deforestation in the short-term scale. In the long-term scale (e.g. to 2100), a guiding hypothesis for future research may be that indirect effects (e.g., as mediated by catchment dynamics) are as important as the direct effects of climate warming on aquatic ecosystems.
KW  - deforestation
KW  - climate change
KW  - temperate regions
KW  - reservoir
KW  - eutrophication
KW  - process-based modeling
Y1  - 2022
U6  - https://doi.org/10.1016/j.watres.2022.118721
SN  - 0043-1354
SN  - 1879-2448
VL  - 221
PB  - Elsevier Science
CY  - Amsterdam [u.a.]
ER  - 
TY  - THES
A1  - Hippel, Barbara von
T1  - Long-term bacteria-fungi-plant associations in permafrost soils inferred from palaeometagenomics
N2  - The arctic is warming 2 – 4 times faster than the global average, resulting in a strong feedback on northern ecosystems such as boreal forests, which cover a vast area of the high northern latitudes. With ongoing global warming, the treeline subsequently migrates northwards into tundra areas. The consequences of turning ecosystems are complex: on the one hand, boreal forests are storing large amounts of global terrestrial carbon and act as a carbon sink, dragging carbon dioxide out of the global carbon cycle, suggesting an enhanced carbon uptake with increased tree cover. On the other hand, with the establishment of trees, the albedo effect of tundra decreases, leading to enhanced soil warming. Meanwhile, permafrost thaws, releasing large amounts of previously stored carbon into the atmosphere. So far, mainly vegetation dynamics have been assessed when studying the impact of warming onto ecosystems. Most land plants are living in close symbiosis with bacterial and fungal communities, sustaining their growth in nutrient poor habitats. However, the impact of climate change on these subsoil communities alongside changing vegetation cover remains poorly understood. Therefore, a better understanding of soil community dynamics on multi millennial timescales is inevitable when addressing the development of entire ecosystems. Unravelling long-term cross-kingdom dependencies between plant, fungi, and bacteria is not only a milestone for the assessment of warming on boreal ecosystems. On top, it also is the basis for agriculture strategies to sustain society with sufficient food in a future warming world.
The first objective of this thesis was to assess ancient DNA as a proxy for reconstructing the soil microbiome (Manuscripts I, II, III, IV). Research findings across these projects enable a comprehensive new insight into the relationships of soil microorganisms to the surrounding vegetation. First, this was achieved by establishing (Manuscript I) and applying (Manuscript II) a primer pair for the selective amplification of ancient fungal DNA from lake sediment samples with the metabarcoding approach. To assess fungal and plant co-variation, the selected primer combination (ITS67, 5.8S) amplifying the ITS1 region was applied on samples from five boreal and arctic lakes. The obtained data showed that the establishment of fungal communities is impacted by warming as the functional ecological groups are shifting. Yeast and saprotroph dominance during the Late Glacial declined with warming, while the abundance of mycorrhizae and parasites increased with warming. The overall species richness was also alternating. The results were compared to shotgun sequencing data reconstructing fungi and bacteria (Manuscripts III, IV), yielding overall comparable results to the metabarcoding approach. Nonetheless, the comparison also pointed out a bias in the metabarcoding, potentially due to varying ITS lengths or copy numbers per genome. 
The second objective was to trace fungus-plant interaction changes over time (Manuscripts II, III). To address this, metabarcoding targeting the ITS1 region for fungi and the chloroplast P6 loop for plants for the selective DNA amplification was applied (Manuscript II). Further, shotgun sequencing data was compared to the metabarcoding results (Manuscript III). Overall, the results between the metabarcoding and the shotgun approaches were comparable, though a bias in the metabarcoding was assumed. We demonstrated that fungal shifts were coinciding with changes in the vegetation. Yeast and lichen were mainly dominant during the Late Glacial with tundra vegetation, while warming in the Holocene lead to the expansion of boreal forests with increasing mycorrhizae and parasite abundance. Aside, we highlighted that Pinaceae establishment is dependent on mycorrhizal fungi such as Suillineae, Inocybaceae, or Hyaloscypha species also on long-term scales. 
The third objective of the thesis was to assess soil community development on a temporal gradient (Manuscripts III, IV). Shotgun sequencing was applied on sediment samples from the northern Siberian lake Lama and the soil microbial community dynamics compared to ecosystem turnover. Alongside, podzolization processes from basaltic bedrock were recovered (Manuscript III). Additionally, the recovered soil microbiome was compared to shotgun data from granite and sandstone catchments (Manuscript IV, Appendix). We assessed if the establishment of the soil microbiome is dependent on the plant taxon and as such comparable between multiple geographic locations or if the community establishment is driven by abiotic soil properties and as such the bedrock area. We showed that the development of soil communities is to a great extent driven by the vegetation changes and temperature variation, while time only plays a minor role. The analyses showed general ecological similarities especially between the granite and basalt locations, while the microbiome on species-level was rather site-specific. A greater number of correlated soil taxa was detected for deep-rooting boreal taxa in comparison to grasses with shallower roots. Additionally, differences between herbaceous taxa of the late Glacial compared to taxa of the Holocene were revealed.
With this thesis, I demonstrate the necessity to investigate subsoil community dynamics on millennial time scales as it enables further understanding of long-term ecosystem as well as soil development processes and such plant establishment. Further, I trace long-term processes leading to podzolization which supports the development of applied carbon capture strategies under future global warming.
N2  - Die Arktis erwärmt sich schneller als der weltweite Durschnitt, was die dortigen Ökosysteme wie die borealen Nadelwälder stark beeinflusst. Die Baumgrenze verschiebt sich durch veränderte Wachstumsbedingungen nach Norden und breitet sich in Tundra-Gegenden aus. Das führt zu komplexen Auswirkungen auf den Kohlenstoffkreislauf, da durch das Baumwachstum vermehrt CO2 im Boden gespeichert wird. Andererseits wird der Albedo-Effekt der Tundra verringert und der Boden erwärmt sich verstärkt. Das wiederum führt zum Tauen von Permafrost und setzt große Mengen an gespeichertem Kohlenstoff frei. Bislang wurde vor allem die Auswirkung der Erwärmung auf Vegetationsdynamiken untersucht. Für ein gesundes Pflanzenwachstum stehen die meisten Landpflanzen in engem Austausch mit einer Vielzahl an Bakterien und Pilzen. Es ist bislang wenig verstanden, wie diese Bodengemeinschaften durch den Klimawandel beeinflusst werden. Es ist deshalb notwendig, verstärkt auch die Langzeitabhängigkeiten der Pflanzen von Mikroorganismen zu betrachten. Dies ist nicht nur ein Meilenstein bei der Untersuchung des Klimawandels auf arktische Ökosysteme. Zudem wird so die Entwicklung angepasster Strategien im Bereich der Landwirtschaft ermöglicht, was die Grundlage dafür ist, die wachsende Bevölkerung auch in Zukunft mit ausreichend Nahrungsmitteln versorgen zu können.
Im ersten Teil meiner Arbeit untersuche ich das Potential, die Dynamiken von Bodenmikroorganismen aus Seesedimenten zu rekonstruieren. Ich habe gezeigt, dass molekulargenetische Analysen das sowohl für Pilze als auch Bakterien auf großen Zeitskalen ermöglichen. Eine Zuweisung der Mikroorganismen zu ihren Funktionen im Ökosystem ermöglichte, Dynamiken in den Nährstoffkreisläufen sowie in Pilzökologien zu verstehen.
Die Analyse der komplexen Assoziationen von Pilzen und Pflanzen bildete den zweiten Teil meiner Arbeit. Hier konnte ich zeigen, dass Pilze und Pflanzen spezifische Muster in ihren Vorkommen miteinander zeigen und dass die Vegetation das Pilzvorkommen auch auf großen Zeitskalen beeinflusst. Die Tundravegetation des Spätglazials war vor allem von Flechten und Hefevorkommen dominiert, während die Einwanderung von borealen Wäldern in die untersuchten Gebiete zu zunehmder Mykorrhiza- und Parasitenverbreitung führte. Ich habe auch gezeigt, dass die Etablierung von Pinaceen langfristig von spezifischen Mykorrhiza-Pilzen wie Suillineae, Inocybaceae oder Hyaloscypha-Arten abhängt.
Das dritte Ziel meiner Arbeit war es, zeitliche Dynamiken in der Zusammensetzung von Bodenorganismen im Bezug zur Entstehung von Böden zu rekonstruieren. Mir gelang es, die Verwitterung von Basalt nachzuvollziehen und daraus die Entstehung von Podsol abzuleiten. Ein Vergleich zu Bodengesellschaften aus Granit- und Sandstein-Einzugsgebieten zeigte, dass sich die Granit- und Basalt-Bodeneigenschaften ähneln. Allerdings zeigten die Pflanzen an den Standorten ein sehr ortsspezifisches Mikrobiom und somit eine lokale Anpassung an die Wachstumsbedingungen.
Ich konnte mit dieser Arbeit zeigen, dass die Rekonstruktion von Bodenmikroorganismen im Vergleich zur Vegetation einen Einblick in Ökosystemdynamiken unter Klimawandel ermöglicht. Dies ermöglicht ein besseres Verständnis von Bodenentstehungsprozessen und vereinfacht die Entwicklung angewandter carbon capture Strategien.
KW  - sedimentary ancient DNA
KW  - ecology
KW  - lake sediment
KW  - Arctic
KW  - ecosystem reconstruction
KW  - climate change
KW  - treeline dynamics
KW  - microbial soil communities
KW  - plant-microbe interactions
KW  - Arktis
KW  - Klimawandel
KW  - Ökologie
KW  - Ökosystem-Rekonstruktion
KW  - Seesediment
KW  - mikrobielle Bodengemeinschaften
KW  - Pflanzen-Mikroben-Interaktionen
KW  - sedimentary ancient DNA
KW  - Baumgrenzen-Dynamik
Y1  - 2024
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-636009
ER  - 
TY  - JOUR
A1  - Katzenberger, Anja
A1  - Levermann, Anders
A1  - Schewe, Jacob
A1  - Pongratz, Julia
T1  - Intensification of very wet monsoon seasons in India under global warming
JF  - Geophysical research letters
N2  - Rainfall-intense summer monsoon seasons on the Indian subcontinent that are exceeding long-term averages cause widespread floods and landslides. 

Here we show that the latest generation of coupled climate models robustly project an intensification of very rainfall-intense seasons (June-September). 
Under the shared socioeconomic pathway SSP5-8.5, very wet monsoon seasons as observed in only 5 years in the period 1965-2015 are projected to occur 8 times more often in 2050-2100 in the multi-model average. 

Under SSP2-4.5, these seasons become only a factor of 6 times more frequent, showing that even modest efforts to mitigate climate change can have a strong impact on the frequency of very strong rainfall seasons. 

Besides, we find that the increasing risk of extreme seasonal rainfall is accompanied by a shift from days with light rainfall to days with moderate or heavy rainfall. Additionally, the number of wet days is projected to increase.
KW  - Indian monsoon
KW  - climate modeling
KW  - extreme seasons
KW  - climate change
KW  - CMIP6
KW  - India
Y1  - 2022
U6  - https://doi.org/10.1029/2022GL098856
SN  - 0094-8276
SN  - 1944-8007
VL  - 49
IS  - 15
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kuhla, Kilian
A1  - Willner, Sven N.
A1  - Otto, Christian
A1  - Geiger, Tobias
A1  - Levermann, Anders
T1  - Ripple resonance amplifies economic welfare loss from weather extremes
JF  - Environmental research letters : ERL / Institute of Physics
N2  - The most complex but potentially most severe impacts of climate change are caused by extreme weather events. In a globally connected economy, damages can cause remote perturbations and cascading consequences-a ripple effect along supply chains. Here we show an economic ripple resonance that amplifies losses when consecutive or overlapping weather extremes and their repercussions interact. This amounts to an average amplification of 21% for climate-induced heat stress, river floods, and tropical cyclones. Modeling the temporal evolution of 1.8 million trade relations between >7000 regional economic sectors, we find that the regional responses to future extremes are strongly heterogeneous also in their resonance behavior. The induced effect on welfare varies between gains due to increased demand in some regions and losses due to demand or supply shortages in others. Within the current global supply network, the ripple resonance effect of extreme weather is strongest in high-income economies-an important effect to consider when evaluating past and future economic climate impacts.
KW  - consecutive disasters
KW  - economic ripple resonance
KW  - repercussion resonance
KW  - weather extremes
KW  - supply network
KW  - climate impacts
KW  - climate change
Y1  - 2021
U6  - https://doi.org/10.1088/1748-9326/ac2932
SN  - 1748-9326
VL  - 16
IS  - 11
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - GEN
A1  - Pearce, Warren
A1  - Özkula, Suay M.
A1  - Greene, Amanda K.
A1  - Teeling, Lauren
A1  - Bansard, Jennifer S.
A1  - Omena, Janna Joceli
A1  - Rabello, Elaine Teixeira
T1  - Visual cross-platform analysis
BT  - Digital methods to research social media images
T2  - Zweitveröffentlichungen der Universität Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe
N2  - Analysis of social media using digital methods is a flourishing approach. However, the relatively easy availability of data collected via platform application programming interfaces has arguably led to the predominance of single-platform research of social media. Such research has also privileged the role of text in social media analysis, as a form of data that is more readily gathered and searchable than images. In this paper, we challenge both of these prevailing forms of social media research by outlining a methodology for visual cross-platform analysis (VCPA), defined as the study of still and moving images across two or more social media platforms. Our argument contains three steps. First, we argue that cross-platform analysis addresses a gap in research methods in that it acknowledges the interplay between a social phenomenon under investigation and the medium within which it is being researched, thus illuminating the different affordances and cultures of web platforms. Second, we build on the literature on multimodal communication and platform vernacular to provide a rationale for incorporating the visual into cross-platform analysis. Third, we reflect on an experimental cross-platform analysis of images within social media posts (n = 471,033) used to communicate climate change to advance different modes of macro- and meso-levels of analysis that are natively visual: image-text networks, image plots and composite images. We conclude by assessing the research pathways opened up by VCPA, delineating potential contributions to empirical research and theory and the potential impact on practitioners of social media communication.
T3  - Zweitveröffentlichungen der Universität Potsdam : Wirtschafts- und Sozialwissenschaftliche Reihe - 199 
KW  - research methodology
KW  - visual analysis
KW  - social media
KW  - climate change
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-515539
SN  - 1867-5808
IS  - 2
ER  - 
TY  - JOUR
A1  - Pearce, Warren
A1  - Özkula, Suay M.
A1  - Greene, Amanda K.
A1  - Teeling, Lauren
A1  - Bansard, Jennifer S.
A1  - Omena, Janna Joceli
A1  - Rabello, Elaine Teixeira
T1  - Visual cross-platform analysis
JF  - Information, Communication and Society: digital methods to research social media images
N2  - Analysis of social media using digital methods is a flourishing approach. However, the relatively easy availability of data collected via platform application programming interfaces has arguably led to the predominance of single-platform research of social media. Such research has also privileged the role of text in social media analysis, as a form of data that is more readily gathered and searchable than images. In this paper, we challenge both of these prevailing forms of social media research by outlining a methodology for visual cross-platform analysis (VCPA), defined as the study of still and moving images across two or more social media platforms. Our argument contains three steps. First, we argue that cross-platform analysis addresses a gap in research methods in that it acknowledges the interplay between a social phenomenon under investigation and the medium within which it is being researched, thus illuminating the different affordances and cultures of web platforms. Second, we build on the literature on multimodal communication and platform vernacular to provide a rationale for incorporating the visual into cross-platform analysis. Third, we reflect on an experimental cross-platform analysis of images within social media posts (n = 471,033) used to communicate climate change to advance different modes of macro- and meso-levels of analysis that are natively visual: image-text networks, image plots and composite images. We conclude by assessing the research pathways opened up by VCPA, delineating potential contributions to empirical research and theory and the potential impact on practitioners of social media communication.
KW  - research methodology
KW  - visual analysis
KW  - social media
KW  - climate change
Y1  - 2018
U6  - https://doi.org/10.1080/1369118X.2018.1486871
SN  - 1468-4462
SN  - 1369-118X
VL  - 23
IS  - 2
SP  - 161
EP  - 180
PB  - Routledge
CY  - London
ER  - 
TY  - JOUR
A1  - Palmer, Matthew D.
A1  - Gregory, Jonathan
A1  - Bagge, Meike
A1  - Calvert, Daley
A1  - Hagedoorn, Jan Marius
A1  - Howard, Tom
A1  - Klemann, Volker
A1  - Lowe, Jason A.
A1  - Roberts, Chris
A1  - Slangen, Aimee B. A.
A1  - Spada, Giorgio
T1  - Exploring the drivers of global and local sea‐level change over the 21st century and beyond
JF  - Earth's future
N2  - We present a new set of global and local sea‐level projections at example tide gauge locations under the RCP2.6, RCP4.5, and RCP8.5 emissions scenarios. Compared to the CMIP5‐based sea‐level projections presented in IPCC AR5, we introduce a number of methodological innovations, including (i) more comprehensive treatment of uncertainties, (ii) direct traceability between global and local projections, and (iii) exploratory extended projections to 2300 based on emulation of individual CMIP5 models. Combining the projections with observed tide gauge records, we explore the contribution to total variance that arises from sea‐level variability, different emissions scenarios, and model uncertainty. For the period out to 2300 we further breakdown the model uncertainty by sea‐level component and consider the dependence on geographic location, time horizon, and emissions scenario. Our analysis highlights the importance of local variability for sea‐level change in the coming decades and the potential value of annual‐to‐decadal predictions of local sea‐level change. Projections to 2300 show a substantial degree of committed sea‐level rise under all emissions scenarios considered and highlight the reduced future risk associated with RCP2.6 and RCP4.5 compared to RCP8.5. Tide gauge locations can show large ( > 50%) departures from the global average, in some cases even reversing the sign of the change. While uncertainty in projections of the future Antarctic ice dynamic response tends to dominate post‐2100, we see substantial differences in the breakdown of model variance as a function of location, time scale, and emissions scenario.
KW  - climate change
KW  - CMIP5 models
KW  - RCP scenarios
KW  - sea-level projections
KW  - tide gauge observations
Y1  - 2020
U6  - https://doi.org/10.1029/2019EF001413
SN  - 2328-4277
VL  - 8
IS  - 9
SP  - 1
EP  - 25
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - GEN
A1  - Palmer, Matthew D.
A1  - Gregory, Jonathan
A1  - Bagge, Meike
A1  - Calvert, Daley
A1  - Hagedoorn, Jan Marius
A1  - Howard, Tom
A1  - Klemann, Volker
A1  - Lowe, Jason A.
A1  - Roberts, Chris
A1  - Slangen, Aimee B. A.
A1  - Spada, Giorgio
T1  - Exploring the drivers of global and local sea‐level change over the 21st century and beyond
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - We present a new set of global and local sea‐level projections at example tide gauge locations under the RCP2.6, RCP4.5, and RCP8.5 emissions scenarios. Compared to the CMIP5‐based sea‐level projections presented in IPCC AR5, we introduce a number of methodological innovations, including (i) more comprehensive treatment of uncertainties, (ii) direct traceability between global and local projections, and (iii) exploratory extended projections to 2300 based on emulation of individual CMIP5 models. Combining the projections with observed tide gauge records, we explore the contribution to total variance that arises from sea‐level variability, different emissions scenarios, and model uncertainty. For the period out to 2300 we further breakdown the model uncertainty by sea‐level component and consider the dependence on geographic location, time horizon, and emissions scenario. Our analysis highlights the importance of local variability for sea‐level change in the coming decades and the potential value of annual‐to‐decadal predictions of local sea‐level change. Projections to 2300 show a substantial degree of committed sea‐level rise under all emissions scenarios considered and highlight the reduced future risk associated with RCP2.6 and RCP4.5 compared to RCP8.5. Tide gauge locations can show large ( > 50%) departures from the global average, in some cases even reversing the sign of the change. While uncertainty in projections of the future Antarctic ice dynamic response tends to dominate post‐2100, we see substantial differences in the breakdown of model variance as a function of location, time scale, and emissions scenario.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1353 
KW  - climate change
KW  - CMIP5 models
KW  - RCP scenarios
KW  - sea-level projections
KW  - tide gauge observations
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-549881
SN  - 1866-8372
IS  - 9
ER  - 
TY  - JOUR
A1  - Leins, Johannes A.
A1  - Grimm, Volker
A1  - Drechsler, Martin
T1  - Large-scale PVA modeling of insects in cultivated grasslands
BT  - the role of dispersal in mitigating the effects of management schedules under climate change
JF  - Ecology and evolution
N2  - In many species, dispersal is decisive for survival in a changing climate. Simulation models for population dynamics under climate change thus need to account for this factor. Moreover, large numbers of species inhabiting agricultural landscapes are subject to disturbances induced by human land use. We included dispersal in the HiLEG model that we previously developed to study the interaction between climate change and agricultural land use in single populations. Here, the model was parameterized for the large marsh grasshopper (LMG) in cultivated grasslands of North Germany to analyze (1) the species development and dispersal success depending on the severity of climate change in subregions, (2) the additional effect of grassland cover on dispersal success, and (3) the role of dispersal in compensating for detrimental grassland mowing. Our model simulated population dynamics in 60-year periods (2020-2079) on a fine temporal (daily) and high spatial (250 x 250 m(2)) scale in 107 subregions, altogether encompassing a range of different grassland cover, climate change projections, and mowing schedules. We show that climate change alone would allow the LMG to thrive and expand, while grassland cover played a minor role. Some mowing schedules that were harmful to the LMG nevertheless allowed the species to moderately expand its range. Especially under minor climate change, in many subregions dispersal allowed for mowing early in the year, which is economically beneficial for farmers. More severe climate change could facilitate LMG expansion to uninhabited regions but would require suitable mowing schedules along the path. These insights can be transferred to other species, given that the LMG is considered a representative of grassland communities. For more specific predictions on the dynamics of other species affected by climate change and land use, the publicly available HiLEG model can be easily adapted to the characteristics of their life cycle.
KW  - bilinear interpolation
KW  - climate change
KW  - dispersal success
KW  - land use
KW  - large marsh grasshopper
KW  - spatially explicit model
Y1  - 2022
U6  - https://doi.org/10.1002/ece3.9063
SN  - 2045-7758
VL  - 12
IS  - 7
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - GEN
A1  - Huber, Veronika
A1  - Krummenauer, Linda
A1  - Peña-Ortiz, Cristina
A1  - Lange, Stefan
A1  - Gasparrini, Antonio
A1  - Vicedo-Cabrera, Ana Maria
A1  - Garcia-Herrera, Ricardo
A1  - Frieler, Katja
T1  - Temperature-related excess mortality in German cities at 2 °C and higher degrees of global warming
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Background: Investigating future changes in temperature-related mortality as a function of global mean temperature (GMT) rise allows for the evaluation of policy-relevant climate change targets. So far, only few studies have taken this approach, and, in particular, no such assessments exist for Germany, the most populated country of Europe.

Methods: We assess temperature-related mortality in 12 major German cities based on daily time-series of all-cause mortality and daily mean temperatures in the period 1993-2015, using distributed-lag non-linear models in a two-stage design. Resulting risk functions are applied to estimate excess mortality in terms of GMT rise relative to pre-industrial levels, assuming no change in demographics or population vulnerability.

Results: In the observational period, cold contributes stronger to temperature-related mortality than heat, with overall attributable fractions of 5.49% (95%CI: 3.82-7.19) and 0.81% (95%CI: 0.72-0.89), respectively. Future projections indicate that this pattern could be reversed under progressing global warming, with heat-related mortality starting to exceed cold-related mortality at 3 degrees C or higher GMT rise. Across cities, projected net increases in total temperature-related mortality were 0.45% (95%CI: -0.02-1.06) at 3 degrees C, 1.53% (95%CI: 0.96-2.06) at 4 degrees C, and 2.88% (95%CI: 1.60-4.10) at 5 degrees C, compared to today's warming level of 1 degrees C. By contrast, no significant difference was found between projected total temperature-related mortality at 2 degrees C versus 1 degrees C of GMT rise.

Conclusions: Our results can inform current adaptation policies aimed at buffering the health risks from increased heat exposure under climate change. They also allow for the evaluation of global mitigation efforts in terms of local health benefits in some of Germany's most populated cities.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1430 
KW  - temperature-related mortality
KW  - climate change
KW  - Future projections
KW  - Germany
KW  - global mean temperature
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-516511
SN  - 1866-8372
ER  - 
TY  - JOUR
A1  - Huber, Veronika
A1  - Krummenauer, Linda
A1  - Peña-Ortiz, Cristina
A1  - Lange, Stefan
A1  - Gasparrini, Antonio
A1  - Vicedo-Cabrera, Ana Maria
A1  - Garcia-Herrera, Ricardo
A1  - Frieler, Katja
T1  - Temperature-related excess mortality in German cities at 2 °C and higher degrees of global warming
JF  - Environmental Research
N2  - Background: Investigating future changes in temperature-related mortality as a function of global mean temperature (GMT) rise allows for the evaluation of policy-relevant climate change targets. So far, only few studies have taken this approach, and, in particular, no such assessments exist for Germany, the most populated country of Europe.

Methods: We assess temperature-related mortality in 12 major German cities based on daily time-series of all-cause mortality and daily mean temperatures in the period 1993-2015, using distributed-lag non-linear models in a two-stage design. Resulting risk functions are applied to estimate excess mortality in terms of GMT rise relative to pre-industrial levels, assuming no change in demographics or population vulnerability.

Results: In the observational period, cold contributes stronger to temperature-related mortality than heat, with overall attributable fractions of 5.49% (95%CI: 3.82-7.19) and 0.81% (95%CI: 0.72-0.89), respectively. Future projections indicate that this pattern could be reversed under progressing global warming, with heat-related mortality starting to exceed cold-related mortality at 3 degrees C or higher GMT rise. Across cities, projected net increases in total temperature-related mortality were 0.45% (95%CI: -0.02-1.06) at 3 degrees C, 1.53% (95%CI: 0.96-2.06) at 4 degrees C, and 2.88% (95%CI: 1.60-4.10) at 5 degrees C, compared to today's warming level of 1 degrees C. By contrast, no significant difference was found between projected total temperature-related mortality at 2 degrees C versus 1 degrees C of GMT rise.

Conclusions: Our results can inform current adaptation policies aimed at buffering the health risks from increased heat exposure under climate change. They also allow for the evaluation of global mitigation efforts in terms of local health benefits in some of Germany's most populated cities.
KW  - temperature-related mortality
KW  - climate change
KW  - Future projections
KW  - Germany
KW  - global mean temperature
Y1  - 2020
U6  - https://doi.org/10.1016/j.envres.2020.109447
SN  - 0013-9351
SN  - 1096-0953
VL  - 186
SP  - 1
EP  - 10
PB  - Elsevier
CY  - San Diego, California
ER  - 
TY  - GEN
A1  - Stoof-Leichsenring, Kathleen Rosemarie
A1  - Pestryakova, Luidmila Agafyevna
A1  - Epp, Laura Saskia
A1  - Herzschuh, Ulrike
T1  - Phylogenetic diversity and environment form assembly rules for Arctic diatom genera
BT  - a study on recent and ancient sedimentary DNA
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Aim This study investigates taxonomic and phylogenetic diversity in diatom genera to evaluate assembly rules for eukaryotic microbes across the Siberian tree line. We first analysed how phylogenetic distance relates to taxonomic richness and turnover. Second, we used relatedness indices to evaluate if environmental filtering or competition influences the assemblies in space and through time. Third, we used distance-based ordination to test which environmental variables shape diatom turnover. Location Yakutia and Taymyria, Russia: we sampled 78 surface sediments and a sediment core, extending to 7,000 years before present, to capture the forest-tundra transition in space and time respectively. Taxon Arctic freshwater diatoms. Methods We applied metabarcoding to retrieve diatom diversity from surface and core sedimentary DNA. The taxonomic assignment binned sequence types (lineages) into genera and created taxonomic (abundance of lineages within different genera) and phylogenetic datasets (phylogenetic distances of lineages within different genera). Results Contrary to our expectations, we find a unimodal relationship between phylogenetic distance and richness in diatom genera. We discern a positive relationship between phylogenetic distance and taxonomic turnover in spatially and temporally distributed diatom genera. Furthermore, we reveal positive relatedness indices in diatom genera across the spatial environmental gradient and predominantly in time slices at a single location, with very few exceptions assuming effects of competition. Distance-based ordination of taxonomic and phylogenetic turnover indicates that lake environment variables, like HCO3- and water depth, largely explain diatom turnover. Main conclusion Phylogenetic and abiotic assembly rules are important in understanding the regional assembly of diatom genera across lakes in the Siberian tree line ecotone. Using a space-time approach we are able to exclude the influence of geography and elucidate that lake environmental variables primarily shape the assemblies. We conclude that some diatom genera have greater capabilities to adapt to environmental changes, whereas others will be putatively replaced or lost due to the displacement of the Arctic tundra biome under recent global warming.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1442 
KW  - ancient sedimentary DNA
KW  - Arctic lakes
KW  - assembly rules
KW  - climate change
KW  - diatoms
KW  - environmental filtering
KW  - phylogenetic diversity
KW  - Siberian tree line
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-515485
SN  - 1866-8372
IS  - 5
ER  - 
TY  - JOUR
A1  - Stoof-Leichsenring, Kathleen Rosemarie
A1  - Pestryakova, Luidmila Agafyevna
A1  - Epp, Laura Saskia
A1  - Herzschuh, Ulrike
T1  - Phylogenetic diversity and environment form assembly rules for Arctic diatom genera
BT  - a study on recent and ancient sedimentary DNA
JF  - Journal of Biogeography
N2  - Aim This study investigates taxonomic and phylogenetic diversity in diatom genera to evaluate assembly rules for eukaryotic microbes across the Siberian tree line. We first analysed how phylogenetic distance relates to taxonomic richness and turnover. Second, we used relatedness indices to evaluate if environmental filtering or competition influences the assemblies in space and through time. Third, we used distance-based ordination to test which environmental variables shape diatom turnover. Location Yakutia and Taymyria, Russia: we sampled 78 surface sediments and a sediment core, extending to 7,000 years before present, to capture the forest-tundra transition in space and time respectively. Taxon Arctic freshwater diatoms. Methods We applied metabarcoding to retrieve diatom diversity from surface and core sedimentary DNA. The taxonomic assignment binned sequence types (lineages) into genera and created taxonomic (abundance of lineages within different genera) and phylogenetic datasets (phylogenetic distances of lineages within different genera). Results Contrary to our expectations, we find a unimodal relationship between phylogenetic distance and richness in diatom genera. We discern a positive relationship between phylogenetic distance and taxonomic turnover in spatially and temporally distributed diatom genera. Furthermore, we reveal positive relatedness indices in diatom genera across the spatial environmental gradient and predominantly in time slices at a single location, with very few exceptions assuming effects of competition. Distance-based ordination of taxonomic and phylogenetic turnover indicates that lake environment variables, like HCO3- and water depth, largely explain diatom turnover. Main conclusion Phylogenetic and abiotic assembly rules are important in understanding the regional assembly of diatom genera across lakes in the Siberian tree line ecotone. Using a space-time approach we are able to exclude the influence of geography and elucidate that lake environmental variables primarily shape the assemblies. We conclude that some diatom genera have greater capabilities to adapt to environmental changes, whereas others will be putatively replaced or lost due to the displacement of the Arctic tundra biome under recent global warming.
KW  - ancient sedimentary DNA
KW  - Arctic lakes
KW  - assembly rules
KW  - climate change
KW  - diatoms
KW  - environmental filtering
KW  - phylogenetic diversity
KW  - Siberian tree line
Y1  - 2020
U6  - https://doi.org/10.1111/jbi.13786
SN  - 0305-0270
SN  - 1365-2699
VL  - 47
IS  - 5
SP  - 1166
EP  - 1179
PB  - Wiley-Blackwell
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Hickmann, Thomas
A1  - Widerberg, Oscar
A1  - Lederer, Markus
A1  - Pattberg, Philipp H.
T1  - The United Nations Framework Convention on Climate Change Secretariat as an orchestrator in global climate policymaking
JF  - International review of administrative sciences : an international journal of comparative public administration
N2  - Scholars have recently devoted increasing attention to the role and function of international bureaucracies in global policymaking. Some of them contend that international public officials have gained significant political influence in various policy fields. Compared to other international bureaucracies, the political leeway of the Secretariat of the United Nations Framework Convention on Climate Change has been considered rather limited. Due to the specific problem structure of the policy domain of climate change, national governments endowed this intergovernmental treaty secretariat with a relatively narrow mandate. However, this article argues that in the past few years, the United Nations Framework Convention on Climate Change Secretariat has gradually loosened its straitjacket and expanded its original spectrum of activity by engaging different sub-national and non-state actors into a policy dialogue using facilitative orchestration as a mode of governance. The present article explores the recent evolution of the United Nations Framework Convention on Climate Change Secretariat and investigates the way in which it initiates, guides, broadens and strengthens sub-national and non-state climate actions to achieve progress in the international climate negotiations. <br /> Points for practitioners <br /> The Secretariat of the United Nations Framework Convention on Climate Change has lately adopted new roles and functions in global climate policymaking. While previously seen as a rather technocratic body that, first and foremost, serves national governments, the Climate Secretariat increasingly interacts with sub-national governments, civil society organizations and private companies to push the global response to climate change forward. We contend that the Climate Secretariat can contribute to global climate policymaking by coordinating and steering the initiatives of non-nation-state actors towards coherence and good practice.
KW  - climate change
KW  - environmental policymaking
KW  - intergovernmental relations
KW  - international bureaucracies
KW  - sub-national and non-state actors
Y1  - 2021
U6  - https://doi.org/10.1177/0020852319840425
SN  - 0020-8523
SN  - 1461-7226
VL  - 87
IS  - 1
SP  - 21
EP  - 38
PB  - Sage
CY  - Los Angeles, Calif. [u.a.]
ER  - 
TY  - THES
A1  - Windirsch-Woiwode, Torben
T1  - Permafrost carbon stabilisation by recreating a herbivore-driven ecosystem
T1  - Stabilisierung von Permafrostkohlenstoff durch die Wiedereinführung eines Herbivor-geprägten Ökosystems
N2  - With Arctic ground as a huge and temperature-sensitive carbon reservoir, maintaining low ground temperatures and frozen conditions to prevent further carbon emissions that contrib-ute to global climate warming is a key element in humankind’s fight to maintain habitable con-ditions on earth. Former studies showed that during the late Pleistocene, Arctic ground condi-tions were generally colder and more stable as the result of an ecosystem dominated by large herbivorous mammals and vast extents of graminoid vegetation – the mammoth steppe. Characterised by high plant productivity (grassland) and low ground insulation due to animal-caused compression and removal of snow, this ecosystem enabled deep permafrost aggrad-ation. Now, with tundra and shrub vegetation common in the terrestrial Arctic, these effects are not in place anymore. However, it appears to be possible to recreate this ecosystem local-ly by artificially increasing animal numbers, and hence keep Arctic ground cold to reduce or-ganic matter decomposition and carbon release into the atmosphere.
By measuring thaw depth, total organic carbon and total nitrogen content, stable carbon iso-tope ratio, radiocarbon age, n-alkane and alcohol characteristics and assessing dominant vegetation types along grazing intensity transects in two contrasting Arctic areas, it was found that recreating conditions locally, similar to the mammoth steppe, seems to be possible. For permafrost-affected soil, it was shown that intensive grazing in direct comparison to non-grazed areas reduces active layer depth and leads to higher TOC contents in the active layer soil. For soil only frozen on top in winter, an increase of TOC with grazing intensity could not be found, most likely because of confounding factors such as vertical water and carbon movement, which is not possible with an impermeable layer in permafrost. In both areas, high animal activity led to a vegetation transformation towards species-poor graminoid-dominated landscapes with less shrubs. Lipid biomarker analysis revealed that, even though the available organic material is different between the study areas, in both permafrost-affected and sea-sonally frozen soils the organic material in sites affected by high animal activity was less de-composed than under less intensive grazing pressure. In conclusion, high animal activity af-fects decomposition processes in Arctic soils and the ground thermal regime, visible from reduced active layer depth in permafrost areas. Therefore, grazing management might be utilised to locally stabilise permafrost and reduce Arctic carbon emissions in the future, but is likely not scalable to the entire permafrost region.
N2  - Mit dem arktischen Boden als riesigem und temperatursensiblen Kohlenstoffspeicher ist die Aufrechterhaltung niedriger Bodentemperaturen und gefrorener Bedingungen zur Verhinde-rung weiterer Kohlenstoffemissionen, die zum globalen Klimawandel beitragen, ein Schlüs-selelement im Kampf der Menschheit, die Erde weiterhin bewohnbar zu halten. Vorangehen-de Studien ergaben, dass die Bodenbedingungen in der Arktis während des späten Pleisto-zäns im Allgemeinen kälter und dadurch stabiler waren, als Ergebnis eines Ökosystems, das von großen pflanzenfressenden Säugetieren und weiten Flächen grasartiger Vegetation do-miniert wurde - der Mammutsteppe. Gekennzeichnet durch hohe Pflanzenproduktivität (Gras-land) und geringe Bodenisolierung aufgrund von Kompression und Schneeräumung durch Tiere, ermöglichte dieses Ökosystem eine tiefreichende Entwicklung des Permafrosts. Heut-zutage, mit der vorherrschenden Tundra- und Strauchvegetation in der Arktis, sind diese Ef-fekte nicht mehr präsent. Es scheint aber möglich, dieses Ökosystem lokal durch künstliche Erhöhung der Tierbestände nachzubilden und somit den arktischen Boden kühl zu halten, um den Abbau von organischem Material und die Freisetzung von Kohlenstoff in die Atmosphäre zu verringern.
Durch Messungen der Auftautiefe, des Gesamtgehalts des organischen Kohlenstoffs und Stickstoffs, des stabilen Kohlenstoff-Isotopenverhältnisses, des Radiocarbonalters, der 
n-Alkan- und Alkoholcharakteristika sowie durch Bestimmung der vorherrschenden Vegetati-onstypen entlang von Beweidungsgradienten in zwei unterschiedlichen arktischen Gebieten habe ich festgestellt, dass die Schaffung ähnlicher Bedingungen wie in der Mammutsteppe möglich sein könnte. Für durch Permafrost beeinflusste Böden konnte ich zeigen, dass eine intensive Beweidung im direkten Vergleich mit unbeweideten Gebieten die Tiefe der Auftau-schicht verringert und zu höheren Gehalten an organischem Kohlenstoff im oberen Bodenbe-reich führt. Für im Winter nur oberflächlich gefrorene Böden konnte kein Anstieg des organi-schen Kohlenstoffgehalts mit zunehmender Beweidungsintensität festgestellt werden, höchstwahrscheinlich aufgrund von Störfaktoren wie vertikalen Wasser- und Kohlenstoffbe-wegungen, die nicht durch eine undurchlässige Schicht wie beim Permafrost begrenzt sind. In beiden Gebieten führte eine hohe Tieraktivität zu einer Umwandlung der Vegetation hin zu artenarmen, von Gräsern dominierten Landschaften mit weniger Sträuchern. Die Analyse von Lipid-Biomarkern ergab, dass das verfügbare organische Material zwar zwischen den Unter-suchungsgebieten unterschiedlich war, aber sowohl in Permafrostgebieten als auch in saiso-nal gefrorenen Böden in Bereichen mit hoher Tieraktivität weniger stark zersetzt war als unter geringerer Beweidungsintensität. Zusammenfassend beeinflusst eine hohe Tieraktivität die Zersetzungsvorgänge in arktischen Böden und das thermische Regime des Bodens, was sich in einer reduzierten Tiefe der Auftauschicht in Permafrostgebieten widerspiegelt. Daher könn-te das Beweidungsmanagement in Zukunft aktiv eingesetzt werden, um den Permafrost lokal zu stabilisieren und gefroren zu halten sowie die Kohlenstoffemissionen in der Arktis zu ver-ringern. Aufgrund der Größe der Fläche, die in der terrestrischen Arktis von Permafrost be-einflusst ist, wird ein solches Beweidungsmanagement aber nicht als Maßnahme auf die ge-samte Permafrostregion ausgedehnt werden können.
KW  - permafrost
KW  - carbon
KW  - climate change
KW  - grazing
KW  - Arctic
KW  - Arktis
KW  - Kohlenstoff
KW  - Klimawandel
KW  - Beweidung
KW  - Permafrost
Y1  - 2024
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-624240
ER  -