@article{WieczorekKolmogorovKruseetal.2017, author = {Wieczorek, Mareike and Kolmogorov, Alexei and Kruse, Stefan and Jacobsen, Inga and Nitze, Ingmar and Nikolaev, Anatoly N. and Heinrich, Ingo and Pestryakova, Luidmila Agafyevna and Herzschuh, Ulrike}, title = {Disturbance-effects on treeline larch-stands in the lower Kolyma River area (NE Siberia)}, series = {Silva Fennica : a quarterly journal for forest science}, volume = {51}, journal = {Silva Fennica : a quarterly journal for forest science}, number = {3}, publisher = {The Finnish Society of Forest Science}, address = {Helsinki}, issn = {0037-5330}, doi = {10.14214/sf.1666}, pages = {20}, year = {2017}, abstract = {Tree stands in the boreal treeline ecotone are, in addition to climate change, impacted by disturbances such as fire, water-related disturbances and logging. We aim to understand how these disturbances affect growth, age structure, and spatial patterns of larch stands in the north-eastern Siberian treeline ecotone (lower Kolyma River region), an insufficiently researched region. Stand structure of Larix cajanderi Mayr was studied at seven sites impacted by disturbances. Maximum tree age ranged from 44 to 300 years. Young to medium-aged stands had, independent of disturbance type, the highest stand densities with over 4000 larch trees per ha. These sites also had the highest growth rates for tree height and stem diameter. Overall lowest stand densities were found in a polygonal field at the northern end of the study area, with larches growing in distinct " tree islands". At all sites, saplings are significantly clustered. Differences in fire severity led to contrasting stand structures with respect to tree, recruit, and overall stand densities. While a low severity fire resulted in low-density stands with high proportions of small and young larches, high severity fires resulted in high-density stands with high proportions of big trees. At waterdisturbed sites, stand structure varied between waterlogged and drained sites and latitude. These mixed effects of climate and disturbance make it difficult to predict future stand characteristics and the treeline position.}, language = {en} } @article{vonHippelStoofLeichsenringSchulteetal.2022, author = {von Hippel, Barbara and Stoof-Leichsenring, Kathleen R. and Schulte, Luise and Seeber, Peter Andreas and Epp, Laura Saskia and Biskaborn, Boris and Diekmann, Bernhard and Melles, Martin and Pestryakova, Luidmila Agafyevna and Herzschuh, Ulrike}, title = {Long-term funguseplant covariation from multi-site sedimentary ancient DNA metabarcoding}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {295}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2022.107758}, pages = {18}, year = {2022}, abstract = {Climate change has a major impact on arctic and boreal terrestrial ecosystems as warming leads to northward treeline shifts, inducing consequences for heterotrophic organisms associated with the plant taxa. To unravel ecological dependencies, we address how long-term climatic changes have shaped the co-occurrence of plants and fungi across selected sites in Siberia. We investigated sedimentary ancient DNA from five lakes spanning the last 47,000 years, using the ITS1 marker for fungi and the chloroplast P6 loop marker for vegetation metabarcoding. We obtained 706 unique fungal operational taxonomic units (OTUs) and 243 taxa for the plants. We show higher OTU numbers in dry forest tundra as well as boreal forests compared to wet southern tundra. The most abundant fungal taxa in our dataset are Pseudeurotiaceae, Mortierella, Sordariomyceta, Exophiala, Oidiodendron, Protoventuria, Candida vartiovaarae, Pseudeurotium, Gryganskiella fimbricystis, and Tricho-sporiella cerebriformis. The overall fungal composition is explained by the plant composition as revealed by redundancy analysis. The fungal functional groups show antagonistic relationships in their climate susceptibility. The advance of woody taxa in response to past warming led to an increase in the abun-dance of mycorrhizae, lichens, and parasites, while yeast and saprotroph distribution declined. We also show co-occurrences between Salicaceae, Larix, and Alnus and their associated pathogens and detect higher mycorrhizal fungus diversity with the presence of Pinaceae. Under future warming, we can expect feedbacks between fungus composition and plant diversity changes which will affect forest advance, species diversity, and ecosystem stability in arctic regions.}, language = {en} } @article{TianCaoDallmeyeretal.2018, author = {Tian, Fang and Cao, Xianyong and Dallmeyer, Anne and Lohmann, Gerrit and Zhang, Xu and Ni, Jian and Andreev, Andrei and Anderson, Patricia M. and Lozhkin, Anatoly V. and Bezrukova, Elena and Rudaya, Natalia and Xu, Qinghai and Herzschuh, Ulrike}, title = {Biome changes and their inferred climatic drivers in northern and eastern continental Asia at selected times since 40 cal ka BP}, series = {Vegetation History and Archaeobotany}, volume = {27}, journal = {Vegetation History and Archaeobotany}, number = {2}, publisher = {Springer}, address = {New York}, issn = {0939-6314}, doi = {10.1007/s00334-017-0653-8}, pages = {365 -- 379}, year = {2018}, abstract = {Recent global warming is pronounced in high-latitude regions (e.g. northern Asia), and will cause the vegetation to change. Future vegetation trends (e.g. the "arctic greening") will feed back into atmospheric circulation and the global climate system. Understanding the nature and causes of past vegetation changes is important for predicting the composition and distribution of future vegetation communities. Fossil pollen records from 468 sites in northern and eastern Asia were biomised at selected times between 40 cal ka bp and today. Biomes were also simulated using a climate-driven biome model and results from the two approaches compared in order to help understand the mechanisms behind the observed vegetation changes. The consistent biome results inferred by both approaches reveal that long-term and broad-scale vegetation patterns reflect global- to hemispheric-scale climate changes. Forest biomes increase around the beginning of the late deglaciation, become more widespread during the early and middle Holocene, and decrease in the late Holocene in fringe areas of the Asian Summer Monsoon. At the southern and southwestern margins of the taiga, forest increases in the early Holocene and shows notable species succession, which may have been caused by winter warming at ca. 7 cal ka bp. At the northeastern taiga margin (central Yakutia and northeastern Siberia), shrub expansion during the last deglaciation appears to prevent the permafrost from thawing and hinders the northward expansion of evergreen needle-leaved species until ca. 7 cal ka bp. The vegetation-climate disequilibrium during the early Holocene in the taiga-tundra transition zone suggests that projected climate warming will not cause a northward expansion of evergreen needle-leaved species.}, language = {en} } @article{StuenziKruseBoikeetal.2022, author = {Stuenzi, Simone Maria and Kruse, Stefan and Boike, Julia and Herzschuh, Ulrike and Oehme, Alexander and Pestryakova, Luidmila A. and Westermann, Sebastian and Langer, Moritz}, title = {Thermohydrological impact of forest disturbances on ecosystem-protected permafrost}, series = {Journal of geophysical research : Biogeosciences}, volume = {127}, journal = {Journal of geophysical research : Biogeosciences}, number = {5}, publisher = {American Geophysical Union}, address = {Washington}, issn = {2169-8953}, doi = {10.1029/2021JG006630}, pages = {24}, year = {2022}, abstract = {Boreal forests cover over half of the global permafrost area and protect underlying permafrost. Boreal forest development, therefore, has an impact on permafrost evolution, especially under a warming climate. Forest disturbances and changing climate conditions cause vegetation shifts and potentially destabilize the carbon stored within the vegetation and permafrost. Disturbed permafrost-forest ecosystems can develop into a dry or swampy bush- or grasslands, shift toward broadleaf- or evergreen needleleaf-dominated forests, or recover to the pre-disturbance state. An increase in the number and intensity of fires, as well as intensified logging activities, could lead to a partial or complete ecosystem and permafrost degradation. We study the impact of forest disturbances (logging, surface, and canopy fires) on the thermal and hydrological permafrost conditions and ecosystem resilience. We use a dynamic multilayer canopy-permafrost model to simulate different scenarios at a study site in eastern Siberia. We implement expected mortality, defoliation, and ground surface changes and analyze the interplay between forest recovery and permafrost. We find that forest loss induces soil drying of up to 44\%, leading to lower active layer thicknesses and abrupt or steady decline of a larch forest, depending on disturbance intensity. Only after surface fires, the most common disturbances, inducing low mortality rates, forests can recover and overpass pre-disturbance leaf area index values. We find that the trajectory of larch forests after surface fires is dependent on the precipitation conditions in the years after the disturbance. Dryer years can drastically change the direction of the larch forest development within the studied period.}, language = {en} } @phdthesis{Schulte2022, author = {Schulte, Luise}, title = {Dynamics of Larix (Mill.) species in Siberia during the last 50,000 years inferred from sedimentary ancient DNA}, doi = {10.25932/publishup-55878}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-558782}, school = {Universit{\"a}t Potsdam}, pages = {xi, 121}, year = {2022}, abstract = {The deciduous needle tree larch (Larix Mill.) covers more than 80\% of the Asian boreal forests. Only a few Larix species constitute the vast forests and these species differ markedly in their ecological traits, most importantly in their ability to grow on and stabilize underlying permafrost. The pronounced dominance of the summergreen larches makes the Asian boreal forests unique, as the rest of the northern hemisphere boreal forests is almost exclusively dominated by evergreen needle-leaf forests. Global warming is impacting the whole world but is especially pronounced in the arctic and boreal regions. Although adapted to extreme climatic conditions, larch forests are sensitive to varying climatic conditions. By their sheer size, changes in Asian larch forests as range shifts or changes in species composition and the resulting vegetation-climate feedbacks are of global relevance. It is however still uncertain if larch forests will persist under the ongoing warming climate or if they will be replaced by evergreen forests. It is therefore of great importance to understand how these ecosystems will react to future climate warmings and if they will maintain their dominance. One step in the better understanding of larch dynamics is to study how the vast dominant forests developed and why they only established in northern Asia. A second step is to study how the species reacted to past changes in the climate. The first objective of this thesis was to review and identify factors promoting Asian larch dominance. I achieved this by synthesizing and comparing reported larch occurrences and influencing components on the northern hemisphere continents in the present and in the past. The second objective was to find a possibility to directly study past Larix populations in Siberia and specifically their genetic variation, enabling the study of geographic movements. For this, I established chloroplast enrichment by hybridization capture from sedimentary ancient DNA (sedaDNA) isolated from lake sediment records. The third objective was to use the established method to track past larch populations, their glacial refugia during the Last Glacial Maximum (LGM) around 21,000 years before present (ka BP), and their post-glacial migration patterns. To study larch promoting factors, I compared the present state of larch species ranges, areas of dominance, their bioclimatic niches, and the distribution on different extents and thaw depths of permafrost. The species comparison showed that the bioclimatic niches greatly overlap between the American and Asian species and that it is only in the extremely continental climates in which only the Asian larch species can persist. I revealed that the area of dominance is strongly connected to permafrost extent but less linked to permafrost seasonal thaw depths. Comparisons of the paleorecord of larch between the continents suggest differences in the recolonization history. Outside of northern Asia and Alaska, glacial refugial populations of larch were confined to the southern regions and thus recolonization could only occur as migration from south to north. Alaskan larch populations could not establish wide-range dominant forest which could be related to their own genetically depletion as separated refugial population. In Asia, it is still unclear whether or not the northern refugial populations contributed and enhanced the postglacial colonization or whether they were replaced by populations invading from the south in the course of climate warming. Asian larch dominance is thus promoted partly by adaptions to extremely continental climates and by adaptations to grow on continuous permafrost but could be also connected to differences in glacial survival and recolonization history of Larix species. Except for extremely rare macrofossil findings of fossilized cones, traditional methods to study past vegetation are not able to distinguish between larch species or populations. Within the scope of this thesis, I therefore established a method to retrieve genetic information of past larch populations to distinguish between species. Using the Larix chloroplast genome as target, I successfully applied the method of DNA target enrichment by hybridization capture on sedaDNA samples from lake records and showed that it is able to distinguish between larch species. I then used the method on samples from lake records from across Siberia dating back up to 50 ka BP. The results allowed me to address the question of glacial survival and post-glacial recolonization mode in Siberian larch species. The analyzed pattern showed that LGM refugia were almost exclusively constituted by L. gmelinii, even in sites of current L. sibirica distribution. For included study sites, L. sibirica migrated into its extant northern distribution area only in the Holocene. Consequently, the post-glacial recolonization of L. sibirica was not enhanced by northern glacial refugia. In case of sites in extant distribution area of L. gmelinii, the absence of a genetic turn-over point to a continuous population rather than an invasion of southern refugia. The results suggest that climate has a strong influence on the distribution of Larix species and that species may also respond differently to future climate warming. Because species differ in their ecological characteristics, species distribution is also relevant with respect to further feedbacks between vegetation and climate. With this thesis, I give an overview of present and past larch occurrences and evaluate which factors promote their dominance. Furthermore, I provide the tools to study past Larix species and give first important insights into the glacial history of Larix populations.}, language = {en} } @article{RudayaNazarovaNovenkoetal.2016, author = {Rudaya, Natalia and Nazarova, Larisa B. and Novenko, Elena and Andreev, Andrei and Kalugin, Ivan and Daryin, Andrei and Babich, Valery and Li, Hong-Chun and Shilov, Pavel}, title = {Quantitative reconstructions of mid- to late holocene climate and vegetation in the north-eastern altai mountains recorded in lake teletskoye}, series = {Global and planetary change}, volume = {141}, journal = {Global and planetary change}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0921-8181}, doi = {10.1016/j.gloplacha.2016.04.002}, pages = {12 -- 24}, year = {2016}, abstract = {We report the first high-resolution (20-50 years) mid- to late Holocene pollen records from Lake Teletskoye, the largest lake in the Altai Mountains, in south-eastern West Siberia. Generally, the mid- to late Holocene (the last 4250 years) vegetation of the north-eastern Altai, as recorded in two studied sediment cores, is characterised by Siberian pine-spruce-fir forests that are similar to those of the present day. A relatively cool and dry interval with July temperatures lower than those of today occurred between 3.9 and 3.6 ka BP. The widespread distribution of open, steppe-like communities with Artemisia, Chenopodiaceae and Cyperaceae reflects maximum deforestation during this interval. After ca. 3.5 ka BP, the coniferous mountain taiga spread significantly, with maximum woody coverage and taiga biome scores between ca. 2.7 and 1.6 ka BP. This coincides well with the highest July temperature (approximately 1 degrees C higher than today) intervals. A short period of cooling about 13-1.4 ka BP could have been triggered by the increased volcanic activity recorded across the Northern Hemisphere. A new period of cooling started around 1100-1150 CE, with the minimum July temperatures occurring between 1450 and 1800 CE. (C) 2016 Elsevier B.V. All rights reserved.}, language = {en} } @article{OverduinHaberlandRybergetal.2015, author = {Overduin, Pier Paul and Haberland, Christian and Ryberg, Trond and Kneier, Fabian and Jacobi, Tim and Grigoriev, Mikhail N. and Ohrnberger, Matthias}, title = {Submarine permafrost depth from ambient seismic noise}, series = {Geophysical research letters}, volume = {42}, journal = {Geophysical research letters}, number = {18}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0094-8276}, doi = {10.1002/2015GL065409}, pages = {7581 -- 7588}, year = {2015}, abstract = {Permafrost inundated since the last glacial maximum is degrading, potentially releasing trapped or stabilized greenhouse gases, but few observations of the depth of ice-bonded permafrost (IBP) below the seafloor exist for most of the arctic continental shelf. We use spectral ratios of the ambient vibration seismic wavefield, together with estimated shear wave velocity from the dispersion curves of surface waves, for estimating the thickness of the sediment overlying the IBP. Peaks in spectral ratios modeled for three-layered 1-D systems correspond with varying thickness of the unfrozen sediment. Seismic receivers were deployed on the seabed around Muostakh Island in the central Laptev Sea, Siberia. We derive depths of the IBP between 3.7 and 20.7m15\%, increasing with distance from the shoreline. Correspondence between expected permafrost distribution, modeled response, and observational data suggests that the method is promising for the determination of the thickness of unfrozen sediment.}, language = {en} } @article{NitzeGrosseJonesetal.2017, author = {Nitze, Ingmar and Grosse, Guido and Jones, Benjamin M. and Arp, Christopher D. and Ulrich, Mathias and Fedorov, Alexander and Veremeeva, Alexandra}, title = {Landsat-Based Trend Analysis of Lake Dynamics across Northern Permafrost Regions}, series = {Remote sensing}, volume = {9}, journal = {Remote sensing}, publisher = {MDPI}, address = {Basel}, issn = {2072-4292}, doi = {10.3390/rs9070640}, pages = {28}, year = {2017}, abstract = {Lakes are a ubiquitous landscape feature in northern permafrost regions. They have a strong impact on carbon, energy and water fluxes and can be quite responsive to climate change. The monitoring of lake change in northern high latitudes, at a sufficiently accurate spatial and temporal resolution, is crucial for understanding the underlying processes driving lake change. To date, lake change studies in permafrost regions were based on a variety of different sources, image acquisition periods and single snapshots, and localized analysis, which hinders the comparison of different regions. Here, we present a methodology based on machine-learning based classification of robust trends of multi-spectral indices of Landsat data (TM, ETM+, OLI) and object-based lake detection, to analyze and compare the individual, local and regional lake dynamics of four different study sites (Alaska North Slope, Western Alaska, Central Yakutia, Kolyma Lowland) in the northern permafrost zone from 1999 to 2014. Regional patterns of lake area change on the Alaska North Slope (-0.69\%), Western Alaska (-2.82\%), and Kolyma Lowland (-0.51\%) largely include increases due to thermokarst lake expansion, but more dominant lake area losses due to catastrophic lake drainage events. In contrast, Central Yakutia showed a remarkable increase in lake area of 48.48\%, likely resulting from warmer and wetter climate conditions over the latter half of the study period. Within all study regions, variability in lake dynamics was associated with differences in permafrost characteristics, landscape position (i.e., upland vs. lowland), and surface geology. With the global availability of Landsat data and a consistent methodology for processing the input data derived from robust trends of multi-spectral indices, we demonstrate a transferability, scalability and consistency of lake change analysis within the northern permafrost region.}, language = {en} } @article{NitzeGrosse2016, author = {Nitze, Ingmar and Grosse, Guido}, title = {Detection of landscape dynamics in the Arctic Lena Delta with temporally dense Landsat time-series stacks}, series = {Remote sensing of environment : an interdisciplinary journal}, volume = {181}, journal = {Remote sensing of environment : an interdisciplinary journal}, publisher = {Elsevier}, address = {New York}, issn = {0034-4257}, doi = {10.1016/j.rse.2016.03.038}, pages = {27 -- 41}, year = {2016}, abstract = {Arctic permafrost landscapes are among the most vulnerable and dynamic landscapes globally, but due to their extent and remoteness most of the landscape changes remain unnoticed. In order to detect disturbances in these areas we developed an automated processing chain for the calculation and analysis of robust trends of key land surface indicators based on the full record of available Landsat TM, ETM +, and OLI data. The methodology was applied to the similar to 29,000 km(2) Lena Delta in Northeast Siberia, where robust trend parameters (slope, confidence intervals of the slope, and intercept) were calculated for Tasseled Cap Greenness, Wetness and Brightness, NDVI, and NDWI, and NDMI based on 204 Landsat scenes for the observation period between 1999 and 2014. The resulting datasets revealed regional greening trends within the Lena Delta with several localized hot-spots of change, particularly in the vicinity of the main river channels. With a 30-m spatial resolution various permafrost-thaw related processes and disturbances, such as thermokarst lake expansion and drainage, fluvial erosion, and coastal changes were detected within the Lena Delta region, many of which have not been noticed or described before. Such hotspots of permafrost change exhibit significantly different trend parameters compared to non-disturbed areas. The processed dataset, which is made freely available through the data archive PANGAEA, will be a useful resource for further process specific analysis by researchers and land managers. With the high level of automation and the use of the freely available Landsat archive data, the workflow is scalable and transferrable to other regions, which should enable the comparison of land surface changes in different permafrost affected regions and help to understand and quantify permafrost landscape dynamics. (C) 2016 Elsevier Inc. All rights reserved.}, language = {en} } @misc{NiemeyerHerzschuhPestryakova2015, author = {Niemeyer, Bastian and Herzschuh, Ulrike and Pestryakova, Luidmila Agafyevna}, title = {Vegetation and lake changes on the southern Taymyr peninsula, northern Siberia, during the last 300 years inferred from pollen and Pediastrum green algae records}, series = {The Holocene}, volume = {25}, journal = {The Holocene}, number = {4}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-404882}, pages = {11}, year = {2015}, abstract = {Siberian arctic vegetation and lake water communities, known for their temperature dependence, are expected to be particularly impacted by recent climate change and high warming rates. However, decadal information on the nature and strength of recent vegetation change and its time lag to climate signals are rare. In this study, we present a Pb-210/Cs-137 dated pollen and Pediastrum species record from a unnamed lake in the south of the Taymyr peninsula covering the period from AD 1706 to 2011. Thirty-nine palynomorphs and 10 morphotypes of Pediastrum species were studied to assess changes in vegetation and lake conditions as probable responses to climate change. We compared the pollen record with Pediastrum species, which we consider to be important proxies of climate changes. Three pollen assemblage zones characterised by Betula nana, Alnus viridis and Larix gmelinii (1706-1808); herbs such as Cyperaceae, Artemisia or Senecio (1808-1879), and higher abundance of Larix pollen (1955-2011) are visible. Also, three Pediastrum assemblage zones show changes of aquatic conditions: higher abundances of Pediastrum boryanum var. brevicorne (1706-1802); medium abundances of P. kawraiskyi and P. integrum (1802-1840 and 1920-1980), indicating cooler conditions while less eutrophic conditions are indicated by P. boryanum, and a mainly balanced composition with only small changes of cold- and warm-adapted Pediastrum species (1965-2011). In general, compositional Pediastrum species turnover is slightly higher than that indicated by pollen data (0.54 vs 0.34 SD), but both are only minor for this treeline location. In conclusion, the relevance of differentiation of Pediastrum species is promising and can give further insights into the relationship between lakes and their surrounding vegetation transferred onto climatic conditions.}, language = {en} }