@article{LiTianRudayaetal.2022,
  author    = {Li, Wenjia and Tian, Fang and Rudaya, Natalya A. and Herzschuh, Ulrike and Cao, Xianyong},
  title     = {Pollen-based holocene thawing-history of permafrost in Northern Asia and its potential impacts on climate change},
  series = {Frontiers in Ecology and Evolution},
  volume    = {10},
  journal   = {Frontiers in Ecology and Evolution},
  publisher = {Frontiers Media},
  address   = {Lausanne},
  issn      = {2296-701X},
  doi       = {10.3389/fevo.2022.894471},
  pages     = {13},
  year      = {2022},
  abstract  = {As the recent permafrost thawing of northern Asia proceeds due to anthropogenic climate change, precise and detailed palaeoecological records from past warm periods are essential to anticipate the extent of future permafrost variations. Here, based on the modern relationship between permafrost and vegetation (represented by pollen assemblages), we trained a Random Forest model using pollen and permafrost data and verified its reliability to reconstruct the history of permafrost in northern Asia during the Holocene. An early Holocene (12-8 cal ka BP) strong thawing trend, a middle-to-late Holocene (8-2 cal ka BP) relatively slow thawing trend, and a late Holocene freezing trend of permafrost in northern Asia are consistent with climatic proxies such as summer solar radiation and Northern Hemisphere temperature. The extensive distribution of permafrost in northern Asia inhibited the spread of evergreen coniferous trees during the early Holocene warming and might have decelerated the enhancement of the East Asian summer monsoon (EASM) by altering hydrological processes and albedo. Based on these findings, we suggest that studies of the EASM should consider more the state of permafrost and vegetation in northern Asia, which are often overlooked and may have a profound impact on climate change in this region.},
  language  = {en}
}
@article{BerbenBoin'tZandtetal.2022,
  author    = {Berben, Tom and Bo, Franco Forlano and in 't Zandt, Michiel H. and Yang, Sizhong and Liebner, Susanne and Welte, Cornelia U.},
  title     = {The Polar Fox Lagoon in Siberia harbours a community of Bathyarchaeota possessing the potential for peptide fermentation and acetogenesis},
  series = {Antonie van Leeuwenhoek : international journal of general and molecular microbiology},
  volume    = {115},
  journal   = {Antonie van Leeuwenhoek : international journal of general and molecular microbiology},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {0003-6072},
  doi       = {10.1007/s10482-022-01767-z},
  pages     = {1229 -- 1244},
  year      = {2022},
  abstract  = {Archaea belonging to the phylum Bathyarchaeota are the predominant archaeal species in cold, anoxic marine sediments and additionally occur in a variety of habitats, both natural and man-made. Metagenomic and single-cell sequencing studies suggest that Bathyarchaeota may have a significant impact on the emissions of greenhouse gases into the atmosphere, either through direct production of methane or through the degradation of complex organic matter that can subsequently be converted into methane. This is especially relevant in permafrost regions where climate change leads to thawing of permafrost, making high amounts of stored carbon bioavailable. Here we present the analysis of nineteen draft genomes recovered from a sediment core metagenome of the Polar Fox Lagoon, a thermokarst lake located on the Bykovsky Peninsula in Siberia, Russia, which is connected to the brackish Tiksi Bay. We show that the Bathyarchaeota in this lake are predominantly peptide degraders, producing reduced ferredoxin from the fermentation of peptides, while degradation pathways for plant-derived polymers were found to be incomplete. Several genomes encoded the potential for acetogenesis through the Wood-Ljungdahl pathway, but methanogenesis was determined to be unlikely due to the lack of genes encoding the key enzyme in methanogenesis, methyl-CoM reductase. Many genomes lacked a clear pathway for recycling reduced ferredoxin. Hydrogen metabolism was also hardly found: one type 4e [NiFe] hydrogenase was annotated in a single MAG and no [FeFe] hydrogenases were detected. Little evidence was found for syntrophy through formate or direct interspecies electron transfer, leaving a significant gap in our understanding of the metabolism of these organisms.},
  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}
}
@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}
}