@article{MiesnerHerzschuhPestryakovaetal.2022,
  author    = {Miesner, Timon and Herzschuh, Ulrike and Pestryakova, Luidmila Agafyevna and Wieczorek, Mareike and Zakharov, Evgenii S. and Kolmogorov, Alexei I. and Davydova, Paraskovya V. and Kruse, Stefan},
  title     = {Forest structure and individual tree inventories of northeastern Siberia along climatic gradients},
  series = {Earth system science data : ESSD},
  volume    = {14},
  journal   = {Earth system science data : ESSD},
  number    = {12},
  publisher = {Copernicus},
  address   = {G{\"o}ttingen},
  issn      = {1866-3508},
  doi       = {10.5194/essd-14-5695-2022},
  pages     = {5695 -- 5716},
  year      = {2022},
  abstract  = {We compile a data set of forest surveys from expeditions to the northeast of the Russian Federation, in Krasnoyarsk Krai, the Republic of Sakha (Yakutia), and the Chukotka Autonomous Okrug (59-73 degrees N, 97-169 degrees E), performed between the years 2011 and 2021. The region is characterized by permafrost soils and forests dominated by larch (Larix gmelinii Rupr. and Larix cajanderi Mayr). Our data set consists of a plot database describing 226 georeferenced vegetation survey plots and a tree database with information about all the trees on these plots. The tree database, consisting of two tables with the same column names, contains information on the height, species, and vitality of 40 289 trees. A subset of the trees was subject to a more detailed inventory, which recorded the stem diameter at base and at breast height, crown diameter, and height of the beginning of the crown. We recorded heights up to 28.5 m (median 2.5 m) and stand densities up to 120 000 trees per hectare (median 1197 ha(-1)), with both values tending to be higher in the more southerly areas. Observed taxa include Larix Mill., Pinus L., Picea A. Dietr., Abies Mill., Salix L., Betula L., Populus L., Alnus Mill., and Ulmus L. In this study, we present the forest inventory data aggregated per plot. Additionally, we connect the data with different remote sensing data products to find out how accurately forest structure can be predicted from such products. Allometries were calculated to obtain the diameter from height measurements for every species group. For Larix, the most frequent of 10 species groups, allometries depended also on the stand density, as denser stands are characterized by thinner trees, relative to height. The remote sensing products used to compare against the inventory data include climate, forest biomass, canopy height, and forest loss or disturbance. We find that the forest metrics measured in the field can only be reconstructed from the remote sensing data to a limited extent, as they depend on local properties. This illustrates the need for ground inventories like those data we present here. The data can be used for studying the forest structure of northeastern Siberia and for the calibration and validation of remotely sensed data.},
  language  = {en}
}
@article{KruseStuenziBoikeetal.2022,
  author    = {Kruse, Stefan and St{\"u}nzi, Simone Maria and Boike, Julia and Langer, Moritz and Gloy, Josias and Herzschuh, Ulrike},
  title     = {Novel coupled permafrost-forest model (LAVESI-CryoGrid v1.0) revealing the interplay between permafrost, vegetation, and climate across eastern Siberia},
  series = {Geoscientific model development : GMD ; an interactive open access journal of the European Geosciences Union},
  volume    = {15},
  journal   = {Geoscientific model development : GMD ; an interactive open access journal of the European Geosciences Union},
  number    = {6},
  publisher = {Copernicus},
  address   = {G{\"o}ttingen},
  issn      = {1991-959X},
  doi       = {10.5194/gmd-15-2395-2022},
  pages     = {2395 -- 2422},
  year      = {2022},
  abstract  = {Boreal forests of Siberia play a relevant role in the global carbon cycle. However, global warming threatens the existence of summergreen larch-dominated ecosystems, likely enabling a transition to evergreen tree taxa with deeper active layers. Complex permafrost-vegetation interactions make it uncertain whether these ecosystems could develop into a carbon source rather than continuing atmospheric carbon sequestration under global warming. Consequently, shedding light on the role of current and future active layer dynamics and the feedbacks with the apparent tree species is crucial to predict boreal forest transition dynamics and thus for aboveground forest biomass and carbon stock developments. Hence, we established a coupled model version amalgamating a one-dimensional permafrost multilayer forest land-surface model (CryoGrid) with LAVESI, an individual-based and spatially explicit forest model for larch species (Larix Mill.), extended for this study by including other relevant Siberian forest species and explicit terrain. <br /> Following parameterization, we ran simulations with the coupled version to the near future to 2030 with a mild climate-warming scenario. We focus on three regions covering a gradient of summergreen forests in the east at Spasskaya Pad, mixed summergreen-evergreen forests close to Nyurba, and the warmest area at Lake Khamra in the southeast of Yakutia, Russia. Coupled simulations were run with the newly implemented boreal forest species and compared to runs allowing only one species at a time, as well as to simulations using just LAVESI. Results reveal that the coupled version corrects for overestimation of active layer thickness (ALT) and soil moisture, and large differences in established forests are simulated. We conclude that the coupled version can simulate the complex environment of eastern Siberia by reproducing vegetation patterns, making it an excellent tool to disentangle processes driving boreal forest dynamics.},
  language  = {en}
}
@article{RadosavljevicLantuitKnoblauchetal.2022,
  author    = {Radosavljevic, Boris and Lantuit, Hugues and Knoblauch, Christian and Couture, Nicole and Herzschuh, Ulrike and Fritz, Michael},
  title     = {Arctic nearshore sediment dynamics - an example from Herschel Island - Qikiqtaruk, Canada},
  series = {Journal of marine science and engineering},
  volume    = {10},
  journal   = {Journal of marine science and engineering},
  number    = {11},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2077-1312},
  doi       = {10.3390/jmse10111589},
  pages     = {18},
  year      = {2022},
  abstract  = {Increasing arctic coastal erosion rates imply a greater release of sediments and organic matter into the coastal zone. With 213 sediment samples taken around Herschel Island-Qikiqtaruk, Canadian Beaufort Sea, we aimed to gain new insights on sediment dynamics and geochemical properties of a shallow arctic nearshore zone. Spatial characteristics of nearshore sediment texture (moderately to poorly sorted silt) are dictated by hydrodynamic processes, but ice-related processes also play a role. We determined organic matter (OM) distribution and inferred the origin and quality of organic carbon by C/N ratios and stable carbon isotopes delta C-13. The carbon content was higher offshore and in sheltered areas (mean: 1.0 wt.\%., S.D.: 0.9) and the C/N ratios also showed a similar spatial pattern (mean: 11.1, S.D.: 3.1), while the delta C-13 (mean: -26.4 parts per thousand VPDB, S.D.: 0.4) distribution was more complex. We compared the geochemical parameters of our study with terrestrial and marine samples from other studies using a bootstrap approach. Sediments of the current study contained 6.5 times and 1.8 times less total organic carbon than undisturbed and disturbed terrestrial sediments, respectively. Therefore, degradation of OM and separation of carbon pools take place on land and continue in the nearshore zone, where OM is leached, mineralized, or transported beyond the study area.},
  language  = {en}
}
@article{DallmeyerKleinenClaussenetal.2022,
  author    = {Dallmeyer, Anne and Kleinen, Thomas and Claussen, Martin and Weitzel, Nils and Cao, Xianyong and Herzschuh, Ulrike},
  title     = {The deglacial forest conundrum},
  series = {Nature Communications},
  volume    = {13},
  journal   = {Nature Communications},
  number    = {1},
  publisher = {Nature Publishing Group UK},
  address   = {[London]},
  issn      = {2041-1723},
  doi       = {10.1038/s41467-022-33646-6},
  pages     = {10},
  year      = {2022},
  abstract  = {How fast the Northern Hemisphere (NH) forest biome tracks strongly warming climates is largely unknown. Regional studies reveal lags between decades and millennia. Here we report a conundrum: Deglacial forest expansion in the NH extra-tropics occurs approximately 4000 years earlier in a transient MPI-ESM1.2 simulation than shown by pollen-based biome reconstructions. Shortcomings in the model and the reconstructions could both contribute to this mismatch, leaving the underlying causes unresolved. The simulated vegetation responds within decades to simulated climate changes, which agree with pollen-independent reconstructions. Thus, we can exclude climate biases as main driver for differences. Instead, the mismatch points at a multi-millennial disequilibrium of the NH forest biome to the climate signal. Therefore, the evaluation of time-slice simulations in strongly changing climates with pollen records should be critically reassessed. Our results imply that NH forests may be responding much slower to ongoing climate changes than Earth System Models predict. <br /> Deglacial forest expansion in the Northern Hemisphere poses a conundrum: Model results agree with the climate signal but are several millennia ahead of reconstructed forest dynamics. The underlying causes remain unsolved.},
  language  = {en}
}
@article{KruseHerzschuh2022,
  author    = {Kruse, Stefan and Herzschuh, Ulrike},
  title     = {Regional opportunities for tundra conservation in the next 1000 years},
  series = {eLife},
  volume    = {11},
  journal   = {eLife},
  publisher = {eLife Sciences Publications},
  address   = {Cambridge},
  issn      = {2050-084X},
  doi       = {10.7554/eLife.75163},
  pages     = {24},
  year      = {2022},
  abstract  = {The biodiversity of tundra areas in northern high latitudes is threatened by invasion of forests under global warming. However, poorly understood nonlinear responses of the treeline ecotone mean the timing and extent of tundra losses are unclear, but policymakers need such information to optimize conservation efforts. Our individual-based model LAVESI, developed for the Siberian tundra-taiga ecotone, can help improve our understanding. Consequently, we simulated treeline migration trajectories until the end of the millennium, causing a loss of tundra area when advancing north. Our simulations reveal that the treeline follows climate warming with a severe, century-long time lag, which is overcompensated by infilling of stands in the long run even when temperatures cool again. Our simulations reveal that only under ambitious mitigation strategies (relative concentration pathway 2.6) will ~30\% of original tundra areas remain in the north but separated into two disjunct refugia.},
  language  = {en}
}
@article{LiPostlBoehmeretal.2022,
  author    = {Li, Chenzhi and Postl, Alexander K. and B{\"o}hmer, Thomas and Cao, Xianyong and Dolman, Andrew M. and Herzschuh, Ulrike},
  title     = {Harmonized chronologies of a global late Quaternary pollen dataset (LegacyAge 1.0)},
  series = {Earth system science data : ESSD},
  volume    = {14},
  journal   = {Earth system science data : ESSD},
  number    = {3},
  publisher = {Copernics Publications},
  address   = {Katlenburg-Lindau},
  issn      = {1866-3508},
  doi       = {10.5194/essd-14-1331-2022},
  pages     = {1331 -- 1343},
  year      = {2022},
  abstract  = {We present a chronology framework named LegacyAge 1.0 containing harmonized chronologies for 2831 pollen records (downloaded from the Neotoma Paleoecology Database and the supplementary Asian datasets) together with their age control points and metadata in machine-readable data formats. All chronologies use the Bayesian framework implemented in Bacon version 2.5.3. Optimal parameter settings of priors (accumulation.shape, memory.strength, memory.mean, accumulation.rate, and thickness) were identified based on information in the original publication or iteratively after preliminary model inspection. The most common control points for the chronologies are radiocarbon dates (86.1 \%), calibrated by the latest calibration curves (IntCal20 and SHCal20 for the terrestrial radiocarbon dates in the Northern Hemisphere and Southern Hemisphere and Marine20 for marine materials). The original publications were consulted when dealing with outliers and inconsistencies. Several major challenges when setting up the chronologies included the waterline issue (18.8\% of records), reservoir effect (4.9 \%), and sediment deposition discontinuity (4.4 \%). Finally, we numerically compare the LegacyAge 1.0 chronologies to those published in the original publications and show that the reliability of the chronologies of 95.4\% of records could be improved according to our assessment. Our chronology framework and revised chronologies provide the opportunity to make use of the ages and age uncertainties in synthesis studies of, for example, pollen-based vegetation and climate change. The LegacyAge 1.0 dataset, including metadata, datings, harmonized chronologies, and R code used, is openaccess and available at PANGAEA (https://doi.org/10.1594/PANGAEA.933132; Li et al., 2021) and Zenodo (https://doi.org/10.5281/zenodo.5815192; Li et al., 2022), respectively.},
  language  = {en}
}
@article{CourtinAndreevRaschkeetal.2021,
  author    = {Courtin, J{\´e}r{\´e}my and Andreev, Andrei and Raschke, Elena and Bala, Sarah and Biskaborn, Boris and Liu, Sisi and Zimmermann, Heike and Diekmann, Bernhard and Stoof-Leichsenring, Kathleen R. and Pestryakova, Luidmila Agafyevna and Herzschuh, Ulrike},
  title     = {Vegetation changes in Southeastern Siberia during the late pleistocene and the holocene},
  series = {Frontiers in Ecology and Evolution},
  volume    = {9},
  journal   = {Frontiers in Ecology and Evolution},
  publisher = {Frontiers Media},
  address   = {Lausanne},
  issn      = {2296-701X},
  doi       = {10.3389/fevo.2021.625096},
  pages     = {18},
  year      = {2021},
  abstract  = {Relationships between climate, species composition, and species richness are of particular importance for understanding how boreal ecosystems will respond to ongoing climate change. This study aims to reconstruct changes in terrestrial vegetation composition and taxa richness during the glacial Late Pleistocene and the interglacial Holocene in the sparsely studied southeastern Yakutia (Siberia) by using pollen and sedimentary ancient DNA (sedaDNA) records. Pollen and sedaDNA metabarcoding data using the trnL g and h markers were obtained from a sediment core from Lake Bolshoe Toko. Both proxies were used to reconstruct the vegetation composition, while metabarcoding data were also used to investigate changes in plant taxa richness. The combination of pollen and sedaDNA approaches allows a robust estimation of regional and local past terrestrial vegetation composition around Bolshoe Toko during the last similar to 35,000 years. Both proxies suggest that during the Late Pleistocene, southeastern Siberia was covered by open steppe-tundra dominated by graminoids and forbs with patches of shrubs, confirming that steppe-tundra extended far south in Siberia. Both proxies show disturbance at the transition between the Late Pleistocene and the Holocene suggesting a period with scarce vegetation, changes in the hydrochemical conditions in the lake, and in sedimentation rates. Both proxies document drastic changes in vegetation composition in the early Holocene with an increased number of trees and shrubs and the appearance of new tree taxa in the lake's vicinity. The sedaDNA method suggests that the Late Pleistocene steppe-tundra vegetation supported a higher number of terrestrial plant taxa than the forested Holocene. This could be explained, for example, by the "keystone herbivore" hypothesis, which suggests that Late Pleistocene megaherbivores were able to maintain a high plant diversity. This is discussed in the light of the data with the broadly accepted species-area hypothesis as steppe-tundra covered such an extensive area during the Late Pleistocene.},
  language  = {en}
}
@article{HeimLisovskiWieczoreketal.2022,
  author    = {Heim, Birgit and Lisovski, Simeon and Wieczorek, Mareike and Morgenstern, Anne and Juhls, Bennet and Shevtsova, Iuliia and Kruse, Stefan and Boike, Julia and Fedorova, Irina and Herzschuh, Ulrike},
  title     = {Spring snow cover duration and tundra greenness in the Lena Delta, Siberia},
  series = {Environmental research letters},
  volume    = {17},
  journal   = {Environmental research letters},
  number    = {8},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {1748-9326},
  doi       = {10.1088/1748-9326/ac8066},
  pages     = {18},
  year      = {2022},
  abstract  = {The Lena Delta in Siberia is the largest delta in the Arctic and as a snow-dominated ecosystem particularly vulnerable to climate change. Using the two decades of MODerate resolution Imaging Spectroradiometer satellite acquisitions, this study investigates interannual and spatial variability of snow-cover duration and summer vegetation vitality in the Lena Delta. We approximated snow by the application of the normalized difference snow index and vegetation greenness by the normalized difference vegetation index (NDVI). We consolidated the analyses by integrating reanalysis products on air temperature from 2001 to 2021, and air temperature, ground temperature, and the date of snow-melt from time-lapse camera (TLC) observations from the Samoylov observatory located in the central delta. We extracted spring snow-cover duration determined by a latitudinal gradient. The 'regular year' snow-melt is transgressing from mid-May to late May within a time window of 10 days across the delta. We calculated yearly deviations per grid cell for two defined regions, one for the delta, and one focusing on the central delta. We identified an ensemble of early snow-melt years from 2012 to 2014, with snow-melt already starting in early May, and two late snow-melt years in 2004 and 2017, with snow-melt starting in June. In the times of TLC recording, the years of early and late snow-melt were confirmed. In the three summers after early snow-melt, summer vegetation greenness showed neither positive nor negative deviations. Whereas, vegetation greenness was reduced in 2004 after late snow-melt together with the lowest June monthly air temperature of the time series record. Since 2005, vegetation greenness is rising, with maxima in 2018 and 2021. The NDVI rise since 2018 is preceded by up to 4 degrees C warmer than average June air temperature. The ongoing operation of satellite missions allows to monitor a wide range of land surface properties and processes that will provide urgently needed data in times when logistical challenges lead to data gaps in land-based observations in the rapidly changing Arctic.},
  language  = {en}
}
@article{HerzschuhLiBoehmeretal.2022,
  author    = {Herzschuh, Ulrike and Li, Chenzhi and Boehmer, Thomas and Postl, Alexander K. and Heim, Birgit and Andreev, Andrei A. and Cao, Xianyong and Wieczorek, Mareike and Ni, Jian},
  title     = {LegacyPollen 1.0},
  series = {Earth system science data : ESSD},
  volume    = {14},
  journal   = {Earth system science data : ESSD},
  number    = {7},
  publisher = {Copernicus},
  address   = {G{\"o}ttingen},
  issn      = {1866-3508},
  doi       = {10.5194/essd-14-3213-2022},
  pages     = {3213 -- 3227},
  year      = {2022},
  abstract  = {Here we describe the LegacyPollen 1.0, a dataset of 2831 fossil pollen records with metadata, a harmonized taxonomy, and standardized chronologies. A total of 1032 records originate from North America, 1075 from Europe, 488 from Asia, 150 from Latin America, 54 from Africa, and 32 from the Indo-Pacific. The pollen data cover the late Quaternary (mostly the Holocene). The original 10 110 pollen taxa names (including variations in the notations) were harmonized to 1002 terrestrial taxa (including Cyperaceae), with woody taxa and major herbaceous taxa harmonized to genus level and other herbaceous taxa to family level. The dataset is valuable for synthesis studies of, for example, taxa areal changes, vegetation dynamics, human impacts (e.g., deforestation), and climate change at global or continental scales. The harmonized pollen and metadata as well as the harmonization table are available from PANGAEA (https://doi.org/10.1594/PANGAEA.929773; Herzschuh et al., 2021). R code for the harmonization is provided at Zenodo (https://doi.org/10.5281/zenodo.5910972; Herzschuh et al., 2022) so that datasets at a customized harmonization level can be easily established.},
  language  = {en}
}
@article{WeineltStegemannTheloeetal.2022,
  author    = {Weinelt, Ferdinand Anton and Stegemann, Miriam Songa and Theloe, Anja and Pf{\"a}fflin, Frieder and Achterberg, Stephan and Weber, Franz and D{\"u}bel, Lucas and Mikolajewska, Agata and Uhrig, Alexander and Kiessling, Peggy and Huisinga, Wilhelm and Michelet, Robin and Hennig, Stefanie and Kloft, Charlotte},
  title     = {Evaluation of a meropenem and piperacillin monitoring program in intensive care unit patients calls for the regular assessment of empirical targets and easy-to-use dosing decision tools},
  series = {Antibiotics : open access journal},
  volume    = {11},
  journal   = {Antibiotics : open access journal},
  number    = {6},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2079-6382},
  doi       = {10.3390/antibiotics11060758},
  pages     = {17},
  year      = {2022},
  abstract  = {The drug concentrations targeted in meropenem and piperacillin/tazobactam therapy also depend on the susceptibility of the pathogen. Yet, the pathogen is often unknown, and antibiotic therapy is guided by empirical targets. To reliably achieve the targeted concentrations, dosing needs to be adjusted for renal function. We aimed to evaluate a meropenem and piperacillin/tazobactam monitoring program in intensive care unit (ICU) patients by assessing (i) the adequacy of locally selected empirical targets, (ii) if dosing is adequately adjusted for renal function and individual target, and (iii) if dosing is adjusted in target attainment (TA) failure. In a prospective, observational clinical trial of drug concentrations, relevant patient characteristics and microbiological data (pathogen, minimum inhibitory concentration (MIC)) for patients receiving meropenem or piperacillin/tazobactam treatment were collected. If the MIC value was available, a target range of 1-5 x MIC was selected for minimum drug concentrations of both drugs. If the MIC value was not available, 8-40 mg/L and 16-80 mg/L were selected as empirical target ranges for meropenem and piperacillin, respectively. A total of 356 meropenem and 216 piperacillin samples were collected from 108 and 96 ICU patients, respectively. The vast majority of observed MIC values was lower than the empirical target (meropenem: 90.0\%, piperacillin: 93.9\%), suggesting empirical target value reductions. TA was found to be low (meropenem: 35.7\%, piperacillin 50.5\%) with the lowest TA for severely impaired renal function (meropenem: 13.9\%, piperacillin: 29.2\%), and observed drug concentrations did not significantly differ between patients with different targets, indicating dosing was not adequately adjusted for renal function or target. Dosing adjustments were rare for both drugs (meropenem: 6.13\%, piperacillin: 4.78\%) and for meropenem irrespective of TA, revealing that concentration monitoring alone was insufficient to guide dosing adjustment. Empirical targets should regularly be assessed and adjusted based on local susceptibility data. To improve TA, scientific knowledge should be translated into easy-to-use dosing strategies guiding antibiotic dosing.},
  language  = {en}
}