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Dive into the research topics where Stefan Kruse is active.

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Featured researches published by Stefan Kruse.


Tree Genetics & Genomes | 2018

High gene flow and complex treeline dynamics of Larix Mill. stands on the Taymyr Peninsula (north-central Siberia) revealed by nuclear microsatellites

Stefan Kruse; L. S. Epp; Mareike Wieczorek; L. Pestryakova; K. R. Stoof-Leichsenring; Ulrike Herzschuh

Arctic treelines are facing a strong temperature increase as a result of recent global warming, causing possible changes in forest extent, which will alter vegetation-climate feedbacks. However, the mode and strength of the response is rather unclear, as potential changes are happening in areas that are very remote and difficult to access, and empirical data are still largely lacking. Here, we assessed the current population structure and genetic differentiation of Larix Mill. tree stands within the northernmost latitudinal treeline reaching ~ 72° N in the southern lowlands of the Taymyr Peninsula (~ 100° E). We sampled 743 individuals belonging to different height classes (seedlings, saplings, trees) at 11 locations along a gradient from ‘single tree’ tundra over ‘forest line’ to ‘dense forest’ stands and conducted investigations applying eight highly polymorphic nuclear microsatellites. Results suggest a high diversity within sub-populations (HE = 0.826–0.893), coupled, however, with heterozygote deficits in all sub-populations, but pronounced in ‘forest line’ stands. Overall, genetic differentiation of sub-populations is low (FST = 0.005), indicating a region-wide high gene flow, although ‘forest line’ stands harbour few rare and private alleles, likely indicating greater local reproduction. ‘Single tree’ stands, located beyond the northern forest line, are currently not involved in treeline expansion, but show signs of a long-term refuge, namely asexual reproduction and change of growth-form from erect to creeping growth, possibly having persisted for thousands of years. The lack of differentiation between the sub-populations points to a sufficiently high dispersal potential, and thus a rapid northward migration of the Siberian arctic treeline under recent global warming seems potentially unconstrained, but observations show it to be unexpectedly slow.


Geoscientific Model Development Discussions | 2018

Implementing spatially explicit seed and pollen dispersal in the individual-based larch simulation model: LAVESI-WIND 1.0

Stefan Kruse; Alexander Gerdes; Nadja Kath; Ulrike Herzschuh

It is of major interest to estimate the feedback of arctic ecosystems to the global warming we expect in upcoming 10 decades. The speed of this response is driven by the potential of species to migrate, tracking their climate optimum. For this, sessile plants have to produce and disperse seeds to newly available habitats, and pollination is needed for the seeds to be viable. These two processes are also the vectors that pass genetic information through a population. A restricted exchange among subpopulations might lead to a maladapted population due to diversity losses. Hence, a realistic implementation of these dispersal processes into a simulation model would allow an assessment of the importance of diversity for the migration 15 of plant species in various environments worldwide. To date, dynamic global vegetation models have been optimised for a global application and overestimate the migration of biome shifts in currently warming temperatures. We hypothesise that this is caused by neglecting important fine-scale processes, which are necessary to estimate realistic vegetation trajectories. Recently, we built and parameterised a simulation model LAVESI for larches that dominate the latitudinal treelines in the northernmost areas of Siberia. In this study, we updated the vegetation model by including seed and pollen dispersal driven by 20 wind speed and direction. The seed dispersal is modelled as a ballistic flight, and for the pollination of seeds produced, we implemented a wind-determined and distance-dependent probability distribution function using a von Mises distribution to select the potential pollen donor. This individual-based and spatially explicit implementation of both dispersal processes makes it easily feasible to inherit plant traits and genetic information to assess the impact of migration processes on the genetics. The final model can substantially help in unveiling the important drivers of migration dynamics and, with this, guide the 25 improvement of recent global vegetation models.


Biogeosciences Discussions | 2018

Dispersal distances and migration rates at the arctic treeline in Siberia – a genetic and simulation based study

Stefan Kruse; Alexander Gerdes; Nadja Kath; Laura Saskia Epp; Kathleen Rosmarie Stoof-Leichsenring; Luidmila A. Pestryakova; Ulrike Herzschuh

A strong temperature increase in the Arctic is expected to lead to latitudinal treeline shift. This tundra–taiga turnover would cause a positive vegetation–climate feedback due to albedo decrease. However, reliable estimates of tree migration rates are currently lacking due to the complex processes involved in forest establishment, which depend strongly on seed dispersal. We aim to fill this gap using LAVESI, an individual-based and spatially explicit Larix vegetation simulator. LAVESI was designed to simulate plots within homogeneous forests. Here, we improve the implementation of the seed dispersal function via field-based investigations. We inferred the effective seed dispersal distances of a typical open-forest stand on the southern Taymyr Peninsula (northern central Siberia) from genetic parentage analysis using eight nuclear microsatellite markers. The parentage analysis gives effective seed dispersal distances (median ∼ 10 m) close to the seed parents. A comparison between simulated and observed effective seed dispersal distances reveals an overestimation of recruits close to the releasing tree and a shorter dispersal distance generally. We thus adapted our model and used the newly parameterised version to simulate south-to-north transects; a slow-moving treeline front was revealed. The colonisation of the tundra areas was assisted by occasional long-distance seed dispersal events beyond the treeline area. The treeline (∼ 1 tree ha−1) advanced by ∼ 1.6 m yr−1, whereas the forest line (∼ 100 trees ha−1) advanced by only ∼ 0.6 m yr−1. We conclude that the treeline in northern central Siberia currently lags behind the current strong warming and will continue to lag in the near future.


Ecological Modelling | 2016

Treeline dynamics in Siberia under changing climates as inferred from an individual-based model for Larix

Stefan Kruse; Mareike Wieczorek; Florian Jeltsch; Ulrike Herzschuh


Ecology | 2017

Dissimilar responses of larch stands in northern Siberia to increasing temperatures—a field and simulation based study

Mareike Wieczorek; Stefan Kruse; Laura Saskia Epp; Alexei Kolmogorov; Anatoly N. Nikolaev; Ingo Heinrich; Florian Jeltsch; L. Pestryakova; Romy Zibulski; Ulrike Herzschuh


Supplement to: Wieczorek, M et al. (2017): Dissimilar responses of larch stands in northern Siberia to increasing temperatures-a field and simulation based study. Ecology, 98(9), 2343-2355, https://doi.org/10.1002/ecy.1887 | 2017

Field and simulation data for larches growing in the Taimyr treeline ecotone

Mareike Wieczorek; Stefan Kruse; Laura Saskia Epp; Alexei Kolmogorov; Anatoly N. Nikolaev; Ingo Heinrich; Florian Jeltsch; Ludmila A Pestryakova; Romy Zibulski; Ulrike Herzschuh


Silva Fennica | 2017

Disturbance-effects on treeline larch-stands in the lower Kolyma River area (NE Siberia)

Mareike Wieczorek; Alexei Kolmogorov; Stefan Kruse; Inga Jacobsen; Ingmar Nitze; Anatoly N. Nikolaev; Ingo Heinrich; Luidmila A. Pestryakova; Ulrike Herzschuh


In supplement to: Wieczorek, M et al. (accepted): Dissimilar responses of larch stands in northern Siberia to increasing temperatures - a field and simulation based study. Ecological | 2017

Simulation results for larches growing in the Taimyr treeline ecoton

Mareike Wieczorek; Stefan Kruse; Laura Saskia Epp; Alexei Kolmogorov; Anatoly N. Nikolaev; Ingo Heinrich; Florian Jeltsch; Ludmila A Pestryakova; Romy Zibulski; Ulrike Herzschuh


EPIC3PAGES OSM, Zaragoza, 2017-05-09-2017-05-13 | 2017

Larch species turnovers and vegetation change in the arctic - boreal treeline ecotone during the Holocene

Laura Saskia Epp; Stefan Kruse; Nadja Kath; Luidmila A. Pestryakova; Ulrike Herzschuh


Supplement to: Kruse, S et al. (2016): Treeline dynamics in Siberia under changing climates as inferred from an individual-based model for Larix. Ecological Modelling, 338, 101-121, https://doi.org/10.1016/j.ecolmodel.2016.08.003 | 2016

Treeline dynamics in Siberia under changing climates as inferred from an individual-based model for Larix, supplementary material

Stefan Kruse; Mareike Wieczorek; Florian Jeltsch; Ulrike Herzschuh

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Laura Saskia Epp

American Museum of Natural History

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Luidmila A. Pestryakova

North-Eastern Federal University

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Alexei Kolmogorov

North-Eastern Federal University

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Anatoly N. Nikolaev

North-Eastern Federal University

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