Background project: Understanding self-reinforcing feedbacks of woody expansion under contrasting permafrost conditions in boreal ecosystems
Boreal ecosystems are warming twice as fast as the average global rate and are experiencing fast changes. At many locations shrubs and trees have been establishing in open ecosystems such as tundra or subarctic-alpine meadows, gradually expanding the forest limit. At other locations, shrubs and trees are dying as melting permafrost increases water levels. The mechanisms of these opposite vegetation changes remain too poorly understood to accurately predict the net consequence of receding permafrost for regional or global warming. Shrubs and trees can establish successfully on well-drained soils of upland sites and also on slightly elevated microsites in poorly drained ecosystems. It has been hypothesized that shrubs can facilitate tree seedling establishment but may compete with trees for resources, especially if rooting space and/ or nutrients are limited. We aim to conduct field experiments and surveys to better understand: 1) the balance between facilitative and competitive interactions between shrubs and trees in boreal ecosystems differing in permafrost conditions 2) how these interactions are affected by topographical position in the landscape and 3) the consequence of woody expansion for soil C pools and fluxes. We propose to study these mechanisms in upslope forest and valley peatlands along a longitudinal permafrost gradient in the Great Khingan mountains of north-eastern China.
We are looking for a highly motivated and independent Chinese student aiming for an academic career who is fluent in English (speaking and writing) with a background in ecology or a related discipline who is willing to write a CSC grant proposal under supervision of an international team to conduct her/his PhD in Wageningen University, in The Netherlands.
Collaborating Institutes: Wageningen University, the Netherlands; Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, ChangchunContact: Juul.Limpens@wur.nl, Milena.Holmgren@wur.nl, Wangxianwei@iga.ac.cn
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