PhD Candidate 'Shrub decline instead of shrub expansion in Siberian lowland tundra?'
Nowadays, there is great concern about the effects of climate change on the world's ecosystems. Arctic tundra ecosystems are changing rapidly as the Arctic climate is warming twice as fast as the world average. Expansion of shrub vegetation has been widely observed in the Arctic landscape, but has recently halted for reasons yet unknown. This project addresses potential shrub decline due to abrupt thaw of ice-rich permafrost (permanently frozen ground). Such local permafrost collapse causes soil subsidence resulting in new open water features, e.g. thaw ponds, in which the pre-existing dwarf shrub vegetation drowns. Thaw of permafrost and the resulting release of carbon dioxide and methane is considered one of the most significant potential feedbacks from terrestrial ecosystems to the climate system.
In this project, the PhD candidate will examine the dynamics and mechanisms of shrub expansion and shrub decline at a remote Siberian lowland tundra site which appears highly sensitive to climate warming. Methodology includes 1) field and remote sensing monitoring of thaw pond and vegetation changes, 2) setting up a novel field experiment to test whether extreme precipitation may trigger abrupt permafrost thaw, and 3) using dendrochronology on drowned dwarf shrubs. We expect that the proposed research on the drivers of shrub decline and expansion in an understudied Arctic region will generate a novel perspective on Arctic landscape changes. A detailed description of the project is available.
This job comes from a partnership with Science Magazine and