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Image: Matthias Siewert

Greening of the Arctic: gradual or abrupt?

Research project financed by the Swedish Research Council.

Climate change is leading to more productive Arctic ecosystems. However, despite strong forcing of warming temperature, changes in the vegetation are not happening everywhere at the same speed, for example at treelines. This project will use drones, satellite data and modeling to investigate factors that lead to vegetation adjustment consistent with climate change or delayed adaptation due to ecosystem stability. This aims to get a better understanding of Arctic carbon dynamics.

Head of project

Matthias Siewert
Associate professor

Project overview

Project period:

2022-01-01 2025-12-31

Participating departments and units at Umeå University

Department of Ecology and Environmental Science

Research area


External funding

Swedish Research Council

Project description

Climate change is increasingly warming up Arctic ecosystems and removing climate envelops for vegetation. In response, a general increased vegetation productivity trend (‘greening’) has been observed in satellite imagery. However, this trend is not uniform with large areas exposing stability and even conflicting reduced productivity. While there is ample evidence for widespread shrub encroachment and treeline movement into tundra ecosystems, there is also a significant time lag between projected and observed trends. This is raising a conundrum as to why, despite driving forces of climate change pressuring these systems, we do not see a uniform linear response of vegetation.

In this project, I will investigate whether abrupt regime shifts and alternative stables states can explain conflicting patterns in Arctic greening. I will test this hypothesis at local scale using an island treeline system marked by alternating patches of forest, shrubland and tundra, as well as at regional and circumarctic scale. I will combine unmanned aerial vehicle (UAV) imagery, ground sampling, historic aerial photography and satellite time series to characterize the systems. The findings will be translated into models explicitly allowing for non-linearity and alternative stable states. Finally, these will be linked to biogeochemical data (e.g. soil carbon storage, biomass, CO 2 fluxes) to get a landscape understanding of future changes in Arctic carbon balances on a 100-year time horizon.

The project will be associated the Umeå University Climate Impacts Research Centre (CIRC) in Abisko.

External funding

Latest update: 2022-02-08