Reindeer-mediated climate feedbacks in a changing tundra landscape

The Arctic shrub expansion is likely to have global implications.

However, our current concept of shrub expansion are biased and only applicable to tall deciduous shrubs, which reinforce climate warming. In contrary, evergreen shrubs may drive processes mitigating climate change.

Recent findings show a strong expansion of evergreen shrubs across the Arctic, in some cases aided by selective herbivory by semi-domestic reindeer.

Our overall goal is to integrate the role of reindeer browsing with ongoing climate-driven vegetation change and to expand current views on the resulting climate feedbacks.

Using a three-decade-long reindeer exclusion experiment we address two big unknowns: 1) Can mammalian herbivores reduce trace gas emissions in Arctic ecosystems, and 2) Can mammalian herbivores influence landscape-level albedo and thereby modulate microclimate and ground surface temperatures?

By assessing the effects evergreen vs deciduous shrubs have on emissions of CO2, CH4, and biogenic volatile organic compounds, in combination with albedo changes using multi-scale remote sensing and scale it to the landscape level, we will provide the first integrated assessment of different ecosystem feedbacks.

This to generate a holistic view of feedback mechanisms related to herbivory.

Thus, our results will generate data which are currently lacking to calibrate and validate recent model developments and therefore be of major importance for constructing future projections of a changing Arctic.