MPI-BGC Colloquium

Abstract:

The “greening” of the land surface at high latitude has been directly attributed to greenhouse gas emissions, and is rising in the public consciousness as a large-scale human impact on the environment. Models predict dramatic redistribution of vegetation in the Arctic over the next decades as tundra is replaced by deciduous shrubs. Vegetation change on this scale will have profound consequences for ecosystem structure and function, not least in determining the climate feedbacks associated with carbon release from thawing permafrost.

The dominant paradigm asserts that Arctic plants are predominantly nutrient limited as a result of slow rates of mineralisation in cold, wet soils. Warmer temperatures are therefore expected to stimulate growth as mineralisation increases. While Arctic plants and soils are highly responsive to mineral nutrient availability, there are some problems with the idea of mineralisation as the key “bottom-up” control over plant nutrient uptake. In this talk I will discuss the biogeochemical mechanisms by which plant nutrient acquisition may determine growth sensitivity to climate, and the ultimate impact of Arctic greening on the carbon cycle.