Abstract

Terrestrial biosphere dynamics, e.g. carbon cycling and vegetation distribution, are influenced by climate in many ways and on many time-scales. They affect in turn the climate system by their effects on the growth rate of atmospheric greenhouse gas concentrations and biogeophysical properties of the land-surface. These interactions are essential for understanding observed past and present atmospheric and climatic changes, and for projecting future climate change as the consequence of anthropogenic greenhouse gas emissions. Studies of these interactions rely on numerical models of the terrestrial biosphere , linking processes at the scale of a single leaf to processes at the scale of individual ecosystems, biomes and continents. In this talk, I give a broad overview on some of the key issues in terrestrial biosphere modelling that affect our ability to understand biosphere dynamics under global change, and biosphere-climate interactions. I particularly highlight the need to account for nutrient interactions in the assessment of climate-carbon cycle feedback and given an overview on the current understanding (and modelling capacity) of nitrogen cycle interactions with climate either directly via the emissions of the greenhouse gas N2O , or indirectly, via the effect of nitrogen availability on terrestrial carbon cycling.