The terrestrial biosphere interacts strongly with the climate, providing both positive and negative feedbacks due to biogeophysical and biogeochemical processes. Some of these feedbacks can be quite large. Surface climate is determined by the balance of fluxes, which can be changed by radiative (e.g., albedo) or non-radiative (e.g., water cycle related processes) terms. Both radiative and non-radiative terms are controlled by details of vegetation. High-latitude climate is strongly influenced by snow albedo feedback, which is drastically reduced by the darkening effect of vegetation. In semi-arid tropical systems, such as the Sahel or northeast Brazil, vegetation exerts both radiative and hydrological feedbacks. (reference)
Terrestrial biosphere photosynthetic productivity changes in response to changes in temperature, precipitation, carbon dioxide and other nutrients. If climate becomes more favourable for growth, productivity increases, and carbon uptake from the atmosphere is enhanced. Organic carbon compounds in soils, originally derived from plant material, are respired and digested at different rates depending on a multitude of factors. Shifts in ecosystem structure in response to a changing climate can alter the partitioning of carbon between the atmosphere and the land surface. Migration of boreal forest northward into tundra would initially lead to an increase in carbon storage in the ecosystem due to the larger biomass of trees than of herbs and shrubs. However, a more rapid warming of the environment may cause the same boreal forests to be highly susceptible to forest fires and become a dramatic source of atmospheric carbon dioxide. Similarly, a shift from tropical rainforest to savannah, on the other hand, would result in a net flux of carbon from the land surface to the atmosphere.
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