Understanding predicted shifts in diazotroph biogeography using resource competition theory

[摘要] We examine the sensitivity of the biogeography of nitrogen fixers toa warming climate and increased aeolian iron deposition in thecontext of a global earth system model. We employ concepts from theresource-ratio theory to provide a simplifying and transparentinterpretation of the results. First we demonstrate that a set ofclearly defined, easily diagnosed provinces are consistent with thetheory. Using this framework we show that the regions most vulnerableto province shifts and changes in diazotroph biogeography are theequatorial and South Pacific, and central Atlantic. Warmer anddustier climates favor diazotrophs due to an increase in the ratioof supply rate of iron to fixed nitrogen. We suggest that theemergent provinces could be a standarddiagnostic for global change models, allowing for rapid andtransparent interpretation and comparison of model predictions andthe underlying mechanisms. The analysis suggeststhat monitoring of real world province boundaries, indicated bytransitions in surface nutrient concentrations, would providea clear and easily interpreted indicator of ongoing globalchange.

[学科分类] 地球化学与岩石