Reconciling inconsistencies in precipitation–productivity relationships: implications for climate change
Summary Precipitation ( PPT ) is a primary climatic determinant of plant growth and aboveground net primary production ( ANPP ) over much of the globe. Thus, PPT – ANPP relationships are important both ecologically and to land–atmosphere models that couple terrestrial vegetation to the global carbon cycle. Empirical PPT – ANPP relationships derived from long‐term site‐based data are almost always portrayed as linear, but recent evidence has accumulated that is inconsistent with an underlying linear relationship. We review, and then reconcile, these inconsistencies with a nonlinear model that incorporates observed asymmetries in PPT – ANPP relationships. Although data are currently lacking for parameterization, this new model highlights research needs that, when met, will improve our understanding of carbon cycle dynamics, as well as forecasts of ecosystem responses to climate change. Contents Summary 41 I. Introduction 41 II. The PPT–ANPP relationship: spatial vs temporal models 42 III. Inconsistencies with a linear temporal model 43 IV. Revision of the temporal PPT–ANPP model to better forecast climate change impacts 44 V. Conclusions 45 Acknowledgements 46 References 46