Seasonal, not annual precipitation drives community productivity across ecosystems

Robinson, T.M.P, K.J. La Pierre, M.A. Vadeboncoeur, K.M. Byrne, S.E. Colby, and M.L. Thomey

Presented at the All Scientist Meeting (2011-04-15 to 2011-04-15 )

1. Understanding drivers of aboveground net primary production (ANPP) has long been a goal of ecology. Decades of investigation have shown total annual precipitation to be an important determinant of ANPP within and across ecosystems. However recent individual site studies have shown precipitation during specific seasons of the year can more effectively predict ANPP.

2. We used AIC to determine whether seasonal or total precipitation better predicted ANPP across a range of terrestrial ecosystems, from deserts to forests, using long-term data from 36 plant communities. We also determined whether ANPP responses were dependent on ecosystem type or plant functional group.

3. We found that seasonal precipitation generally explained ANPP better than total precipitation, but that responsiveness to seasonal precipitation was not correlated with ecosystem type or plant functional group. Precipitation in multiple parts of the growing season often correlated with ANPP, but rarely interacted with each other.

4. Examining seasonal precipitation can significantly improve ANPP predictions across a broad range of ecosystems and plant types, with implications for understanding current and future ANPP variation. Further work examining precipitation timing relative to species phenology may further improve climate change predictions.