The effect of rainfall gradients on gross primary productivity (GPP) across the Isthmus of Panama

Abstract:

As climate changes, tropical forests will be affected by changes in precipitation and temperature, resulting in feedbacks to global climate and processes. The Functionally-Assembled Terrestrial Ecosystem Simulator (FATES) model, being developed at Berkeley Lab, is structured and parameterized to represent ecological dynamics of tropical forests under different environmental regimes. In this analysis, we assimilated and characterized climate data measured from three sites (Parque Nacional Metropolitano (PNM), Barro Colorado Island (BCI), and Parque Nacional San Lorenzo (SLZ) along a rainfall gradient in Panama. We examined the effects of the rainfall gradient on the Functionally Assembled Terrestrial Ecosystem Simulator (FATES) predictions of GPP. We found as precipitation increased GPP increased between the three sites, and we found no differences in wet season GPP per leaf area across sites, indicating solar radiation (SR) is driving differences in GPP across the rainfall gradients sites. We also found canopy biomass was highest at SLZ, BCI then PNM during the wet season. However, understory biomass had a declining effect across all sites in the wet season. This work assists in the development and evaluation of the FATES model and aids in predicting the impacts of climate change on forest ecosystem processes and functions.