Modeling phosphorus limitation on terrestrial carbon uptake in the tropical Asia

Background/Question/Methods

In the terrestrial ecosystems, the neglect of phosphorus (P) limitation can result in overestimation of carbon (C) uptake in different ecosystem models. At global scale, tropical ecosystems store approximately 25–40% of biomass C and contribute to approximately 32–43% net primary production (NPP). Therefore, tropical ecosystems are considered as the most C sinks. However, the C sink capacity of tropical ecosystems is constrained by the P availability, which is strongly bound to iron and aluminum oxides in highly weathered tropical soils. In this study, used a process based Dynamic Land Ecosystem Model (DLEM 2.0), with fully coupled C, nitrogen, hydrological, and P cycles, to quantify the  net carbon exchange (NCE: net primary productivity – heterotrophic respiration) in the tropical Asia during 1901–2010. The specific objectives of this research were to determine the magnitude and spatial patterns of NCE as limited by P limitation in tropical Asia during 1901–2010. 

Results/Conclusions

The simulation results from the DLEM 2.0 were validated against the field observations on terrestrial net primary productivity, C, nitrogen, and P ratio in the foliage and plant litter pools obtained from different geographical locations. As compared to field data, the DLEM 2.0 is able to simulate net primary productivity (R²=0.89), foliar nitrogen to P ratio (R²=0.74), carbon to P ratio in the litter pools (R²=0.8). Our DLEM 2.0 simulation results provide insights on how P limitation can affect the C uptake in the tropical Asia.