A productivity and carbon cycle analysis for a tropical montane rainforest

Tropical forests play an important role in the global carbon cycle. However, various kinds of tropical regions contribute different to the global carbon cycle. One approach to quantify this contribution is to directly measure carbon flux via eddy covariance techniques, which is in general difficult to apply in tropical montane forests. Forest inventory data in combination with process based forest models allow also to investigate the local carbon balance of a forest ecosystem. We parameterized such a forest model for a tropical montane forest in South Ecuador. The aim of our study is to analyze the carbon balance of this tropical mountain forest and how the balance depends from the successional state of the forest. For this application the forest model FORMIND was extended with a local carbon balance module. The simulated aboveground biomass reached equilibrium state after 500 years with aboveground biomass of around 150 t/ha. In late successional phase the investigated forest net ecosystem exchange values (NEE) fluctuates around zero with a variation of 0.3 tC/(ha y) for an area of 10 ha. In early succession the local forest acts as a carbon sink with approx. 4.5 tC/(ha yr). Simulated variability of the net ecosystem exchange is the range of measured field data.