Tropical rain forests play important roles in the global carbon cycle. Prof. Zhang Yiping and his research team of XTBG conducted eddy covariance carbon flux measurement over six years (from 2003 to 2008)  in a tropical seasonal rain forests in Xishuangbanna, southwest China. The primary objetive was to investigate: (1) if the forest was a carbon sink or source, (2) the seasonal and inter-annual variation of the ecosystem carbon fluxes. 

 The study detected an unexpected seasonal pattern of net ecosystem carbon exchange. Carbon was lost during the rainy season and stired during the dry season. Strong seasonality of ecosystem respiration was suggested to primarily account for the seasonal pattern. The annual net uptake of CO2 by the forest varied from 0.98 to 2.35 metric tons of carbon per hectare between 2003 and 2008. 6-year averaged sink strength was 1.68 metric tons of carbon per hectare.

The research observation entitled “Respiration controls the unexpected seasonal pattern of carbon flux in an Asian tropical rain forest” was published in Atmospheric Environment (2010) 44: 3886-3893. doi:10.1016/j.atmosenv.2010.07.027.