Studies on the Flux Distribution and Energy Closure in Xishuangbanna Tropical Seasonal Rainforest, China

Abstract:

In order to explore the energy distribution and energy balance closure of the tropical seasonal rainforest in Xishuangbanna, China, the energy flux characteristics and closure features in different seasons were analyzed by using the continuous monitoring results of the eddy covariance system and conventional meteorological instruments. The results showed that the annual net radiation, latent heat flux, sensible heat flux, soil heat flux and heat storage were 4 546.07, 2 453.24, 492.22, -10.47 and 45.93 MJ/m², respectively. It was suggested that soil was a heat source. The latent and sensible heat fluxes were accounted for 54.0% and 10.8% of the net radiation, respectively. The main form of energy dissipation was evapotranspiration. There was obvious diurnal variation and seasonal dynamics in radiation and energy, and the diurnal variation of each energy components almost showed a unimodal trend of high daytime and low nighttime. The overall albedo ranged from 0.10 to 0.12, with a little fluctuation, and the seasonal variation of the Bowen ratio was significant, fluctuating from 0 to 0.8 throughout the year. The annual closure of tropical seasonal rainforest was 0.67, which varied from 0.51 to 0.79 when the heat storage was not considered, and from 0.53 to 0.80 when the heat storage was taken into account. Therefore, the contribution of heat storage to energy closure was small in tropical seasonal rainforest with dense forest canopies, and neglecting heat storage was not the main cause for energy non-closure.

Key words:Tropical seasonal rainforest;Eddy covariance system;Heat storage;Energy