Authors : Bin Wang, Jie Li, Liang Zhao, Shixiao Xu, Yanhong Tang, Mingyuan Du and Song Gu
Abstract: Measurements of Net Ecosystem CO2 Exchange (NEE) were made, using eddy covariance to investigate the biophysical regulation of an Elymus nutans artificial pasture in the Three-River Source Region on the Qinghai-Tibetan Plateau during 2008. The hourly maximum rates of NEE was -7.89 μmol CO2/m2/sec (negative values representing net carbon uptake). The maximum daily NEE for the pasture was -2.91 g/cm2/day. The annual NEE sums in pasture was 140.01 g cm2/year. For the entire growing period, the light response curves of daytime NEE showed a medium apparent quantum yield (α = -0.0275 μmol μmol-1). However, the α values varied with varied with canopy development, air temperature (Ta) and Soil Water Content (SWC) and Vapor Pressure Deficit (VPD). Piecewise regression results suggested that the optimal Ta and VPD for hourly daytime NEE were 14.1°C and 0.65 kPa, respectively. During the entire growing period, the daytime NEE decreased as the SWC increased. The apparent temperature sensitivities of ecosystem respiration (Q10) was 3.0 for the entire growing season and it was significantly controlled by soil moisture. During the growing season, the leaf area index explained approximately 32.5% of the variation in daily NEE.
Bin Wang, Jie Li, Liang Zhao, Shixiao Xu, Yanhong Tang, Mingyuan Du and Song Gu, 2013. Biophysical Regulation of Net Ecosystem Carbon Dioxide Exchange over an Artificial Pasture in the Three-River Source Region of the Qinghai-Tibetan Plateau. Journal of Animal and Veterinary Advances, 12: 1512-1523.