Comparative study of the net exchange of CO2 in 3 types of vegetation ecosystems on the Qinghai-Tibetan Plateau

Abstract

Using the eddy covariance method, from 1 July 2003 to 30 June 2004, we conducted the observation and analysis of ecosystem CO2 flux in 3 types of alpine meadow vegetation (Kobresia humilis, Potentilla fruticosa shrub and Kobresia tibetica swamp meadows) on the Qinghai-Tibetan Plateau. The results show that the Kobresia humilis meadow, the shrub meadow and the swamp meadow’s highest CO2 uptake rates are 16.78, 10.42 and 16.57 μmol·m−2·s−1 respectively, while their highest CO2 release rates are 8.22, 7.73 and 18.67 μmol·m−2·s−1 respectively. The Kobresia humilis meadow and shrub meadow’s annual atmospheric uptakes are 282 g CO2/m2 and 53 g CO2/m2, respectively, while swamp meadow’s annual atmospheric release is 478 g CO2/m2. This proves that the Kobresia humilis meadow and the shrub meadow on the Qinghai-Tibetan Plateau have relatively low potential for CO2 uptake and release compared to C4 grasslands, a number of lowland grasslands, and forests. Moreover, swamp meadow has relatively high release potential. This, in turn, reveals clear differences in carbon source/sink between different types of vegetation in the Qinghai-Tibetan Plateau alpine meadow ecosystem. These differences are mainly brought by differences in the vegetations’ photosynthetic capacity and soil respiration.