Net ecosystem exchange of carbon dioxide fluxes and its driving mechanism in the forests on the Tibetan Plateau

Abstract

Boreal forests sequester massive amounts of atmospheric carbon dioxide (CO2), and the contribution from the mid-high-latitude coniferous forests is considerable. This study quantified the net ecosystem exchange (NEE) of CO2 flux and its driving factors in a spruce forest in the Qilian Mountains. The results indicated that the NEE presented a robust temporal pattern ranging from −26.09 to 12.35 g C m−2 on a day-to-day basis. Furthermore, cumulative monthly NEE flux varied between −194.61 g C m−2 and 33.56 g C m−2. Forest ecosystems are vital carbon sinks that sequester/store carbon dioxide from April to September, especially from June to August. The annual NEE flux was a robust carbon sink of 545.99 g C m−2. Forest NEE was significantly driven by latent heat flux, net radiation, air temperature, and precipitation (P < 0.001). Regression coefficient of fitting model was 49.2% using latent heat flux, air temperature, and precipitation. In addition, future warming and precipitation scenarios may have considerably negative and positive effects, respectively, on the carbon sink.