Predominance of Precipitation and Temperature Controls on Ecosystem CO2 Exchange in Zoige Alpine Wetlands of Southwest China

Abstract

Net ecosystem exchange (NEE) of carbon dioxide (CO 2 ) was measured at Zoige wetland using the eddy covariance technique. Analysis of CO 2 fluxes in two years showed Zoige wetland was a net CO 2 sink of −47.1 and −79.7 gC m −2 a −1 in 2008 and 2009, respectively. The peak NEE value was −0.54 mg CO 2 m −2 s −1 (the negative value signifies net ecosystem carbon gain from air). The maximal daily integrated NEE was −4.1 gC m −2 d −1 during the peak growth season (from July to August). Gross ecosystem photosynthesis was likely more variable than ecosystem respiration at both seasonal and interannual timescales in this wetland. Our data strongly suggested that the combination of precipitation and temperature, as well as phenological stage of vegetation, controlled the dynamics of ecosystem carbon gain, even in drought years. Therefore, an accurate representation of these parameters in climate models is critical to the success of forecasting carbon budgets of alpine wetlands.

Modeling Carbon Fluxes Using Multi-Temporal MODIS Imagery and CO2 Eddy Flux Tower Data in Zoige Alpine Wetland, South-West China

“…Gap-filling approaches such as the mean diurnal variation (MDV) ) and the interpolation methods (Baldocchi 2003) were used to fill the data gaps. More details of the data quality control are described by Hao et al (2011).…”

“…To note, at high altitudes, the seasonal variation in temperature is high. In alpine ecosystems, low temperature is often the major environmental variable constraining R 2 , the coefficient of determination; RMSE the root of mean square error; RMD the relative mean deviation ***Significant at probability levels of 0.0001 fluxes (Huxman et al 2003;Hao et al 2011). Previous studies of the same alpine wetland have pointed out the importance of temperature in controlling C fluxes (e.g.…”

“…The wetland has been shown to be very sensitive to climatic changes , and this region is characterized by continuously increasing air temperature and declining precipitation (Tian 2005;Hao et al 2011;Chen et al 2013). These climate changes have the potential to significantly alter the wetland C budget.…”

Rewetting Decreases Carbon Emissions from the Zoige Alpine Peatland on the Tibetan Plateau

“…Rewetting degraded peatlands raises the water level, turning the peatland environment from aerobic to anaerobic, which, in turn, lowers the activity of aerobic soil microbes, thereby slowing down the decomposition of organic matter and, ultimately, decreasing CO 2 emissions and increasing CH 4 emissions [19]. Plant physiological changes can also affect the dynamics of CO 2 and CH 4 emissions [5]. Vascular plants can be used as conduits for saturated soil gas emissions, and most soils release CO 2 and CH 4 through plants rather than through diffusion or ebullition [36,45,46].…”

“…Peatlands cover 3% of the world's land surface and store approximately 15-30% of the global soil carbon (C) [1][2][3][4], potentially inducing significant impacts on the local climate [5][6][7][8][9]. The Intergovernmental Panel on Climate Change (IPCC) states that intense human activities have contributed to global and regional climate change by warming and changing precipitation patterns [10][11][12][13], and that peatland C balances are significantly related to climate variation and are also exceedingly sensitive to climate change [8].…”