Abstract. The unique climate of the alpine wetland meadow is characterized by long cold winters and short cool summers with relatively high precipitation. These factors shorten the growing season for vegetation to approximately 150 to 165 days and prolong the dormant period to almost 7 months. Understanding how environmental variables affect the processes that regulate carbon flux in alpine wetland meadow on the Qinghai-Tibetan plateau is critical important because alpine wetland meadow plays a key role in the carbon cycle of the entire plateau. To address this issue, Gross Primary Production (GPP), Ecosystem Respiration (Reco), and Net Ecosystem CO2 Exchange (NEE) were examined for an alpine wetland meadow at the Haibei Research Station of the Chinese Academy of Sciences. The measurements covered three years and were made using the eddy covariance method. Seasonal trends of both GPP and Reco, followed closely changes in Leaf Area Index (LAI). Reco, exhibited the same exponential variation as soil temperature with seasonally-dependent R10 (the ecosystem respiration rate (μmol CO2 m−2 s−1) at the soil temperature reach 283.16 K (10°C)). Yearly average GPP, Reco, and NEE (which were 575.7, 676.8 and 101.1 gCm−2, respectively, for 2004 year, and 682.9, 726.4 and 44.0 gCm−2 for 2005 year, and 630.97, 808.2 and 173.2 gCm−2 for 2006 year) values indicated that the alpine wetland meadow was a moderately important source of CO2. The observed carbon dioxide fluxes in this alpine wetland meadow plateau are high in comparison with other alpine meadow environments such as Kobresia humilis meadow and shrubland meadow located in similar areas. And the cumulative NEE data indicated that the alpine wetland meadow is a source of atmospheric CO2 during the study years. CO2 emissions are large on elevated microclimatology areas on the meadow floor regardless of temperature. Furthermore, relatively low Reco, levels occurred during the non-growing season after a late rain event. This result is contradicted observations in alpine shrubland meadow. The timing of rain events had more impact on ecosystem GPP and NEE.
Response of carbon dioxide emissions to sheep grazing and N application in an alpine grassland – Part 1: Effect of sheep grazing
