Open AccessGrowing season net ecosystem CO 2 exchange of two desert ecosystems with alkaline soils in Kazakhstan
Author(s) -
Li Longhui,
Chen Xi,
Tol Christiaan,
Luo Geping,
Su Zhongbo
Publication year - 2014
Publication title -
ecology and evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.17
H-Index - 63
ISSN - 2045-7758
DOI - 10.1002/ece3.910
Subject(s) - ecosystem , environmental science , abiotic component , soil water , eddy covariance , primary production , photosynthetically active radiation , alkali soil , terrestrial ecosystem , carbon cycle , precipitation , growing season , ecology , environmental chemistry , atmospheric sciences , chemistry , geography , photosynthesis , botany , soil science , biology , geology , meteorology
Abstract Central Asia is covered by vast desert ecosystems, and the majority of these ecosystems have alkaline soils. Their contribution to global net ecosystem CO 2 exchange ( NEE ) is of significance simply because of their immense spatial extent. Some of the latest research reported considerable abiotic CO 2 absorption by alkaline soil, but the rate of CO 2 absorption has been questioned by peer communities. To investigate the issue of carbon cycle in Central Asian desert ecosystems with alkaline soils, we have measured the NEE using eddy covariance ( EC ) method at two alkaline sites during growing season in Kazakhstan. The diurnal course of mean monthly NEE followed a clear sinusoidal pattern during growing season at both sites. Both sites showed significant net carbon uptake during daytime on sunny days with high photosynthetically active radiation ( PAR ) but net carbon loss at nighttime and on cloudy and rainy days. NEE has strong dependency on PAR and the response of NEE to precipitation resulted in an initial and significant carbon release to the atmosphere, similar to other ecosystems. These findings indicate that biotic processes dominated the carbon processes, and the contribution of abiotic carbon process to net ecosystem CO 2 exchange may be trivial in alkaline soil desert ecosystems over Central Asia.