内蒙古锡林河流域羊草草原生态系统碳素循环研究

STUDY ON THE CARBON CYCLE OF LEYMUS CHINENSIS STEPPE IN THE XILIN RIVER BASIN 

采用野外调查和模型预测方法相结合，对内蒙古锡林河流域一个永久试验样地内的羊草（Ｌｅｙｍｕｓｃｈｉｎｅｎｓｉｓ（Ｔｒｉｎ．）Ｔｚｖｅｌ．）草原群落的碳素贮量、主要流量和周转速度等进行了初步估计，研究了长期过度放牧对整个流域羊草草原土壤有机碳贮量的影响。结果表明：１）羊草群落净初级生产固碳量的多年实测平均值为（２３１．２５±７４．４１）ｇＣ·ｍ－２·ａ－１，向土壤中的碳素输入量为２２０．７５ｇＣ·ｍ－２·ａ－１，土壤呼吸量的模型预测值为（１８１．０３±４６．３２）ｇＣ·ｍ－２·ａ－１；２）该群落碳素输入略大于输出，其理论积累率为１９．８８ｇＣ·ｍ－２·ａ－１，实测积累率为３９．７２ｇＣ·ｍ－２·ａ－１；３）近４０年来，过度放牧致使锡林河流域羊草草原表层（０～２０ｃｍ）土壤的有机碳贮量下降了约１２．４％。

Based on the past researches, an initial study on the carbon cycle of Leymus chinensis (Trin.) Tzvel. steppe in the Xilin river basin of Neimenggu (Inner Mongolia) was conducted by combining field surveys and the CENTURY model simulation. The major results were summarized as follows: 1) Observed annual amount of carbon fixation via primary production for a L. chinensis community on a fenced site in the basin averaged (231.25±74.41) gC·m -2 ·a -1 , average annual carbon input into soil was about 220.75 gC·m -2 ·a -1 , while carbon output from the community via soil respiration was estimated to be (181.03±46.32) gC·m -2 ·a -1 by CENTURY model simulation; 2) The community had a simulated net carbon gain of about 19.88 gC·m -2 ·a -1 and an observed carbon gain of 39.72 gC·m -2 ·a -1 ; 3) About 12.4% of carbon originally stored in soil had been lost due to over grazing over the recent 40 year period in Leymus chinensis steppe in the Xilin river basin.