不同降雨量年份鄂尔多斯高原油蒿灌丛生态系统碳交换特征

Ecosystem carbon exchange in Artemisia ordosica shrubland of Ordos Plateau in two different precipitation years

采用涡度相关技术对欠雨年(2011年)和丰雨年(2012年)鄂尔多斯高原油蒿灌丛生态系统CO2交换量特征及其影响因子进行研究.结果表明:在两个不同降雨量年份,油蒿灌丛生态系统CO2交换量日动态根据CO2吸收峰值的出现分为两种模式,即单峰型和双峰型;2011年生长季内CO2通量共出现3个明显的吸收峰值和3个释放峰值,2012年生长季内CO2交换量出现4个吸收峰值和1个释放峰值;2011年6—9月,油蒿灌丛生态系统表现为弱的碳汇,10月转变为碳源;2012年整个生长季,油蒿灌丛生态系统均呈现为碳汇.丰雨年比欠雨年生长季的油蒿灌丛生态系统固碳量增加了268.90 mg CO2·m-2·s-1;在日尺度上,生态系统CO2交换量受光合有效辐射的控制,在生长季尺度上,非生物因素(降雨量、土壤含水量)和生物因素(生态系统净初级生产力)共同制约油蒿灌丛生态系统CO2交换量的变化.

Characteristics of ecosystem carbon exchange and its impact factors in Artemisia ordosica shrubland in 2011 （low precipitation） and 2012（ high precipitation）, Ordos Plateau, were studied using eddy covariance methods. The results showed that the diurnal dynamics of ecosystem carbon ex- change could be expressed as single-peak and double-peak curves in the two different precipitation years. In 2011, three carbon absorption peaks and three carbon release peaks of ecosystem carbon exchange presented in the growing season. In 2012, four carbon absorption peaks and one carbon release peak appeared in the growing season. The A. ordosica shrubland was a net carbon sink from June to September and a carbon source in October in 2011. In 2012, A. ordosica shrubland was a net carbon sink in the whole growing season. The amount of carbon fixed by A. ordosica shrubland in the growing season in 2012 was 268.90 mg CO2·m-2·s-1 higher than that in 2011. The eco- system carbon exchange of A. ordosica shrubland was controlled by PAR （photosynthetically active radiation） on the day scale, and affected by both abiotic （precipitation and soil water content） and biotic （aboveground net primary productivity） factors on the growing season scale.