盐生荒漠土壤CO_2通量及其环境影响因素

Soil CO_2 flux and its environmental affecting factors in a saline desert

以古尔班通古特沙漠南缘原始盐生荒漠为对象,利用LI-8150多通道土壤CO_2通量系统对原始盐生荒漠多枝柽柳群落地表CO_2通量进行连续观测,探讨土壤CO_2通量的日、季变化及其环境影响因素。结果表明:1)在整个生长季内,盐生荒漠土壤CO_2通量呈现2种不同的日变化过程,一种为单峰型,另一种为双峰型,推断引起土壤CO_2通量日过程差异的主要原因是高温抑制了微生物的活性;2)土壤CO_2通量的季节变化不明显,尤其是当日过程为双峰型时,土壤CO_2通量基本在一个较稳定的区间(0.13~0.3 g C·m^(-2)·d^(-1))波动,伴随降雨事件的发生,土壤CO_2通量呈"脉冲式"增加;3)在整个降雨周期,土壤呼吸的日过程也呈现出双峰-单峰-双峰的变化过程。本研究表明,水分是盐生荒漠土壤CO_2通量的主要限制因子。

Taking the southern Gurbantunggut Desert in Xinjiang as the object, and by using LI-8150 multichannel soil CO2 flux system, a continuous measurement of surface soil CO2 flux under Tamarix ramosissima population in an original saline desert was conducted during growth season, with the diurnal and seasonal variations of the CO2 flux and related environmental affecting factors analyzed. During the whole growth season of the population, the diurnal variation of the CO2 flux presented two distinct patterns, one was single-peaked, and the other was bimodal. The difference in the diurnal variation of the CO2 flux could be mainly caused by the inhibition of soil microbial activity by high temperature. The seasonal variation of the CO2 flux was not apparent, being fluctuated within a stable range （0.13-0.3 g C·m-2·d-1） especially when the diurnal variation was bimodal. When rainfall events happened, the CO2 flux increased in impulse type. During the rainfall cycle, the diurnal CO2 flux varied in bimodal-singlepeaked-bimodal type. Soil moisture content was the main factor limiting the soil CO2 flux in the saline desert.