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生物土壤结皮(BSC)是荒漠生态系统组成和地表景观的重要特征,在荒漠系统碳的源-汇功能中发挥着重要的作用。本文以沙坡头人工植被区两种典型的BSC(苔藓结皮和藻类结皮)为研究对象,通过对土壤水分的连续测定,确定BSC光合和呼吸作用的有效湿润时间及其与土壤水分、温度和太阳辐射的关系,建立了土壤水分驱动下的固碳模型。以2012年5月19—25日为例,计算了苔藓结皮和藻类结皮在试验期间的日固碳量,并估算了两类结皮的年际固碳量。结果表明:苔藓结皮和藻类结皮由于自身水文物理性质的差别显著影响到其下层土壤水分和温度的变化;降雨是BSC固碳活性的重要来源,并且苔藓结皮更容易受到非降雨水(如雾水、凝结水等)的影响而使其固碳潜力大于藻类结皮。初步估算苔藓结皮和藻类结皮的年固碳量分别可以达到33.33g·m-2·a-1和14.01g·m-2·a-1,其中由非降雨水所引起的固碳量达到了6.58g·m-2·a-1和2.65g·m-2·a-1,分别占到了全年固碳量的19.7%和18.9%。充分肯定了BSC在荒漠人工植被区碳汇的功能。
Biological soil crusts (BSC) are important features of desert ecosystem composition and surface landscape and play an important role in the source-sink function of carbon in desert systems. In this paper, two typical BSC (moss crusts and algal crusts) in the artificial vegetation area of Shapotou were studied. Through the continuous determination of soil moisture, the effective wetting time of photosynthesis and respiration of BSC and the relationship between them and soil moisture, Temperature and solar radiation, established a soil-driven carbon sequestration model. Taking May 19-25, 2012 as an example, the daily carbon sequestration of moss crusts and algal crusts was calculated and the interannual carbon sequestration of two types of crusts was estimated. The results showed that the changes of soil moisture and temperature in lower layers of moss crusts and algal crusts significantly affected by their hydrological and physical properties. Rainfall was an important source of BSC carbon sequestration activity and moss crusts were more susceptible to non-rainfall Such as fog water, condensed water, etc.) to make it more carbon sequestration potential than algal crusts. The preliminary estimation of annual carbon sequestration in moss crusts and algal crusts could reach 33.33 g · m -2 · a -1 and 14.01 g · m -2 · a -1, respectively, of which the carbon sequestration caused by non-rainfall water Reached 6.58g · m-2 · a-1 and 2.65g · m-2 · a-1, accounting for 19.7% and 18.9% of the annual carbon sequestration respectively. Fully affirmed the function of BSC in the desert artificial vegetation area carbon sink.