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利用乙炔还原法对腾格里沙漠东南缘沙坡头地区3种生物土壤结皮(藻结皮、地衣结皮和苔藓结皮)的固氮活性及生物结皮固氮活性对模拟不同降雨量(1、3和5 mm)、温度(13、24和28℃)和光强(0、400和1 000μmol/(m2.s))的响应进行研究。结果表明:不同类型生物结皮的固氮活性差异显著,依次为:藻结皮(16.6 mmol/(m2.h))>地衣结皮(6.9 mmol/(m2.h))>苔藓结皮(2.6 mmol/(m2.h));水分和温度对生物结皮的固氮活性具有显著影响,光强无显著影响。生物结皮的固氮活性在3和5 mm降雨显著高于1 mm降雨;在24℃下显著高于13℃;并且,3种生物结皮的固氮活性对环境因子变化的敏感性不同。生物结皮具有固氮能力,特别是结皮演替早期的藻结皮,它们对荒漠生态系统土壤氮素输入具有重要贡献,而降雨量和温度是控制生物结皮固氮活性的2个关键因素。
The nitrogen fixation activity and biological activity of nitrogen fixation of three kinds of biological soil crusts (algal crusts, lichen crusts and moss crusts) in Shapotou area, southeast of Tengger Desert, , 3 and 5 mm), temperature (13, 24 and 28 ° C) and light intensity (0,400 and 1 000 μmol / (m2.s)). The results showed that the nitrogen fixation activities of different types of biological crusts were significantly different, followed by: algal crusts (16.6 mmol / (m2.h))> lichen crusts (6.9 mmol / (m2.h))> moss crusts mmol / (m2.h)). Moisture and temperature had a significant effect on the nitrogen fixation activity of the biological crusts, with no significant effect on the light intensity. The nitrogen fixation activity of the biological crust was significantly higher than that of the rainfall of 1 mm at 3 and 5 mm rainfall, significantly higher than 13 ° C at 24 ° C, and the nitrogen fixation activity of the three kinds of biological crusts had different sensitivity to environmental factor changes. Biological crusts have nitrogen fixation ability, especially in the early succession of crustal algal crusts, which contribute to soil nitrogen input to desert ecosystem. Rainfall and temperature are the two key factors to control nitrogen fixation of biological crusts.