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利用乙炔还原法,测定腾格里沙漠东南缘沙坡头地区不同年代建植的人工植被固沙区和相邻自然植被区藻结皮的固氮活性及其对水分和温度的响应特征。结果表明,不同植被区藻结皮的固氮活性在4.31～16.6mmol.m-2.h-1;人工植被区藻结皮的固氮活性与植被恢复时间呈显著的正相关关系,自然植被区藻结皮的固氮活性显著小于52龄人工植被区,但显著高于16龄人工植被区;藻结皮的固氮活性与叶绿素a含量和盖度呈显著正相关关系;模拟降雨量<1.1～1.5mm,不同人工植被区和自然植被区藻结皮的固氮活性随着模拟降雨量的增加而急剧增加,但当1.1～1.5mm<模拟降雨量<5mm时,藻结皮的固氮活性随模拟降雨量的增加无显著增加;不同植被区藻结皮的固氮活性与温度的关系表现出一致的变化趋势,当温度为13℃时,藻结皮的固氮活性显著低于最热月的均温(24℃)。
The acetylene reduction method was used to determine the nitrogen fixation activity and its response to water and temperature of algal crusts of artificial vegetation cover and adjacent natural vegetation areas built in different years in Shapotou area, southeast margin of Tengger Desert. The results showed that the nitrogen fixation activity of algal crusts in different vegetation areas was 4.31 ~ 16.6mmol.m-2.h-1. The nitrogen fixation activity of algal crusts in artificial vegetation areas had a significant positive correlation with vegetation recovery time. The nitrogen fixation activity of crust was significantly less than that of 52-year-old artificial vegetation area, but significantly higher than that of 16-year artificial vegetation area. The nitrogen fixation activity of algal crust was positively correlated with chlorophyll-a content and coverage, and simulated rainfall <1.1-1.5mm , The nitrogen fixation activities of algal crusts in different artificial vegetation areas and natural vegetation areas increased sharply with the increase of simulated rainfall. However, the nitrogen fixation activity of algal crusts with the simulated rainfall of 1.1 ~ 1.5mm simulated rainfall The nitrogen fixation activity of algal crusts in different vegetation areas showed a consistent trend with temperature. When the temperature was 13 ℃, the nitrogen fixation activity of algal crusts was significantly lower than that of the hottest months (24 ℃).