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氮素限制在陆地生态系统中普遍存在,在干旱受损生态系统中表现得尤为明显.生物土壤结皮是干旱、半干旱区受损生态系统植被恢复过程中的重要组成部分和氮源贡献者.以黑岱沟露天煤矿植被恢复区广泛分布的两类典型生物土壤结皮(藻类结皮和藓类结皮)为研究对象,通过野外调查采集样品,在实验室条件下测定了两类结皮的固氮活性,分析了其固氮活性对水热因子的响应特征及其与草本、结皮盖度的关系.结果表明:不同演替阶段人工植被及相邻撂荒地和天然植被下生物土壤结皮的固氮活性在9~150μmol C2H4·m-2·h~(-1),藻类结皮(平均为77μmol C2H4·m-2·h~(-1))显著高于藓类结皮(17μmol C2H4·m-2·h~(-1)).人工植被区3种常见植被类型下藻类和藓类结皮固氮活性均表现为“灌-草型”显著高于“乔-灌型”和“乔-灌-草型”.藻类和藓类结皮的固氮活性与样品相对含水量(10%~100%)和培养温度(5~45℃)均呈显著的二次函数关系,其固氮活性随水分、温度升高均呈先上升后下降的趋势,分别在60%和80%相对含水量时达到最大固氮速率,其最适固氮温度均为25℃.藻类结皮固氮活性与草本盖度呈显著的二次函数关系,草本盖度超过20%时固氮活性开始降低,藓类结皮固氮活性与草本植物盖度呈显著负相关.两类结皮固氮活性与其盖度均呈显著的正相关关系,随结皮盖度增加其固氮活性显著升高.露天煤矿植被恢复区两类生物土壤结皮固氮活性差异主要由结皮组成生物体即隐花植物的差异所致,不同植被类型下的水热差异及不同植被演替阶段草本、结皮盖度的差异是影响生物土壤结皮氮固定的关键因子,生物土壤结皮在人工植被区的拓殖发育及其氮输入是系统健康发展的重要标志.
Nitrogen limitation is ubiquitous in terrestrial ecosystems and is particularly evident in drought-damaged ecosystems. Biological soil crusts are an important component of vegetation restoration in damaged ecosystems in arid and semi-arid regions and nitrogen contributors Taking two types of typical biological soil crusts (algal crusts and moss crusts) widely distributed in the vegetation recovery area of Heidaigou open - pit coal mine as the research object, samples were collected through field investigation and two types of knots were measured under laboratory conditions And the relationship between nitrogen fixation activity and hydrothermal factor and its relationship with herb and crustal cover were analyzed.The results showed that there were significant differences between the artificial vegetation and biological soils in the adjacent abandoned land and natural vegetation in different successional stages The nitrogen fixation activity of the skin was significantly higher than that of the moss crust (17 μmol, C2H4 · m-2 · h-1) and the algal crust C2H4 · m-2 · h ~ (-1)). The activities of nitrogen fixation of algae and moss under the three common vegetation types in artificial vegetation area were all significantly higher than that in “irrigation-grass type” Nitrogen-fixing activity of algae and moss crusts correlates with relative water content (10% -100%) and The incubation temperature (5 ~ 45 ℃) showed a significant quadratic function, and the nitrogen fixation activity increased at first and then decreased with the increase of water and temperature, reaching the maximum nitrogen fixation rate at 60% and 80% relative water content respectively , And the optimal nitrogen fixation temperature was 25 ° C. The nitrogen fixation activity of algal crusts showed a significant quadratic function relationship with herb coverage. When the herb coverage exceeded 20%, the nitrogen fixation activity began to decrease. The nitrogen fixation activity of moss crusts was significantly lower than that of herbaceous plants There was a significant negative correlation between the nitrogen fixation activity and the coverage of the two types of crusts.The nitrogen fixation activity of the two types of biological soils in the vegetation restoration area of opencast coal mine was significantly increased Mainly caused by the differences of the crustaceous cryptophytes, the hydrothermal difference under different vegetation types and the difference of the cover of herb and crust at the succession stages of vegetation are the key factors affecting the nitrogen fixation of biological soil crusts, The development of biological soil crust in the artificial vegetation area and its nitrogen input is an important symbol of the healthy development of the system.