科尔沁沙地持续放牧和不同强度放牧后封育草场中生物结皮生物量和土壤因子的变化

Impact of Overgrazing and Enclosing on Biomass and Soil Factors of the Microbiotic Soil Crusts in Horqin Sandy Land

通过对科尔沁沙地放牧后封育样地和放牧样地生物结皮生物量的研究,探讨了不同样地生物结皮生物量的变化规律及其与环境因子的相互关系。结果表明,封育样地藓类和藻类植物的生物量显著高于放牧样地;在封育样地内,轻度、中度放牧封育区显著高于重度放牧封育区(P<0.05)。封育样地生物结皮的土壤微生物量碳、氮含量高于放牧样地,并且各样区藓结皮土壤微生物量碳、氮含量显著高于藻结皮(P<0.05)。在封育样地内表现为轻度、中度放牧封育区土壤微生物量碳、氮含量较高,重度放牧封育区含量较低,体现出不同强度放牧封育停牧后对土壤微生物量碳、氮影响的滞后效应。藻类植物的生物量与结皮厚度、有机质含量和粉黏粒呈极显著正相关(P<0.01),与细沙呈显著正相关(P<0.05),与粗沙呈极显著负相关(P<0.01)。藓类植物的生物量与结皮厚度、有机质含量、粉黏粒呈显著正相关(P<0.05),与粗沙呈负相关,但不显著。藻类植物的生物量与土壤因子之间的相关性更为密切。

The biomass of microbiotic soil crusts in grasslands under different grazing intensity in Horqin Sandy Land was measured, and then the variation of biomass of microbiotic soil crusts and its correlation with soil factors were analyzed in the paper. The results show that the biomass of moss crusts and alga crusts in the sampling plots of the enclosed grassland is significantly higher than that of the unclosed grassland. For the sampling plots of the enclosed grassland, and the biomass of moss crusts and alga crusts in the lightly grazing grassland and moderately grazing grassland is significantly higher than that of the severely grazing grassland（P〈0. 05）. The content of carbon and nitrogen in microbiotic soil crusts in the sampling plots of the enclosed grassland is significantly higher than that of the unclosed grassland, and for the sampling plots of the enclosed grassland, the contents of carbon and nitrogen in microbiotic soil crusts in the lightly grazing grassland and moderately grazing grassland is significantly higher than that of severely grazing grassland. The contents of carbon and nitrogen in moss crusts is significantly higher than that of the alga crusts in all sampling plots（P〈0.05）. The biomass of alga crusts is positively correlated with crusts thickness, content of organic component, silty clay （P〈0.01） and fine sand （P〈0.05）, while it is negatively correlated with coarse sand （P〈0. 01）. The biomass of moss crusts is positively correlated with crusts thickness, content of organic component and silty clay （P〈0.05）, while it is negatively correlated with coarse sand, but the correlation isn＇ t significant. The correlation of the biomass of alga crusts with soil factors is more significant than that of moss crusts with soil factors.