围封对天山北坡中段温性草原植被特征和土壤理化性质的影响

Effects of Enclosure on Vegetation Characteristics and Soil Physical and Chemical Properties of Temperate Grassland

以新疆天山北坡中段的温性草原为研究区域,分析不同围封年限(2年、10年和11年)对植被特征(植物群落组成、丰富度和生物量)及土壤理化性质(土壤pH、容重、电导率、碳氮含量)的影响。结果表明:与未围封草地相比,围封2年后豆科植物所占总地上生物量的比例增加了11.81%,5~10cm和10~20cm土壤全氮含量及密度显著降低。围封10年后禾本科植物的比例降低了30.08%,10~20cm土壤容重、全氮含量及密度和有机碳密度均显著降低。围封11年后禾本科植物的比例降低了48.46%,杂类草比例增加了219.40%;植物物种丰富度和地上活体及凋落物生物量显著增加;土壤表层容重和pH值显著降低;10~20cm土壤有机碳含量显著增加。随着围封年限的增加,地上生物量显著增加,土壤pH值显著降低。因此,围封年限越长对植被特征和土壤理化性质的影响范围越广、程度越深。

The effects of different enclosure years(2 years,10 years and 11 years)on vegetation characteristics(plant community composition,richness and biomass)and soil physical and chemical properties(soil pH,bulk density,electrical conductivity,carbon and nitrogen content)in temperate grassland were analyzed in the middle section of the northern slope of Tianshan Mountain,Xinjiang.The results showed that compared with unenclosed grassland,the proportion of legumes in total aboveground biomass in creased by 11.81%after 2 years of enclosure,and the total nitrogen content and density of 5~10cm and 10~20cm soil were significantly reduced.After 10 years of enclosure,the proportion of gramineous plants decreased by 30.08%,and the soil bulk density,content and density of total nitrogen,and organic carbon density of 10~20cm soil were significantly reduced.After 11 years of enclosure,the proportion of gramineous plants decreased by 48.46%,and the proportion of weeds increased by 219.40%.Plant species richness,above-ground and litter biomass combined with the organic carbon content of 10~20cm soil increased significantly,while soil surface bulk density and pH value decreased significantly.It can be concluded that with the increase of enclosure duration,aboveground biomass increased significantly,and soil pH decreased significantly.Therefore,the longer the enclosure,the wider and deeper the impact on vegetation characteristics and soil physical and chemical properties.