东祁连山不同退化草地植物群落特征与土壤养分特性

为探究东祁连山不同退化草地植物群落特征、土壤养分特性及其相关性,以轻度退化草地、中度退化草地和重度退化草地为研究对象,采用野外调查、室内测定和数据统计分析相结合的方法,分析了不同退化草地植被特征、土壤养分特性及其之间的相关性。结果表明:(1)从轻度退化草地-重度退化草地,植物群落特征(地上生物量、高度、密度、频度和总盖度)整体呈现降低趋势,且差异显著(P<0.05),中度退化草地Margalef指数、Shannon指数和Evenness指数最高,Dominance指数最低;(2)研究区植物共有19科38属41种,生态适应性较强的植物主要集中在豆科、禾本科、菊科和蔷薇科,不同退化草地植被型分别为矮生嵩草(K.humilis)+赖草(Leymus secalinus)、矮生嵩草+高山唐松草(Thalictrum alpinum)、矮生嵩草+赖草,其中矮生嵩草是各退化草地的优势种,不同退化草地的功能群以杂类草占优势,其次是禾草类,毒草类所占的比例最少;(3)随草地退化程度加重,土壤速效氮、有效磷、有机碳和含水量呈降低的趋势,而pH整体呈现升高的趋势;(4)不同退化草地土壤因子对植被生长贡献率最高分别为速效氮、有效磷和含水量。综上,随着草地退化程度加重,植物群落结构向单一趋势过渡,土壤养分含量减少,且土壤因子对植物贡献率也相应发生变化。

Characteristics of Plant Community and Soil Nutrient of Different Degraded Grasslands in East Qilian Mountains

In order to study the community features, soil nutrient characteristics and their correlations in different degraded grasslands of East Qilian Mountains, the lightly degraded grassland (LDG), moderately degraded grassland (MDG) and heavily degraded grassland (SDG) were taken as the research objects, and the combination of field investigation, laboratory measurement and data statistical analysis was adopted. The results showed that:(1) The characteristics of plant communities, including aboveground biomass, height, density, frequency and vegetation coverage, showed a decreasing trend from LDG to SDG, and the difference was significant (P < 0.05). And the species Margalef index, Shannon index and Evenness index of the MDG were the maximum, however, the Dominance index was the minimum. (2) There were 19 families, 38 genera and 41 species in the study area, and the plants with strong ecological adaptability mainly concentrated in Legumes, Gramineae, Compositae and Rosaceae. The vegetation types of different degraded grasslands included K. humilis with Leymus secalinus, K. humilis with Thalictrum alpinum, K. humilis with L. secalinus, among which K. humilis was the dominant species in different degraded grasslands. In different degraded grasslands, the functional groups were dominated by forbs, followed by Gramineae grasses and poison grasses. (3) With the aggravation of grassland degradation, soil available nitrogen, available phosphorus, organic carbon and water content all decreased, while pH increased. (4) The highest contribution rate of soil factors to vegetation growth in different degraded grasslands was the available nitrogen, available phosphorus and water content, respectively. In summary, with the aggravation of grassland degradation, the community structure of plants was changing to a single trend, soil nutrient content was reduced and the contribution rate of soil factors to plants was also changed accordingly.