草地功能群和土壤特征对小叶锦鸡儿建植密度的响应

Response of Herb Functional Group and Soil Property to Planting Density of Caragana microphylla in Vegetation-Soil System

以内蒙古中部农牧交错区和林格尔县天然草地为对照,比较相同林龄不同密度小叶锦鸡儿人工灌木草地功能群及土壤特征。结果表明,与天然草地相比,建植小叶锦鸡儿灌木林没有改变草地植被功能群均匀度和优势度指数,但功能群物种组成结构发生了改变,表现为:随着小叶锦鸡儿林分密度增加,禾本科生物量和物种丰富度显著增加,豆科生物量显著增多但物种丰富度无显著变化,菊科和杂草类植物生物量及物种丰富度均显著减少。建植小叶锦鸡儿灌木林可以提高土壤水分与养分含量,建植密度为1200棵/hm^2的小叶锦鸡儿灌木林更有助于土壤涵养水分,且其土壤碱解氮、速效磷和速效钾含量均增加,有助于改善土壤环境,利于植被生长,优化灌木利用资源。

In this study, the herb functional groups and soil characteristics of the artificial shrub grassland of Caragana microphylla with the same forest age and two different densities were compared with the natural grassland in Horinger county, which is located in the agro-pastoral ecotone of central Inner Mongolia. The results showed that (1) Compared with the natural pasture, two kinds densities (1200 plants/hm2 and 2500 plants/hm2) of planting Caragana microphylla both had no significant differences on functional group of evenness and dominance index, but planting Caragana microphylla could change the species composition of functional group. With the increasing of the Caragana microphylla plantation’s density, the biomass and species richness of gramineous plants increased significantly, the biomass of leguminous plants increased significantly, but the species richness did not change significantly. The biomass and species richness of compositae and weeds decreased significantly.(2) Compared with the natural pasture, planting Caragana microphylla shrubs could improve the content of soil water and nutrient. Planting density of 1200/hm2 Caragana microphylla shrubs was more conducive to soil water conservation, and the content of soil alkali-hydrolytic nitrogen, available phosphorus and available potassium were increased, which was conducive to improving soil environment, vegetation growth and optimizing the use of shrubs resource. Above all, 1200 plants/hm2 of Caragana microphylla was a suggested plantation density in arid grassland agro-pastoral ecotone.