Study On Impact Of Mowing And Grazing On Vegetation And Soil Of Typical Steppe In Xilingol,Inner Mongolia

By route and located monitoring survey on Xinlingol typical steppe in mowing and grazing, studieson species composition and community structure, soil characteristics of vegetation succession of typicalsteppe were conducted, and analysis of variation law was done on vegetation and soil change insuccession of typical steppe. The main results are as follows:(1) According to functional group composition and aboveground biomass,19Leymus chinensiscommunities and Stipa spp. communities in mowing and grazing in different section in typical steppezone were divided into4successional stages, non-degraded, light, moderate and severe degradation ofby cluster analysis. Moderate degraded communities were further divided into four types, includingcommunities which annual and biennial plants accounting for a large proportion, communities whichArtemisia frigida occupied an important position, communities which Cleistogenes quarrosa was thedominant species and communities which forbs were dominant species. Severely degraded communitiesincluded two types: communities which Artemisia frigida and Potentilla acaulis were dominantspecies, community which annual and biennial plants were dominant species. Grassland ecosystemdegraded with the decreasing of forage feeding level in mowing and grazing in typical steppe. Speciesbiodiversity index including Shannon-weaver index (H) were the highest in moderate degraded statecommunities, and the lowest in non-degraded communities, respectively1.99and1.38. Soil organicmatter was the highest in non-degraded and light degraded grassland and the lowest in the severedegraded grassland, respectively47.08g/kg,45.35g/kg and21.46g/kg.(2)Different community had different succession trends in mowing. The community of Leymuschinensis as a single dominant species was relatively stable community relying on self-regulation ofvegetative propagation, which mowing utilization had not significant impact on it. The community StipaKrylovii+Leymus chinensis+Artemisia frigida showed recovery succession in short term. Stipakrylovii replaced Leymus chinensis and became the most dominant species. The community Leymuschinensis+Cleistogenes quarrosa+Agropyron michnoi showed degraded succession. Leymus chinensislost the dominant position and Artemisia frigida and biennial plant Artemisia scoparia increased. Thecommunity structure was unstable.(3)Leymus chinensis mono-dominant community showed no association with VR value1.03. Inmowing the community remained stable state and species was dispersed independent relationship. Thecommunities in succession state showed a negative association, respectively VR value0.91,0.77and0.91. And communities were in relatively unstable state. The same species pairs showed differentassociation properties and association degree.(4) The niche breadth of species showed difference in different succession state communities. Thesame species pair showed different niche overlaps in different community. Community niche overlapwas higher in succession state than stable Leymus chinensis community.(5)Soil organic matter and nutrition were highest in none degraded Leymus chinensis grassland, and lowest in degraded grassland. The N/P ration of main species and community in grazing communityis significantly lower than mowing community, and the contents of N, P in grazing community weresignificantly higher than mowing community. Leymus chinensis had a stable N/P ratio in differentsuccession state under mowing and grazing. The N/P ratio of Cleistogenes quarrosa and Artemisiafrigid were low and changed between9.91-11.69、11.35-15.83.