Effects Of Enclosure On Soil Quality In The Subalpine Steppe

This research chose long-term fenced sample plots in Bayanbulak as the study object, and selectedthree grassland types, i.e., alpine steppe, alpine meadow steppe and alpine meadow. Statistics were carriedon to analyze the quality of soil inside and outside the fenced and its spatial-temporal variation by usingsoftware such as SPSS, GS+, Surfer and so on. Main research results are as following:Firstly, through analyzing soil physical properties inside and outside of the fence, we found that thenatural moisture of surface soil inside the fence of alpine meadow was observably higher than that outsidethe fence. There is no significant difference between natural moistures of the surface soil inside and thoseoutside the fence for alpine steppe and alpine meadow steppe. Surface soil bulk density inside the fence ofalpine meadow was observably lower than that outside the fence, the difference of surface soil bulk densityinside and outside the fence for alpine steppe, and alpine meadow steppe was not significant.Secondly, after comparing soil chemical properties inside and outside of the fence, we found thatsurface soil organic matter contents inside the fence of alpine steppe were observably higher than thoseoutside the fence. However, soil organic matter contents inside and outside the fence of alpine meadowsteppe and alpine meadow were not different significantly. The surface soil alkali hydrolyzable nitrogencontents inside the fence of three types of grassland were higher than those outside the fence and the soilalkali hydrolyzable nitrogen contents inside and outside the fence of alpine steppe, alpine meadow steppewere different significantly. The surface soil available potassium contents inside the fence of alpinemeadow steppe and alpine meadow were observably lower than those outside the fence, but the surface soilavailable potassium content inside the fence of alpine steppe was observably higher than outside the fence.Thirdly, by researching soil biological properties inside and outside of the fence, we found that thesurface soil catalase activities inside the fence of alpine steppe and alpine meadow steppe were higher thanoutside the fence. Soil catalase activities inside and outside the fence of alpine meadow steppe weresignificantly different. The surface soil urease activities inside the fence of the three types of grasslandwere significantly lower than those outside the fence. The surface soil phosphatase activity inside andoutside the fence of three types of grassland had no significant difference.Fourthly, by researching vertical variation of soil quality inside and outside of the fence, we found thatsoil organic matter, total nitrogen, total phosphorus, total potassium and phosphatase of alpine steppe weremainly concentrated in the surface soil. Soil organic matter, total nitrogen and phosphatase activity allshowed decreasing tendencies with increasing soil depth. Soil total phosphorus, total potassium, catalaseactivity decreased firstly and then increased with the increase of soil depth. Soil urease activity increasedfirstly and then decreased and rose again. The changes of subsoil total nitrogen, total phosphorus and total potassium outside the fence were higher than those inside the fence. The vertical changes of soil catalaseand urease activity were much stronger than that of phosphatase.Fifthly, by researching spatial heterogeneity of soils inside and outside of the fence, we concluded thatsoil organic carbon, alkali hydrolyzable nitrogen, available potassium, porosity and mechanicalcomposition inside and outside the fence of alpine steppe all had different degrees of spatial variability inthe vertical and horizontal directions. From the horizontal direction, the distribution of soil organic carbon,alkali hydrolyzable nitrogen, available potassium, porosity and mechanical composition inside and outsidethe fence were different for different places. From the vertical direction, the variances of upper soil organiccarbon inside and outside the fence were apparently higher than those underlying the soil. However, thevariances of upper soil alkali hydrolyzable nitrogen, and available potassium were apparently lower thanthose of underlying soil, the variance of soil porosity was not apparent.Finally, impacts of enclosed time on soil qualities of the three types of grassland were quite different.Surface soil organic matter contents of three types of grassland in2011were significantly increased thanthose in2006. However, surface soil total phosphorus contents in2011were significantly lower than thosein2006. With the increase of enclosed time, surface soil urease activity of alpine meadow in2011wasobservably higher than that in2006. Surface soil phosphatase activities of three types of grassland droppedsignificantly. The effects of enclosed time on surface soil bulk density, total nitrogen, total potassium andcatalase were indistinctive.