Research On Soil Permeability Of Different Plant Communities Types In Jinyun Mountain

Soil permeability is the important index to appraise soil source of water conserve and to reflect soil resist corrode ability,and it is important content to the study of the soil moisture.It is not only helpful to find the mechanism of surface-flowing producing and soil erosion,but also helpful to accumulate theory experience for the study of soil factor of regional soil erosion.In order to definitude soil permeability of typical plant communities of Jinyun Mountain,this paper studied the soil of different plant community by means of infiltration ring and 70 type permeameter that has certain theory and practice value to regional protection of natural forests and ecological construction of reservoir area of Three Gorges.In addition,the variation tendency of the physical and chemical properties of soil with different succession stage of plant community of Jinyun Mountain,the relation of soil permeability and community succession,the primary influence factors and grade about soil permeability have been studied.And two kinds of infiltration meathods were compared. Finally the results show that:1.From rudimentary to senior to develop with plant community,natural moisture content,field capacity,overall porosity,non-capillary,organic content showed the trend of increasing,bulk gravity were exactly opposite,then grain composition,capillary porosity,pH were not obvious in this respect.But to forest community,the sand content and＞0.25mm water-stable aggregate increased, clay content decreased.2.The undisturbed soil infiltration process of plant community in Jinyun was divided into 3 phase:the initial phase(0-5 min),the transition phase(5-30 min)and the stable phase(30-180 min); the relationship between soil infiltration rate and time can be expressed as Y=aX^-b;the initial permeability coefficient was lmperata cylindrical community＜Cinnamomun camphora community＜Pinus massoniana & Cinnamomun camphora community＜Cunninghamia Lanceolata & Cinnamomun camphora community＜Pinus massoniana community＜Machilus pingii community＜Phyllostachys pubescens community＜Neosinocalamus affinis community＜Gordonia acuminate community＜Gordonia acuminate community;the stable permeability coefficient was Gordonia acuminate community＞Neosinocalamus affinis community＞Gordonia acuminate community＞Phyllostachys pubescens community＞Machilus pingii community＞Pinus massoniana & Cinnamomun camphora community＞Pinus massoniana community＞Cunninghamia Lanceolata & Cinnamomun camphora community＞Cinnamomun camphora community＞Imperata cylindrical community;the amounts of 30min cumulated infiltration was Gordonia acuminate community＞Neosinocalamus affinis community＞Gordonia acuminate community＞PHyllostachys pubescens community＞Machilus pingii community＞Pinus massoniana & Cinnamomun camphora community＞Pinus massoniana community＞Cinnamomun camphora community＞Cunninghamia Lanceolata & Cinnamomun camphora community＞Imperata cylindrical community;As the time to attain the stable permeability,Gordonia acuminate community was the longest,Imperata cylindrical community was the shortest,and the former was as more 3 times as the latter,Machilus pingii community was 136～171min and Gordonia acuminate community was 136～156min.As a whole,the undisturbed soil permeability capability of plant community in Jinyun Mountain increased with the advancement of community succession.3.The stable permeability coefficient of disturbed soil was Gordonia acuminate community＞Neosinocalamus affinis community＞Pinus massoniana & Cinnamomun camphora community＞Machilus pingii community＞Pinus massoniana community＞Gordonia acuminate community＞Cunninghamia Lanceolata & Cinnamomun camphora community＞PHyllostachys pubescens community＞Cinnamomun camphora community＞Imperata cylindrical community;when bulk gravity was 1.20 g/cm³,the stable permeability coefficient islmperata cylindrical community＜Phyllostachys pubescens community＜Gordonia acuminate community＜Cinnamomun camphora community＜Neosinocalamus affinis community＜Cunninghamia Lanceolata & Cinnamomun camphora community＜Gordonia acuminate community＜Machilus pingii community＜Pinus massoniana & Cinnamomun camphora community＜Pinus massoniana community,and it assumed the positive correlativity with sand content;the stable permeability coefficient have significantly linear inverse correlation with bulk gravity,expressed by y=ax+b.4.The primary influence factors to natural state soil infiltration were bulk gravity,overall porosity,non-capillary,organic content by PCA.the related degree to the stable permeability coefficient and vegetation characteristic parameter could also be obtained by gray related degrees of law:build thing degree(0.7623)＞lay wood last degree(0.6152)＞junk of thicknesseses withered(0.5664)＞of canopy densities(0.4717).5.The stable permeability coefficient of undisturbed soil assumes the remarkable line inverse correlation relations with the bulk gravity,assumes the extremely remarkable power correlation with the overall porosity and non-capillary,assumes the remarkable line correlation with organic matter, without remarkable correlation with natural moisture content,grain composition,＞0.25mm water-stable aggregate,pH.6.The soil permeability of plant community can be divided into five grades by ring method:the 5th grade was sichuan which permeability was the strongest;the 4th grade was Neosinocalamus affinis community and Gordonia acuminate community;the third grade was Phyllostachys pubescens community,Machilus pingii community,Pinus massoniana & Cinnamomun camphora community.;the second grade was Pinus massoniana community,Cunninghamia Lanceolata & Cinnamomun camphora community,Cinnamomun camphora community;the permeability of Imperata cylindrical community was the worst,which lied in the first grade.The soil permeability of plant community can be divided into four grades by 70 type permeameter method:the 4th grade was Gordonia acuminate communitywhich permeability was also the strongest;the third grade was Neosinocalamus affinis community and Pinus massoniana & Cinnamomun camphora community, Machilus pingii community;the second grade was Pinus massoniana community,Gordonia acuminate community,Cunninghamia Lanceolata & Cinnamomun camphora community, Phyllostachys pubescens community,the permeability ofCinnamomun camphora community Imperata cylindrical community was the worst,which lied in the first grade.It had higher relevance with two kinds of methods that examine the grading to the soil permeability of plant community,so thant it showed the undisturbed soil permeability of typical plant community in Jinyun Mountain mainly could be divided into five grades.7.The stable permeability coefficient obtained by ring method and by 70 type permeameter method differed greatly,disobeyed normal distribution,presented the greatly strengthened variability.The C_v of the laster(1.11)was bigger than the former(0.99).This related to soil kind, instrument of method principle,etc.have difference with two methods;the stable permeability coefficient examed by two methods assumed the extremely remarkable correlation,expressed by y=0.179x+0.7689.