| The soil fertility is macroscopic reflection of soil chemical,physical and biological characters.In fact, they truly represented the soil quality and have a direct bearing on plant growth is soil fertility.The Phyllostachys Pubescens as a economical plant that covers the biggest area and the most widely distributed in China, plays an important role in ecological construction and economical development.But because of the human and natural cause,the ecosystems of Phyllostachys Pubescens have not yet reached ideal situation in product and productive,especially the degradation of soil fertility have bad effect in Phyllostachys Pubescens growth. In the study of soil fertility quality, research on the soil fertility quality of Phyllostachys Pubescens infrequent.Therefore,have comprehensive study of soil fertility quality of Phyllostachys Pubescens is very important to provide theoretic basis and methods in development of the Phyllostachys Pubescens and promote ecological service function.Taking the soil in the core area of moso forest in Shunan Bamboo-sea,Yibin, Sichuan, as study project, using methods of kilometer grid distribution points and topographic map in 1:10000,samples in equidistance and regularly.21 indexes including the bulk density, organic matter,acid phosphatase were selected as the evaluation indexes.Use principal component analysis builded the evaluation index system of soil fertility quality.Analyzed the soil fertility quality with statistics and geostatistics.Drawed the spatial distribution map of evaluation indexes of soil fertility quality with krigiging interpolation method.Drawed spatial distribution map in whole area.Analyzed the matching suitation of the Phyllostachys Pubescens growth and distribution of soil fertility quality level.Analyzed the ecological stoichiometry of element including c,n,p.Provided some forest management measures and countermeasures.The results were showed as the followings:(1) The principal component analysis showed, the cumulative variance contribution of first six principal component is 81.986% and 81.429%.The evaluation Indexes that including organic matter,rapidly available potassium(RAK), available phosphorus,soil bulk density,maximum water-holding capacity,minimum water-holding capacity, total porosity, acid phosphatase are most important to the soil fertility quality.They are key factor that influence soil fertility quality, can be as evaluation index system in research area.(2)Through statistical analysis,the content of organic matter reduce with soil layer increasing; content of rapidly available potassium(RAK) in 20-40cm soil layer is slightly more than0-20cm soil layer,and unstablely.The average value of available phosphorus not more than 2.3mg/kg in 0-20cm and 20-40cm soil layer, available phosphorus is insufficient in whole area,needs a large number of supplement; content of bulk density is increase by soil layer increasing;content of total porosity is 59.30% å’Œ 57.13% in 0-20cm and 20-40cmsoil layer,soil water permeab ility is good,it is help for the plant grow,the Permeability of soil slightly reduce with soil layer increasing,content ofmaximum water-holding capacity is 66.89% and 60.1% in 0-20cm and 20-40cm soil layer,content of minimum water-holding capacity is 66.89% and 60.1% in 0-20cm and 20-40cm soil layer;content of acid phosphatase is 0.17mg*g-1*h-1 indifferent soil layer,soil enzyme activity is stablely.(3) The normal distribution test showed,each index have normal distribution.The Skew test of evaluation indexes have positive and negative;acid phosphatase in 20-40cm soil layer is not meet the request of the geostatistics,Pw of other indexes are greater than 0.05,in line with the normal distribution.(4)Semivariance and spatial auto-correlation analysis showed that theory of semi-variance function models of same index in different soil layer is consistent. Available potassium(RAK) use index model fitting is best;bulk density, minimum water-holding capacity,organic matter,available phosphorus use Gaussian model fitting is best;maximum water-holding capacity use spherical model in 0-20cm soil layer,use Gaussian model in 20-40cm soil layer,total porosity use Gaussian model in 0-20cm soil layer,use index model in 20-40cm soil layer,acid phosphatase use Gaussian model in 0-20cm soil layer; bulk density and organic matter are fitting better,random variabilityof maximum water-holding capacity and minimum water-holding capacity are large changes;organic matter,available potassium (RAK),total porosity have structural spatial variability in different soil layer;maximumwater-holding capacity,minimum water-holding capacity and total porosity have weakly spatial auto-correlation; organic matter and available potassium have strongly spatial auto-correlation in different soil layer,acid phosphatase also have strongly spatial auto-correlation in 0-20cm soil layer; bulk show density moderate variation in different soil layer,available potassium show moderate spatial auto-correlation in 0-20cm soil layer,show strongly spatial auto-correlation in 20-40cm soil layer;The range is between 1042-1687m,greater than grid spacing which is 1000m,meet Kriging interpolation demand.(5) Spatial distribution of indexes in different soil layer is distributions likes patchy. Show the rend that lower in west and higher in east,content of fertility Factor in center and north higher than the surrounding area,center to east all high.(6) The soil fertility quality is classified into five classed in the study site. On the whole,the area of class â…¡ is biggest,class â… is second,last is class â…¢,class â…£, class V.The area that have higher soil fertility quality of class â… and class â…¡ in 0-20cm soil layer are distribute in center and north.Class â…¢,ass â…£,class V are distribute from center to east and west;The area that have higher soil fertility quality of class â… and class â…¡ in 20-40cm soil layer are distribute in center and northeast,Class â…¢,class â…£,class â…¤ are distribute in west and southeast.(7) The higher of soil fertility quality,diameter of Phyllostachys Pubescens is bigger,â… -bamboo and â…¡-bamboo is more than â…¢-bamboo,the shoot output and number of bamboo is increase;The lower of soil fertility quality,the diameter of Phyllostachys Pubescens is smaller, â…¢-bamboo is more than â… -bamboo and â…¡-bamboo,the shoot output and number of bamboo is reduce.(8) The ecological stoichiometry characteristics is closely related to soil fertility quality,the ecological stoichiometry change obviously,reduce with soil fertility quality,individual soil fertility class,the ratio of ecological stoichiometry is different.Content of C,N,P changes relatively stable,have internal stability,conform to the "Internal stability" hypothesis.(9) The natural factor including geographical conditions,climatic characteristics, Soil parent material and human activities are major factor that make spatial variability of soil fertility quality class.In specific forest management,must fertilize appropriately,care the tending of soil,scientific management;controlthe number of visitors,plan the tourist routes and whole area,reduce the influence of visitors,protect environment.Thus,Improve water-physical properties,permeability,water impoundment of soil. |
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