Research On Species Diversity And Soil Physical And Chemical Properties Under Pinus Tabuliformis Plantation On Loess Plateau

The research takes different development stages and different areas of Pinus tabuliformisplantation in Loess Plateau as the research object, through the typical sample plot surveymethod, species diversity, soil physical and chemical characteristics were analyzed in thethirty-six standard plots, and make a correlation analysis among all the physical and chemicalindicators. Firstly, we analyzed the Changes of soil physical-chemical properties and speciesdiversity of Pinus tabuliformis plantation of development stages and different areas in LoessPlateau, Secondly, on the basis of the principal component analysis of species diversity andsoil physical and chemical properties, extracted the main factors affecting the growth of Pinustabuliformis plantation, and evaluate the quality under the plantation of Pinus tabuliformis.Provide scientifically basis for Pinus tabuliformis plantation sustainable management.The main results were as follows:1. Twenty-five families, fourty-eight genera and fifty-five species plants appears inunderstory of Pinus tabuliformis plantation of different development stages, and Asteraceaeand Rosaceae plant occupies a higher proportion of all plants, the main shrub plants are Rosahugonis, Cotoneaster zabelli, Acer ginnala and Swida alba, the main herb plants are Carextristachya, Elymus dahuricus, Duchesnea indica and Heteropappus altaicus. With the growthof forest age, the number of subjects in the understory species belongs to gradually increase toreach a maximum of mature forest stage.From Immature timber to Mature forest, the speciesrichness index and diversity index was shrub layer＞herbaceous layer and from Young forestto immature timber, was herbaceous layer＞shrub layer. Species richness, species diversityindex and evenness index were showed largest in Young forest and smallest in immaturetimber in herbaceous layer, and showed largest in mature forest and smallest in Young forestin shrub layer.The different of the number of species between different areas was significantly. Thedescending sort is: JingYuan＞ZhengNing＞ChunHua＞HuaChi＞HeShui＞HuanXian＞ZhenYuan＞GuYuan. Species richness, species diversity index and evenness index were showed largest in HuanXian and smallest in ZhengNing in herbaceous layer, and showedlargest in JingYuan and smallest in HuanXian in shrub layer.2. In different stages of Pinus tabuliformis plantation, the change of the soil moisturecontent is not obvious, the variation range is15.73%～18.91%;The soil bulk density and the soil porosity in mature fores-t were better than others, and thevariation range are0.92～1.26g·cm-3and52.27～68.99%; With the increase of the forestage, the soil organic matter and total nitrogen content increased, and the variation range are9.88～61.46g·kg-1和0.58～2.89g·kg-1, but soil pH value decreased, and the variation rangeis7.15～7.69; The contents of Available P, Available K, nitrate and ammonium contentpresent certain fluctuations; Correlation analysis showed that there were correlations betweenorganic matter, total nitrogen and soil pH value, while an extremely significant positivecorrelation between organic matter and total nitrogen, and an significant negative correlationbetween soil pH value and total nitrogen, and between soil pH value and organic matter.Changes of soil organic matter in soil surface layer between eight countieswere:JingYuan＞ZhengNing＞ChunHua＞HeShui＞ZhenYuan＞HuaChi＞HuanXian＞GuYuan, and Changes of soil total nitrogen in soil surface layer between eight counties were:JingYuan＞ZhengNing＞HeShui＞HuaChi＞ChunHua＞ZhenYuan HuanXian＞GuYuan.3. In Pinus tabuliformis plantation of different developmental stages of Ziwuling region,species richness and diversity index are significant positive correlate with total nitrogen, Soilmoisture, and significant negative correlate with soil bulk density and pH value in shrub layer;All diversity indexes are significant negative correlate with total nitrogen, available P andavailable K, and significant positive correlate with pH value in herb layer. All diversityindexes are significant positive correlate with organic matter and total Nitrogen in shrub layer,and are significant negative correlate with organic matter and total Nitrogen in herb layerunder the Pinus tabuliformis plantation of different areas on Loess Plateau.The comprehensive evaluation value of different developmental stages in descendingorder are mature forest(2.88)＞immature timber(2.76)＞nearly mature forest(1.17)＞youngforest(﹣4.56)＞slope wasteland(﹣9.03), and The comprehensive evaluation value ofdifferent areas in descending order are Jingyuan（5.59）＞Zhengning（4.75）＞Chunhua（3.05）＞Heshui（2.19）＞Huachi（-0.13）＞Huanxian（-1.42）＞Guyuan（-6.90）＞Zhenyuan（-7.14）.