| Quercus aliena var. acuteserrata community, batula albo-sinensis community, Pinustabulaeformis community and Pinus armandii community in centra south Qinling Mountainswere studied by sample-plot survey and laboratory tests. In this research, the soil nutrientschanges of Quercus aliena var. acuteserrata community, batula albo-sinensis community,Pinus tabulaeformis community and Pinus armandii community were discussed to study onthe effect and mechanism of thinning on soil nutrients and to evaluate the function of variouskinds of forestry technical measures. The study is also in order to provide scientific basis forthe maintenance of the ecological functions and the healthy sustainable development.and thereasonable management of forests. The results are as followed:Considered the soil nutrients of four kinds of stands, when unthinned, the soil nutrientscondition of Quercus aliena var. acuteserrata community is the best, the soil nutrientscondition of batula albo-sinensis community is in the second place, the soil nutrientscondition of Pinus tabulaeformis community and Pinus armandii community is relativelypoor. When the stand factors and site factors are similar, the soil nutrients condition ofbroad-leaved forest is better than that of coniferous forest. In different forests the soilnutrients content of A soil layer is higher than that of B soil layer and the C layer.Thinning could significantly improve the soil nutrient status of forest, which A soil layeris more obvious than other layers in different tree species stands with different thinningintensities.(1) In soil of half-mature Quercus aliena var. acuteserrata forest, water content,organic matter content, TN content, NO3--N content are the highest with the thinning intensityat15%, the content of TP, AP, TK and AK is the highest with the thinning intensity at20%;(2)In soil of half-mature Pinus tabulaeformis forest, the content of organic matter, TN andNO3--N, NH4+-N, TP, AP and AK is the highest with the thinning intensity at20%, the contentof TK is the highest with the thinning intensity at15%;(3) In soil half-mature batulaalbo-sinensis forest, the content of NH4+-N is the highest with the thinning intensity at20%,other nutrients indexes content is the highest with the thinning intensity at25%;(4) In soil ofhalf-mature Pinus armandii forest, TP content is lower than the unthinned stand, and otherindexes of soil nutrient content is the highest with the thinning intensity at20%.According to species biological characteristics and the target of thinning, scientific thining intensity adopted. In this study, light thinning is mainly in order to make contributionto give better play to the ecological function of forest. Through the study found:(1) Thinningintensity of half-mature Quercus aliena var. acuteserrata forest should be determined as15%or20%;(2) Thinning intensity of half-mature Pinus tabulaeformis forest should bedetermined as20%;(3) Thinning intensity of half-mature batula albo-sinensis forest shouldbe determined as25%, more should be studied if stronger thining intensity be taken;(4)Thinning intensity of half-mature Pinus armandii forest should be determined as20%.Thinning intensity and thinning time should be in accordance with Nutritionalrequirement rules. Different species in different growth periods have different nutrientdemand, which requires different tree species in different growth stages should adopt differentmanagement mode, in order to maximize the expected results. |
