Study On Site Classification And Site Quality Evaluation Of Slash Pine Forest For Timber And Resin

The classification and evaluation of forest sites is an important basis for forest management and forest vegetation restoration.Based on a sample survey of slash pine(Pinus Elliottii Engelm)forest for timber and resin in the main distribution areas in Anhui Province,we identified the dominant factors which affected forest growth by the principal component analysis using SPSS 23 statistical analysis software,then classified the site types of slash pine forest for timber and resin in Anhui Province.Established a steering curve equation using the Richard model,then compiled the site index table of slash pine forest for timber and resin based on the model,and conducted the site quality evaluation.(1)Selected the site factors such as slope,slope direction,slope position,soil type,soil thickness,humus thickness,soil moisture,etc.,use principal component analysis to determined the main influencing factors by principal component analysis,and then according to the contribution rate of each site factor in each component select the dominant factors.Finally determine the slope,soil thickness,humus thickness as the dominant factor and divided into 12 site types.The suitable site types of slash pine forest for timber and resin is Slope-thin soil layer-thin humus layer、Slope-thin soil layer-thin humus layer、Gentle slope-moderately thick soil layer-thin humus layer、Gentle slope-thick soil layer-Thick humus layer.And The economic benefits of Gentle slope-moderately thick soil layer-thin humus layer、Gentle slope-thick soil layer-Thick humus layer are relatively higher.(2)By fitting Richard’s model,Weibull’s model,Campaign’s model,Logistic’s model,parabola’s model and other models,the maximum R2 model and the minimum RMS residual model are selected to determine the steering curve model,and finally the model is determined as Chad’s model.The site index table was compiled by the method of variation coefficient.Chi-square test and landing point test were carried out on the site index table.The test results were all qualified.Therefore,the research results have the value of popularization and application.(3)Use the site index table,combined with the comprehensive benefits evaluate the site quality of Pinus elliottii Forest for timber and resin in Anhui Province.Soil types have a significant impact on the growth of Pinus elliottii,and yellow-red soil is more conducive to the growth of Pinus elliottii.From the regional distribution,the growth of Pinus elliottii in southern Anhui is better than central Anhui.The economic benefits of different stand conditions and different use stands are also different.Accroding to investment and income data:The net income of the forest for the resin is greater than 0 in the site with the site index≥8;The net income of the timber forest is less than 0 in the site with the site index≤8,and greater than 0 in the site with site index≥10;The net benefit of forest for timber and resin is greater than 0 in the site where the site index is≥8.