The Research On Site Classification And Site Quality Evaluation Of Camellia Oleifera Abel.Foresty In Longlin County

Camellia oleifera Abel,is a unique oil plant with high economic value in southern China.It is called "oriental olive oil" by international market.The site classification and site quality evaluation of Camellia olefera forest in Longlin County are of great significance to the development of it Industry in this region.In this study,the site conditions of Camellia oleifera forest in Longlin County were classified and evaluated by DEM topographic factor extraction,quantitative theoretical model,principal component analysis and significance test.(1)The results of DEM topographic factor analysis show that the altitude of Longlin County ranges from 374 to 1 938 m,the low mountain area is the most,followed by the middle mountain area,the least is the hilly area;the slope is mainly concentrated in 0-35°,most are gentle slopes;the results of slope direction re-classification are more shady slopes than sunny slopes.(2)Six main site factors affecting the growth of Camellia oleifera forest in Longlin County were analyzed qualitatively and classified into 18 categories.Significance test results of all site factors showed that the six site factors had significant effects on the growth of Camellia oleifera in the study area.Except for the slope direction,the other five factors reached extremely significant levels.(3)The results of KMO statistical test were acceptable,and the value(0.575)was greater than 0.5,and the Bartlett spherical test value(P<0.01),indicating that there were significant differences among the site factors involved in the test.The principal component analysis of the customs clearance showed that the four principal components with the largest characteristic values were extracted,from large to small,reflecting the soil types and soil conditions.Layer thickness,slope gradient and position reflecting topography,elevation reflecting topography,and slope position factors reflecting light conditions.(4)The site classification system of Camellia oleifera forest in the study area was established by combining the comprehensive multi-factor approach with the dominant factor approach.Three site type sub-regions were established by the first dominant factor soil type,nine site type sub-regions were established by the second dominant factor slope,and 27 site type sub-regions were established by the third dominant factor landform,with the fourth dominant factor as the dominant factor.54 site types were established in the sub-slope direction,of which 36 site types were included in the actual Camellia oleifera forest.The two site types(33.45%)and the low mountain site type group(23.09%)in the lime soil gentle slope were the largest.(5)The standard deviation of tree height(0.206)and the coefficient of variation(7.93%)were the smallest of the four indexes,and the tree height was determined as the index of site quality evaluation of Camellia oleifera forest in the study area.The model of height growth process of Camellia oleifera forest was established with 8 sample plots and the largest proportion of sample plots and representative site types.It was found that the response of the six site types to the Logistic model was the best except that the site types on the low mountain and sunny slopes on the gentle slopes of yellow soil responded best to the Korf model and the site types on the shady slopes on the gentle slopes of limestone soil responded best to the Gompertz model.Finally,based on the data of the whole plot,the theoretical equation of height growth of Logistic trees in Longlin County was established.The coefficient of determination(R2)was 0.975,and the expression of the equation was determined as follows:y =5.773/1+4.510e-0.066t(6)The site quality of Camellia oleifera forest in Longlin County was divided into four grades,and the site quality was evaluated.The forest land area accounted for 10.57%of the total area of Camellia oleifera forest in Longlin County,which was mainly distributed in the red soil site type sub-region,accounting for 98.11%of the total area of the grade ?.Grade? is the most suitable area,accounting for 66.20%of the total area of the four grades,mainly distributed in the limestone site type sub-region of limestone soil gentle slope low mountain site type group and yellow soil gentle slope low mountain shady slope site type,accounting for 65.69%of the total area of the grade;Grade III is the more suitable area of Camellia oleifera forest in the study area.20.79%of the total area is located on the sunny slope of the low hills on the gentle slopes of yellow soil,accounting for 62.77%of the total area of the grade;the unsuitable area is at grade IV,and the forest area accounts for only 2.43%of the total area of Camellia oleifera forest in the study area.It is distributed in all three sub-areas of the site types,but the quantity is small.