Site Classification And Site Quality Evaluation Of Chinese Fir Plantation In Jiangle State-owned Forestry

Fujian Province is important producing area of Cunninghamia lanceolata(Chinese fir),which is an essential afforestation tree species of collectively owned forest area.Because of its fast-growing and high-yield characteristics as well as great carbon sequestration potential,studies of Chinese fir on biomass and productivity are significant.Different yields of Chinese fir growing in the same habitat due to different site conditions.Based on this background,forest site classification and site quality evaluation of Chinese fir plantation is of good guiding significance to develop reasonable planning layout in plantations.Through the investigation and analysis of site factors in Chinese fir plantation of Jiangle,Fujian Province,using the data from secondary forest resource inventory and permanent plots,principal component analysis was applied.The dominant site factors were selected according to KMO value and Bartlett verification result.Using the indicative function,qualitative factors of site factors were transformed to quantitative factors,multiple regression equations which could describe factor index were built based on quantification theory Ⅰ.Afterwards,the site quality quantitative score table and site quality grade evaluation table were established to predict the growth potential of Chinese fir.The results were as follows:1.Site classification of Chinese fir(1)Principal component analysis was conducted by using SPSS software to analyze site factors which influencing the Chinese fir growth,based on KMO value and Bartlett test,the research is suitable to use principal component analysis.In the variance interpretation table,the first three factors could explain 81.60%of total,therefore the first three factors were selected to describe site classification.The dominant factor affecting the growth of Chinese fir is elevation,slope,and soil thickness;(2)According to the ranking,elevation was the most influential factor.Therefore,the growth conditions of Chinese fir were divided into three types,namely:low elevation site type group,middle elevation site type group and high elevation site type group;(3)According to slope factor and soil thickness factor,the site conditions of Chinese fir plantation were subdivided into 36 site types.2.Site quality evaluation of Chinese fir(1)Among site factors,both quantitative factors like elevation,slope,thickness of humus layer,etc.and qualitative factors such as slope aspect and so on existed.In this study,all qualitative factors were transformed to quantitative factors,based on which,original data reflect table was designed;(2)Using SPSS to calculate the correlation coefficient of each item affecting Chinese fir growth,and to verify its rationality.Rarking the contribution value of each item in the prediction equation,the results showed the order of importance as follows:soil thickness,elevation,slope,humus thickness,slope aspect,soil type 5 slope position;(3)Seven prediction equations were obtained via using the quantitative theory Ⅰ method,site quality quantitative score table and site quality grade evaluation table were established;(4)Four grades of site quality named as excellent,good,medium and bad were classified of Chinese fir plantation in the research area.Most of the quality grade of Chinese fir plantation in Jiangle stated-owned forestry is above intermediate level.