Study On Stand Structure And The Optimizing Model Of Phyllostachys Edulis And Trees Mixed Forests In Min Northwest

This paper mainly focus on pure forest of Phyllostachys edulis,Mixed forest of Phyllostachys edulis and Cunninghamia lanceolata forest,Mixed forest of Phyllostachys edulis and Camphora officinarumin northwest area of Fujian province.The spatial and non-spatial structure features of several stands of P.edulis wereanalyzed.Considering the optimization of spatial structure as goals.Taking constraint condition based on non-spatial structure into consideration.Optimization decision model of stand spatial structure for mixed forest of P.edulis were established to adjust and optimize the spatial structure of forest stand,and compare the spatial structure of the stand before and after optimization.The main results were as follows:(1)The plant diversity of several mixed forest stands were significantly higher than the pure forest of P.edulis.The stand of plant diversity was six P.edulis and four C.lanceolata mixed stands The distribution of stand diameter of different mixed P.edulis stand were compared,both like a single peak and asymmetric mountain shape curve,and the trees were distributed in the arithmetic average diameter of stands.The age structure of stands is extramly unreasonable,the number of young P.edulis were less and Ⅳ degree of P.edulis above the proportion of large number of bamboo,bamboo aging serious,the aging of bamboo forest is serious.(2)Through the analysis of the spatial structure of several stands,the distribution of pure forest of P.edulis was clustered,the distribution pattern of the mixed forest of P.edulis and C.officinarum was evenly distributed,the distribution of the mixed forest of P.edulis and C.lanceolata were close to the random distribution.The mixed forest of Redulis and can increase the degree of species isolation,and their stand structure is more stable than pure forest.The mixed forest of P.edulis and C.lanceolata belong to weak degree of mingning,the average mingning of the mixed forest of P.edulis and C.lanceolata were between 0.44 and 0.49,which belonged to weak to moderate mixed state.Each state of the different mixed forest of P.edulis was in the middle of the growth state,the average neighborhood comparison of six P.edulis and four C.lanceolata mixed stands(the proportion of C.lanceolatatree is about 40%respectively)was the smallest.The reasonable stand structure could reduce the competitive pressure of the trees,and improve the environment of forest growth.(3)The diversity of spatial structure of mixed P.edulis stand showed that the frequency of trees that was growed in middle dominance degree and middle mingling,random distribution and middle mingling,random distribution and subdominant or middle dominance degree in the mixed forest of P.edulis and C.lanceolata was higher than pure forest.The frequency of trees that was random distribution and low mingling,random distribution and advantage,advantage or subdominant and low mingling in the mixed forest of P.edulis and C.offlcinarum was higher than pure forest.(4)The optimizing model of stand spatial structure for mixed forest of P.edulis for mixed P.edulis forest was easablished based on the five spatial structure indices of the clustering index,mingling,competition index of intersection angle,neighborhood comparison and uniform angle index.And the paper puts forward nineconstraints on the purpose of sustainable management of mixed P.edulis forest.Using this model to adjust and optimize the spatial structure of the mixed forest of P.edulis and C.lanceolata.The results showed that the spatial structure of the selected forest was better than that before cutting,and the spatial structure of the forest was significantly improved,which more benifit for.forest multifunctional benefits.