The Study Of Comprehensive Benefit Evaluation Of Cryptomeria Fortunei Plantation In The West Margin Of Sichuan Basin

The evaluation of comprehensive benefits of forest is the basis for formulating management measures and estimating dynamic change of forest benefit and it has a very important realistic meaning. Aiming at the Cryptomeria fortunei plantation in the west margin of Sichuan basin, the present study are focused on the timber output and economic benefit, but the study on developing ecological benefit are very lack. In this paper, we unified the economic and ecological benefit of forest land and established the evaluation system of the comprehensive benefit of Cryptomeria fortunei plantation. Using AHP combined the quantitative analysis and qualitative analysis, we try to bulid a comprehensive performance evaluation system of Cryptomeria fortunei plantation with the factors of forest and tree species,and choose 25 plots (6 plots of sapling forest,12 plots of middle age forest,7 plots of near-mature forest) to evaluate the index of comprehensive benefits. At the same time using the system assessment 9 plots in Chongzhou forest farm in different management measures (untreated,thinning, replanting of indigenous broadleaf species number after thinning).At the same time, go a step further on site division of general timber forest, short rotation timber plantation, soil and water conservation forests and water conservation forests of Cryptomeria fortunei. Combined with the actual situation on the basis of the benefit evaluation, proposed directional management measures of commercial forest and public welfare forest of Cryptomeria fortunei, in order to develop the leading function of different forests. The following conclusions are drawn through research:(1)Using AHP to evaluate the comprehensive benefit, selection of timber output function, the function of water conservation, soil fixation and fertility preservation function, function of fixing carbon and releasing oxygen, biological diversity protection function of five factors as the elements of reservoir evaluation, selection of forest volume, forest total vegetation coverage, species structure, litter thickness, slope, stand average DBH, humus thickness, stand age, canopy density, community structure, soil thickness and stand average tree height as the indexs of evaluation.(2)The ranking for the element layer of the weighting factor value evaluation is:timber output function> biodiversity conservation function>function of fixing carbon and releasing oxygen> water conservation function> solid soil fertilizer function. The weights were:0.5936,0.1715,0.1310,0.0677,0.0362. The index layer weights for each factor is:stand volume>understory vegetation coverage> age> tree structure> thickness of the litter layer>stand average tree height> soil thickness> average DBH> woodland slope> the community structure>forest humus layer thickness> forest crown closure. The weights were:0.5936,0.1015,0.0866,0.0571,0.0475,0.0273,0.0272, 0.0172,0.0131,0.0129,0.0091,0.0072.(3)The index of the comprehensive benefits of Cryptomeria fortunei plantation in the west margin of Sichuan basin is 0.524. In each age, sapling forest, middle age forest, near mature forest, the average efficiency index are:0.386,0.545,0.816.(4)9 plots of different handling modes(untreated,thinning, replanting of indigenous broadleaf species number after thinning),the comprehensive benefit index are:0.776、0.776、 0.776; 0.815、0.815、0.819; 0.917、0.9、0.594.(5)By the analysis of comprehensive benefit index,in water conservation;solid soil fertilizer and biological diversity protection,the thinning and replanting of indigenous broadleaf species number after thinning are better than untreated plots.(6)To create artificial commercial forest of Cryptomeria fortunei, initial density in per-hectare is 3598-4498, attention should be paid to thinning time, every time the number of thinning intensity is less than 40%, accumulation intensity is less than 20%, the centralized management can reduce infrastructure, human and other investment; when create a water conservation forest of Cryptomeria fortunei, we can choose to build the conifer and broad-leaved mixed forests in order to enhance the value of water conservation.