| Water shortage problems are becoming increasingly prominent with the rapid socio-economic development,therefore,it is an important ecological task to effectively protect water resources. As a producer in ecosystem, forest plays an important role in water conservation. However,it is difficult fore most plantations to be active in water-conserving as they are single structured currently. For this reason,it is necessary to adjust the structures of water-conserving plantations.In this paper,research on plantations in Dawujia watershed of aohan County,Chifeng City were set about from the perspective of factors influencing water-conserving function. It makes discussion of how forest and soil structures influence water conservation function,and comprehensively evaluates that of various vegetation types. At the same time, in line with operable and scientific principles, it screenes out extrinsic factors and cofactors that influence water conservation function,and puts forward the concept of low-functional forest, as well as its defining standards and targeted updates technical measures;the paper also tries to quantitatively describe the stand structure with interfere index, and proposes target stand structure;in addition,it makes discussion of reasonable area allocation of different forest types as well as target forest coverage in water-conserving areas, the paper also gives advices in adjusting and target structure. The results are as follows:(1) Using of neighborhood interference model to research Populus simonii, pinus tabulaeformis,Larix principis-rapprectii and other forest structure,standing forest interference index and trees DBH, tree height and crown area were negatively correlated, while, compared with ratio of height to diameter were positive correlation; identified forest types under specific conditions of the neighborhood interference radius, that is, Populus simonii mixed caragana microphylla in hills, pure Populus simonii forest in mountain, Populus simonii forest in plains neighborhood radius of influence, respectively 3m,5m,6m; pure Pinus tabulaeformis forest neighborhood radius of influence for the 5m; Larix principis-rupprechtii neighborhood influence was 3m.(2) Through the stem analysis data, convection within the main tree species Populus simonii, Ulmus pumila,Pinus tabulaeformis and Larix principis-rupprechtii in north China's growth process and biomass were studied. The results showed that all species of the tree height, diameter at breast height, timber volume growth has accumulated follows three times multinomial; the same time, the growth of various tree species subject to a certain degree of inhibition, the reason being subject to the environment,particularly water factor,the stand density was related too; Populus simonii, Ulmus pumila,Pinus tabulaeformis and Larix principis-rupprechtii and other trees in north China the number of mature age, respectively 14a, 20a, 13a, 17a.(3) Using of principal component analysis from the point of litter layer and soil layer, overall merit the River Plantation in a comprehensive evaluation of water conservation function. The results show that quantitative indicators of water conservation function variation range of 1.95~8.91, in order for the mixed broadleaf-conifer forest> broad leaved forest>coniferous forest>mixed broadleaf-shrub forest>mixed conifer-shrub forest>mixed shrub forest>shrub forest. Conifer-water conservation function better in the mixed broadleaf-conifer forest, followed by broad-leaved forest, coniferous forest, mixed forest of broad irrigation, mixed forest of needle irrigation, mixed mulberry apricot shrub forest, shrub Caragana microphylla water conservation function was low.(4) Through typical correlation analysis with the litter layer, soil sluice factors and stand gauge factors. the results showed that 8 stands of forest vegetation types in the performance of 14 water factors on the water conservation function related factors were more typical, where the greatest impact most closely related to tree height, diameter at breast height, hectare accumulation, the annual volume growth volume, closed-degree, ground litter cover, under coverage, community structure of eight factors, and can be divided the forest vegetation on water conservation function of forest indicators of high and low factor.(5) Using principal component analysis, cluster analysis, bayes discriminant analysis, typical discriminatory analysis ,to differentiate different species composition of the water conservation function of forest vegetation types, and functional category of low-function standâ…£into technical parameters are listed.(6) Through the analytic hierarchy process (AHP)for target water conservation function of forest vegetation types to conduct a comparative evaluation of the composition. The results showed that combination of tree structure for the mixed broadleaf-conifer forest 21.78%, Poplars forest 21.54%, Pinus tabulaeformis forest 20.97% , Prunus sibirica 12.28%, Caragana korshinkii forest 11.8%, economic forest 11.63%;objective planning for the forest coverage is 47.86% in research area and 69% in Dawujia watershed of aohan County.(7) By measuring the main tree species,shrubs,trees,mixed species suitability evaluation combined effect of the study area. The results showed that 10 kinds of tree species to reach suitable hygiene requirements, Poplars and Ulmus pumila showed the relevance of a wider suitable range, followed by Salix flavida, Pinus tabulaeformis was main species in barren hills and slopes ecological management;shrub species in the area suitability strong,in which ansu apricot showed a wider suitable range, followed by Hedysarum mongolicum,Hippophae rhamnoidea;tree mixed broadleaf-conifer forest put up great suitability, followed by mixed trees and bushes.(8) According to the distribution of low-functional forest characteristics, land occupation condition and in which the age-class etc.,under the guidance of Near natural theory and forest health theory, after an investigation, planning, transformation and other steps to steady progress in Poplars, Pinus tabulaeformis, Larix principis-rapprectii and shrubs with low functional stands renovation technology, to raise variety of forest renewal and transformation model. |
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