Evaluation On Relict Water And Soil Conservation Forest In Beijing Low Mountain Area

Forest plays very important role in adjusting ecosystem balance as the principal part of terrestrial ecosystem and important natural resource for people to live on. Moreover forestry quality has the direct relation to the play of forestry function,with the increase of the number of afforestation yearly, people pay more attention to the quality of forest increasingly. However, there were a large number of relict forest in low mountain areas of beijing because of the interference of human activity, unreasonable technology of afforestation, restriction of site conditions and so on.Therefore, in order to provide some theoretical foundation for promote forest quality, it's time to make an all-around investigation and quality's evaluation to relict water and soil conservation forests in Beijing low mountain.There have set up fourty standard plots in six countries's typical areas in Beijing low mountain,and individuals to every wood for Pinus tabulaeformis, Platycladus orientalis, Robinia pseudoacacia, Quercus L, Populus davidiana, scrub forest and so on, investigate bush, herbaceous plant and seedling distribution situation simultaneously site condition investigation, soil survey, hydrology investigation and related investigations. The main research results this points as follows:(1) Beijing low mountain vegetation structure is not stable trendIn Beijing to low mountain from vegetation investigation can see, there are quite a few follow stand results desultorily, erratic. This situation by planting technology on tree or influence, on the other hand also influenced by local site condition the influence. To some extent, the effect will be the site conditions for more direct.(2)The reasonable construction machine of relict water and soil conservation forests evaluation index systemCombined with the local actual condition, using the mathematical statistics method and expert consultation screened level 3 total 17 evaluation index, evaluation index involving stand integrity, stability and site conditions stand three primary index. The fuzzy matrix combined with mathematical method to determine each index standards.(3) Establish a comprehensive model evaluationUsing the hierarchical analysis and expert analysis the method of combining the every evaluation index sure a weight and SPSS mathematical statistical methods to determine the final second water and soil conservation forests evaluation model. The comprehensive model established by the formula is: S＝(?)WiXiAccording to the model calculation and front of each indicator as determined by dividing the standards, systems analysis software SPSS again for comprehensive evaluation score value of clustering analysis. Will CanCiLin level into four levels:①the comprehensive evaluation value of more than eight points for high-quality forests;②in the comprehensive evaluation value into level 5-8 CanCiLin, belong to growth potential shape that stop human interference, try to time can restore automatically;③in the comprehensive evaluation value 2-5 into secondary CanCiLin, belong to tending transformation model, adopt thinning or some other measures can restore;④in the comprehensive evaluation value of two points below CanCiLin, belong to a category 3 type, will existing logging reconstruction stand all cut down, and then press reasonable tree species and reasonable structure to planting.(4) Use evaluation system and comprehensive evaluation model to take 40 sample which are evaluatedDetermine the subordinate counties in Beijing 40 of the six relict forest sample level, according to the weight value in each index analysis, and then relict forest formation reasons to take effective reform measures.