Health Assessment Of Forest Community Structure In Beijing SongShan Nature Reserve

Forest health assessment is a hot point in ecological study nowadays, and how to establish an objective and accurate assessment system is the most difficult part. This article used correlation test and Principal component analysis in SPSS 12.0 to find out the most important indexes to forest community structure from mass of easily achieveable biodiversity factors and structure quantitative characters. And then, through AHP method, weight coefficient of health assessment can be calculated. Finally, the health ordering and health grading of forest communities' structure can be drew out.Using method above, this article appraised typical associations' structure health within 4 kinds of main formation (including pine forest, Quercus Mongolica Forest, Poplar-Birch Forest, and Deciduous Broad-leaved Mixed Forest) of SongShan nature reserve in the base of data which investigated during 2000 to 2006.This paper got results as follow:(1) Plant association is the basic unit of forest health assessment, and every formation should be appraised by different indexes with different weight;(2) Health assessment indexes for pine forest include 9 indexes, such as grass coverage, shrub coverage, tree number, etc. The result turns out the Association Carex lanceolata -Lespedeza davutica- Pinus tabulaegomis is the most health, and the Association Glycine soja -Philadelphus pekinensis- Pinus tabulaegomis has the lowest score;(3) For Quercus mongolica forest, there are 8 the most important factors to structure health, including simpson index, shrub coverage, tree species, and so on. The Association Carex lanceolata -Deutzia grandiflora- Quercus mongolica is the most health, and the Association Carex lanceolata -Philadelphus pekinensis- Quercus mongolica has the lowest score. But in total, Quercus mongolica associations' health situation are closely;(4) For poplar - birch forest, there 6 the most important factors to structure health, including shrub coverage, seedling amount, grass coverage, etc. The Association Carex lanceolata -Rosa bella- Betula platyphylla is the most health, and the Association Saussurea nivea-Rubus carataegifolius- Betula dahurica has the lowest score.;(5) For Deciduous Broad-leaved Mixed Associations, there are 6 the most important factors to structure health assessment, such as tree number, grass density, coverage, Shannon diversity index, ect. The most health association is Association Saussurea nivea -Corylus mandshurica- Betula platyphylla+ Betula dahurica, and the lowest is the Association Saussurea nivea-Lespedeza floribunda-Quercus mongolica+ Fraxinus rhynchophylla.