Study On The Relationship Between Forest Communities And Their Environmental Factors In Kanas National Geopark, Xinjiang

Through investigation of forest vegetation and their environmental factors in Kanas national geopark in Xinjiang province, numerical classification and ordination of forest communities were studied by two-way indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA), and the types of forest communities and their distribution pattern were analyzed. Forest communities were directly analyzed by detrended canonical correspondence analysis (DCCA), and their major environmental factors and the rate of environmental interpretation were revealed. Principal component analysis (PCA) was employed to analyze the dominant factors of soil fertility of forest communities, and then evaluated soil fertility of forest communities by establishing integrated soil quality model, and also revealed soil fertility of different successional stages. The main results showed:The forest communities in Kanas were classified into 9 types, which are Larix sibirica-Pinus sibirica forest, Betula pendula-Abies Sibirica forest, B. pendula forest, B. pendula-L. sibirica forest, L. sibirica-B. pendula forest, L. sibirica-Picea obovata-B. pendula forest, P. obovata-L. sibirica forest, L. sibirica-Populus tremula forest and P. tremula forest.The characteristics of the distribution of main species of forest communities in Kanas are more obvious. Larix sibirica distributed throughout the tourism region, Pinus sibirica in the shady slope of the higher elevation(1700～2100m), Picea obovata in the shady slope of the lower or middle elevation(1300～1800m), Abies Sibirica only in the semi-shady slope of lower elevation(1200～1400m), Betula pendula in the shady slope of the lower elevation(1400～1800m) and semi-shady slope of the lower or middle elevation(1200～1600m), Populus tremula in the semi-sunny slope of the lower elevation(1300～1400m).The most important factors for the forest communities were soil water content, elevation, slope, conductivity, soil density and organic matter content. Environmental factors accounted for 79.41% of distribution pattern of forest vegetation, of which topographical factors alone explained 12.50%, edaphic factors was 48.53%, and the interaction of topographical and edaphic variation was 18.38%. In addition, 20.59% of distribution pattern was undetermined.The main factors which contribute to forest soil fertility in Kanas national geopark are organic matter content, available N, available K, total salt, SO42- and Na++K+. The integrated soil fertility indexes of different forest communities range from 0.186 to 0.938 and the weighted average is 0.428. The descending order of soil fertility of different forest types was: broad-leaved forest, broad-leaved and needle forest, needle and broad-leaved mixed forest, needle mixed forest. The descending order of soil fertility of different succession series was: the primary, the middle, the end.