Abstract:

Rational classification of vegetation types in a region by applying quantitative methods and analysis of the environmental factors influencing their distributions are indispensable for research, conservation and management of ecosystems in the region. We conducted a field investigation on forty-three vegetation plots (20 m×20 m) in Xiaodonggou forest area of the Altai Mountain in northwest China. In each plot data of the main environmental factors, including elevation, slope, aspect, large stone content, and grazing disturbance conditions, were recorded. The soil characteristics of water content, total nitrogen, total phosphorus, and soil organic matter were measured. The results showed that among the 43 plots, We identified 23 woody plant species which belonged to 16 genera in 14 families. Cluster analysis classified the woody communities into 6 types, including 5 tree communities and 1 shrub community. The 6 community types respectively were shrubs, Populus tremula, Populus laurifolia, Betula pendula, Larix sibirica, and a mixed community of Abies sibirica + Larix sibirica+ Picea obovata and they had different distribution patterns along the major environmental gradients in the Altai Mountain. The DCCA ordination showed that the topographical factors of elevation, slope position, and aspect, and the soil factors of soil type, soil total nitrogen content, soil total phosphorus content, soil water content, and large stone content, were the major environmental factors affecting plant species distribution in the Xiaodonggou area. The distribution of the vegetations in the area was mainly controlled by the interactions of topographical and soil factors.

Key words: Altai Mountain, cluster analysis, DCCA, community type, environmental factors