Abstract:

Patterns of species diversity along the altitude on the northern slope of Xiaodonggou in the Altai mountains were explored. The results indicated that: the vegetation structure and composition were generally simple, and the diversity was low. Diversity order of the following three life forms was: trees < shrubs < herbaceous plants. Diversities of trees and shrubs exhibited a unimodal pattern with increasing altitude, peaking at the range of 1 600 m-1 800 m. The herbaceous plant diversity exhibited a monotonically increasing trend with the increase of altitude. Change in total diversity of the three life forms along the altitudinal gradient showed a unimodal pattern. Mixed coniferous broadleaved forest (1 600 m -1 700 m) had higher species diversity, where peak values for trees, shrubs, and total species diversity appeared. In the study area, tree crown density decreased along the altitudinal gradient, so that the diversity of herbaceous plants had an increasing trend along the altitudinal gradient accordingly.

Key words: northern slope, altitudinal gradient, species diversity, Xiaodonggou