关键词: 大围山, 地理成分, 海拔梯度, 聚类分析

Abstract:

Altitudinal gradients incorporate multiple resource gradients which vary continuously in different fashions. Studies of mountain floristic patterns along altitudinal gradients has revealed regular patterns of the flora along environmental gradients, changing trends in biodiversity along altitudinal gradients as well as a better understanding of biological fitness. To explore the floristic compositional characteristics and the ecological significance of floristic patterns along altitudinal gradients in the China National Natural Reserve of Dawei Mountain in southeast Yunnan, the flora was quantified along two transects, one on the southwest slope and the other on the northeast slope of the reserve, including a vertical vegetation transect. Further investigations were conducted on the flora of Dawei Mountain which have ever been accounted for in the literature, such as Flora of Yunnan, The Seed Plant in Yunnan and so on. The structural characteristics of the flora and the altitudinal distribution patterns of its floristic components were analyzed. Systematic cluster analysis was applied to the data to determine how composition changed with changes in altitude and climate. The conclusions can be summarized as follows: 1) There was a strong boundary that differentiated tropical floristic elements from evergreen broad-leaved forests at an altitude of approximately 1 500 m; 2) Cluster analysis showed that humid rain forests occurred below 700 m a.s.l, mountain rain forests were between 700 m and 1 500 m, monsoon evergreen broad-leaved forests were between 1 300 m and 1 800 m, and the mountain mossy evergreen broad-leaved forest occurred above 1 800 m a.s.l. Non-representative mountain mossy dwarf forests (above 2 100 m) in the area are distributed on windward slopes and barren land on the mountain slopes.

Key words: Dawei Mountain, Altitudinal gradient, Clustering analysis