新疆阿尔泰山前平原河谷林的区系及环境特征

FLORA AND ENVIRONMENTAL FEATURES OF RIVER VALLEY FORESTS IN THE PEDIMENT PLAIN OF ALTAI DISTRICT OF XINJIANG

In the pediment plain of the Altai District in Xinjiang there are mesic river valley forests dominated by Populus trees. Tn this paper their flora, geographical elements, lifeform spectrum and environmental features are reported. In the forests, the principal species are hygro-mesophytes and mesophytes; the second are xero-mesophytes, and xerophytes, while the hydrophytes make up only a small part. All the species can be divided into 12 species-guoups, of which 9 are mesic or hygro-mesic, 2 are xeric and the remaining one is xero-mesic species. 30.3% of rhe species are Circumboreal elements, followed by Old Continent (20.2%), Cosmopolitan (19.3%), Central Asian (16.4%), Mediterranean, west-& Centre-Asian and Temperate Asian elements. In the forests, perennial herbs and grasses are common (48.6% of the total species), with deciduous broadleaved shrubs, annuals, deciduous microphyll trees and hydrophytes also being found. Accouding to the Q-cluster analysis, 9 environmental factors are divided into four types, of which 3 are zonal and 1 is azonal.