Vegetation-environment Relationships Between Northern Slope of Karlik Mountain and Naomaohu Basin, East Tianshan Mountains

Plant communities are the results of interactions between vegetation and environment. Generally, vegetation distribution patterns are mainly controlled by environmental factors such as climate, topography and soils at a regional scale. However, vegetation patterns can influence variations in both soil water content and soil nutrients. The analysis of vegetation-environment relationships has been a central issue in geobotany, with researchers attempting to determine the factors that control the distribution and variation of vegetation composition for over a century.

The region between the northern slope of Karlik Mountain and Naomaohu Basin is located in the easternmost part of the Tianshan Mountains, and lies on both the massif of the Junggar Basin and the geological fold-uplift belt of the Tianshan Mountains. The arid landscape in this region formed by unique mountain-oasis-desert landscape complex, is quite different from other parts of the world. Many researches on relationships between vegetation patterns and environmental factors have been carried out on the mid-section and on the west of the Tianshan Mountains, but seldom on the East Tianshan Mountains with drier climates and fragile environments.

Based on data from field investigation and applying the Canonical Correspondence Analysis (CCA), Prof. QIAN Yibing and her research team discussed the vegetation-environment relationships between the northern slope of Karlik Mountain and Naomaohu Basin. The results showed that for the zonal vegetation, community diversity of mountain vegetation is higher than that of the desert vegetation due to environmental factors. The CCA ordination diagram revealed that the composition and distribution of vegetation types are mainly determined by altitude, soil pH and soil salt content. With increasing elevation, the soil pH and total salt content decrease but the contents of soil organic matter, soil water, total nitrogen and total phosphorus increase gradually.

In the CCA ordination diagrams, the sample plots and main species can be divided into five types according to their adaptations to the environmental factors. Type I is composed of desert vegetation distributed on the low mountains, hills, plains and deserts below an elevation of 1900 m; type II is distributed in the mountain and desert ecotone with an elevation of 1900–2300 m, and includes steppe desert, desert steppe and wetland meadow; type III is very simply composed of only salinized meadow; type IV is distributed above an elevation of 2300 m, containing mountain steppe, meadow steppe, subalpine meadow and alpine meadow; type V only contains salinized meadow. The results showed that with increasing elevation, species combination changes from the xerophytic shrubs, semi-shrubs and herbs distributed in the low altitude zone with arid climate to the cold-tolerant perennial herbs growing in the high altitudinal zone with cold climate.

The result has been published on Chinese Geographic Science, 2012, 22(3): 288-301. The paper can be downloaded from http://www.springerlink.com/content/mq83528j47172862/.