第四章 现代森林-草原过渡带的生态分析 - Global Index of Vegetation .DOC

Vegetation of the woodland-steppe transition at the southeastern edge of the Inner Mongolia Plateau Hongyan Liu1, 2, *, Haiting Cui1, Richard Pott2, Martin Speier2 1Department of Geography, Peking University, Beijing, 100871, P. R. China 2Institut f(r Geobotanik der Universit(t Hannover, Nienburger Strasse 17, D-30167, Hannover, Germany *Tel. +86 10 Fax +86 10 Email lhy@urban.pku.edu.cn Published on Journal of Vegetation Sciences, 2000, 11(4): 525~532 Abstract: The vegetation of the woodland-steppe transition in southeastern Inner Mongolia, where the East Asian monsoon climate reaches its northwestern edge, is described and analysed in this paper. The communities are classified in a phytocoenological way. 12 major types of woodland, shrubland, meadow, fen, open woodland and steppe are differentiated and described according to 133 relevés. DCA results show that precipitation plays a crucial role in the distribution of grassland communities while woodland and shrubland communities are controlled by both warmth and humidity conditions. Four vegetation zones can be distinguished. From woodland zone to woodland-grassland zone, the temperature decreases and the precipitation increases with the rising of the altitude, which leads to the conditions suitable for the meadow and fen communities. Transiting to the woodland-steppe zone, the temperature increases while the precipitation decreases with the gradual lowering of altitude, steppe communities form a matrix and woodlands have patchy distribution. From woodland-steppe zone to steppe zone, the precipitation rather than temperature decreases obviously, as a result the woodland communities disappear gradually. In a local scale, geomorphologic conditions determine the vegetation pattern of the study area. The existence of the sandy land permits different woodland types occur together in the woodland-steppe transition. The distribution of woodland and steppe communities in a discrete site is depended