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Abstract

A study on the Napahai ecosystem stability based on changes of vegetation cover.

Abstract

This study took the dynamic changes of vegetation cover as indicator to evaluate the ecosystem stability of Napahai Lake, used 3 historical pattern of vegetation distribution of 1985, 2005, 2011 in Napahai lake as basic material, analysed the ecosystem stability of Napahai Lake by Arcgis 9.3. The results showed that: (1) In the past 30 years, under the intense artificial interferences such as agriculture, graziery, tourism, Napahai Lake keep a relatively good ecological functions, showed a good ecosystem stability. The total area of vegetation cover did not decrease obviously, the area and the locations of farm lands nearly keep the same as before, area of aquatic communities decreased while the area of pasture increased. (2) The ecosystem stability of Napahai Lake depends on local special seasonal water flooding condition, all kinds of the herbal species in plant communities have flexible adaptation to various water condition, which ensures the vegetation can survive regardless how the water conditions change, meanwhile seasonal water flooding is beneficial for both ecosystem rehabilitation and resisting disturbance. (3) If artificial interferences damage the seasonal water flooding continuously, the drought process will speed up and Napahai ecosystem will suffer invasion of Euphorbia jolkinii at large scale, or will degrade into bare sandy land and loss its basic ecological functions.