嵩草草甸退化和恢复过程中主要牧草演替和地表特征变化

以青藏高原高寒草甸禾草、矮嵩草和小嵩草的重要值及斑块变化为对象,研究其在嵩草草甸退化和恢复过程中的变化规律。结果表明,退化中的嵩草草甸小嵩草重要值显著高于矮嵩草和禾草,样带调查显示在小嵩草样带矮嵩草盖度急剧降低,黑斑盖度增加近一倍,小嵩草斑块分布普遍;重牧小嵩草草甸小嵩草成为优势种,重要值显著高于矮嵩草和禾草(P＜0.05),黑斑面积增大,塌陷增多,矮嵩草斑块出现几率小;恢复中的小嵩草草甸禾草重要值增大,矮嵩草恢复慢,恢复斑块上禾草成为优势种,小嵩草斑块接近消失,黑斑和秃斑面积急剧缩小,植被盖度增加;恢复较好的草甸禾草成为样地的优势种,矮嵩草和小嵩草的重要值低(零星斑块分布),没有黑斑和秃斑出现。高寒草甸退化引起优势植物更替,地表黑斑和秃斑严重,封育和减牧措施能够有效恢复退化的草甸。

The main forage succession and ground surface characteristic changes during degradation and restoration of alpine Kobresia meadow

The change of soil surface characteristics during degradation and restoration of alpine Kobresia meadow was followed together with the important value changes of Kobresia pygmaea, K. humilis and Gramineae and of their patch dispersal. During degradation, the value of K. pygmaea was significantly more important than that of K. humilis and Gramineae(P＜0.05). In a transect, the coverage of K. humilis was rapidly reduced, the coverage of black patch increased to nearly double, and patches of K. pygmaea were widely dispersed. K. pygmaea is the dominant species in seriously grazed K. pygmaea meadow, and its importance is significantly higher than that of K. humilis and Gramineae(P＜0.05), the coverage of black patch increased, then collapsed. The emergency ratio of K. humilis patch is little. In the course of restoration, the importance of Gramineae increased, K. humilis was not common, and in the restoration patch, Gramineae became the dominant species while K. pygmaea nearly disappeared and the coverage of black patch and bald patch shrunk, but plant coverage increased. Gramineae became the dominant species in the better restoration meadow, and the importance of K. pygmaea and K. humilis decreased: there was no black patch or bald patch. Alpine meadow degradation resulted in a succession of dominant species, but black patch and bald patch were universal. Fencing and light grazing measures can effectively restore degraded meadows.