草地群落放牧干扰梯度β多样性研究

β diversity of grassland communities along gradient of grazing disturbance.

放牧过程通过牲畜的啃食、践踏作用干扰草场环境，使草地群落的物种组成发生变化，植物种群的优势地位发生更替．结果表明，随放牧干扰强度加重，从盐湿化草甸到典型草原，群落植物种丰富度呈下降趋势．β多样性测度结果显示，盐湿化草甸和羊草杂类草草甸群落物种变化的中度干扰出现在轻牧→中牧阶段，并在整个放牧干扰进程中，表现较低的稳定性；草甸草原和典型草原群落出现在中牧→重牧阶段；而荒漠草原物种变化表现出高度的稳定性，从轻牧到过牧物种替代仅１～３种．

razing disturbs grassland environment through gnawing and treading of livestock, which changes species composition and population's dominant. This study showed that the species richness in communities gradually decreased with the aggravating of grazing intensity from saline moist meadows to typical steppe communities. The measurement of β diversity showed that on saline moist meadows, the intermediate disturbance of species change occurred during the course of light to moderate grazing stage, with a low stability during the whole grazing; while on meadow steppes and typical steppes, it occurred during the course of moderate to heavy grazing stage. Desert steppe showed a high stability throughout grazing system, and the species change from light to over grazing was only 1～3. The stability of grassland community diversity was as follows: desert steppe>typical steppe≥meadow steppe>saline moist meadow.