关键词: 高寒草甸, 物种重要值, 返青期休牧, 生态位宽度, 生态位重叠

Abstract: We studied the effects of rest grazing on plant niches in an alpine meadow. In the study,five rest-grazing periods in the spring were set and named 0 d (grazing),20 d,30 d,40 d,and 50 d in Maqin County,Guoluo Prefecture,then we monitored and calculated the importance values of major species in plant communities under various grazing treatments for two consecutive years. Simultaneously,we studied the effects of resting grazing time on niche width and niche overlap of alpine meadow plant species by using rest grazing time as the environmental gradient. The results showed that:Compared with grazing,the most significant increase in importance value was Anaphalis lactea and Elymus nutans,which increased by 455.6% and 106.3%. The niche widths of Kobresia pygmaea (0.997),Ajania tenuifolia (0.995),and Scirpus distigmaticus (0.993) were the highest;The top three niche overlap values were Kobresia pygmaea and Lancea tibetica (0.997),Kobresia pygmaea and Poa pratensis (0.996),Scirpus distigmaticus and Kobresia pygmaea (0.996),Elymus nutans and Poa pratensis(0.995). It can be seen that under the treatment of 40 days of rest grazing,the growth of cyperaceae and poaceae plants was promoted,while the growth and development of poisonous weeds were inhibited. Therefore,the species with higher importance values tended to have large niche width.

Key words: Alpine meadow, Importance value, Rest grazing, Niche width, Niche overlap