Li Lin, Xingliang Xu, Guangmin Cao, Fawei Zhang, Yikang Li, Bo Fan, Qian Li, Junjie Huang
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引用次数: 0
Abstract
Abstract Background Due to the effects of climate change and overgrazing in recent decades, alternative stable states in the alpine Kobresia meadow degradation process have coexisted in the same geographical and climatic environment, with variations occurring among microsites. Methods We used a space‐for‐time substitution approach to explore the synergies of microsite variation according to its numerical characteristics and the proportion of each stable state at various stages of succession in alpine Kobresia meadows on the Qinghai–Tibetan Plateau. Results (1) The highest average aboveground biomass in summer was 196.2 ± 20.3 g m −2 , with significantly higher levels of biomass in ≤3.65 sheep unit ha −1 than in other levels of grazing intensity, while the parameters showed no significant differences among grazing intensity levels in >3.65 sheep unit ha −1 . (2) The importance of plant functional groups, aboveground biomass, and niche breadth of Poaceae and Cyperaceae significantly decreased as the grazing intensity increased. (3) The effects of ≥0°C accumulated temperature, total precipitation, altitude, longitude, and latitude cumulatively contributed less than 20% of the variation in the distribution of functional group characteristics across microsites. Conclusions (1) Overgrazing decreases primary production in alpine Kobresia meadows, but ecosystem responses regulate plant community structure and botanical components so as to partially counteract grazing disturbance. (2) Overgrazing changed the proportion of microsites, which in turn led to regime shift in the plant community and subsequent synergies between the microsites of plant communities and their stable states.
近几十年来,由于气候变化和过度放牧的影响,高寒矮林草甸退化过程在相同的地理和气候环境中存在多种稳定状态,但不同的微站点之间存在差异。方法利用空间-时间替代方法,从微站点变化的数值特征和演替不同阶段各稳定状态所占比例等方面探讨微站点变化的协同效应。结果(1)夏季平均地上生物量最高,为196.2±20.3 g m−2,≤3.65羊单位ha−1放牧强度下的生物量显著高于其他放牧强度,≤3.65羊单位ha−1放牧强度下各参数差异不显著。(2)随着放牧强度的增加,禾科和苏科植物功能群的重要性、地上生物量和生态位宽度显著降低。(3)≥0℃积温、总降水量、海拔、经度和纬度对微点间功能基团分布的影响小于20%。结论(1)过度放牧降低了高山矮嵩草草甸的初级生产,但生态系统响应调节了植物群落结构和植物成分,从而部分抵消了放牧干扰。(2)过度放牧改变了植物群落微站点的比例,从而导致植物群落微站点的制度转变,从而导致植物群落微站点与其稳定状态之间的协同作用。