【摘要】 为了明晰金露梅（Potentillafruticosa）灌丛草甸植物群落对退化演替的响应,以空间代时间的方法,于2018年8月中旬在青藏高原祁连山南麓分别选取原生、中度、重度和极度4种不同演替阶段的金露梅灌丛草甸,对其植被群落进行研究,以探究金露梅灌丛草甸生态功能退化过程中植被群落及土壤养分的演变特征。结果表明,（1）随着退化程度的加剧,地上生物量和地下生物量现存量均呈逐渐减小趋势,且原生金露梅灌丛地上生物量（387.73±25.53）g?m^-2和中度退化样地（328.55±36.23） g?m^-2显著高于重度退化样地（210±35.04） g?m^-2和极度退化样地（182.19±49.99） g?m^-2（P<0.05）,放牧改变了植物群落结构,禾草和莎草地上生物量逐渐减小,而杂类草地上生物量逐渐增加。（2）与地上生物量相似,原生金露梅灌丛（48 46.01±747.10）g?m^-2和中度退化样地（4 723.99±505.64）g?m^-2地下生物量现存量显著高于重度退化样地（2 590.75±276.45）g?m^-2和极度退化样地（1 011.84±163.46） g?m^-2（P<0.05）,且随着退化程度的加剧,表层土壤全碳、全氮和有机质呈增加趋势,地下根系生物量趋于向表层土壤发展。（3）随着退化程度的加剧,群落物种丰富度逐渐下降,且原生金露梅灌丛和中度退化样地物种丰富度显著高于重度退化和极度退化样地（P<0.05）。此外,群落物种丰富度与地上生物量呈显著正相关（P<0.05）。研究表明,过度放牧会导致植被群落发生分化,物种丰富度下降,最终导致金露梅灌丛草甸退化为杂类草草地,甚至黑土滩次生裸地。研究结果对今后退化金露梅灌丛草甸的放牧管理具有重要的指导意义。更多还原

【Abstract】 We aimed to elucidate the characteristic of response of Potentilla fruticosa communities in the northern Qinghai-Tibet Plateau to degradation using the space-time substitution method. Three Potentilla fruticosa meadows at different stages of degradation（i.e., no degradation, moderate degradation, heavy degradation, and extreme degradation） located in the northern Qinghai-Tibet Plateau were selected for the experiment in mid-august 2018. We used these meadows to explore the response characteristics of the native plant communities when exposed to varying degrees of degradation. We found that both the aboveground biomass and belowground biomass of plant communities decreased as degradation became more severe; the aboveground biomass in no degradation（387.73±25.53） g?m^-2 and moderate degradation plots（328.55±36.23） g?m^-2 was significantly higher than that of heavy degradation（210±35.04） g?m^-2 and extreme degradation plots（182.19±49.99） g?m^-2（P<0.05）. In addition, we found that grazing-induced degradation significantly affected the structure of plant communities. The aboveground biomass of grass and sedge gradually decreased as grazing became more intense, while the aboveground biomass of forbs increased. Similar to the aboveground biomass, the belowground biomass in no degradation（4 846.01±747.10） g?m^-2 and moderate degradation plots(4 723.99±505.64 g?m^-2) was significantly higher than that of heavy degradation（2 590.75±276.45） g?m^-2 and extreme degradation plots（1 011.84±163.46） g?m^-2（P<0.05）. Furthermore, the total carbon, total nitrogen, and organic matter in the surface soil increased with grazing intensity, and the root systems tended to allocate more biomass to the surface soil as grazing intensity increased. Additionally,as degradation increasing, the species richness of plant communities decreased gradually, with the species richness of no degradation and moderate degradation plots being significantly higher than that of heavy degradation and extreme degradation plots. Our results suggest that overgrazing might lead to the differentiation of vegetal communities and a decrease in species richness, and might ultimately result in further degradation of native Potentilla fruticosa meadows into forbs meadows and possibly even lead to secondary infertility. Our results could be helpful for better management decisions concerning the conservation of Potentilla fruticosa meadows in future.更多还原