Abstract:

The aim of this work was to explore the pattern of changes in aboveground vegetation and the characteristics of the underground bud bank in plateau pika （Ochotona curzoniae） mounds and their peripheries after different restoration periods in the alpine meadow at the northern slope of the Qilian Mountains. Analyses of aboveground vegetation and the underground bud bank were conducted for plateau pika mounds at four stages of restoration； new mounds， old mounds， abandoned mounds， and native vegetation （as the control）. The results show that： 1） The underground bud bank of the mounds included three types of buds， namely tiller buds， rhizome buds， and root sprout buds， with rhizome buds and tiller buds being the dominant types. 2） The number of plant species colonizing the bare patches of the mounds gradually increased as the restoration period for the mounds became longer. The species richness， vegetation cover， and plant density of the aboveground vegetation， as well as the number of species and total density of the underground bud bank in the mounds showed the same trends across different restoration stages； that is， new mounds<old mounds<abandoned mounds<native vegetation （control）. Moreover， there were extremely significant differences in the values of those parameters among the mounds at different restoration stages； 3） For the peripheral areas of the mounds， there were no significant differences in the species richness， vegetation cover， or plant density of the aboveground vegetation， nor were there significant differences in the number of species and total density of the underground bud bank among mounds at different stages of restoration， and the vegetation characteristics of the mound edge areas were consistent with those of the native vegetation； 4） The number of species in the underground bud bank of the mounds was extremely significantly and positively correlated with that in the underground bud bank of the mound edge areas. The species richness， vegetation coverage， and plant density of the aboveground vegetation in the mounds were extremely significantly and positively correlated with the number of species， total bud density， number of tiller buds， and number of rhizome buds in the underground bud bank in the mounds； positively correlated with the total bud density and number of tiller buds of the underground bud bank in the mound edge areas； and extremely significantly and negatively correlated with the number of rhizome buds of the underground bud bank in the mound peripheries. The alpine meadow at the northern slope of the Qilian Mountains has relatively low temperatures and abundant precipitation. The presence of pika mounds alters the original relative competition intensity of the grassland， allowing for natural restoration of vegetation and renewal of grassland vegetation by regulating the composition （proportion） of the underground bud bank in the mounds and their peripheries. This has a profound impact on the structure and dynamics of grassland plant communities and on ecosystem functions.

Key words: alpine meadow, plateau pika, mound degraded area, bud bank characteristics