高寒草甸植物群落对牦牛和高原鼠兔干扰的短期响应研究OA

Yaks and plateau pikas are two key biotic disturbance agents affecting the structure and functioning of alpine meadow ecosystems on the Qinghai-Xizang Plateau.However,the individual and combined effects of these herbivores on plant community structure and niche characteristics remain poorly understood.In this study,a field-controlled experiment was conducted in the Zoige alpine meadow using four treatments:combined yak and plateau pika disturbance(+Y+P),plateau pika disturbance only(−Y+P),yak disturbance only(+Y−P),and no distur-bance by either yaks or plateau pikas(−Y−P).We evaluated the independent and interactive effects of these short-term disturbances on plant community composition,structure,and niche dynamics of dominant species.The results showed that:(1)Species diversity did not differ significantly among treatments,whereas yak disturbance significantly increased community light transmittance(P<0.05).(2)Yak disturbance significantly reduces the aboveground bio-mass of Poaceae(P<0.05).Yak disturbance,plateau pika disturbance,and their interaction all significantly affected the aboveground biomass of Cyperaceae,with the highest biomass observed in the treatment without herbivore dis-turbance(P<0.05).Under yak exclusion,plateau pika disturbance significantly reduces forbs aboveground biomass(P<0.05).Yak disturbance significantly decreases the proportional biomass of Poaceae while increasing the propor-tion of forbs(P<0.05).(3)Under combined disturbance,Kobresia humilis exhibited the widest horizontal niche breadth(Bi=2.90),whereas exclusion of yak resulted in a narrower niche breadth(Bi=1.00)and reduced relative resource occupancy(R<0).In the absence of herbivore disturbance,the proportion of species pairs with high niche overlap increases to 63.9%.Complete horizontal niche overlap occurred between Potentilla anserina and Gentiana macrophylla under combined disturbance(Oik=1.00).Overall,yak and plateau pika disturbances jointly regulate plant community structure and resource utilization patterns in alpine meadows.This study provides a scientific basis for early warning of herbivore-induced degradation in alpine meadow ecosystems.