Analysis on the Space and Population Variation of Bullfrogs in Lalu Wetland,Xizang

Zhu Wenjin; Li Jixiang; Wei Lishi; Ciwang Baji; Pubu

doi:10.3969/j.issn.1004-3403.2025.04.003

Abstract：Biological invasion has now become a global hot issue.Since the publication of the first list of invasive species in China in 2003,the American bullfrog has established a natural population in the wild environment of most areas in China,causing serious ecological and environmental problems.Located on the Qinghai-Tibet Plateau,Lalu Wetland is characterized by high altitude and fragile ecological environment,which plays an important role in main-taining the ecological balance of Lhasa.In order to understand the population and living environment of bullfrogs in Lalu Wetland,a survey was carried out here from May to July,2021.The field survey mainly adopted the line tran-sect method.Habitat preference coefficient was used to analyze the characteristics of bullfrog's habitat selection,and their population trend was predicted based on survey results.The results showed that bullfrogs in Lalu wetland were concentrated in three areas:the grass pond at the northern gate,the pedestrian path of Luding North Road in the cen-tral-western wetland and the entrance and exit of Dangre West Road in the south,displaying a trend of gradual ex-pansion,The overall population density of bullfrogs was not high according to the four sampling sites.The highest population density was observed at the northern gate(ρ=0.016),(ρ=0.005)followed by the entrance and exit in the south,and the pedestrian path(total length at 500m)in the central-western wetland showed lower population density(ρ1=0.001,ρ2=0.004).By analyzing the characteristics of bullfrogs'habitat selection,it was found that bullfrogs pre-fer still water,relatively shaded areas,moderate water temperature(12～25℃),higher ambient temperature(15～30℃),shallow water depth(30～60 cm),high herb coverage(>80%),moderate herb height(40～80 cm),close dis-tance from roads(≤50m),moderate distance from residential sites(100～200 m),close distance from large water bodies is(≤50 m).Despite the slow growth in population at present,according to the information of bullfrogs'di-etary habits,population number and living state,it is inferred that they have occupied a niche in the Lalu Wetland ecosystem,posing potential threats.Bullfrogs in the wetland should be monitored to prevent them from causing irre-versible damage to the the Lalu Wetland ecosystem.