The Vertical Distribution Pattern And Species Diversity Of Non-flying Small Mammals In The Lebu Valley Of Xizang,China

The Lebu Valley region of the Eastern Himalayas,located in the eastern foothills of the Himalayas known as the roof of the world,has unique and diverse biomes and ecosystems and plays an important role in the protection of global ecology and biodiversity.The species diversity composition and vertical distribution pattern of non-flying small mammals are important components of biodiversity in the Lebu Valley area.As the vertical distribution pattern of species diversity along the altitude gradient has received extensive attention in biodiversity research and protection,the previous conclusions about the composition of species diversity and the vertical distribution pattern of space can be roughly divided into four types,namely: rich The pattern of monotonous decreasing degree with increasing altitude,that is,monotonic decreasing richness patterns;low altitude level and then monotonous low altitude first increasing and then monotone decreasing pattern,That is,low plateau patterns with a mid-elevation peak;the single-peak pattern with the highest mid-altitude,that is,mid-elevation peaks.Among them,the peak pattern is the most common and common pattern among the four types of vertical distribution of species diversity of each animal group,accounting for 45%.The Himalayas is located on the southern edge of the Qing-Tibet Plateau.Its southern wing valley is a typical mountain ecosystem with an altitude difference of more than 6 000 m.It has rich habitat types and unique biological groups.It is a hotspot area for biodiversity research and protection.Located in the eastern foothills of the Himalayas,Lebu Valley in Cuona County,Tibetbelongs to the eastern Himalayas,with an altitude difference of more than 6 500 m and rich vegetation types.region.In natural ecosystems,small mammals are characterized by many species,large biomass,wide distribution,and short reproduction cycles.Most terrestrial ecosystems are distributed,which plays an important role in energy transfer and material circulation.Therefore,small mammals Classes have become an important research object in the study of vertical distribution patterns.Some scholars have conducted investigations on non-flying small mammals in the Lebu Valley area.For example,Wang Dalin et al.(1995)conducted a small mammal survey in the Cuona area of Tibet from June to July 1993.The survey area included Lebu Valley,but due to the lack of comprehensive and in-depth research,there is no discussion on the vertical distribution pattern of species diversity of small mammals.Hu Yiming et al.(2018)The vertical distribution pattern of mammalian species diversity in the Himalayas involves mammal surveys.In order to better grasp the resource status of non-flying small mammals in this area,as well as the species composition and spatial vertical distribution pattern,for this purpose,a field survey was conducted in the Lebu Valley area of the eastern foothills of the Himalayas to analyze the non-flying small mammals in the area Species distribution and floristic composition,in order to discuss the vertical distribution pattern of species diversity of non-flying small mammals in the southern wing valley of the East Himalayas and whether it conforms to the most common distribution pattern in the mid-region,and to analyze the main influencing factors of the distribution pattern.The study of the pattern of the vertical gradient of biodiversity in high-altitude areas provides more basic data sources and references,and shows the biodiversity and vertical distribution patterns of non-flying small mammals in this important area to the world.We conducted a field survey of non-flying small mammals in the Lebu Valley,East Himalayas,and completed the following research contents at the regional and local scales:(1)Species diversity group of non-flying small mammals in the Lebu Valley(Local scale);(2)fauna composition of non-flying small mammals in Lebu Valley area(local scale);(3)vertical distribution pattern of species diversity of non-flying small mammals in Lebu Valley area(local scale);(4)According to the results of the vertical distribution pattern of non-flying small mammals in the Lebu Valley area and related studies in the East Himalayas,speculate the characteristics of the vertical distribution pattern of non-flying small mammals in the entire East Himalaya and analyze the key factors of its impact(Regional scale).From July 2018 to August 2019,two field surveys and studies were carried out on the Everest Reserve,and the selected research altitude range was 2 300-5 000 m.A total of 45 sample plots with 9 300 m altitude sections were continuously set along the altitude gradient.The total number of cloth clips is 16 200,and the field investigation work is 65 days.The specific results are as follows:(1)A total of 372 specimens were collected in this investigation,which belonged to 3 orders,5 families and 10 species,namely: rodents,gray-bellied rats(Niviventer eha);Alticola stoliczkanus;and needle-hair rats(Niviventer fulvescens);White-bellied squirrel to be determined1(Niviventer sp.);White-bellied squirrel to be determined 2(Niviventer sp.);Yellow-breasted rat(Rattus tanezumi);Orange-bellied squirrel(Drmomys lokria),Laura worm Order,long-tailed shrew(Soriculus caudatu);large-clawed long-tail shrew(Soriculus nigrescens),lagomorpha,Tibetan pika(Ochotona thibetana).Among them,two species to be determined were captured at the altitude of 2,300-2,900 m,which are the white-bellied rat to be determined species 1Niviventer sp.And the white-bellied rat to be determined species 2 Niviventer sp.Further mitochondrial DNA Cytb gene sequence identification.(2)The flora and protection level of all specimens are respectively the gray-bellied mouse Niviventer eha,protection level-(LC);Alpineola stoliczkanus protection level-(NT);Niviventer fulvescens protection level-(LC);White-bellied Rats: To be determined 1 Niviventer sp.Protection class(unknown);Long-tailed shrew Soriculus caudatu Protection class-(LC);Large-clawed long-tailed shrew Soriculus nigrescens Protection class-(LC);White-bellied rat Species 2 Niviventer sp.Protection level-(unknown);Yellow-breasted rat Rattus tanezumi protection level-(VU);Tibetan rat rabbit Ochotona thibetana protection level-(VU);Orange-bellied squirrel Drmomys lokria protection level-(VU).In terms of the division of zoogeographical fauna in China,the 10 species recorded this time,except for the two unknown species unknown,belong to 2 species in the Eastern Realm and 8 species in the Paleo-Northern boundary,and 1 species unique to China.(3)According to the results of the sampling survey of Lebu Valley,the observed species richness is the highest at 2 600-2 900 m above sea level.After reaching the peak,the curve shows a gradual decreasing trend and rises to 3 800-4 100 m above sea level But it is not obvious,it tends to be gentle after 4,400 m,and interpolation is carried out(interpolation is carried out on therange of species' altitude distribution during the analysis,that is,a species is considered to be continuously distributed between its highest and lowest elevation)The later abundance also showed a decreasing trend.Compared with the observed species,the abundance decreased slightly at an altitude of 2 900-4 100 m.The vertical distribution pattern of non-flying small mammals was a mid-peak pattern.The results of the study showed that the species richness of non-flying small mammals in the valley peaked at an elevation of 2 600-2 900 m,and then decreased with the increase of elevation,that is,from the lowest elevation to the middle elevation,the peak began to decrease to the trend shows the characteristics of the mid-peak pattern.The Middle Himalayan and East Himalayas have similar physical geography and climatic conditions.Therefore,we believe that the vertical distribution pattern of small mammals in the East Himalaya Valley may also conform to the mid-peak pattern.The east-west trend of the Himalayas has led to the similar geographical and climatic characteristics of the valleys in the south wing.For example,the valleys have a north-south trend,affected by the Indian Ocean warm current climate,and have a similar vertical vegetation distribution.The vertical distribution exhibits similar characteristics.Therefore,it is believed that under the background of the high-altitude region in the East Himalayas,geographic and climatic conditions may be the key factors affecting the vertical distribution pattern of species diversity.