| Species diversity distribution pattern and its influencing factors are important contents of conservation ecology,which is of great significance to biodiversity conservation.Zhangjiajie City,Hunan province,located in the northeast of Wuling mountains,is a priority area biodiversity conservation,with abundant amphibian species,but lacks systematic resource survey and distribution pattern research.In order to understand resource situation of amphibian in Zhangjiajie City and analyse the vertical distribution pattern and geographic pattern of amphibian's species richness,we used 10×10 km grid to divide Sangzhi county,Yongding district and Wulingyuan district of Zhangjiajie City into 56 grids.According to the principle of the accessibility,habitat integrity,and random,we selected 40 grids from 56 grids to carry out the field surveys of amphibians using line transect method from July to August 2019,September 2019,June to September 2020,and March to April 2021.Among them,the number of survey grids in Sangzhi County,Yongding District and Wulingyuan District of Zhangjiajie City was 22,16 and 2,and the number of the line transect was 71,40 and 7,respectively.The vertical distribution pattern of the amphibian was constructed by selecting the latter from the linear regression model and quadratic regression model.The composition differences of different altitudes were obtained by fuzzy cluster analysis,and the species richness distribution pattern and its influencing factors was predicted based on Maxent model with climate factors.The main results are as follows:(1)A total of 49 species of amphibians were recorded in Zhangjiajie city,belonging to 2 orders,10 families and 25 genera,accounting for 10.79%of the total amphibians in China.Among there were 43 species,10 families and 2 orders in Sangzhi County,30 species,2 orders,8 families in Yongding District,and 26 species,8 families,2 orders in Wulingyuan District.Leptobrachella wulingensis,and Odorrana sangzhiensis were two new species found in the field survey.There are five species of state second-class protected animals,namely pseudohynobius flavomaculatus,Andrias davidianus,yaotriton broadoridgus,leptobrachium Boringii,hoplobatrachus chinensis.In the study area,the pseudohynobius flavomaculatus and yaotriton broadoridgus were only distributed in Sangzhi County,Leptobrachium boringii was distributed in Sangzhi County and Wulingyuan District,Andrias davidianus and Hoplobatrachus chinensis were distributed in Sangzhi County,Wulingyuan District and Yongding District within the study area.(2)In terms of fauna,the amphibians in Zhangjiajie City are mainly common species from Central China to South China,mixed with common species from Central China and Central China to Southwest China.From the perspective ecological types,running water type(R)is dominant.In terms of degree of risk and protection grade,the amphibians in Sangzhi County are more threatened,followed by Wulingyuan District and Yongding District.From different regional diversity,the species diversity of amphibians in Wulingyuan District are the highest;the species richness of amphibians in Sangzhi County is higher than that in Yongding District,but the diversity and evenness are lower than that in Wulingyuan District.The results of grid diversity comparison showed that the highest species diversity was in the northwest and central in Zhangjiajie City.(3)The amphibians in Zhangjiajie City are mainly distributed below the altitude of 900 m,and the number of amphibian species in Zhangjiajie City is more than 24,and the number of species reaches the peak at 500-700 m.The main distribution habitats of amphibians in Zhangjiajie City is river and evergreen broad-leaved forest.Among them,Polypedates megacephalus,quasipaa spinosa,Odorrana schmackeri,Bufo gargarizans gargarizans,Andrias davidianus are the most widely distributed,with range of above 1 300 m,while Odorrana chloronota,Odorrana sangzhiensis,Boulengerana guentheri,Rhacophorus leucofasciatus are the least,with range of below 300 m.The altitudinal pattern is mid peak by fitting curve of quadratic regression,and the equation of regression just only explain 10%(R2=0.1021).The results of cluster analysis showed that there was different in amphibian species composition between different altitude.(4)The max temperature of warmest month(BIO2),the mean diurnal range(BIOS),and precipitation of driest quarter(BIO 17),and precipitation of coldest(BIO19)were selected by PCA for to build the model.The highest species richness in Zhangjiajie City is in the northwest of Sangzhi county,with the highest number of species ranging from 12 to 15,followed by the northeast of Sangzhi County,the southeast of Yongding District and the east of the middle of Wulingyuan District,with the highest number of species ranging from 8 to 12.The comprehensive results showed that the areas with higher amphibian richness in Zhangjiajie city were in the northwest and southeast.The Jackknife results showed that the top three factors of percentage contribution were the max temperature of warmest month(BIO5),the precipitation of driest quarter(BIO17)and the mean diurnal range(BIO2),the distribution of percentage contribution were 49.94± 40.34%,20.07 ± 28.29 and 18.33 ± 32.46,respectively,and the permutation importance was 54.24 ± 40.32,13.87± 24.08 and 19.75 ± 32.32.According to the current situation of high endangered degree,insufficient protection and lack of long-term monitoring of amphibians,the following suggestions are put forward:? enhancing habitat protection;? strengthening law enforcement;?accelerating the establishment the small nature reserve;? carrying out long-term monitoring;?strengthening publicity and education. |
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