Study Of The Relationship Between Amphibians’ Distribution And Environmental Factors At Multi-scale In Agricultural Region On The Lower Reaches Of The Yellow River,China

In the agricultural landscape of the lower reaches of the Yellow River,it is very important to protect the habitat and maintain the amphibians according to study the environmental factors that affecting the distribution of amphibians.In this study,taking Fengqiu County,Xinxiang City,Henan province as the study area,based on the different habitat types of amphibians’ survival and reproduction,we investigated the distribution of amphibians in ponds.The environmental variables of habitat scale include: p H(hydrogen ion concentration),turbidity(TURB),total phosphorus(TP),dissolved oxygen(DO),chemical oxygen demand(COD),emergent coverage(EMER),pond-interior vegetation coverage(VEGinterior),pond-edge vegetation coverage(VEGedge),pond depth(PD),benthic fauna predators(PRE).According to the different migration and dispersal ability of the amphibians,we divide into four distance thresholds on landscape scale: 250 m,500 m,1000 m and 2000 m,and the landscape variables include: patch density(PD),largest patch index(LPI),landscape shape index(LSI),contagion index(CONTAG),landscape division index(DIVISION),aggregation index(AI),Shannon’s Diversity index(SHDI),Simpson’s Diversity Index(SIDI),Shannon’s Evenness Index(SHEI),Simpson’s Evenness index(SIEI).The results show that:(1)The study found that the amphibians including Bufo gargarizans,Palophylax nigromaculata,Palophylax plancyi,Fejervarya limnocharis and Kaloula borealis.Pond-interior vegetation coverage(VEGinterior)is the sum of emergent plants coverage,floating plants coverage and submerged plants coverage,pond-edge vegetation coverage(VEGedge)is the total land coverage of buffer zone around the pond(about 5 m),benthic fauna predators(PRE)mainly prey on the eggs and tadpoles of amphibians.(2)The environmental factors of habitat scale are mainly water quality variables,vegetation variables,pond morphological variables and benthic fauna predators variables.We analyzed the correlation between the relative abundance of different amphibian species and amphibians and the optimal habitat environment variables,and the results show that: B.gargarizans and TURB showed a significant correlation(p=0.01974),P.nigromaculata,P.plancyi and EMER significantly correlated(p=0.0471,p=0.0369),there was a correlation between F.limnocharis and EMER(p=0.0578).The environmental factoral that affecting amphibian species were different in four habitat types.In the semi natural ponds,P.plancyi was significantly correlated with EMER and VEGinterior(r=0.597,r=0.628),P.nigromaculata was significantly associated with PRE(r=0.546).In the farmland habitat types,P.plancyi was significantly correlated with VEGinterior and EMER(r=0.764,r=0.719),B.gargarizans and PD showed a significant positive correlation(r=0.786).In the Lotus Ponds,P.plancyi and PD showed a very significant positive correlation(r=0.943).In the adjacent residential ponds,B.gargarizans and TURB has a very significant positive correlation(r=0.852),there was a significant correlation between P.plancyi,P.nigromaculata and PRE(r=0.725 r=0.728).(3)In the landscape scale: the correlation analysis of landscape scale environmental factors and amphibians under four dispersal distances shows that: under the 250 m dispersal ability,P.nigromaculata,amphibians relative abundance and LSI has significant correlation(r=0.423,r=0.423);under 500 m dispersal ability,amphibians relative abundance and LSI significantly correlated(r=0.325);when the disperal ability is 2000 m,the relationship between B.gargarizans and SHEI was significant(r=0.339).Therefore,the conservation and management of amphibians should be carried out on the habitat scale as well as landscape scale at the same time.At the habitat scale,it can protect the good hydrological condition of the habitat and reduce the water pollution,especially increase the plant coverage in and out of the ponds and the coverage of the emergent plants.On the landscape scale,different measures should taken according to the different dispersal ability of amphibians.In order to form a good connection between dominant patch types,we should increase the degree of aggregation of different patch types in landscape,especially the degree of aggregation between the pond patches.It suggests that in ordertopromote the protection of amphibian biodiversity and habitat in agricultural landscape,what we should do is change the space of habitat patches,short the average distance between ponds,reduce the degree of isolation between the pond habitat and the interference of human activities,or create new habitat through restoration measures,keep the existing pond patches.