Herpetofaunal assemblage of ramaroshan wetland complex, Achham, Nepal

Abstract

Herpetofauna are key bio-indicators of environmental health and habitat quality and are useful to assess habitat conditions of threatened ecosystems. Herpetofaunal diversity along elevational gradient in Nepal has rarely been studied. This study was carried out in Ramaroshan Wetland Complex (RWC) of Achham District, Sudurpaschim Province, Nepal which is one of the threatened wetlands due to anthropogenic activities. It aimed to explore the land use and land cover (LULC) changes in the RWC quantifying the area of wetlands and document the diversity and distribution pattern of herpetofauna. The LULC in the area (13.94 Km 2 ) was analyzed for 1989, 2000, 2010 and 2021 using supervised classification of remote sensing images from United States Geological Survey (USGS) geo-portal. Herpetofaunal survey were conducted by line-transect and opportunistic survey. Environmental variables such as nearest distance to the settlement, nearest distance to water, elevation, habitat type, etc. were measured along each transect. LULC analysis showed a considerable change in the land use pattern of the RWC from 1989 to 2021. Among major five LULC classes, vegetation (39%) was the dominant. The results demonstrated that there was a decrease in barren land, grassland and water body by 2% each from 1989 to 2021. Agricultural land and vegetation were increased by 3% and 2%, respectively. A total of 179 individuals of herpetofauna belonging to 11 species under five families and two orders i.e., Anura and Squamata, were recorded. Dicroglossidae family was the most dominant among them. The herpetofaunal community had Shannon-Wiener diversity index of H=1.88312 and evenness E=0.3642. Results showed that herpetofauna are not uniformly distributed along the elevational gradient (1401m to 2540m asl) of the RWC. The highest abundance of herpetofauna was found in agricultural land at an elevation of 2300m asl. Amphibian abundance increased with increasing distance to nearest water sources, whereas reptile abundance decreased with an increase in distance to water sources and increased with increase in distance to settlement. The study concluded that the wetland in the RWC is declining and herpetofaunal community in the area has low diversity.