Impac of Mikania Micrantha on the forage availability and use of Chital (Axis axis) in northern part of Chitwan park Nepal

Abstract

Mikania micrantha has been creating serious problem in protected areas by invading natural habitats and threatening to biological diversity and ecosystem services. It has decreased the forage availability of herbivore species. The study was conducted in northern part of Chitwan National Park from October 2021 to January 2022 to assess the impact of Mikania micrantha on forage availability and use of Chital. GPS coordinates were taken on each 5*5 m quadrate and Mikania micrantha cover percentage was calculated by visual estimation. The GPS coordinates were interpolated in ArcGIS 10.7 for IDW measurement and prominence value of each study site was calculated for abundance of Mikania micrantha. Riverine forest was found to be most invaded habitat by Mikania micrantha with 76% of the studied plot covered with Mikania micrantha followed by Grassland with 70% and Sal forest was least invaded with 56% of plot studied had Mikania micrantha presence. IDW of each study area and prominence value showed that Icharni Island had highest abundance of Mikania micrantha and least abundance was seen in Chitrasen. Microhistological technique was used to determine the diet of Chital. Microphotographs of 101 plants was prepared and 1260 fragments of 42 pellet sample was analyzed. A total of 49 species of plants belonging to 24 family was constituted in the diet of Chital. The animal fed on 12 grass species, 11 shrub, 17 tree species, 6 forbs and 3 climbers. Grass contributed 56% while browse contributed 39% in the diet of Chital. Imperata cylindrica was the most occurred plant species in the pellet of Chital indicating it as most important food of the animal. Dietary niche breadth of Chital was lowest in Icharni Island (0.394) whereas it was highest in Chitrasen Community Forest (0.632). The Jacob’s electivity index showed most preference to grasses by chital. Linear regression analysis revealed that increase in Mikania micrantha cover percentage decreased the cover percentage of native forage. The invasion impact of Mikania micrantha was observed in Riverine forest along the forest edge. The understory shrubs of riverine forest was most affected by the invasion of the plant. Grassland was smothered by the Mikania micrantha restricting its growth. Sal forest was least affected by it.