ECOLOGICAL CONSEQUENCES OF REALLOCATING LANDS FOR ANTHROPOGENIC ACTIVITIES FROM A LONG- ABANDONED TANK CASCADE

Abstract

bstract: Years of civil war and unsupportive infrastructure forced most of the cas- cade systems in the northern regions of Sri Lanka to be abandoned for decades. Ab- sence of anthropogenic activities, chiefly agriculture, let these regions to flourish to- wards late pioneer to climax successional state, and reestablish as a secondary forest landscape. The objective of this study was to identify ecological impact of human settlement plans with a crop-animal based agroecosystem in a late successional land- scape in a tank cascade. The study area was located in the upper catchment of Pa- daviya tank cascade system bordering the Northern Province. A Visual Encounter Survey was conducted for identifying ecological resources, floristic and faunal rich- ness and vegetation/habitat types and a bio-diversity survey was carried out by op- portunistic and randomized walks within the area. The flora species were recorded against their habitats. Vertebrate fauna species of mammals, reptiles, birds, and am- phibians were recorded separately, while some visible invertebrate groups were rec- orded based on both direct and indirect evidence. The majority of the vegetation be- longs to secondary forests, tropical dry mixed evergreen forests, tropical scrubs, and rock-out crops. The vegetation comprised with 187 floral species, while 157 were found to be native and eight were identified as endemic. Within the region, 20 threat- ened or nearly threatened species were observed, and the 20 exotic species found uncovered the footprints of past anthropogenic activities. Diospyros nummulariifolia, Cryptcoryne wendtii and Polyalthia suberosa were exclusively found within the re- gion. Recorded faunal species number was 126 with 22 mammal species, which in- cluded eight threatened or nearly threatened mammal species. The habitat stretched over 500 hectares, thus human settlements would inevitably lead to loss of forest cover and faunal habitats, depletion of threatened and endemic species, interference to migratory pathways including elephants, soil erosion, water pollution leading to human-elephant conflict. Keywords: Endemic; Faunal richness; Floral species; Huma