Analysis of Forest Cover Loss in Wilpattu forest complex: a remotely sensed change detection and fragmentation analysis

Abstract

Wilpattu Forest complex is the largest protected area in Sri Lanka and it is a designated Ramsar wetland cluster. It contains a range of diverse terrestrial habitats including various forest types and a coastline with large coastal sand dunes. However, this vital ecosystem is under threat of fragmentation and degradation due to increasing human interventions. Habitat fragmentation is a serious threat to the rich biodiversity in this ecosystem. The objective of this study was to assess the loss of forest cover within the region, to examine the spatial pattern of forest cover fragmentation and to predict the potential forest cover change in 2025 using remote sensing and GIS techniques. Two Landsat 5 TM satellite images of 1992 and Landsat 8 OLI-TIRS image of 2018 were classified using unsupervised and supervised techniques to obtain three land use/ land cover classes namely, forest, non-forest and water. Forest cover change during 1992 and 2018 was analysed using classified images. Finally, future changes were modelled to assess possible threat to the forest cover. The analysis revealed that Wilpattu forest complex has lost 19,524 ha of its forest reserves to other land uses within the last 26 years and the highest impact was seen in the upper Wilpattu forest where about 7.48% area has lost from forest to other land uses. Study also proved that the total forest area is becoming more fragmented affecting the balance of the valuable natural ecosystem of the area. Lack of availability in proper forest boundaries and classification issues were identified as main limitations in this study. However, it must be emphasized that immediate actions are needed to prevent further degradation of this sensitive ecosystem.