A spatial ecological assessment of fragmentation and disturbance effects of infrastructure construction and land conversion in Gunung Halimun Salak National Park, Indonesia

Habitat loss and fragmentation have been identified as one of the sources of biodiversity loss. Those issues are predominantly triggered by human activities such as the development of settlements, conversion of forest habitat into agricultural areas, and the development of infrastructure such as transportation and pipelines. Gunung Halimun Salak National Park (GHSNP) as one of the protected areas in Indonesia is deforested each year by approximately 1,473 ha or 1.3% of the total area while the capability of GHSNP to rehabilitate the degraded forest is only 500-800 ha annually because of a limited budget and at the shortage of human resources. The focus of this study was primarily on an ecological assessment of landscape scale habitat impacts on mammals and birds caused by infrastructure construction and land conversion. This was accomplished, by firstly identifying the current land cover and land cover change over a 15-year periods within the study area, GHSNP, Indonesia, as a case study; secondly, by assessing a class-level landscape metrics and their changes to detect forest fragmentation over a 15-year period within GHSNP; and finally, by analysing changes in the habitat network caused by fragmentation, land conversion, and disturbance. The potential effects on wildlife were also discussed, including how to derive and interpret such fragmentation effects and disturbance by applying Geographical Information System (GIS)-based quantitative modelling. Results of this study show that land cover in GHSNP has changed drastically with Forest and Agriculture experiencing the biggest decrease and increase by 35.63% and 463.74% respectively. It was also found that landscape metrics for forest cover in GHSNP show changes with a decrease in class area (CA), patch size (MPS), patch size coefficient of variation (PSCoV), mean shape index (MSI), mean core area (MCA) and mean proximity index (MPI) and an increase in number of patch (NP) and edge density (ED). These suggests that the forest cover in GHSNP has been fragmented for the past fifteen years. Regarding the effects of fragmentation and disturbance on mammals and birds, the responses of the forest-grassland mammals (high area and medium area demands), forest mammals (area below 1500 metres above sea level and area above 1500 metres above sea level and bird profiles (forest area) were similar to each other, with class area (CA) and number of patches (NP) being reduced as a response to both effects, except for small mammals requiring forest area below 1500 metres above sea level, which underwent a relatively huge increase in the number of patch for the disturbed area. Nevertheless, among all Ecological profiles established, mammals having a high area demand are considered to be most impacted from fragmentation and disturbance effects.