Sprawling crisis? - Urbanization from the perspective of protected areas near Kolkata, India

Kurzfassung

India is one of the fastest urbanizing countries worldwide. Within the predicted future population growth, the urban population will be the key driver. This study provides sound methodology for the spatiotemporal analysis of the relationships between human settlement expansion and protected areas (PAs). The expansion of the megacity Kolkata and of other urban areas in its surroundings is analyzed over four time steps (1977, 1989, 2000, and 2010) to detect the dimension and the direction of their advances towards three PAs: two small wildlife sanctuaries and the Sundarban Tiger Reserve in the Sundarban mangrove forests. Landsat imagery was selected to provide a long time-series and to simultaneously cover a large spatial extent. In addition, the study presents a classification procedure which uses the same medium-resolution Landsat data to assess the development of rural settlements in the study area. Human pressure on protected areas is steadily increasing in the study area as distance between urban areas and PAs decreases. The results show that all urban areas expanded dramatically, and that the proximity between urban areas and the investigated PAs increased in two of the three cases. While the development of Kolkata is the most pressuring urban area for two of the PAs, in one case smaller urban areas are more important. In addition a significant areal increase of the rural settlements was detected. For the two sanctuaries, urban areas and rural settlement already cover a large area in their closest surroundings, and human influences are already very high due to the nature of their protection. Rural population mainly affects the Tiger Reserve through resource extraction of timber and non-timber forest products for subsistence. However, poaching, for example, is also triggered by the demand for resources from urban areas. The proximity between these and the reserve increased by about 10 km over the four time steps. The results exemplify the increasing vulnerability of PAs with respect to the increasing human dominance in their surroundings. Earth observation data and adequate methodology can provide relevant and large-scale information on the development of human settlements to assess potential risks for nature conservation.