Effect of urbanization on the dynamics of ecosystem services: An analysis for decision making in Kolkata urban agglomeration

Urbanization has profound influence on the changes of land use and land cover, which on the other hand exert significant impact on ecosystem services and their values, especially in the urban agglomerations. Kolkata urban agglomeration of India has been selected to determine the causes in changes of ecosystem services under present and projected land use land cover scenario. Land use land cover maps of 1990, 2000, 2010 and 2020 were prepared by support vector machine method, using LANDSAT satellite imageries and projected up-to 2040 using CA–Markov model. Built-up land was increased by 65.39% during 1990–2020 and will further increase to 76.88% by 2040. Built-up lands are mainly encroaching crop lands and wetlands. During the period of fifty years (1990–2040), the ecosystem service value will decrease from $38,486.49 to $28,060.79, with annual rate of decrement of 0.54%. During the same period, the spatial extent of very low ecosystem service value will be increased from 16.60 to 58.88%; whereas, the area coverage of very high ecosystem service value will be decreased from 2.69 to 2.35%. Water supply contributed highest ecosystem service value followed by disturbance regulation and nutrient cycling; whereas, lacking in soil formation, pollination and biological control services contributed lowest. The study will help in decision making process for sustainable management of natural resources and also provide useful guideline for the quality improvement in urban ecosystems.