The Human Appropriation of Ecosystem Service Values (HAESV) in the Sundarban Biosphere Region Using Biophysical Quantification Approach

Human appropriation, especially unusual changes in land-use and land cover, significantly affects ecosystem services and functions. Driven by the growth of the population and the economy, human demands on earth's land surface have increased dramatically in the past 50 - 100 years. The area studied was divided into six major categories; cropland, mangrove forest, sparse vegetation, built-up urban area, water bodies and sandy coast, and the land coverage was calculated for the years 1973, 1988, 2002 and 2013. The spatial explicit value of the primary regulatory and supporting ecosystem services (climate regulation, raw material production, water regulation) were quantified through the indirect market valuation approach. A light use efficiency based ecosystem model, i.e. Carnegie- Ames-Stanford-Approach (CASA) was employed to estimate the carbon sequestration and oxygen production services of the ecosystem. The ArcGIS matrix transform approach calculated LULC dynamics among the classes. Investigation revealed that the built-up urban area increased from 42.9 km2 in 1973 to 308 km2 in 2013 with a 6.6 km2 yr-1 expansion rate. Similarly, water bodies (especially inland water bodies increased dramatically in the north central region) increased from 3392.1 sq.km in 1973 to 5420 sq.km in 2013 at the expense of semi-natural and natural land resulting in significant changes of ecological and ecosystem services. However, the area occupied by dense mangrove forest decreased substantially during the 40 years (1973 -2013); it was recorded to cover 2294 km2 in 1973 and 1820 km2 in 2013. The results showed that the estimated regulatory and supporting ecosystem services respond quite differently to human appropriation across the regions in both the economic and ecological dimensions. While evaluating the trade-of between human appropriation and ecosystem service changes, it has been estimated that the ecosystem service value of organic matter provision services decreased from 755 US ha-1 in 2000 to 608 US ha-1 in 2013. Therefore, the rigorous and centralised policy for sustainable and regionally balanced land-use planning has been essential in the recent era for economic viability, and ecosystem preservation, to prevent undesirable outcomes.