runoff from each sub watershed. The model determines the amount of water running off each pixel as the precipitation less the fraction of the water that undergoes evapotranspiration. 2) Sediment retention Sedimentation is a natural process that contributes to healthy ecosystems, but too much may have severe consequences 16. The sediment retention module in the InVEST uses the Universal Soil Loss Equation (USLE) 18 together with sediment approach for sediment deposition, both at grid cell scale. 3) Carbon storage Carbon stocks in different land covers were estimated using the InVEST model, that requires an estimate of the amount of carbon stored in the four basic carbon pools: aboveground and belowground biomass, dead organic matter and soil organic matter (9, 13, 19, 20). This is followed by production of carbon stocks map based on available coefficient on biomass carbon stocks per unit area in each land use type. 4) Habitat quality Habitat quality is defined as the landscapes’ ability to provide suitable conditions for the persistence of an organism 17. The model uses a habitat-based approach, where habitat quality and rarity serve as a proxy for biodiversity. Consequently, habitats of high quality are considered intact with functioning within its range of historic variability 17, 21. The habitat quality was estimated based on the relative impact of threats, sensitivity of habitat to threats, distance between habitats and sources of threats and location of protected areas. C. State of ecosystem services The status of ecosystem services and change was analyzed by combining four ecosystem services into very low, low, moderate, high, and very high category. D. Projecting future land use scenarios The future land uses for the year 2033 were simulated using the CLUMondo model for three scenarios: 1) business as usual; 2) integrated land uses; 3) biodiversity conservation. The criteria considered the existing trend and most possible trend of the factors considered in simulation. IV. RESULTS and DISCUSSION A. Land use change The major land use in the study area is the forest cover. The agricultural land use types consisted of cassava, paddy rice, sugarcane, corn, mixed orchard, and mixed perennials. The results show the trends of change; particularly plantation, which has increased from no area under plantation in 1989 to 7.02% of total study area in 2013 (Table 1). Due to the Royal Thai Government’s reforestation promotion campaign, perennial crops, such as eucalyptus, bamboo, and rubber plantations were grown after 1989. Mixed orchard was also found to be increasing during the first period (1989 -2000), from 6,590 ha to 12,188 ha. The built-up area increased from 0.30% (1989), 0.82% (2000), 4.32% (2007) to 4.50% (2013). B. Impact of land use on ecosystem services The results showed that there was no area considered to have high overall ecosystem services (combined four services). Nearly 43% area has high degree of ecosystem service, whereas 23% moderate and another 35% area had low to very low (Figure 2). Analysis of the land use distribution indicated that mostly the decrease in services occurred in agriculture areas suggesting that the increased agroforestry type plantations have direct negative effects on biodiversity and ecosystems services. There was a large amount 138 Proceedings of the International Conference on Climate Change, Biodiversity and Ecosystem Services for the Sustainable Development Goals (SDGs): Policy and Practice 27-29 June 2016, Cha-am, Phetchaburi, Thailand
Proceedings of International Conference on Climate Change, Biodiversity and Ecosystem Services for the Sustainable Development Goals : Policy and Practice 27-29 June 2016 at the Sirindhorn International Environmental Park, Cha-am, Phetchaburi, Thailand
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