Modeling of nutrient retention ecosystem services in oil palm plantations in Sei Jentikar sub-watershed using ISPO policy approach

Abstract

Indonesia already has regulations on oil palm plantations that try to maintain good ecosystem services. The regulations are contained in ISPO. However, this regulation has not been fully implemented in oil palm plantations in Sei Jentikar sub-watershed. In this paper, we identify land cover and model N and P nutrient retention in oil palm plantations in the current condition and when ISPO is applied in Sei Jentikar sub-watershed. The method used was land cover identification using supervised classification and rivers using DEMNAS assisted by Google Earth Pro and modeling using the InVEST device. The identification results show the existing condition of oil palm plantation land covering an area of 16 962.99 ha. Meanwhile, when ISPO is applied in the oil palm plantation, the area that cannot be planted is 956.43 ha. This area has a predicted yield of around 2 226.41 tonnes/ha/year. Nutrient retention modeling results in N and P nutrient exports in existing conditions which will increase when approaching the river. Meanwhile, when scenario 2 is implemented, the export of nutrients will decrease in the buffer river. This shows scenario 2 can maintain ecosystem services nutrient retention, but will result in a reduction of value from oil palm production.