Pendugaan Emisi CO2 Berdasarkan Kedalaman Drainase Akibat Alih Guna Lahan. (Studi Kasus: Daerah Eks Proyek Lahan Gambut Sejuta Hektar, Kalimantan Tengah).

Abstract

Mega Rice Project in Central Kalimantan which was implemented in early 1990s was meant for human settlement and rice cultivation. It involved extensive deforestation of peat swamp forests and draining of peatlands by means of massive network of canal drainage. These resulted in loss of carbon stocks, peat oxidation, CO2 emissions, and peat subsidence as water table depth (WTD) decreased. In some cases peat fires was inevitable causing further emission of greenhouse gases. Estimates of whole system emissions of CO2 were carried out using land-cover and WTD scenarios. Land-cover change scenario was based on chronological land-cover in 2003 and 2006 and logistic regression approach was employed to determine the significance of affecting variables. Eight variables selected were percent of forest fire, WTD, deforestation rate, percent of area used for forest plantation, economic value of key commodity, population density, distance of hot spots from to settlement and to river. From the crossed-tabulated land-cover change during 2003-2006 it was derived 33 logistic regression equations, 20 of which have coefficient of determination (R2) more than 50% and the remaining 13 equations have R2 less than 50%. Based on a series of F-test it was found that the independence variables significantly affect land-cover change at confidence level of 95%. Furthermore, the sensitive test was conducted, which demonstrates that 72% of spatially explicit predicted land cover is an agreement with the observed ones. The equations were then used to predict the likely land-cover in 2020 Emission of CO2 is predicted from drained and undrained primary forest, secondary forest, shrub vegetation and agricultural crops growing on peatlands based on the drainage model derived by Hooijeret al. (2006) and experimental-based estimates proposed by Jauhiainen et al. (2001, 2004, and 2005). It was demonstrated that CO2 emissions from the whole system of ex-Mega Rice Project in 2020 using experimental model was28.80Mt CO2/ha/yrwhen drained and only15.14 Mt CO2/ha/yr if the landscape was not drained. The drainage model gave much less estimate of 17.65 Mt CO2/ha/yr.