Pendugaan Potensi Cadangan Karbon Hutan di Atas Permukaan pada Ekosistem Mangrove Berbasis Synthetic Aperture Radar L-BAND

https://doi.org/10.22146/mgi.13080

Yudi Fatwa Hudaya(1*), Hartono Hartono(2), Sigit Heru Murti(3)

(1) Balai Besar Penelitian Bioteknologi dan Pemuliaan Tanaman Hutan, Kementrian Kehutanan, Indonesia
(2) Fakultas Geografi, Universitas Gadjah Mada, Yogyakarta, Indonesia
(3) Fakultas Geografi, Universitas Gadjah Mada, Yogyakarta, Indonesia
(*) Corresponding Author

Abstract


ABSTRAK Kebijakan pemerintah untuk menurunkan tingkat emisi GRK (Gas Rumah Kaca) dari sektor kehutanan membutuhkan sistem pendugaan kandungan karbon hutan untuk cakupan wilayah geografis yang luas dan waktu pengukuran yang cepat. Salah satu alternatifnya melalui pemanfaatan citra satelit synthetic aperture radar (SAR). Penelitian ini bertujuan untuk membuktikan sensitivitas gelombang-L dari citra ALOS PALSAR terhadap nilai kandungan karbon di atas permukaan pada hutan mangrove. Penelitian dilakukan pada kawasan hutan mangrove, di Kabupaten Kubu Raya, Provinsi Kalimantan Barat. Metode penyusunan model dilakukan berdasarkan analisis quantitatif menggunakan persamaan regresi, dengan cara mengkorelasikan nilai backscatter yang diekstrak dari citra ALOS PALSAR Res.50m pada polarisasi HH dan HV dengan nilai kandungan biomassa aktual hasil pengukuran lapangan berbasis plot alometrik. Model penduga yang dihasilkan kemudian digunakan untuk menghitung jumlah cadangan karbon dan sebarannya secara geografis.  Ditemukan hubungan yang kuat dengan koefisien determinasi (R2) mencapai 62% pada polarisasi HH dengan bentuk persamaan Y=1647e0,358BS_HH dan, 98,6% pada polarisasi HV dengan bentuk persamaan Y = 6,828BS_HV2 + 279,4BS_HV + 2870; Berdasarkan model persamaan tersebut dihasilkan dua buah peta kelas kerapatan karbon model-1 (HH) dan model-2 (HV).  Kandungan biomassa di atas permukaan (Aboveground biomass-AGB) pada hutan mangrove di Kabupaten  Kubu Raya diketahui sebesar 178,43 Mg/ha; sedangkan potensi karbon di atas permukaan (aboveground biomass carbon) diketahui sebesar 5.334.454,9 Mg (Megagram) atau 5,3 Mt (Megaton) karbon, dan kemampuan dalam menyerap karbondioksida (CO2) adalah sebesar 19,451 Mt (Megaton) CO2 equivalent. Sensitivitas gelombang-L citra ALOS PALSAR terhadap objek yang diamati diperkirakan akan menurun pada saat karbon aktual tertinggi di lapangan mencapai 335,15 Mg ha-1. Dalam konteks mitigasi perubahan iklim, hutan mangrove di Kubu Raya dengan luas 71.069,21 Ha apabila dipertahankan keberadaannya maka akan berkontribusi mengurangi tingkat emisi GRK dari sektor kehutanan sebesar 0,76 %. 

 

ABSTRACT The government policy to reduce the GHG (Green House Gas) emision from forestry sector, the need for sufficient forest carbon stock measurement system which encompass a faster measurement and covering broader geographic area to estimate the potential of forest carbon stock is now growing, one of which is the use of synthetic aperture radar (SAR) in radar remote sensing systems. The objectives of this study are to demonstrate the strong relationship between the L-band backscatter of ALOS PALSAR and the aboveground carbon stock in mangrove forest; and its sensitivity level. The information resulted from this study can be useful in reducing strategies of GHG (Green House Gases) emision, due to the climate change mitigation efforts in Indonesia. The study site was located at the area of mangrove forest, in Kubu Raya regency, West Kalimantan. The estimation models for aboveground biomass carbon stock was obtained from a quantitative analysis using regression method; i.e. by correlating the values of ALOS PALSAR 50m Res. backscatters at HH and HV polarization with the actual biomass total amount resulted from field -based allometric plots measurements. The estimation models were subsequently use for forest carbon stocks quantification in mangroves, and its distribution geographically. Strong relationship was found with coefficient of determination (R2) 62 % on HH polarization based on the equation model of Y=1647e0,358BS_HH  and , 98.6 % on HV polarization based on the equation model of Y = 6,828BS_HV2 + 279,4BS_HV + 2870; two models of carbon density classification maps i.e. model-1 (HH) and model-2 (HV) are also resulted from the two equation models. The quantity of AGB (aboveground biomass) of  mangrove forest in Kubu Raya district found as 178.43 Mg/ ha, while the aboveground biomass carbon is 5,334,454.9 Mg (Mega grams) or 5,3 Mt (Mega tons) of carbon, and the capacity of carbon dioxide (CO2) sequestration is 19.451 Mt (megatons) CO2 equivalent. The Sensitivity of L-band of ALOS PALSAR illumination on the object was expected to reach its saturation point when the highest total amount of actual carbon stock at field achieved the 335,15 Mg ha-1. In the context of climate change mitigation, the 71,069.21 ha area of mangrove forests in Kubu Raya if it remain save and be avoided from further deforestation and forest degradation, it will contribute to reduce the rate of GHG emissions from forestry sector by 0.76 %. 


Keywords


ALOS PALSAR; mangrove; Gas Rumah Kaca; alometrik; karbon; ALOS PALSAR; mangrove; Green House Gas; allometry; carbon




DOI: https://doi.org/10.22146/mgi.13080

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Accredited Journal, Based on Decree of the Minister of Research, Technology and Higher Education, Republic of Indonesia Number 30e/KPT/2018

Volume 31 No 2 the Year 2017 for Volume 35 No 2 the Year 2021

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