Pemanfaatan Citra Landsat untuk Estimasi Biomassa Atas Permukaan dari Berbagai Penutupan Lahan dengan Pendekatan Indeks Vegetasi (Studi Kasus Kabupaten Mamuju Utara, Sulawesi Barat)

Abstract

Biomass is highly relevant to climate change issues and plays important role in the carbon cycle. Biomass is the total organic matter produced by a plant that is expressed in units of tonnes dry weight per unit area (Brown, 1997). Vegetation index is the percentage reflectance of solar radiation by the leaf surface that correlates with the concentration of chlorophyll (Carolita, 1995). Estimation of biomass can be done with three approaches, namely modeling, field measurements and remote sensing (Lu, 2006). Of the three approaches, with a remote sensing approach is preferred because can be used for areas with large extents. The research was conducted through several stages of preparation, data collection, data analysis (geometry correction, interpretation of land cover, vegetation index calculation, the selection model, the estimated biomass of North Mamuju on various land cover). Some transformation of vegetation indices used in this study are the NDVI (Normalized Diferrent vegetation index), TNDVI (transformed Normalized different Vegetation Index), RVI (Ratio Vegetation Index), and TRVI (transformed Ratio Vegetation Index). The purpose of this research was to analyze land cover with Landsat imagery, building a model of the relationship between biomass on the surface with a vegetation index, and know the surface of the biomass estimates for the various land cover in North Mamuju. Land cover in North Mamuju totaling 12 species which are generally dominated by forests, plantations and mixed farms. While mangroves, scrub, moor / field, fields, water bodies, wetlands, open land, farms/ponds and relatively fewer settlements. Correlations NDVI vegetation index has the highest good of the natural vegetation cover and non-natural with R biomass with 60%. The estimated total biomass on the surface in North Mamuju in natural vegetation: primary forest (104,1) ton/ha, the mangrove 79,0 ton/ha, shrubs 36,0 ton/ha and the non-natural vegetation: plantation 66,1 ton/ha, mixed farms 65.1 ton/ha, dry 52,1 ton/ha, rice 5,6 ton/ha. Estimation results are in the range of field measurements of biomass. Amount of biomass stored in each land cover vary, depending on the diversity and density of existing vegetation, soil type and how to manage. Deposits tend to be the greater biomass with increasing plant age.

Biomassa sangat relevan dengan isu perubahan iklim dan berperan penting dalam siklus karbon. Biomassa merupakan total bahan organik yang dihasilkan oleh suatu tanaman yang dinyatakan dalam satuan ton berat kering per satuan luas (Brown, 1997). Indeks vegetasi adalah persentase pemantulan radiasi matahari oleh permukaan daun yang berkorelasi dengan konsentrasi klorofil (Carolita, 1995). Estimasi biomassa dapat dilakukan dengan 3 pendekatan yaitu modeling, pengukuran di lapang dan penginderaan jauh (Lu,2006). Dari tiga pendekatan tersebut, pendekatan dengan penginderaan jauh lebih dipilih karena dapat digunakan untuk kawasan dengan luasan besar. Penelitian ini dilakukan melalui beberapa tahapan yaitu persiapan, pengumpulan data, analisis data (koreksi geometri, interpretasi penutupan lahan, perhitungan indeks vegetasi, pemilihan model, estimasi biomassa Kabupaten Mamuju Utara pada berbagai penutupan lahan). Beberapa indeks vegetasi yang digunakan dalam penelitian ini adalah NDVI (Normalized Diferrent Vegetation Index), TNDVI (Transformed Normalized Diferrent Vegetation Index), RVI (Ratio Vegetation Index), dan TRVI (Transformed Ratio Vegetation Index). Tujuan penelitian ini adalah menganalisis penutupan lahan melalui citra Landsat, membangun model hubungan antara biomass atas permukaan dengan indeks vegetasi, dan mengetahui estimasi biomassa atas permukaan pada berbagai penutupan lahan di Kabupaten Mamuju Utara. Penutupan lahan di Kabupaten Mamuju Utara berjumlah 12 jenis yang pada umumnya didominasi oleh hutan, perkebunan dan kebun campuran. Sedangkan mangrove, semak belukar, tegalan/ladang, sawah, tubuh air, rawa, tanah terbuka, tambak/empang dan pemukiman relatif lebih sedikit. Indeks vegetasi NDVI memiliki korelasi yang paling tinggi baik dari penutupan vegetasi alami maupun non alami dengan biomassa dengan R sebesar 60%. Jumlah estimasi biomassa atas permukaan di Kabupaten Mamuju Utara pada vegetasi alami: hutan primer 104,1 ton/ha, mangrove 79,0 ton/ha, semak belukar 36,0 ton/ha dan pada vegetasi non alami: perkebunan 66,1 ton/ha, kebun campuran 65,1 ton/ha, tegalan 52,1 ton/ha, sawah 5,6 ton/ha.