ESTIMASI SERAPAN KARBON EKOSISTEM MANGROVE PADA LAHAN BEKAS TAMBAK DESA GERONGAN KABUPATEN PASURUAN

Titan Anggia Nursanti, Ir. Ni Putu Diana Mahayani, S.Hut., M.For., Ph.D.

2024 | Skripsi | KEHUTANAN

Vegetasi mangrove menyimpan karbon empat kali lebih banyak dibandingkan hutan terrestrial dan hutan hujan tropis lainnya. Desa Gerongan memiliki bentang lahan berupa tambak yang beberapa diantaranya telah terbengkalai dan ditumbuhi mangrove. Saat ini, belum ada upaya pemanfaatan lestari terhadap potensi mangrove yang besar pada desa ini. Salah satu upaya yang dapat dilakukan adalah dengan memanfaatkan skema pembayaran jasa lingkungan agar memberikan keuntungan secara ekologis dan ekonomis. Penelitian ini bertujuan untuk mengidentifikasi struktur vegetasi mangrove, serta mengestimasikan nilai simpanan dan serapan karbon mangrove Desa Gerongan.

Pengukuran vegetasi dan pengambilan sampel sedimen dilakukan pada petak ukur 10 m x 10 m sebanyak 18 plot. Pengambilan data vegetasi dilakukan secara nondestructive sampling terhadap komunitas pohon dengan DBH > 5 cm, sementara pengambilan sampel tanah dilakukan secara destructive sampling. Estimasi biomassa tegakan dilakukan dengan persamaan alometrik yang selanjutnya dikonversi ke dalam simpanan dan serapan karbon. Karbon organik sedimen diketahui dengan analisis bulk density dan C organik dengan metode Loss on Ignition (LOI) terhadap sampel sedimen.

Berdasarkan Indeks Nilai Pentingnya, vegetasi mangrove di Desa Gerongan didominasi oleh spesies Avicennia marina (54,46), Rhizopohora mucronata (53,06), dan Excoecaria agallocha (47,74). Indeks diverstas Simpson pada vegetasi ini sebesar 0,852. Rata-rata densitas biomassa mangrove di atas dan di bawah permukaan tanah masing-masing sebesar 180 ± 52,25 ton/ha dan 75,63 ± 19,81 ton/ha. Rata-rata simpanan karbon di atas dan di bawah permukaan tanah sebesar 84,85 ± 24,55 tonC/ha dan 35,55 ± 9,31 tonC/ha, serta simpanan karbon sedimen sebesar 425,17 ± 40,00 tonC/ha. Rata-rata serapan CO2 ekosistem sebesar 2002,03 ± 778,49 ton CO2/ha. Jumlah simpanan karbon mangrove Desa Gerongan berada pada rentang yang serupa dengan hutan mangrove alami Nguling Pasuruan dan Tongas Probolinggo.

The capacity of mangrove forest in absorbing and storing carbon is four times higher than terrestrial forests. The mangrove forest of Desa Gerongan represents a naturally regrown mangrove from abandoned ponds. In order to obtain some ecological and financial benefits from the existing mangrove mangrove, the local community has initiative to implement an environmental services payment system. Therefore, this study aims to identify the mangrove vegetation structure in Gerongan Village and to estimate the amount of carbon stored and sequestered by the mangrove ecosystem.

Vegetation and sediment sampling were conducted by establishing 18 plots of 10 m x 10 m. Stand biomass was estimated with non-destructive sampling, measuring trees with a diameter at breast height (DBH) ? 5 cm; individual tree biomass was estimated using allometric equations. The amount of carbon stored and sequestered by each individual was calculated based on its biomass. Using the Loss on Ignition (LOI) method, soil samples were analyzed its bulk density and its organic carbon content to determine the amount of carbon stored in the soil.

Based on its Importance Value Index (IVI), the dominant mangrove species were Avicennia marina (54.46), Rhizophora mucronata (53.06), and Excoecaria agallocha (47.74). The Simpson's diversity index of the vegetation was 0.852. The average density of above-ground and below-ground biomass was 180 ± 52,25 ton/ha and 75,63 ± 19,81 ton/ha, respectively. The average of above-ground, below-ground, and sediment carbon stock was 84,85 ± 24,55 tonC/ha, 35,55 ± 9,31 ton/ha, and 425,17 ±  40,00 5 tons C/ha, respectively. The average CO2 sequestration was estimated at 2002.03 ± 778.49 tons CO2e/ha. The mangrove carbon stock in Gerongan falls within a similar range to the natural mangrove forests in Nguling Pasuruan and Tongas Probolinggo.

Kata Kunci : biomassa mangrove, ekosistem mangrove, simpanan karbon, struktur tegakan; mangrove biomass, mangrove ecosystem, carbon stock, vegetation structure