KEHILANGAN KARBON AKIBAT DRAINASE DAN DEGRADASI LAHAN GAMBUT TROPIKA DI TRUMON DAN SINGKIL ACEH (Carbon Loss from Drainaged and Degradation of Tropical Peatland in Trumon and Singkil, Aceh)

Abstract

ABSTRAK

Ekosistem hutan gambut tropika merupakan penyimpan karbon potensial, tetapi konversi lahan dan penebangan tidak lestari menyebabkan ekosistem ini juga menjadi sumber emisi karbon ke atmosfer. Pengaruh perubahan penutupan lahan dan pembangunan drainase terhadap dinamika muka air, penurunan tanah dan kehilangan karbon masih belum banyak diketahui pada tipologi gambut pesisir dengan bentang lahan yang sempit. Penelitian dilaksanakan pada berbagai tipe penutupan lahan gambut di Trumon dan Singkil, Provinsi Aceh mulai Mei 2013 hingga Oktober 2014. Penyimpanan dan kehilangan karbon dihitung berdasarkan bobot isi, kadar abu, karbon organik tanah, dan kedalaman tanah. Hasil penelitian menunjukkan perubahan penutupan lahan dan pembangunan drainase mempengaruhi tata air, penurunan tanah, dan kehilangan karbon sebesar 38,54 – 58,52%. Penurunan permukaan tanah tertinggi sebesar 5,6 cm/tahun terjadi pada lahan dengan bobot isi rendah dan intensitas drainase yang tinggi. Kehilangan karbon dari degradasi lahan gambut melepaskan sekitar1,352 ton CO₂ eq/ha/tahun. 

ABSTRACT

Tropical peat forest is one of significant atmospheric carbon sequester, but land conversion and illegal logging affects carbon stocks and transform these ecosystem into source of carbon emissions. The influence of land use change and drainage on water table fluctuation, soil subsidence and carbon loss are insufficiently known especially on typhology of narrow marine peatland. A study was conducted in Trumon and Singkil, Aceh Province from May 2012 until October 2014 in various peat land use types. Carbon stocks and carbon loss were calculated from data of bulk density, ash and carbon content, and peat depth. Results showed that land use types and distance from drainage influences the level of water table depth, subsidence rate, and carbon loss 38.54 – 58.52%. The highest subsidence rate occurred on peatlands which low bulk density and highly drainage intensity. Carbon loss from peat degradation released flux 1.352 ton CO₂ eq/ha/year, highly correlated with measured rates of subsidence, depth of water table and bulk density.