Perbandingan Stok Karbon pada Dua Genus Mangrove Berbeda (Avicennia dan Rhizophora) di Estuari Sungai Somber, Teluk Balikpapan

Informasi stok karbon di ekosistem mangrove yang berada di area Teluk Balikpapan masih sedikit, termasuk perbandingan stok karbon pada genus mangrove yang berbeda. Penelitian ini bertujuan untuk membandingkan stok karbon pada dua genus mangrove yang tumbuh di sekitar perairan estuari Sungai Somber di Teluk Balikpapan. Lokasi pengambilan data dibagi menjadi dua yaitu Zona Rhizophora dan Zona Avicennia. Pengambilan data diameter batang pohon pada ketinggian dada dan sampel sedimen sedalam 1-meter dilakukan di tahun 2022. Data diameter batang pohon digunakan untuk menghitung stok karbon pada pohon menggunakan persamaan alometrik biomassa yang tersedia. Sampel sedimen digunakan untuk mengukur jumlah karbon yang tersimpan di sedimen dengan menggunakan metode loss on ignition. Hasil penelitian menunjukkan total stok karbon pada Zona Rhizophora lebih besar dibandingkan Zona Avicennia. Konsentrasi karbon organik di sedimen yang tinggi ditemukan di Zona Rhizophora yang kemudian menyebabkan jumlah karbon yang tersimpan di sedimen Zona Rhizophora 2 kali lipat lebih besar dibandingkan karbon yang tersimpan di sedimen Zona Avicennia. Namun, stok karbon di biomassa pohon mangrove terbesar ditemukan berada di Zona Avicennia yang lebih banyak memiliki ukuran pohon berdiameter besar. Hasil ini mengindikasikan adanya variasi stok karbon di ekosistem mangrove yang terdapat di estuari Sungai Somber berdasarkan genus yang mendominasi.   Current information on carbon stock in mangrove ecosystem growing in the Balikpapan Bay area remains limited, including comparison of the carbon stock based on different mangrove genera. This study aimed to compare carbon stocks between two mangrove genera growing in the estuarine area of Somber River, Balikpapan Bay. The sampling location were divided based on the dominant mangrove genera, namely Rhizophora Zone and Avicennia Zone. Diameter at breast height (DBH) of mangrove trees and 1-meter vertical sediment samples were collected in 2022. The DBH data were used to estimate carbon stock in live-tree biomass using available allometric equations for mangrove. Sediment samples were used to determine carbon stock in the sediment by using the loss on ignition method. The results showed that total carbon stock in the Rhizophora Zone is larger than in the Avicennia Zone. Higher organic carbon concentration in sediment was found in the Rhizophora Zone, resulting in its sediment carbon stock being twice as high as that in the Avicennia Zone. However, carbon stock in the live-tree biomass was greater in the Avicennia Zone where more trees with larger diameters were found. The finding suggests that total carbon stock varies depending on the dominant mangrove genera in the Somber River Estuarine Ecosystem.