PERSAMAAN ALOMETRIK UNTUK PENDUGAAN BIOMASSA NIPAH (Nypa fruticans)

Abstract

Ekosistem mangrove berperan penting dalam mitigasi perubahan iklim melalui simpanan karbon. Namun, kajian mengenai potensi karbon nipah (Nypa fruticans) masih terbatas meskipun populasinya melimpah. Penelitian ini bertujuan membangun model persamaan alometrik untuk menduga biomassa atas permukaan nipah di Cilacap berdasarkan DBH dan tinggi pelepah. Data lapangan dari 24 individu nipah di Kampung Laut, Cilacap, meliputi fraksi pelepah dan daun dianalisis menggunakan regresi nonlinear dengan metode Generalized Non-linear Least Squares (GNLS). Model terbaik dipilih berdasarkan signifikansi parameter, nilai AIC, BIC, RMSE terkecil, dan Radj tertinggi. Model M4 terpilih dengan bentuk persamaa W = 0,133 x (D² × H) 0,580, menghasilkan Radj 0,80 dan RMSE 0,37 kg. Perbandingan dengan model alometrik lainnya menunjukkan model lokal M4 lebih akurat dengan MAD 0,26 kg dan MAPE 28,89%.

Mangrove ecosystems play an important role in climate change mitigation through carbon storage. However, studies on the carbon potential of nipah (Nypa fruticans) remain limited despite its abundant population. This study aims to develop an allometric equation model to estimate the aboveground biomass of nipah in Cilacap based on DBH (diameter at breast height) and frond height. Field data from 24 nipah individuals in Kampung Laut, Cilacap, including frond and leaf fractions, were analyzed using nonlinear regression with the Generalized Non-linear Least Squares (GNLS) method. The best model was selected based on parameter significance, AIC, BIC values, the smallest RMSE, and the highest R2. The M4 model was selected with the equation form W = 0,133 x (D² × H) 0,580, yielding an R2 of 0.80 and RMSE of 0.37 kg. Comparison with other allometric models showed that the local M4 model was more accurate, with an MAD of 0.26 kg and a MAPE of 28.89%.