Judul: Carbon Stock Estimation of Durian Plantations using Remote Sensing Techniques
Abstrak: Durian (Durio zibethinus) merupakan salah satu komoditas dengan produksi yang terus meningkat setiap tahunnya, menyebabkan adanya peralihan fungsi lahan hutan, dan dapat menurunkan stok karbon wilayah tersebut. Penelitian ini bertujuan menjelaskan kondisi stok karbon daerah perkebunan durian, menganalisis kondisi vegetasi daerah perkebunan durian melalui indeks NDVI, serta menentukan kesesuaian model estimasi stok karbon dari NDVI yang telah ada sebelumnya. Penelitian dilakukan selama bulan Januari – Mei 2024. Analisis dilakukan dengan beberapa tahapan, yaitu analisis NDVI dengan data satelit Landsat 8 (band 4 dan band 5), evaluasi kesesuaian 9 model estimasi stok karbon yang ada (Lombok Barat, Banyumas, dan Wonosobo) melalui nilai RMSE dan korelasi pearson, serta penerapan model terbaik untuk estimasi stok karbon 2017 – 2023. Hasil analisis menunjukkan bahwa data lapangan stok karbon di perkebunan durian cenderung mengalami peningkatan seiring meningkatnya umur pohon. NDVI di wilayah perkebunan durian bervariasi pada rentang 0,2911 – 0,3929. Evaluasi model stok karbon menghasilkan galat yang cukup besar dengan korelasi pearson yang lemah disebabkan oleh komoditas yang berbeda. Penerapan model terbaik, C = 422.33(NDVI)^3,0547 menunjukkan adanya kecenderungan peningkatan stok karbon dari tahun 2017 – 2023., The production of durian (Durio zibethinus) has been increasing annually, resulting in the conversion of forest land functions and a reduction in the carbon stock of the region. This research aims to elucidate the carbon stock status of durian plantations, analyze the vegetative condition of durian plantations through the NDVI index, and ascertain the suitability of existing carbon stock estimation models based on NDVI. The research was conducted over the period from January to May 2024. The analysis was conducted in several stages. Initially, NDVI analysis was performed using Landsat 8 satellite data (bands 4 and 5). Subsequently, the suitability of nine existing carbon stock estimation models was evaluated (West Lombok, Banyumas, and Wonosobo) through RMSE and Pearson correlation values. Finally, the most suitable model was applied for carbon stock estimation from 2017 to 2023. The results of the analysis indicate that the field data of carbon stocks in durian plantations tend to increase with increasing tree age. The NDVI in the durian plantation area exhibited a range of 0.2911 to 0.3929. The evaluation of the carbon stock model yielded considerable errors with a weak Pearson correlation due to the differing commodities. The application of the optimal model, C = 422.33(NDVI)^3.0547, demonstrated an increasing trend in carbon stocks from 2017 to 2023.
Keyword: durian, NDVI, pemodelan, stok karbon

Judul: Potensi Ekonomi Manggis dan Durian Terhadap Pendapatan Petani KTH Rimba Lestari Desa Karacak Kecamatan Leuwiliang Kabupaten Bogor
Abstrak: Manggis dan durian menjadi komoditas Desa Karacak yang hasilnya cukup menguntungkan dan menjadikan desa ini sebagai salah satu sentra produksi buah-buahan tersebut. Mengetahui potensi hasil hutan bukan kayu (HHBK) penting dilakukan untuk diperhitungkan nilai ekonomi dalam pemanfaatannya. Penelitian ini bertujuan mengidentifikasi keberadaan dan potensi manggis dan durian beserta nilai ekonomi manggis dan durian terhadap pendapatan petani KTH Rimba Lestari, dan peranannya dalam mendukung keberadaan hutan rakyat di Desa Karacak. Penelitian dilakukan melalui wawancara kepada petani KTH Rimba Lestari sebagai informan dalam mencari data produktivitas manggis dan durian, serta pengukuran di lapangan melalui pembuatan plot contoh. Hasil penelitian menunjukkan nilai ekonomi manggis dan durian memiliki kontribusi dominan dengan rata-rata pendapatan bersih Rp 51.679.000 per tahun atau persentase rata-rata 72,03% terhadap pendapatan rata-rata petani Rp 70.956.522 per tahun. Manggis memiliki kontribusi pendapatan lebih besar yaitu rata-rata pendapatan bersih Rp 33.802.500 per tahun atau persentase 47,35% dibandingkan durian dengan rata-rata pendapatan bersih Rp 17.876.500 per tahun atau persentase 24,68%. Nilai tersebut membuat keberadaan manggis dan durian di lahan petani lebih dominan dari tanaman lain sehingga banyak dibudidayakan dan petani berencana memperbanyak komoditas ini. Rata-rata umur pohon manggis dan durian milik petani sudah berumur tua sehingga dimungkinkan terjadi penurunan produksi yang akan berdampak pada pendapatan petani, sementara rencana petani untuk memperbanyak komoditas ini belum dilakukan. Kondisi tersebut menjadi alasan kuat untuk segera melakukan upaya permudaan guna mempertahankan keberlanjutan tanaman manggis dan durian., Mangosteen and durian have become important commodities in Karacak Village, providing considerable profit and making this village a major production center for these fruits. Assessing the potential of non-timber forest products (NTFPs) is essential to evaluate their economic value. This study aims to identify the presence and potential of mangosteen and durian, as well as their economic value to the income of KTH Rimba Lestari farmers, and their role in supporting community forests in Karacak Village. The research was conducted through interviews with KTH Rimba Lestari farmers to collect data on mangosteen and durian productivity, and field measurements by making sample plots. The results of the study show that the economic value of mangosteen and durian has a dominant contribution with an average net income of Rp 51.679.000 per year or an average percentage of 72,03% to the average farmers income of Rp 70.956.522 per year. Mangosteen has a greater revenue contribution, namely an average net income of Rp 33.802.500 per year or a percentage of 47,35% compared to durian with an average net income of Rp 17.876.500 per year or a percentage of 24,68%. This value makes the existence of mangosteen and durian on farmers land more dominant than other crops so that it is widely cultivated and farmers plan to multiply this commodity. The average age of mangosteen and durian trees owned by farmers is old, so it is possible that there will be a decrease in production that will have an impact on farmers income, while farmers plans to multiply this commodity have not been carried out. This condition is a strong reason to immediately make rejuvenation efforts to maintain the sustainability of mangosteen and durian plants.
Keyword: durian, economic potential, income contribution, mangosteen

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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