Judul: Potential Soil Seed Bank of Understorey in KHDTK Cikampek
Abstrak: Kawasan hutan dengan tujuan khusus (KHDTK) Cikampek merupakan hutan untuk kepentingan umum tanpa mengubah fungsinya. Cadangan biji dalam tanah dapat menjaga keanekaragaman tumbuhan lantai hutan dan stabilitas ekosistem di masa depan. Penelitian ini bertujuan menganalisis komposisi vegetasi tumbuhan lantai hutan, mengeksplorasi cadangan biji tanah, dan kemampuan suksesi alami. Tahapan penelitian yang dilakukan meliputi analisis vegetasi, pengambilan sampel tanah, uji perkecambahan, suksesi alami, pengukuran dan pengambilan data lingkungan, dan analisis data. Vegetasi awal memiliki jumlah individu sebanyak 378 individu, uji perkecambahan menumbuhkan 413 individu, dan vegetasi suksesi memiliki 348 individu. Uji perkecambahan dengan kedalaman 5 cm memiliki nilai indeks keanekaragaman yang lebih tinggi (H’=2,30) dibandingkan dengan kedalaman 10 cm dan 15 cm (H’=1,96). Secara keseluruhan, H’ pada uji perkecambahan (H’=2,33) lebih tinggi dibandingkan vegetasi setelah suksesi (H’=1,79) dan vegetasi awal (H’=1,36). Keanekaragaman spesies yang teramati memiliki nilai indeks kemerataan yang tinggi, uji perkecambahan (E=0,80), suksesi (E=0,75), dan vegetasi awal (E=0,53)., Forest area with the special purposes (KHDTK) in Cikampek serves public purposes without altering its primary function. Soil seed banks sustain forest floor plant diversity and future ecosystem stability. This study aims to analyze the vegetation composition of the forest understorey, explore soil seed reserves, and assess natural succession. The research process encompasses vegetation analysis, soil sampling, germination tests, natural succession assessment, environmental measurements and data collection, as well as data analysis. Initial vegetation comprises a total of 378 individuals, germination tests yielded 413 individuals, and succession vegetation had 348 individuals. The germination test at a depth of 5 cm shows higher diversity index (H’=2,30) compared to depths of 10 cm and 15 cm (H’=1,96). The diversity index of germination test (H’=2,33) is higher than in succession vegetation (H’=1,79) and initial succession (H’=1,36). The observed species diversity demonstrates high evenness values in the germination test (E=0,80), succession (E=0,75), and initial vegetation (E=0,53).
Keyword: analisis vegetasi, indeks nilai penting, keanekaragaman, perkecambahan, suksesi

Judul: Analysis of Soil Fertility at Various Level of Canopy Density in KHDTK Haurbentes, Bogor District, West Java
Abstrak: Kawasan Hutan Dengan Tujuan Khusus (KHDTK) Haurbentes merupakan kawasan hutan yang dimanfaatkan secara khusus menjadi hutan penelitian di kawasan hutan produksi. Kawasan hutan ini harus tetap memperhatikan kelestarian dan kesuburan tanahnya. Tujuan dilakukan penelitian ini adalah untuk menganalisis kesuburan tanah pada berbagai kerapatan tajuk berdasarkan sifat fisik dan kimia tanah. Kerapatan tajuk diukur menggunakan alat spherical densiometer (SD). Sampel tanah diambil di tiga titik secara diagonal pada petak berukuran 20 m × 20 m berdasarkan kerapatan tajuk rendah, sedang, dan tinggi. Parameter yang digunakan untuk menentukan kesuburan tanah yaitu tekstur tanah, pH tanah, C-organik, P2O5 potensial, K2O potensial, kation yang dapat ditukar, KTK, dan kejenuhan basa. Hasil penelitian menunjukkan bahwa kondisi tanah di bawah ketiga tutupan tajuk memiliki tekstur tanah beragam dari debu hingga lempung berpasir, pH tanah masam, C-organik, P2O5, dan kation dapat ditukar yang rendah, K2O yang sedang, dan kejenuhan basa yang rendah. Adapun nilai KTK sangat tinggi pada kerapatan tajuk rendah, sedang, dan tinggi berturut-turut adalah 50,30 me/100g, 52,96 me/100g, dan 53,93 me/100g. Status kesuburan tanah yang ditemukan pada setiap kerapatan tajuk masih tergolong rendah., Special Purpose Forest Area (KHDTK) Haurbentes is a forest area that is specifically used as a research forest in a production forest area. This forest area must still pay attention to the sustainability and fertility of the soil. The purpose of this study was to analyze soil fertility at various canopy densities based on the physical and chemical properties of the soil. The canopy density was measured using a spherical densiometer (SD). Soil samples were taken at three points diagonally on a 20 m × 20 m plot based on low, medium, and high canopy densities. The parameters used to determine soil fertility were soil texture, soil pH, organic C, potential P2O5, potential K2O, exchangeable cations, CEC, and base saturation. The results showed that the soil conditions under the three canopy covers had various soil textures from silt to sandy loam, acidic soil pH, low C-organic, P2O5, and cation exchangeability, moderate K2O, and low base saturation. As for the exceptionally high CEC values at low, medium, and high crown density were 50,30 me/100g, 52,96 me/100g, and 53,93 me/100g, respectively. Soil fertility status of the soil found at each canopy density was still relatively low.
Keyword: c-organik, hutan penelitian, kerapatan tajuk, kesuburan, KTK, c-organic, CEC, crown density, fertility, research forest

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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