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: Composition, Diversity, and Species  Richness of Understory Plants in the Seed Bank of the Ciampea Karst Ecosystem
Abstrak: Simpanan biji merupakan kumpulan cadangan biji yang terkubur di dalam tanah dan berpotensi mampu menggantikan tanaman dewasa. Tujuan penelitian ini mengidentifikasi dan membandingkan komposisi, keanekaragaman, dan kekayaan jenis tumbuhan bawah yang tumbuh dari simpanan biji di kawasan hutan dan bekas tambang ekosistem karst Ciampea. Penelitian ini dilakukan di dua lokasi yaitu kawasan hutan dan bekas tambang dengan membuat plot sebanyak 15 buah berukuran 25 cm x 25 cm dengan kedalaman 3-5 cm di kedua lokasi penelitian. Perkecambahan biji dilakukan di Rumah Kaca Biologi, IPB. Tumbuhan bawah hasil perkecambahan yang telah terindentifikasi terdiri dari 26 jenis yang berasal dari 14 suku. Keanekaragaman jenis tumbuhan bawah di kedua lokasi penelitian tergolong sedang. Jenis tumbuhan bawah yang mendominasi di kedua lokasi penelitian adalah Asplenium adiantum-nigrum L. dengan nilai INP berturut-turut 45,6% dan 64,81%. Kekayaan jenis dan kesamaan jenis tumbuhan bawah di kedua lokasi penelitian tergolong rendah. Perbandingan kesamaan jenis tumbuhan bawah pada simpanan biji dengan vegetasi permukaan pada kawasan bekas tambang relatif lebih tinggi dibandingkan pada kawasan hutan., The seed bank refers to a collection of buried seeds that have the potential to replace mature plants. The objective of this study are to identify and compare the composition, diversity, and species richness of understory plants growing from the seed bank in the forest and former mining areas of the Ciampea karst ecosystem. The research was conducted in two locations, the forest area and the former mining area, by establishing 15 plots measuring 25 cm × 25 cm with a depth of 3-5 cm in both research locations. Seed germination was carried out in the Biology Greenhouse, IPB. The identified understory plants resulting from seed germination consisted of 26 species belonging to 14 families. The species diversity of understory plants in both research locations is considered moderate. The dominant understory plant species in both research locations is Asplenium adiantum-nigrum L. with respective important value percentages of 45,6% and 64,81%. The species richness and similarity of understory plants in both research locations were relatively low. The comparison of species similarity between the seed bank and surface vegetation in the former mining area was relatively higher than in the forest area
Keyword: dominance, karst conservation, regeneration, seedling, vegetation analysis

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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