Judul: Perkembangan regenerasi anakan alam pada rumpang hutan dengan sistem silvikultur TPTJ di IUPHHK-HA PT. Sarpatim, Kalimantan Tengah
Abstrak: Gaps formed by the loss of one or several trees. Gap phase is the initial phase of forest natural regeneration. The purpose of this research is to analyze the pattern of natural regeneration development in forest gaps and forest stand composition at IUPHHK-HA PT. Sarpatim. Analysis of gap natural seedlings composition used single plot and analysis of forest stands used nested line plot at TPTJ and conservation forest area. Results showed that the number of plants species much more on large gaps with species composer is dominated by pioneer species such as Macaranga hypoleuca, M. gigantea, and Breynia oblongifolia otherwise small gaps is dominated by climax species such as Hopea dryobalanoides, Syzygium borneense, Shorea laevis, etc. Dominance values overall is low (C near to 0), richness value is high (R > 5), and diversity value is medium (2 < H’ < 3) up to high (H’ > 3). Result of Pearson correlation test showed that gap size positively correlated with the dominance, richness, and diversity values with the strength of correlation is weak. Forest stand species composition at research sites dominated by the dipterocarp groups such as Shorea smithiana, S. parvifolia, S. leprosula, S. laevis, and Dipterocarpus caudiferus. Dendogram clusters of species similarity do not follow the trend that closeness of felling age has high similarity values due to the high variation of forest sites, microclimate, and forest management activities.
Keyword: Bogor Agricultural University (IPB), species compositions, pioneer species, natural seedlings, forest gaps, climax species

Judul: Komposisi Functional Species Group pada Sistem Silvikultur Tebang Pilih Tanam Jalur di Area IUPHHK-HA PT Sarpatim, Kalimantan Tengah
Abstrak: Forest management can have an impact on changes in forest structure and composition of plant species. Functional species Group (FSG) may explain the unity of the trees species that are selected in a group in a forest management activities so that it can help in explaining the characteristic of biodiversity such as the quality of habitat and ecosystem processes. The purpose of this research is to know the composition of forest vegetation that the production system are managed with a Silvikultur system of TPTJ as seen from the forest structure and composition of the type that belongs to FSG for the stands and natural regeneration in log over area (LOA) and KPPN (The Conservation of Germplasm Area) IUPHHK-HA PT Sarmiento Parakantja Timber (Sarpatim), Central Kalimantan. Analysis of the composition of the stands type and structure used terraced path in the area of TPTJ and KPPN. The results showed that the types of climax on an entire swath of observations, generally have greater proportion than the group of pioneers, the number of the climax type is 100 while pioneer type is 59. The structure of the stands form a J reverse curve, it show that the composition of vegetation recovery on log over areas managed by using TPTJ and KPPN Silvikultur system has balance characteristic of uneven age forest. The value of diversity is high (H'>3). Most of tree and stands community have different communities (ID>50%).
Keyword: Bogor Agricultural University (IPB), composition of species, Forest management, Silviculture system

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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