Judul: Diversitas Semut pada Tumbuhan Sonneratia caseolaris (L.)Engl. di Suaka Margasatwa Muara Angke
Abstrak: Mangrove is a dynamic group of trees with high productivity, which plays a major role in food chain. Ants (Formicidae) are the most abundant insect in the world. Higher biomass and abundance of ant in the tropical rainforest canopy are the reason why the ecological study of ants diversity become essential. Sonneratia caseolaris is a dominant tree species in Muara Angke Nature Reserve (MANR). Study of abundance and composition of ants were needed to indicate stability of this reserve. The research aim to study the diversity of ants and its contribution on S. caseolaris in MANR. The research was conducted from April-June 2012. Observation of ants were conducted in observation track in MANR and were made 8 points for collecting the ants. Collection of ants were conducted using 2 methods, beating sheet and pitfall trap. Result showed that 12 genera from 6 subfamilies and total of 2.280 individuals of ants were found. Camponotus, Oecophylla, and Polyrhachis were dominant genera found in MANR. Shannon-Wiener and Evennens Index value of ants were 0,9 and 0,33 respectively. Beating sheet cought more individual of ants than pitfall trap. We found predatory ants which potentially protect of S. caseolaris from its herbivore
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Judul: Keanekaragaman Serangga di Ekosistem Mangrove: Studi Kasus Hutan Mangrove di Kawasan Pesisir Angke Kapuk, Jakarta Utara
Abstrak: Mangrove is the habitat of various insects which have important function of ecosystem. However, many insect species and their functions in mangrove ecosystem have not been identified yet. This research is aimed to elucidate the species composition of mangrove in relation to the species diversity of insect. This research was conducted in three different mangrove stand in Mangrove Protection Forest of Angke Kapuk and Soedyatmo highway mangrove area. They are monoculture stand of A. marina, mixed stand of A. Marina and R. mucronata, and mixed stand of S. alba and R. mucronata. Sampling was collected by using line quadrat method. There were eight quadrats (10 m × 10 m) suspended at every mangrove stand. Incest traping was using yellow-pan trap method. The result indicates that the mixed stand A. Marina and R. mucronata has the highest value of insects abundance. The dominant insect at every mangrove stand were order of Diptera.
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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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