Judul: Karakteristik Habitat Preferensial Orangutan Pongo pygmaeus wurmbii di Taman Nasional Sebangau
Abstrak: The orangutan Pongo spp. was once widespread in Asia but is now found only on the islands of Borneo and Sumatra. In Central Kalimantan orangutan with the highest population number can be found in Sebangau National Park (SNP). Densities were found to be highest in the tall interior and mixed swamp forest sub-types and also concentrate in habitat + 4 km near from the river. Today, the probability of a direct observation for this animal is very low. The literature study shows that large animals have preferences in their habitat and therefore tend to distribute uniformly or clumped. In consequence, the management of orangutan population and habitat must consider their habitat preference. This study that was carried out in SNP from November to December 2010, were aimed to: (1) determining characteristic of habitat preference for orangutan, (2) identifying dominant habitat factor for orangutan. Tools used in the study consisted of; map of SNP, binoculars, GPS, digital camera, thermo-hydrometer, tally sheet, and measuring tape. Direct field observation and literature review were done to collect data. Based on multiple linear regressions analysis, the dominant habitat factors that determine habitat preference for orangutan were the species number of diet for tree level (X11) and species density of diet for tree level (x14). The equation formulated was Y = - 0.033 + 0.534 X11 - 0.516 X14, indicating that one unit increase of species number of diet for tree level presence by 0.534 points and a one point decrease in species density of the diet for tree level presence by 0.516 points. Using Neu’s method of preferential index’s analysis it was concluded that out of 5 locations studied, 2 locations (mix swamp forest and tall interior forest) had preferential indices greater than 1.
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Judul: Preferensi Habitat Bersarang Orangutan Sumatera (Pongo abelii Lesson, 1827) di Kawasan Hutan Batang Toru Kabupaten Tapanuli Utara – Sumatera Utara
Abstrak: Habitat degradation and persecution are causes of animals extinction in Indonesia. One of them is Sumatran Orangutan (Pongo pygmaeus abelii Lesson, 1827) that now on the red list of the spesies of International Union for Conservation of Nature (IUCN) as a critically endangered species. Batang Toru Forest (BTF) is one of the last 18 habitat units of Sumatran Orangutan in Sumatera. At the present time, BTF is in initiation process of Collaborative Management Base on Sustainability of Intact Ecosystem Unit figuration. Data and information about Sumatran Orangutan (umbrella spesies of BTF) could accelerate the initiation process. One aspect that could complete the reference of Orangutan is the nesting habitat preferention. The objective of this research is discovered the nesting habitat preferention of Sumatran Orangutan at various habitat in BTF. This research conducted during Oktober-Desember 2008 at YEL-SOCP's research station, in 12,5 km2 west block area of BTF. Equipment that used are GPS, binoculars, measuring tape, camera, camera trap, map, flagging tape, stationary, rope, knife, thermometer, and hygrometer. Secondary data are bioecology of Sumatran Orangutan and general condition of research site which collected by interview and literature observation method. Primary data are Orangutan's nest frequency, which collected by the nest survey method, and the structure and composition of vegetation, which collected by vegetation analysis method. The frequency calculated by dividing the total number of nest that found with the length of the track. The structure and composition of vegetation discovered by Importance Value Index and diagram of profile vegetation. BTF's research site consist of three habitat type; peat swamp forest, upper Dipterocarp forest, and the ecoton. Peat swamp forest characterized by the high abundant of mosses and Nephentes spp., which is gradually decrease in ecoton and in upper Dipterocarp forest. Peat swamp forest has the highest vegetation density, which is also gradually decrease in ecoton and in upper Dipterocap forest. The vegetation species that identified as Orangutan's food resources in peat swamp forest are 7 species, in ecotone are 5 species, and in upper Dipterocarp forest are 4 species. The highest nest frequency found in peat swamp forest (18,7 nests/km track). It is caused by the peat swamp forest provides food resources for Orangutan, such as leaves and tree bark, troughout the year. The stand of peat swamp forest has the highest density than the other habitat, so that the estimation of actual nest frequency in peat swamp forest must be more than 18,7 nest/km track. The nest dissemination in various condition ilustrated the nest habitat preferention concerned with time. During the research, Orangutan build nest in upper Dipterocarp forest, while the old nest, found in great quantities in the peat swamp forest and ecoton. The nest can be found in each habitat, with the highest frequency found in peat swamp forest (18,7 nest/km track). This high number caused by the habitats ability to provides Orangutans food resources such as leaves and tree bark troughout the year. This habitats are intact habitat unit of Orangutan, which the stand characteristic of each habitat is not the determining factor of nesting habitat preferention. The nesting
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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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