Judul: Pendugaan Umur Sarang Orangutan Sumatera Reintroduksi (Pongo abelii Lesson 1827) Berdasarkan Perubahan Ukuran dan Warna di Ekosistem Taman Nasional Bukit Tigapuluh (Studi Kasus di Stasiun Reintroduksi Orangutan Sumatera Sungai Pengian Provinsi Jambi)
Abstrak: In the estimation of orangutan population based on nest density, nest decay rate is used as one of the parameters in calculating site-specific value. Nest decay rate has a site-specific characteristic, which is influenced by several factors, such as altitude, type of forest or habitat, temperature, humidity, and the amount of rainfall. Changes in nest color and size are parameters which can be visibly observed, thus nest color and size can be used as indicators in estimating nest decay rate. The objective of this research was to determine the type of nest that can be used as a reference in estimating orangutan population, analyze nest size in relation to nest decay rate estimation, and analyze nest color in relation to nest decay rate estimation. This research was conducted in July until November 2009 at the Sumatran Orangutan Reintroduction Station, Pengian River, Jambi. Vegetation analysis was done in the forest containing nests used for observation. The method used in the research is Ad libitum. Observations were done to 37 nests, consisting of 25 sleep nests and 12 rest nests. Data collecting for each observed nest was done with an interval of one day. The results show that sleep nests are made by orangutans of all ages. Therefore, sleep nests are the type of nest used as reference in the estimation of orangutan populations. For changes in nest size, significant changes of rest nests occurred on days 1 to 3, 3 to 5, 5 to 12, and 12 to 29. From day 29 until the end of the observation, no significant changes occurred. For sleep nests, significant changes occurred on days 1 to 2, 2 to 4, 4 to 7, 7 to 14, 14 to 21, and 21 to 48. No significant changes occurred from day 48 until the last day of observation. Meanwhile, for changes in nest color, significant changes occurred on days 0 to 1, 1 to 6, 6 to 11, 11 to 13, 13 to 14, 14 to 17, 17 to 25, 25 to 36, 36 to 37, 37 to 50, 50 to 51, 51 to 52, 52 to 59, 59 to 62, 62 to 64, 64 to 69, 69 to 70, 70 to 74, 74 to 77, and 77 to 82. Significant changes in size and color of the orangutan nests occurred through several stages, where each stage requires more time to change compared to its previous stages. This tendency is due to the decaying of the nest during early stages that happen more quickly, causing a longer period for changes to occur during the later stage of the nest. By acknowledging the significant changes that occurred in nest size and color, the estimation of orangutan population by estimating the nest decay rate can be done through the observation of changes in nest color and size.
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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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