Judul: Pendugaan Umur dan Laju Pembuatan Sarang Orangutan (Pongo pygmaeus morio, Groves 2001) di Stasiun Penelitan Prefab dan Mentoko Taman Nasional Kutai
Abstrak: Orangutan merupakan satwa endemik yang hanya berada di Sumatera, Kalimantan, Sabah dan Serawak, namun lebih dari 90 % habitatnya berada di Indonesia (Meijaard & Rijksen 2001). Kondisi habitat dan populasi orangutan dari tahun ke tahun semakin menurun sehingga digolongkan sebagai spesies yang sangat genting (critically endangered) untuk orangutan Sumatera karena terjadi penurunan 80% selama 25 tahun dan penurunannya terus berlangsung serta status endangered untuk orangutan Borneo karena terjadi penurunan lebih dari 50 % dalam 60 tahun (IUCN 2006); dan kepunahannya dikhawatirkan akan terjadi tahun 2020 jika tidak ada tindakan pencegahan yang efektif (Meijaard & Rijksen 2001). Resiko kepunahan spesies orangutan dapat dinilai berdasarkan data tentang kepadatan, distribusi spesies dan ukuran populasi (Husson et al. 2009). Penilaian terhadap kepadatan, distribusi dan ukuran populasi dilakukan dengan mendeteksi keberadaan orangutan berdasarkan sarang yang dibuat orangutan setiap hari (Meijaard & Rijksen 2001) dan menghitung kepadatan populasi berdasarkan metode penghitungan sarang (van Schaik et al. 1995). Namun metode ini memiliki keterbatasan karena beberapa parameter yang diukur dipengaruhi oleh faktor lokal dan memerlukan waktu yang sangat panjang sehingga sangat memungkinkan terjadinya kesalahan dalam mengidentifikasi sarang. Beberapa hasil penelitian menunjukkan hasil pendugaan nilai t (lamanya sarang terdekomposisi habis) dan r (laju orangutan membuat sarang) yang sangat bervariasi, padahal variasi nilai pada parameter t, p dan r sangat mempengaruhi hasil estimasi orangutan dan parameter t merupakan sumber kesalahan terbesar dalam menduga populasi orangutan. Penelitian untuk mengurangi tingkat kesalahan dalam pendugaan populasi orangutan melalui pendugaan parameter t dan laju pembuatan sarang (r) di Taman Nasional Kutai dilaksanakan di Stasiun Penelitian Prefab dan Mentoko Taman Nasional Kutai, Kalimantan Timur. Prefab merupakan stasiun penelitian yang dibangun pada tahun 1984 sedangkan Mentoko merupakan stasiun penelitian yang mulai dibangun pada bulan Oktober 2009. Pengambilan data lapangan dilaksanakan selama 5 bulan yaitu pada bulan Oktober 2009 s/d Februari 2010. Penelitian menggunakan metode pengamatan harian terhadap perubahan warna sarang untuk mengetahui umur sarang sedangkan untuk laju pembuatan sarang menggunakan focal animal method. Jumlah unit contoh dalam pengamatan umur sarang yaitu 30 unit contoh untuk Prefab dan 30 di Mentoko. Unit contoh yang digunakan adalah sarang yang baru dibangun orangutan sedangkan untuk laju pembuatan sarang menggunakan masing-masing 30 individu orangutan sebagai unit pengamatan pada kedua wilayah penelitian...dst
Keyword: Pongo pygmaeus, nest age, nest building rates

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: 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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