Judul: Interaction of Bird-Communities with Epiphytic Plants at IPB Dramaga Campus
Abstrak: Epifit memiliki pengaruh langsung maupun tidak langsung terhadap ekosistem di sekitarnya. Kehadiran epifit dapat meningkatkan kompleksitas habitat secara vertikal serta memberikan dampak positif bagi hewan, termasuk burung. Penelitian ini bertujuan mengidentifikasi epifit, pohon inang, dan burung, serta menganalisis hubungan antara komposisi epifit dan pohon inang dengan keanekaragaman dan kelimpahan burung. Penelitian dilakukan di tujuh lokasi di Kampus IPB Dramaga dari Desember 2022 hingga Mei 2023. Data biotik seperti jumlah dan jenis epifit, pohon inang, dan burung, serta data abiotik seperti suhu dan kelembapan dikumpulkan di setiap lokasi. Data dianalisis menggunakan perangkat lunak PAST untuk mendapatkan indeks keanekaragaman dan R untuk melihat korelasi antara burung dengan epifit. Hasil analisis menunjukkan adanya korelasi positif yang signifikan antara jenis epifit dan pohon inang dengan jenis burung. Taman Inovasi-Taman Konservasi dan Taman Hutan Kampus-Biofarmaka merupakan lokasi dengan keanekaragaman dan kelimpahan pohon, epifit, dan burung tertinggi. Lokasi yang memiliki keanekaragaman dan kelimpahan epifit yang tinggi memiliki suhu yang cenderung lebih rendah. Pycnonotus aurigaster, Aegithina tiphia, Sitta frontalis, dan Dicaeum trochileum adalah jenis burung yang memanfaatkan epifit. Keempat jenis tersebut memanfaatkan epifit Asplenium sp. dengan mencari pakan berupa invertebrata di sekitarnya., Epiphytes have direct or indirect influence on surrounding ecosystems. The presence of epiphytes can increase habitat complexity vertically and have a positive impact on animals, including birds. The objectives of this study were to identify species of epiphytes, host trees, and birds and to analyze the relationship between the composition of epiphytes, host trees, and bird diversity and abundance. The research was conducted at seven locations on IPB Dramaga Campus from December 2022 to May 2023. Biotic data, such as the number and type of epiphytes, host trees, and birds, and abiotic data, such as temperature and humidity were collected at each location. Data were analyzed using PAST to examine the diversity indices and used R to look correlation between birds and epiphytes. The analysis showed a significant positive correlation between the species of epiphytes and host trees with bird species. Taman Inovasi-Taman Konservasi and Taman Hutan Kampus-Biofarmaka have the highest diversity and abundance of trees, epiphytes, and birds. Locations with high diversity and abundance of epiphytes tend to have lower temperatures. Pycnonotus aurigaster, Aegithina tiphia, Sitta frontalis, and Dicaeum trochileum are bird species that utilize epiphytes. These four species use Asplenium sp. epiphytes by looking for invertebrates as food around them.
Keyword: Asplenium sp., insektivora, interaksi burung-epifit, Asplenium sp., bird-epiphyte interaction, insectivore

Judul: Diversity of epiphytic ferns and Its host in Campus Darmaga of Bogor Agricultural University, West Java
Abstrak: Paku epifit merupakan kelompok tumbuhan paku yang unik, hidup menempel di permukaan pohon inang tanpa merusaknya. Paku epifit memanfaatkan pohon inang sebagai tempat untuk memperoleh kondisi lingkungan tertentu, sementara nutrisi dan air diperoleh dari deposit yang berada di sekitar permukaan pohon inang. Kampus IPB Darmaga memiliki jenis pohon yang beragam dengan kondisi lingkungan yang lembab, sehingga memungkinkan ditemukannya jenis tumbuhan paku epifit yang beragam. Penelitian ini bertujuan untuk mengetahui keanekaragaman tumbuhan paku epifit dan pohon inangnya beserta faktor-faktor yang mempengaruhinya di kawasan kampus IPB Darmaga- Bogor. Penelitian dilakukan di kawasan kampus IPB Darmaga dengan mengumpulkan spesimen tumbuhan paku epifit dan mencatat karakteristik permukaan pohon inang. Data yang diperoleh kemudian dikelompokkan berdasarkan jenis tumbuhan paku dan jenis pohon inang yang ditempati. Faktorfaktor yang mempengaruhi keberadaan tumbuhan paku dianalisis menggunakan analisis Regresi dan Principal Component Analysis (PCA). Sebanyak 22 jenis paku epifit dan 25 jenis pohon inang ditemukan. Jenis tumbuhan paku yang dominan ialah Davalia denticulata (26,59%), Asplenium nidus (25,99%), Vittaria ensiformis (22,97%), Drymoglossum pilloselloides (20,55%), dan Nephrolepis falcata (20,55%). Jenis pohon inang yang dominan ditempati oleh paku epifit ialah pohon kelapa sawit (Elaeis guineensis). Faktor yang mempengaruhi keanekaragaman jenis paku epifit ialah kekasaran permukaan kulit pohon dan posisi paku pada batang pohon, Epiphytic ferns live attaching on its host without damaging it. Epiphytic ferns use the host to obtain certain environmental condition while nutrients and water obtained from deposits around the host surface. Campus Darmaga of Bogor Agricultural University has various tree species and environmental conditions that suitable for the growth of epiphytic fern. The aim of this study was to describe the diversity of epiphytic ferns and its host in Campus Darmaga of Bogor Agricultural University. The study was conducted in Campus Darmaga of Bogor Agricultural University by collecting the speciments of epiphytic ferns and recording the characteristic of tree stem surface. Data was analyzed using Regression Analysis and Principal Component Analysis (PCA). There are 22 species of epiphytic ferns and 25 species of tree hosts. The dominant species of ferns are Davalia denticulata (26,59%), Asplenium nidus (25,99%), Vittaria ensiformis (22,97%), Drymoglossum pilloselloides (20,55%), and Nephrolepis falcata (20,55%). The dominant host is Elaeis guineensis. The diversity of ferns in Campus Darmaga were affected by the roughness of tree surface and the position of ferns on the tree trunk.
Keyword: paku epifit, pohon inang, keanekaragaman, kulit pohon, posisi paku

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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