Judul: Keragaman dan Jumlah Kelompok Acari Tanah pada Kebun Kelapa Sawit di PTPN VIII Cikasungka Kabupaten Bogor
Abstrak: Oilpalm is one of the plantation commodities which have an important role in generating foreign exchange through the production of palm oil and palm kernel oil. Development of oil palm plantation in Indonesia is supported by the large areal potency, tropical climate and suitable soil. Oilpalm can grow at pH 4,0-6,0, but the optimum pH is between 5,0-5,6. Suitable pH associated with the decomposition process in ecosystems where these plants live. Soil mesofauna is one of components of the soil ecosystem. Its existence and activity in the soil can affect soil fertility. One of soil mesofauna that can be found abundantly is soil acari. Most members of the acari live in soil as well as on the soil surface. Acari has a body length between 0,1 mm to 2,0 mm. Acari body color ranging from light brown to black with varies body shapes. Acari body size will become smaller following to the depth of the soil where they lived. The objective of this study was to determine the soil acari diversity and abundance at area of palm oil productive plants (TM) and immature palm oil plants (TBM). Method of research was extraction of animal from the soil samples using Kempson Extractor, then the soil fauna especially acari was identified using a stereo microscope. Generally, three sub-orders were obtained in each area, namely suborder Oribatida, Gamazina and Uropodina. Results showed the average population of acari from TM area was 2880±1089 individuals m-2, the average population of soil acari from TBM area was 1218±392 individuals m-2. Sub order Oribatida most often found in TBM and TM, as well. From the result, it could be concluded that the older age of the plant, acari population was found to be higher, because the older plant was producing more litter than the younger plants, so it could increase population of soil microbes. Correspondence analysis showed that Gamazina affected by soil properties, pH, Cu, C-organic, N, K, KA, Zn, and Ca.
Keyword: Bogor Agricultural University (IPB), immature palm oil plants, palm oil producing plants, soil mesofauna

Judul: Keanekaragaman Spesies Rayap pada Perkebunan Kelapa Sawit dan Karet Milik Rakyat di Jambi
Abstrak: Oil palm and rubber are potential commodities for international trade and source of income for Indonesia. In the field, these commodities frequently attacked by termites. The diversity of termite species in those two plantation can be influenced by many factors. The aim of this research was to asses the diversity of termites species in oil palm and rubber plantations and factor affecting. Research was conducted on 4 plots (50 m x 50 m) on each plantation in Kabupaten Sarolangun, Jambi. Transects (50 m x 10 m) were set in the midlle of the plots and termite found were collected and identified. In addition, wooden stakes made of rubber wood were driven into the ground inside the subplots and termites attacked those wooden stakes were also collected. The result showed that diversity index were higher on rubber plantation than oil palm. Canopy coverage and type of vegetation affect the diversity of termite. Termite species found on oil palm were to 9 species: C. mohri, M. gilvus, M. insperatus, N. longinasoides, N. proatripennis, P. setiger, S. javanicus, S. medioobscurus and T. propinquus. Meanwhile termite species found on rubber plantation were 12 species: B. flavicans, C. mohri, H. hospitalis, M. insperatus, N. proatripennis, N. javanicus, P. aequalis, P. setiger, S. longirostris, S. medioobscurus, S. tarakensis and T. propinquus
Keyword: Bogor Agricultural University (IPB), wooden stakes., transect, habitat type, Diversity index

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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