Judul: Keanekaragaman Lumut Epifit pada Gymnospermae di Kebun Raya Bogor
Abstrak: Researchs on diversity of epiphytic bryophytes are more common observed on Angiospermae than those on Gymnospermae. Bogor Botanical Garden (BBG) is an ex-situ conservation in which the sample plants are collected around the world for conservation purpose. Trees in the Botanical Garden provide substrats for epiphytic bryophytes. The temperature and humidity in the Botanical Gardens were the optimum range for the bryophyte growth. The aim of this research was to observe diversity of epiphytic bryophytes on Gymnospermae in BBG. The bryophyte samples were collected from Gymnosperm trees in Blok I which is Cycadaceae familly and those in Blok II which are the familly of Pinaceae, Araucariaceae, Gnetaceae, dan Podocarpaceae. Only the trees have ≥ 20 cm (dbh) of trunk base were sampled. Bryophytes were collected from the trunk base at 0-200 cm above the ground, at four cardinal direction (north, south, west, and east). In total 18 species of epiphytic bryophytes were found, included 12 genera and 7 families. The family which had the highest number of species was Lejeuneaceae. The most common species on Gymnosperm trees in the Botanical Garden were Lejeunea tuberculosa and Octoblepharum albidum. Both of them were found at 6 trees of 13 total tree samples. The species were found more frequently at west (2,1%) and north (1,8%) part than east and south part of the host trees. They more frequently inhabit the trunk base on 0-100 cm than 100-200 cm. Key words: Bogor Botanical Garden, diversity, epiphyte bryophyte, Gymnospermae.
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Judul: Keragaman dan Kelimpahan Lumut Hati Epifit di Kebun Raya Bogor
Abstrak: Indonesia has a high biodiversity of plants including bryophytes. Studies on the bryophyte diversity of Indonesia has not comprehensively done. Bogor Botanical Garden is one of the ex-situ conservation providing suitable habitat for bryophytes. Studies on the hepaticae of Bogor Botanical Garden are urgently needed. In this studies, bryophyte sampling were done in three blocks where the collection of Meliaceae, Myrtaceae and Lauraceae. Sampling was done based on the difference of growth position of tree (0-100 cm and 100-200 cm above ground) and at the difference of compass point (west, east, south, and north). Specimens checklist of bryophytes in the Herbarium Bogoriense (BO) as well as the herbarium specimens were studied. There are 92 species leafy liverworts are known at the sampling areas in Bogor Botanical Garden and herbarium specimens record at BO. There are 33 species leafy liverworts of epiphyte hepaticae were collected. In this studies, 7 species are recorded as the same as the BO specimens, the rest of 26 species are different with BO specimens. Lejeuneaceae has the highest diversity number, and highest percentage of coverage. Myrtaceae block has the highest diversity number and species abundance of hepaticae, that is 17 species and 52.9% of the total coverage. All of the blocks, position of tree 0-100 cm has the highest species abundance and frequency. A determination key to the species epiphytic hepaticae of Bogor Botanical Garden is presented.
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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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