Judul: Keanekaragaman Jenis Tumbuhan pada Tanah Ultrabasa di Areal Konsesi PT. INCO Tbk. Sebelum Penambangan Propinsi Sulawesi Selatan
Abstrak: Ultrabasic soils have considerable amount of heavy metal content and cause the existing vegetation to have very unique properties. Soils which develop in ultrabasic soils are very poor due to high content of Fe, Mg, Al and Ni. Ultrabasic soils occupy two altitudinal zonations, namely lowland mafic zone 􀀋􀂔1000 m asl) and upland mafic zone (􀂕 1000 m asl). Areas of ultrabasic soils in this Verbeek mountain range constitutes the concession area of PT INCO Tbk, which in the future will be mined, and therefore there is a need for a study concerning its species diversity. The objective of this study was studying plant species diversity existing in the ultrabasic soils. This research was conducted by vegetation analysis method for vegetation stages of seedlings, saplings, poles, trees, and non tree vegetation. Placements of sample plots was conducted by purposive sampling in each zonation (lowland mafic and upland mafic zones) with size of 20 m X 500 m (1 ha), and for each zone there were two sample plots. Therefore, the total area size of the research sample plots was four hectares. Research results showed that the number of species found in lowland mafic plot (LLM) for tree stage was 61 species, whereas that in upland mafic (ULM) was 19 species. Status of species diversity (H􀂶) in tree stage in the research location was categorized as ranging from low to high. Value of H􀂶 for tree stage ranged between 2.06 􀂱 3.13, value of species richness (R) were 5.96 􀂱 8.53, and value of species evenness (E) were 0.73 􀂱 0.86. Dominant species at tree stage and regeneration in nearly all sample plots was species of Heritiera trifoliata. Other dominant species were Gironniera subequalis, Sloetia elongate and Acmena acuminatissima. Those of local endemic species found in this study were among other things Kjelbergiodendron celebica, Hopea celebica, Lithocarpus celebica, Calophyllum celebicum, Diospyros celebica, Agathis celebica, Garcinia celebica, Metrosideros vera and Sarcotheca celebica. Number of trees in diameter class of 20 cm up was greater in ULM zone, as compared with that in LLM zone. On the other hand, basal area and volume of trees with diameter of 20 cm up was greater in LLM zone. Therefore, in LLM, number of trees was smaller, but the average tree size was greater as compared with that in ULM zone. Level of soil fertility in LLM plots were higher as compared with that in ULM plots. Values of pH in LLM plots were higher as compared with those in ULM plots, whereas contents of Fe, Ni and Al were higher in plots of ULM. Dominant species, such as Heritiera trifoliate , as well as those local tree species which had been mentioned above were tree species which had been adapted to the properties of ultrabasic soils. Therefore, those species need to be maintained in terms of their sustainability and cold be made as priority for rehabilitation of ex mining land in ultrabasic soils
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Judul: Keanekaragaman Tumbuhan Bawah pada Tegakan Sengon Buto (Enterolobium cylocarpum Griseb.) dan Trembesi (Samanea saman Merr.) di Lahan Pasca Tambang Batubara PT Kitadin Embalut, Kutai Kartanegara, Kalimantan Timur
Abstrak: Mining activities have a negative impact on the environment, as the Minister of Energy and Mineral Resources Regulation No. 18 of 2008 regarding the Mine Closure Plan in which requires mining companies to conduct reclamation activities on any pit mine. The research was carried out aimed to assess the composition and diversity of plant species, especially in the areas under coal mine revegetation after PT Kitadin Embalut, Kutai Kartanegara, East Kalimantan. This research conducted on the revegetation area PT Kitadin of sengon buto and trembesi stand planted on the year of 2006 for four month period of observation. Data collection methods used was step undergrowth vegetation, and data analysis is the INP of undergrowth species and analysis of plant diversity. Results showed that the total species found in both stand is 24 species from 20 families which scattered in the stands of sengon buto as many as 22 species from 19 families and the trembesi stands as many as 17 species from 13 families. The most dominated species in both stands is Paspalum conjugatum and Solanum torvum. Diversity level of undergrowth plant under stands of sengon buto and trembesi classified as medium. Richness level of undergrowth plant species is relatively low with a value of Richness (R1) on the stands of sengon buto is 2.56 and richness on the trembesi stands is 1.96. Evenness of undergrowth species under sengon buto and trembesi stands is categorized high because both the values level (E) > 0.6. The similarity index of undergrowth in sengon buto and trembesi stands can be considered as the same because the value of the IS> 75%.
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Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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