Judul: Mintakat dan struktur vegetasi hutan alam Mangrove di Kuala Mandah areal HPH PT.BINA LESTARI I, Riau
Abstrak: Hutan mangrove merupakan suatu tipe hutan yang memiliki ekosistem yang khas dan unik; salah satu sumberdaya alam yang potensial dan perpaduan antara unsur fisik, biologi darat dan laut, sehingga menciptakan keterkaitan dalam ekosistem darat dan laut. Hutan mangrove tersebar hampir di seluruh kepulauan Indonesia dengan luas 3,16% dari luas hutan seluruhnya. Keberadaannya dapat memberikan manfaat bagi kehidupan manusia dan memiliki multifungsi baik fungsi fisik maupun biologis dan ekonomis. Dalam pemanfaatannya, hutan mangrove sering terjadi kesimpangsiuran dan benturan kepentingan antara berbagai pihak. Oleh karena itu diperlukan informasi yang jelas mengenai potensi dan peran hutan mangrove pada ekosistem pesisir, sehingga dapat dipakai sebagai informasi dasar dalam memberikan masukan informasi dalam mangambil keputusan kebijaksanaan dalam pengelolaannya. Salah satu informasi ekologis yang dapat diberikan adalah mengenai kondisi struktur mintakat (zonasi) dan komposisi vegetasi hutan mangrove. Menurut hasil penelitian terdahulu ada beberapa mintakat yang khas mulai dari garis pantai ke arah daratan yang dapat ditemui pada hutan mangove, yaitu: mintakat Avicennia, Rhizophora, Bruguiera dan mintakat hutan darat kering. Sedangkan hasil penelitian yang dilakukan di Kuala Mandah areal HPH PT. Bina Lestari, Riau dengan menggunakan tiga transek kontinu bersambung ditemukan tiga mintakat mangrove yaitu Avicennia marina, Rhizophora apiculata dan Ficus sp sebagai mintakat peralihan antara hutan mangrove dan hutan daratan. Pada penelitian ini ditemukan juga sepuluh jenis vegetasi mangrove dan tiga jenis vegetasi tumbuhan bawah, adapun jenis tersebut adalah...
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Judul: Struktur Vegetasi dan Mintakat Hutan Mangrove di Kuala Bayeun Kabupaten Aceh Timur Provinsi Nanggroe Aceh Darussalam
Abstrak: Width of mangrove forest in Indonesia is 4.250.000 ha, it has spread in some regions in Indonesia and giving great advantages for humans life (Soerianegara and Kusmana, 1993). One of the spreading location of mangrove forest is in Kuala Bayeun, East Aceh. Increasingly the number of population in Indonesia make some threatened to mangrove forest become larger. To prevent a confusion and clash of interests in using mangrove forest, we needed some informations about potentions and functions of mangrove forest. Among of the factors that influenced the policy about mangrove forest management is information details about zonation structure condition and their vegetation compositions the aims of the research are to identify zonation structure of mangrove forest and to know the composition and their structure of vegetations for each zonations. The method to collecting data was done using vegetations analysis. To analyzing data using important value index, variety index, species distribution, canopy profile and standing potention. Monitoring do to 3 growth levels (tree, stake and seedling) with 3 times repeating to each zonations. In Kuala Bayeun East Aceh, it have four zonations of mangrove forest, there are zonation I with 40 – 60 meters width, zonation II with 140 – 170 meters width, zonation III with 50 – 70 meters width, and zonation IV with 60 – 80 meters width. Total variety of mangrove plants were found in four zonations is 23 varieties, specify zonation I, mangrove plant which have dominated in growth, stake and seedling level is Avicennia marina with each the important value index are 115,69%, 136,36% and 72,47%. Mangrove variety index in tree level is 1,297; stake level is 1,274 and seedling level is 1,202. In zonation II, mangrove plant which have dominated in growth, stake and seedling level is Rhizophora apiculata, with each important value index are 127,55%, 145,09% and 93,51%. Variety index of mangrove in growth, stake and seedling continuously are 1,495; 1,476; and 1,353. In zonation III, mangrove plant which have dominated in growth, stake and seedling level is Ceriops decandra, with each important value index are 146,36%, 99,48% and 54,93%. Variety index of mangrove in growth, stake and seedling continuously are 1,594; 1,942 and 1,704. Zonation IV, mangrove plant which have dominated in growth, stake and seedling level is Xylocarpus granatum, with each important value index are 149,06%, 105,15% and 77,31%. Variety index of mangrove in growth, stake and seedling continuously are 0,881; 1,605 and 1,209. Vegetation structure in fourth zonation has one strata, it is stratum C.
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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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