Judul: Struktur Tegakan dan Regenerasi Alami Hutan di Pulau Siberut, Sumatera Barat
Abstrak: Stand structure model is important to estimate the dimensions of forest because it can reduce work in the field. The purpose of this study was to determine the general equation stand structure, the status of biodiversity, and the ability of natural regeneration in virgin forest and other former logged over forests. Data was collected from forest stands represent virgin forest and various stand conditions after logging (1 year, 4 years, and 20 years). For each stand condition, plot lines 20 m x 500 m (1 ha) was made, each of the three plots and then identified tree species, measuring tree diameter ≥ 10 cm, measuring the level of regeneration, and mapping of the vertical stand structure. The result of research shows that negative exponential distribution model is the best model to describe stand structure in the virgin forest condition as well as in many former logged forest conditions. Family distribution model can be used for assessment of tree diameter distribution in various diameter class of dipterocarp, non-dipterocarp, and all species. Biodiversity index value is high (2,94 to 3,87 with index of Shannon and 0,027 to 0,122 with indeks of Simpson) that indicates the level of species diversity in the study area is high and the dominance is centered on a couple of species.
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Judul: Model Dinamika Struktur Tegakan Hutan Alam Bekas Tebangan di Provinsi Kalimantan Tengah, Kalimantan Barat, dan Kalimantan Selatan
Abstrak: Most of the natural forest areas in Indonesia are logged over areas, in which their stand structures are different from those of primary forests. The phenomenon of stand structure dynamics includes recruitment, upgrowth, and mortality. The sustainability of productive forests depends on, among others, forest growth capability, environmental characteristics and proper forest management techniques in accordance with the ability of forest dynamic process. The objective of this study was to obtain dynamic models for the stand structures of logged over natural forests for each diameter classes and tree species groups, and then used them to predict stand structures for the next few years by using a stand structure projection method. This study used periodical measurement data from 44 permanent sample plots (PSP), which were established in the logged over areas of 5 HPH (timber concession companies) in West Kalimantan, 1 HPH in South Kalimantan, and 12 HPH in Central Kalimantan Provinces. Each PSP was one hectare in size, and it had various logging times and measurement periods. Data processing was carried out in the four stages : 1) analyzing the stand growth of each PSP in a 3-year period ; 2) species grouping (i.e. Dipterocarp and Non-Dipterocarp) and diameter grouping into 11 diameter classes (starting from 10-14,99 cm up to 60 cm up; 3) calculating the number and basal area of trees for each species group at each PSP; and 4) analyzing the data by using regression analysis to derive prediction models for projecting the dynamic of stand structures. Results showed that the upgrowth models for Dipterocarpaceae had coefficients of determination (R2) ranging from 14.8% to 70.4%, while those for Non-Dipeterocarpaceae ranging from 12.0% to 92.2%. The fixed models had R2 ranging from 5.4% to 73.0% (for Dipterocarpaceae) and from 5.6% to 82.3% (for Non-Dipeterocarpaceae). For diameter classes with non significant relationships or R2 < 50%, the mean of proportions was used to calculate the probabilities of upgrowth and stay on such diameter classes. The projection result of stand structure dynamics up to 51 years showed that the number of trees was increase. However, the projected stand structures tended to not follow the common “inverse J” curve of stand structure. Therefore, the projected stand structures were only recommended for no more than 12 years, which was also the maximum limit of the after logging period as used for constructing the models.
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Judul: Kajian Penggunaan Zeolit dan Kalsium Oksida sebagai Sumber Pemanas Kemasan Kaleng Panas Sendiri (self-heating can).
Abstrak: Penelitian ini mengkaji penggunaan zeolit sebagai alternatif sumber pemanas pada kemasan kaleng panas sendiri yang umumnya menggunakan kalsium oksida. Pada penelitian ini telah dilakukan proses kalsinasi pada suhu 550 oC selama 24 jam terhadap zeolit dan kalsium oksida untuk pembakaran awal dengan tujuan menghilangkan zat-zat yang tidak diinginkan. Kemudian telah dilakukan pengukuran suhu reaksi campuran sejumlah sampel dengan sejumlah air pada masing-masing perbandingan. Hasil penelitian menunjukkan reaksi air dengan kalsium oksida menghasilkan suhu tertinggi pada perbandingan 3:1 dengan ratarata perubahan suhu 46.37 oC. Sedangkan reaksi air dengan zeolit menghasilkan suhu tertinggi pada perbandingan 1:2 dengan rata-rata perubahan suhu 39.27 oC. Massa kalsium oksida yang digunakan 5.00 gram dan zeolit yang digunakan 28.00 gram. Kemudian telah dilakukan pengukuran perubahan volume sampel yang direaksikan dengan air, hasilnya kalsium oksida dan air memiliki kenaikan volume 1.00 ml sedangkan zeolit memiliki kenaikan volume 2.00 ml. Dari hasil penelitian ini dapat disimpulkan bahwa zeolit ternyata belum mampu untuk menggantikan kalsium oksida sebagai sumber pemanas self-heating can dari aspek kapasitas panas yang dihasilkan dan nilai ekonomis penggunaan bahan.
Keyword: kaleng panas sendiri, kalsium oksida, kemasan aktif, sumber pemanas, zeolit