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: Struktur Tegakan Hutan Alam Sebelum dan Sesudah Penebangan di Areal Konsesi Hutan Pulau Siberut, Sumatera Barat
Abstrak: The structure of forest stands have differences between the conditions before and after logging. It is influenced by some factors on the conditions before and after logging. To be able figure out how big the differences between the structure of forest stands before and after logging, the diameter distribution model can be used in the stands like the model of the family distribution. There are four models of the family distribution commonly used that is an Exponential negative, Gamma, Lognormal and Weibull. From the four of distribution model will be selected the best of family distribution models which can describe the difference in the structure of forest stands. The results of the research show the Exponential negative distribution family model was selected as the best model. Based on results test of Chi-square (X2) an Exponential negative distribution family model was able to explain the difference between the structure of forest stands before and after logging.
Keyword: structure of forest stand., model of forest structure, model of distribution family, Chi-square test

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