Judul: Pemulihan Vegetasi di bawah Tegakan Tua Tengkawang Pelekpek (Shorea mecistopteryx) di KHDTK Haurbentes, Kabupaten Bogor
Abstrak: Luas kawasan hutan di Indonesia mengalami penurunan setiap tahunnya yang diakibatkan oleh laju deforestasi yang selalu meningkat. Hutan dataran rendah di Indonesia didominasi oleh jenis-jenis pohon dari kelompok dipterokarpa yang bernilai komersil tinggi. Salah satu jenis meranti endemik yang berasal dari Pulau Kalimantan adalah Shorea mecistopteryx. Penelitian ini bertujuan menganalisis struktur tegakan, regenerasi alami dan produktivitas dari tegakan S. mecistopteryx. Hasil analisis menunjukkan struktur tegakan S. mecistopteryx yang berumur 83 tahun telah membentuk huruf “J” terbalik, sedangkan struktur tegakan pada umur 32 tahun berbentuk kurva normal. Potensi tegakan S. mecistopteryx pada umur 83 tahun telah menghasilkan potensi tegakan berdiameter 50 cm ke atas sebesar 323,08 m3 /ha dan kelas diameter 40 cm ke atas sebesar 541,78 m3 /ha. Potensi tegakan S. mecistopteryx pada umur 32 tahun telah menghasilkan potensi tegakan untuk kelas diameter 50 cm ke atas sebesar 45,98 m3 /ha dan kelas diamaeter 40 cm ke atas sebesar 497,73 m3 /ha.
Keyword: Shorea mecistopteryx, forest plantation, stand structure, stand volume, natural regeneration

Judul: Pemulihan Vegetasi di Areal Hutan yang Dikelola dengan Sistem TPTJ (Studi Kasus di Areal IUPHHK-HA PT. Suka Jaya Makmur, Kalimantan Barat)
Abstrak: Massive utilization of forest resources became one factor which caused degradation on natural forest. Forest degradation which occurred continuously could cause a change in forest composition. This could happen because seedling from invasive species dominated the area of natural forest. This research aimed to determine the composition and structure recovery of forest stands managed by TPTJ system on area of IUPHHK-HA PT. Suka Jaya Makmur, West Kalimantan. The results showed that non-commercial Dipterocarp species group had the biggest value of density and proportion among all levels Dipterocarp. Curve diameter distribution showed a balanced logged forest. The diversity in all plotarea was high. Kelampai and meranti were dominated in canopy level. Jambu monyet and kelampai were the species that dominated in seedling level. Tree and seedling had a different composition, it was shown by the ID value at >50%. This was shown by cluster analysis which divided into four groups. Commercial species proportion was generally larger than other non-commercial species.
Keyword: selective cutting and line planting, vegetation recovery, forest utilization

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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