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: Understory Plant Diversity and Carbon Stock Potential in Post-Mining Revegetation Land at PT. Berau Coal East Kalimantan
Abstrak: Inventarisasi tumbuhan dan perhitungan karbon dilakukan untuk mengukur keberhasilan revegetasi lahan pascatambang. Penelitian ini bertujuan untuk mengetahui keanekaragaman tumbuhan bawah serta mengetahui potensi simpanan kabon di atas permukaan tanah serta kaitannya terhadap perbedaan umur lahan revegetasi 2018, 2016 dan 2013. Pembuatan plot menggunakan metode petak contoh berukuran 50 m x 50 m sebanyak 3 plot pertegakan umur. Masing-masing plot terdapat 4 (subplot). Pengukuran biomassa dilakukan dengan metode non destruktif dan menggunakan rumus alometrik. Hasil penelitian menunjukkan keanekaragaman ketiga umur revegetasi yang tidak jauh berbeda. Biomassa total dan kandungan karbon tersimpan tertinggi dihasilkan pada revegetasi tahun 2013 dengan total sebesar 81,61 ton/ha dan total kandungan karbon tersimpan sebesar 38,36 ton C/ha sedangkan biomasa total dan simpanan karbon di lahan revegetasi tahun 2018 adalah 33,23 ton/ha dan 15,62 ton C/ha dan biomasa total dan simpanan karbon di lahan revegetasi tahun 2016 adalah 75,48 ton/ha dan 35,48 ton C/ha. Kata kunci: biomassa, karbon, reklamasi, tambang, tumbuhan bawah, Plant inventories and carbon calculations are carried out to measure the success of post-mining land revegetation. Plant inventories and carbon calculations are carried out. This research aims to determine the diversity of understory plants and determine the potential for carbon deposits above ground and their relationship to differences in the age of revegetated land in 2018, 2016 and 2013. Plots were made using the sample plot method measuring 50 m x 50 m with a total of 3 plots. Each plot has 4 (subplots). Biomass measurements are carried out using non-destructive methods and using allometric formulas. The research results show that the diversity of the three revegetation ages is not much different. The highest total biomass and stored carbon content was produced in revegetation in 2013 with a total of 81,61 tons/ha and the total stored carbon content was 38,36 tons C/ha while the total biomass and carbon savings in revegetated land in 2018 was 33,23 tons/ha and 15,62 tons C/ha and total biomass and carbon storage in revegetated land in 2016 was 75,48 tons/ha and 35,48 tons C/ha. Keywords: biomass, carbon, mining, reclamation, undergrowth
Keyword: carbon, mining, reclamation, undergrowth

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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