Judul: Species Composition, Vegetation Structure, and Carbon Absorption in Revegetation Post-Mining Areal PT Berau Coal
Abstrak: Reklamasi lahan pasca tambang wajib dilakukan oleh perusahaan tambang, salah satu perusahaan tambang yang melakukan kegiatan reklamasi pasca tambang yaitu PT Berau Coal. Kegiatan reklamasi dan revegetasi menggunakan pola tanam agroforestri diharapkan dapat memulihkan kerusakan ekologi. Penelitian bertujuan mengetahui komposisi jenis, struktur vegetasi, dan menghitung potensi serapan karbon di areal revegetasi site BMO-1 PT Berau Coal. Pengambilan data dengan metode non destructive sampling menggunakan persamaan allometric pada tegakan revegetasi Blok 1-2, dan Blok 1-4, sebanyak 5 plot pada tiap petak ukur 20 m × 20 m. Hasil indeks nilai penting (INP) tingkat pohon tertinggi yaitu Paraserianthes falcataria, tingkat tiang yaitu Senna siamea, dan tingkat pancang dan semai yaitu Nephelium lappaceum. Indeks keanekaragaman jenis (H’), kekayaan jenis (R), dan kemerataan jenis (E) terbesar pada tingkat pancang. Stratifikasi tajuk pada pola tanam agroforestri termasuk dalam strata B, C, dan D, sedangkan pola tanam monokultur termasuk dalam strata B dan C. Nilai biomassa dan serapan karbon tertinggi pada pola tanam agroforestri yaitu P. falcataria.
Keyword: agroforestry, carbon absorption, revegetation, species composition, vegetation structure

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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