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: Vegetation and Environmental Characteristics in Land Ecosystems Results from Revegetation on Post-Coal Mining Lands PT. Pesona Khatulistiwa Nusantara
Abstrak: Pertambangan batu bara mengakibatkan hilangnya vegetasi yang berada di atas permukaan tanah, mengubah struktur, dan tekstur tanah. Kegiatan revegetasi dilakukan untuk memulihkan kembali kondisi lingkungan. Penelitian ini bertujuan untuk menganalisis karakteristik vegetasi dan lingkungan pada areal revegetasi lahan pascatambang batu bara. Metode penelitian menggunakan analisis vegetasi dan analisis biofisik lingkungan (edafis dan klimatis). Hasil penelitian menunjukkan bahwa hutan alam (ekosistem referensi) memiliki jenis vegetasi yang lebih banyak. Lahan revegetasi yang diamati hanya didominasi oleh satu jenis saja, yaitu sengon laut (Falcataria moluccana), sehingga nilai indeks keanekaragaman jenis, indeks kekayaan jenis, dan indeks kemerataan jenis hutan alam lebih tinggi daripada lahan revegetasi. Nilai indeks kesamaan tergolong tinggi hanya ditemukan pada lokasi lahan revegetasi umur 10 tahun dan 2 tahun pada tingkat pancang dan tiang. Lahan revegetasi umur 10 tahun memiliki total biomassa dan simpanan karbon lebih tinggi dibandingkan lahan revegetasi umur 2 tahun. Karakteristik kesuburan tanah lahan revegetasi umur 2 tahun memiliki nilai rendah daripada kedua lokasi lainnya, karena memiliki pH masam, C-organik sangat rendah, kapasitas tukar kation (KTK) rendah, dan kejenuhan basa (KB) yang sedang., Coal mining results in the loss of aboveground vegetation, changing the structure and texture of the soil. Revegetation activities are carried out to restore environmental conditions. This study aims to analyze the characteristics of vegetation and the environment in the revegetation area of post-coal mining land. The research method used vegetation analysis and biophysical analysis of the environment (edaphic and climatic). The results showed that natural forest (reference ecosystem) has more vegetation types. The revegetated land is only dominated by sengon laut (Falcataria moluccana), so the value of the species diversity index, species richness, and species evenness of natural forest is higher than the revegetated land. High similarity index values were only found in the second location of revegetated land at the sapling and pole levels. The 10-year-old revegetated land had higher total biomass and carbon storage than the 2-year-old revegetated land. Soil fertility characteristics of 2-year-old revegetated land have low values than the two locations, because they have acidic pH, very low C-organic, low cation exchange capacity (CEC), and medium base saturation.
Keyword: coal, post-mining, revegetation, soil, vegetation

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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