Judul: Soil Macrofauna Abundance and Site Characteristics in Limestone Post-Mining Land (PT. Solusi Bangun Indonesia)
Abstrak: Penambangan batu kapur berpotensi menghilangkan fauna tanah dan menurunkan kualitas tanah lahan pascatambangnya. Revegetasi merupakan upaya memulihkan ekosistem dan biodiversitasnya dengan penanaman pohon. Penelitian ini bertujuan untuk menganalisis kelimpahan makrofauna tanah, karakteristik tapak, dan hubungan karakteristik tapak dengan kelimpahan makrofauna tanah di lahan pascatambang kapur PT. Solusi Bangun Indonesia, Narogong, Jawa Barat. Makrofauna tanah dianalisis kelimpahan jenis dan beberapa indeks biodiversitas, sedangkan sampel tanah dianalisis sifat fisik, kimia, dan biologi tanahnya. Analisis data dilakuka dengan uji Beda Nyata Terkecil (BNT) untuk melihat perbedaan kelimpahan makrofauna tanah dan uji korelasi Pearson untuk mengetahui hubungan antara karakteristik tapak dengan kelimpahan makrofauna tanah. Kelimpahan makrofauna tanah pada keempat lokasi penelitian berbeda nyata kecuali pada lahan pascatambang terbuka yang dipengaruhi oleh kondisi klimatis dan edafisnya. Karakteristik tapak dari keempat lokasi penelitian menunjukkan perbedaan yang disebabkan oleh pengelolaan dan revegetasi lahan pascatambang, tahun revegetasi, dan karakteristik vegetasi yang tumbuh.
Keyword: post-lime mining, revegetation, site characteristics, soil macrofauna

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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