Judul: Analysis of Vegetation Development and Soil Properties In Post-Mining Land Revegetation Area at PT Tambang Tondano Nusajaya, North Sulawesi
Abstrak: Kegiatan revegetasi dapat membentuk struktur dan komposisi tegakan serta dapat meningkatkan kualitas tanah. Tujuan penelitian ini yaitu menganalisis perkembangan komposisi dan struktur vegetasi, menganalisis sifat fisik dan kimia tanah, dan menganalisis hubungan antara umur revegetasi dengan sifat-sifat tanah pada areal revegetasi lahan pascatambang. Metode pengambilan data vegetasi yaitu metode Systematic Sampling with Random Start dan metode jalur berpetak (transek), sedangkan untuk data tanah pengambilan contoh tanah secara komposit. Hasil secara keseluruhan terdapat 41 jenis vegetasi pokok, 7 jenis vegetasi sulaman, dan hadirnya 24 jenis alami. Lahan revegetasi umur 9 tahun memiliki rata-rata LBDS mendekati hutan alam yaitu sebesar 1,90 cm2. Hasil analisis struktur vegetasi menunjukkan areal revegetasi umur 3 – 10 tahun memiliki struktur vegetasi yang lengkap. Dari komposisi jenisnya, areal revegetasi yang memiliki jumlah jenis terbanyak yaitu areal revegetasi umur 7 tahun sebanyak 45 jenis. Hasil analisis sifat fisik dan kimia tanah menunjukkan kondisi yang beragam namun dominan telah mampu mendukung pertumbuhan vegetasi. Areal yang memiliki kondisi vegetasi dan karakteristik tanah mendekati hutan alam adalah areal revegetasi umur 10 tahun. Hasil analisis korelasi menunjukkan hubungan antara umur vegetasi dengan sifat tanah sangat lemah kecuali pada variabel C-Organik dan C/N rasio yang memiliki hubungan cukup kuat., Revegetation activities can shape the vegetation stands and can improve soil quality. This study aimed to analyze the development of vegetation composition and structure, analyze the physical and chemical properties of the soil, and analyze the relationship between revegetation age and soil properties. We use the Systematic Sampling method with Random Start and the transect method for collected vegetation data, while the soil sampling is composite. Overall, there are 41 basic species, 7 embroidered species, and 24 natural species. The 9-year-old revegetation land has an average basal area close to natural forest, which is 1,90 cm2. The vegetation structure shows that the revegetation area aged 3-10 years has a complete vegetation structure. The revegetation area aged 7 years has the highest number of species with 45 species. The results of the physical and chemical properties of the soil show that various but dominant conditions have been able to support the growth of vegetation. The 10-year-old revegetation area has vegetation conditions and soil characteristics close to a natural forest. The correlation analysis showed that the relationship between vegetation age and soil properties was very weak, except for the C-Organic variable and the C/N ratio which had a fairly strong relationship.
Keyword: C/N ratio, Organic-C, post gold mining, reclamation, revegetation

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.
Keyword: