Judul: Abundance and Diversity of Soil Surface Arthropods in Revegetated Land at PT. Bukit Asam, South Sumatera
Abstrak: Arthropoda permukaan tanah adalah salah satu hewan penting dalam komunitas terestrial lahan pasca tambang. Penelitian bertujuan menganalisis kelimpahan dan keanekaragaman arthropoda permukaan tanah pada lahan revegetasi di PT Bukit Asam. Metode pengumpulan data dilakukan dengan pitfall trap pada lahan revegetasi angsana (Pterocarpus indicus), merbau (Intsia palembanica), sengon buto (Enterolobium cyclocarpum) berumur 8 tahun serta hutan sekunder sebagai ekosistem kontrol, dilanjutkan dengan pengukuran kondisi lingkungan, identifikasi arthropoda, dan analisis data. Hasil penelitian menunjukkan bahwa ditemukan sebanyak 17 ordo 51 famili 118 morfospesies dengan total 4.802 individu. Lahan revegetasi angsana memiliki nilai kelimpahan dan keanekaragaman arthropoda permukaan tanah tertinggi dengan indeks keanekaragaman jenis (H’) 2,782. Sementara hutan sekunder memiliki nilai kelimpahan dan keanekaragaman jenis terendah dengan indeks (H’) 1,959. Kelimpahan arthropoda permukaan tanah didominasi oleh Ordo Hymenoptera. Adapun ordo yang paling sedikit dijumpai adalah Thysanoptera. Faktor lingkungan memiliki korelasi terhadap kelimpahan arthropoda permukaan tanah., Land surface arthropods are one of the most important animals in the terrestrial community of post-mining land. The study aimed to analyze the abundance and diversity of soil surface arthropods on revegetation land at PT Bukit Asam. Data collection methods were carried out with pitfall traps on 8-year-old angsana (Pterocarpus indicus), merbau (Intsia palembanica), sengon buto (Enterolobium cyclocarpum) revegetation land and secondary forest as a control ecosystem, followed by measurement of environmental conditions, arthropod identification, and data analysis. The results showed that there were 17 orders 51 families 118 morphospecies with a total of 4.802 individuals. The angsana revegetation land had the highest abundance and diversity of ground surface arthropods with a species diversity index (H') of 2,782. Meanwhile, secondary forest has the lowest abundance and diversity of species with an index (H') of 1,959. The abundance of soil surface arthropods is dominated by Hymenoptera Order. The least common orders were Thysanoptera. Environmental factors have a correlation with the abundance of arthropods.
Keyword: Pertambangan, Pitfall trap, Reklamasi, Serangga tanah

Judul: Diversity of Soil Arthropod in the Rehabilitation Zone of Gunung Halimun Salak National Park
Abstrak: Arthropoda tanah merupakan salah satu faktor penentu dari kesuburan tanah dan kehadirannya memiliki peranan penting terhadap ekosistem. Penelitian ini dilaksanakan di Zona Rehabilitasi, Resort Gunung Kendeng, Kawasan Taman Nasional Gunung Halimun Salak (TNGHS). Penelitian bertujuan untuk mengidentifikasi keanekaragaman, menganalisis pengaruh kerapatan vegetasi dan menganalisis pengaruh kondisi lingkungan terhadap keanekaragaman Arthropoda tanah di Zona Rehabilitasi TNGHS. Sampel Arthropoda tanah diambil pada petak pengamatan 50 m x 50 m sebanyak 14 petak pengamatan. Sub petak pengamatan ditempatkan sebanyak 9 kali ulangan secara acak pada tiap petak pengamatan. Pengambilan sampel tanah dan pengukuran faktor lingkungan dilakukan pada sub petak pengamatan berukuran 50 cm x 50 cm sebanyak tiga kali ulangan tiap petak pengamatan. Didapatkan 24 famili Arthropoda tanah yang berasal dari 13 ordo yang berbeda. Indeks keanekaragaman (H’) antara dua kerapatan vegetasi tidak berbeda nyata, pada kerapatan vegetasi tinggi didapatkan H’ 0,80 dan pada kerapatan sedang H’ 0,73. Hubungan keanekaragaman Arthropoda dengan faktor edafis seperti respirasi tanah yaitu berbanding terbalik, sedangkan pH tanah dan ketebalan serasah menunjukkan hubungan yang berbanding lurus. Hubungan faktor klimatis dengan keanekaragaman Arthropoda pada kerapatan vegetasi tinggi adalah berbanding lurus, sedangkan pada kerapatan vegetasi sedang menunjukkan hubungan yang berbanding terbalik., Soil arthropod is one of the determining factors of soil fertility and have an important role in the ecosystem. The research was conducted in the Rehabilitation Zone, Gunung Kendeng Resort, Gunung Halimun Salak National Park (GHSNP). The purpose of this study was to identify the diversity, analyze the effect of vegetation density, and analyze the effect of environmental conditions on soil arthropods in Rehabilitation Zone on GHSNP. Soil arthropod were collected from 50 m x 50 m with a total 14 observation plots. Sub- observation plots were placed 9 repetation in each plot. Soil sampling and environmental factor measurements were taken on 50 cm x 50 cm sub plot with 3 replications. There are 24 families of soil arthropods were obtained from 13 different orders. The index of diversity (H’) between two vegetation densities was not significant, with H’ values 0,80 for hight vegetation density and 0,73 for moderate vegetation density. The relationship between diversity of soil arthropod and edaphic factors such as soil respiration showed an negatively correlation, while pH and soil pH showed a positively correlation. The relationship between climatic factors at high vegetation density showed a linear relation, while at moderate vegetation density showed an inverse relation.
Keyword: soil arthropod, climatic, diversity, edaphic, pitfall trap

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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