Judul: Growth of White Jabon (Anthocephalus cadamba) in The  Gap Planting Research Area at PT. Sarmiento Parakantja Timber, Central  Kalimantan
Abstrak: Sistem silvikultur Tanam Rumpang dan Tebang Rumpang (TRTR) diharapkan dapat meningkatkan produktivitas hutan alam yang mengalami degradasi. Jabon putih yang ditanam pada areal rumpang merupakan salah satu jenis yang potensial untuk dikembangkan dalam sistem TRTR karena pertumbuhannya yang sangat cepat. Penelitian ini bertujuan untuk menganalisis pertumbuhan jabon putih dalam rumpang dan pengaruh kelerengan terhadap pertumbuhan jabon putih. Penelitian dilakukan pada bulan Maret hingga Mei 2022. Kegiatan pengambilan data pertumbuhan jabon putih dilakukan di areal tanam rumpang dengan topografi datar-curam (0% - 40%). Hasil penelitian menunjukkan Jabon putih yang ditanam dalam rumpang memiliki rata-rata pertumbuhan diameter dan tinggi jabon putih yaitu sebesar 3.87 cm/thn dan 215.49 cm/thn. Uji statistik menunjukkan terdapat perbedaan nyata pengaruh kelerengan terhadap pertumbuhan diameter pohon jabon putih, The silvicultural system of gap planting and gap clear cutting (TRTR) is expected to increase the productivity of degraded natural forests. White jabon which is planted in the gap area is one of the species that potentially developed in the TRTR system due to its very fast growth characteristics. This study aims to analyze white jabon growth in the gap area and the effect of slope on it. The study was conducted from March to June 2022. The data collection was carried out in the gap planting area with flat to steep topography (0 - 40%). The results showed that white jabon planted in gap planting area had an average diameter and height growth of 3.87 cm/year and 215.49 cm/year. Statistical tests showed a significant difference in the effect of slope on diameter growth of white jabon.
Keyword: Anthocephalus cadamba, forest degradation, gap planting, growth

Judul: Soil Erosion Study in The Gap Planting Research Area  with Jabon Putih in The PT. Sarmiento Parakantja Timber
Abstrak: Peningkatan produktivitas hutan alam dapat dilakukan dengan menerapkan teknik tanam rumpang. Tujuan dari teknik tanam rumpang adalah untuk merehabilitasi hutan alam terdegradasi dengan penanaman fast growing species lokal non Dipterocarpaceae yang berdaur pendek (5-8 tahun) di dalam areal rumpang. Penelitian ini bertujuan untuk mendapatkan informasi erosi tanah yang terjadi akibat tanam rumpang pada kondisi areal hutan alam, simpukan dan jalur tanam. Penelitian dilakukan pada bulan Mei 2021. Penelitian dilakukan pada dua kelas kelerengan yaitu kelas datar-landai dan kelas sedang. Hasil uji statistik menunjukkan tidak berbeda nyata antara besarnya erosi tanah pada kelas lereng datar-landai dan kelas lereng sedang. Hasil penelitian menunjukan besar erosi tanah yang terjadi secara berturut-turut dari yang terbesar ke terkecil adalah di areal hutan alam, di areal jalur tanam dan di areal jalur simpukan., Increasing the productivity of natural forests can be done by applying the gap planting technique. The purpose of the gap planting technique is to rehabilitate degraded natural forests by planting local intolerant fast-growing species with short cycles (5-8 years) in the gap area. This study aims to obtain information on soil erosion that occurs due to gap planting activities on the condition of natural forest areas, erosion barrier strips, and planting strips. The study was conducted in May 2021. The study was conducted on two slope classes, the flat to sloping class and the moderate class. The result of statistical tests showed that the magnitude of erosion on the flat to sloping class and moderate class was not significantly. The results showed that the amount of soil erosion that occurred successively from the largest to the smallest was the area of natural forest, planting area, and erosion barrier area.
Keyword: erosi tanah, hutan alam terdegradasi, rehabilitasi, tanam rumpang, degraded natural forests, gap planting, rehabilitation, soil erosion

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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