Judul: Produktivitas, Laju Dekomposisi, dan Pelepasan Hara Serasah pada Tegakan Jabon (Anthocephalus cadamba Miq.).
Abstrak: Maintaining the nutrient supply in soil is crucial for sustaining productivity. Nutrient cycling in ecosystem provide available nutrient through inputs, storage pools, and outputs. In nutrient cycle, plant nutrient uptake from soil and return to soil from litterfall, coverground species, and remain harvest plant through decomposition process. Jabon putih (Anthocephalus cadamba Miq.) is one of Indonesia native species which has high prospect for plantation forest and revegetation in degraded ecosystem, such caused by mining operations. The soil of overburden dumps in coal mining are physically, nutritionally and biologically poor. This study was conducted to calculate productivity, decomposition rate, nutrient content and nutrient release to 4-year-old jabon plantation, also to test the application of jabon compost that applied to jabon seedling with soil from coal mine as planting media. Research was conducted at 4-year-old jabon plantation. Method of Litterfall productivity use litterfall collection traps every week during 12 weeks. Decomposition rate was used litter bag technique, with 120 of bags which placed above soil floor. Collecting data for use application of jabon compost was held during10 weeks. Total productivity during 12-week is 22.25 g m-2 week-1 or 11.57 ton ha-1 yr-1. Rate decay constant (k) is 0.09 week-1 and relative decomposition rate was 0.086 g g-1 week-1. Nutrient input from leaf litter, from highest to lowest, in the following order: Ca (238 kg ha-1 )> N (230 kg ha-1)> Mg (151 kg ha-1)> K (110 kg ha-1)> P (44 kg ha-1). Magnesium has the highest percentage of nutrient release that is 98.11 % during 12-week decomposition. Application of jabon compost to soil from coal mine has significant effects on height and diameter growth, total biomass, and shoot and root biomass, but it did not significantly effected on shoot-root ratio. Combination between media and 30 % jabon compost increased plant height by 69 %, diameter by 72 %, and biomass total by 193 % compared with control treatment.
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Judul: Pertumbuhan Semai Jabon (Anthocephalus cadamba Roxb Miq) Pada Media Pasca Penambangan Batubara Yang Diperkaya Fungi Mikoriza Arbuskula, Limbah Batubara dan Pupuk NPK
Abstrak: One of the problems created by coal mining activities is the progressive increase of critical land area size and environmental damage, which are among other things in the form of worsening physical, chemical and biological properties of soils which lead to decrease of soil fertility and disturbed plant growth. Growth and nutrient absorption by Jabon seedlings have been studied in terms of their respond toward application of Arbuscular Mycorrhizal Fungi (AMF), coal waste, and soil media being used after coal mining operation. The experiment was designed as factorial completely randomized design, comprising 3 treatment factors, namely, species of AMF inoculants (control, Glomus sp., and Gigaspora sp.), growth media (control, mixture of 15% south Kalimantan coal, and mixture of 15 % Jambi coal) and concentration of NPK fertilizer (control, 2 gram/polybag, and 4 gram/polybag) with 10 replications, so that in total, there were 270 experimental units. Results showed that interaction between AMF, growth media and fertilizer had significant effects on parameters of diameter increment, shoot biomass, root biomass, total dry weight, index of planting stock quality, and percent of AMF colonization. Parameter of height increment and number of Jabon seedling leaves were affected by interaction between AMF and fertilizer. Treatment combination of AMF inoculants, coal powder, and NPK fertilizer was able to increase the concentration and absorption of nutrients N, P and K. The three treatments combination showed positive correlation between increase in concentration of nutrients N, P and K; and shoot biomass of Jabon seedlings.
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Judul: Kajian frieze groups untuk klasifikasi dan konstruksi desain berdasarkan simetri pada pola
Abstrak: Frieze groups adalah konsep matematika untuk mengklasifikasikan desain pada dua dimensi permukaan yang berulang-ulang dalam satu arah berdasarkan simetri pada pola. Frieze groups merupakan grup yang mempertahankan bentuk pola. Pergerakan bentuk pola terdiri dari translasi, refleksi dan rotasi 180o. Tujuan dari karya ilmiah ini adalah mengkaji sifat Frieze group, mengkaji penggunaan Frieze group dalam mengklasifikasikan simetri pada pola dan mengkonstruksi pola dengan menggunakan software tesselmania. Hasil yang telah diperoleh, bahwa jenis Frieze groups merupakan subgroup dari grup pergerakan pola. Selain itu dapat dilihat dari sifat isomorfik berbagai jenis Frieze groups. Untuk mengkonstruksi sebuah bentuk pola dapat menggunakan salah satu software untuk membentuk sebuah pola bidang datar (dua dimensi) yaitu tesselmania.
Keyword: Frieze groups, Simetri, Pola