Judul: Decomposition Rate and Site Characteristics in the Agroforestry System at Mount Kendeng Resort, Mount Halimun Salak National Park.
Abstrak: Leaf litter has a positive influence on the physical and chemical properties of soil through the provision of organic matter on the soil surface. This study aimed to measure the decomposition rate of leaf litter, and analyze the relationship between site characteristics and environmental conditions on the decomposition rate in agroforestry systems areas. Vegetation analysis was carried out on 50 m x 50 m sample plots totalling 14 plots. In addition, decomposition rate analysis, site characteristics, climate, and correlation tests were carried out. The dominant tree species in agroforestry systems areas was Agathis dammara. The highest and lowest decomposition rates in agroforestry systems areas at Gunung Kendeng Resort were 0.57 g/day and 0.33 g/day, respectively. The correlation between decomposition rate and edaphic factors that had a positive correlation were pH, soil organic matter, organic carbon, and porosity, while soil temperature, soil respiration, and bulk density had a negative correlation. The correlation between decomposition rate and climatic factors that had a positive correlation was moisture, while air temperature and light intensity had a negative correlation., Serasah memiliki pengaruh yang positif terhadap sifat fisik dan kimia tanah melalui penyediaan bahan organik di permukaan tanah. Penelitian ini bertujuan untuk mengukur laju dekomposisi serasah daun, dan menganalisis hubungan karakteristik tapak dan kondisi lingkungan terhadap laju dekomposisi pada areal sistem agroforestri. Analisis vegetasi dilakukan pada plot contoh 50 m×50 m sebanyak 14 plot. Selain itu, dilakukan analisis laju dekomposisi, karakteristik tapak, dan klimatis, serta uji korelasi. Jenis pohon yang mendominasi pada areal sistem agroforestri adalah Agathis dammara. Laju dekomposisi tertinggi dan terendah pada areal dengan sistem agroforestri di Resort Gunung Kendeng secara berturut-turut sebesar 0,57 g/hari dan 0,33 g/hari. Hubungan korelasi laju dekomposisi dengan faktor edafis yang memiliki korelasi positif adalah pH, bahan organik tanah, C-Organik, dan porositas, sedangkan suhu tanah, respirasi tanah, dan bulk density memiliki korelasi negatif. Hubungan korelasi laju dekomposisi dengan faktor klimatis yang memiliki korelasi positif adalah kelembapan, sedangkan suhu udara dan intensitas cahaya memiliki korelasi negatif.
Keyword: agroforestri, dekomposisi, karakteristik edafis, karakteristik klimatis, serasah

Judul: Leaf Litter Decomposition and Soil Characteristics in The Mountain Rainforest Ecosystem of Gunung Halimun Salak National Park (TNGHS)
Abstrak: Hutan hujan pegunungan merupakan salah satu tipe ekosistem hutan hujan tropis dengan ketinggian 1.000 – 2.400 mdpl. Hutan hujan pegunungan di TNGHS terdapat di zona inti yang memiliki kondisi dan fungsi yang masih asli (alami). Serasah merupakan bahan baku proses dekomposisi yang menentukan siklus unsur hara dan kesuburan tapak. Penelitian ini bertujuan untuk menganalisis laju dekomposisi serasah daun pada ekosistem hutan hujan pegunungan dan menganalisis hubungan antara laju dekomposisi serasah daun dengan faktor-faktor lingkungan (kondisi vegetasi, edafis, dan klimatis). Laju dekomposisi serasah daun ekosistem hutan hujan pegunungan pada kelas kerapatan sedang meningkat dari hari ke-30 hingga ke-90. Pada kelas kerapatan tinggi laju dekomposisi serasah daun mengalami peningkatan yang tidak terlalu signifikan dari hari ke-30 hingga hari ke-90. Laju dekomposisi serasah daun memiliki korelasi positif dengan suhu udara, kelembapan udara, intensitas cahaya, bahan organik tanah, C-organik tanah, pH tanah, N-total, dan bulk density, serta memiliki korelasi negatif dengan suhu tanah, respirasi tanah, C/N rasio dan porositas tanah., Mountain rainforest is one of the types of tropical rainforest ecosystems with elevations ranging from 1.000 - 2.400 m asl. Mountain rainforests in TNGHS are located in the core zone, which has original (natural) conditions and functions. Leaf litter serves as the raw material for the decomposition that determines the nutrient cycle and soil fertility. This study aims to analyze the rate of leaf litter decomposition in mountain rainforest ecosystems and to examine the relationship between the rate of leaf litter decomposition in mountain rainforest ecosystems and environmental factors (vegetation conditions, edaphic factors, and climatic factors). The rate of leaf litter decomposition in the lower mountain forest ecosystem increased from day 30 to day 90 in the medium-density class. In the high-density class, the rate of leaf litter decomposition experienced a less significant increase from day 30 to day 90. The rate of leaf litter decomposition is positively correlated with air temperature, air humidity, light intensity, soil organic matter, soil organic carbon, soil pH, N-total, and bulk density, while it is negatively correlated with soil temperature, soil respiration, C/N ratio, and soil porosity.
Keyword: Dekomposisi, Hutan Hujan Pegunungan, Hutan Tropis, Unsur Edafis, Unsur Klimatis

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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