Judul: Soil Properties in Various Agroforestry Lands in Kuningan Regency, West Java
Abstrak: Penurunan kualitas lahan disebabkan oleh deforestasi. Hal ini melibatkan berbagai faktor yang kompleks, seperti pengelolaan lahan, penanaman, yang diusahakan memberikan pengaruh tertentu terhadap sifat tanah. Agroforestri merupakan kondisi lanskap di mana pohon ditanam di lahan pertanian. Agroforestri bermanfaat dari sudut pandang lingkungan karena melestarikan atau meningkatkan kualitas tanah. Penerapan agroforestri bermanfaat dalam aspek ekonomi, sosial dan ekolgi, temasuk meningkatkan kualitas tanah. Sampel tanah penelitian diambil di daerah Jalaksana dan Cilimus, Kabupaten Kuningan, Jawa Barat. Jenis tanah di daerah ini merupakan tanah andosol. Kualitas fisik tanah diukur menggunakan dua pendekatan dalam penelitian ini. Teknik VESS digunakan untuk menilai kualitas struktur tanah yang dinilai dengan nilai structure quality (Sq) VESS. Metode analisis tanah konvensional digunakan untuk menentukan bobot isi dan porositas tanah. Analisis sifat kimia dan biologi tanah juga diamati seperti C-organik tanah, kapasitas tukar kation (KTK), keasaman (pH) tanah, dan keberadaan aktivitas makro-mesofauna tanah. Pengambilan sampel tanah dilakukan pada tujuh jenis penggunaan lahan antara lain agroforestri kompleks lengkuas, agroforestri kompleks kopi, agroforestri sederhana kopi, agroforestri sederhana ubi jalar, monokultur kopi, monokultur jagung, dan hutan alam. Selanjutnya, sebagai data pendukung diantaranya, komponen vegetasi, kerapatan tajuk, dan bobot serasah yang diperoleh untuk penelitian ini. Penelitian ini memiliki tujuan untuk mengevaluasi kualitas fisik tanah berbagai pola penggunaan lahan, termasuk agroforestri di Kabupaten Kuningan, Jawa Barat. Hasil penelitian metode VESS menunjukkan bahwa kualitas fisik tanah bervariasi. mulai dari nilai Sq sebesar 1,16-3,1. Agroforestri kompleks lengkuas memiliki nilai Sq 1,56 yang tidak berbeda nyata dengan lahan hutan alam (Sq 1,16), yang menunjukkan bahwa kedua penggunaan lahan tersebut memiliki kualitas fisik tanah yang sama.. Komponen vegetasi, kerapatan tajuk, dan ketersediaan serasah diduga mempengaruhi perbedaan skor VESS. Hal tersebut juga berpengaruh terhadap sifat fisik, kimia dan keberadaan makro-mesofauna tanah seperti bobot isi, porositas, C-organik, KTK, dan keanekaragaman jenis makro-meso fauna tanah. Skor VESS dan parameter sifat tanah lainnya memiliki korelasi yang sangat kuat (r) (BD = 0,80, porositas tanah =-0,80, SOC =-0,88, KTK = 0,89, indeks keanekaragaman fauna tanah = 0,82). Dalam penelitian ini menunjukkan bahwa, sistem agroforestri multi-strata dapat menjadi strategi pemulihan kualitas tanah pada lahan kritis, dan metode VESS dapat digunakan untuk menganalisis kualitas tanah di wilayah tersebut.
Keyword: VESS method, land management, macro-mesofauna soil, soil organic carbon, soil physical quality

Judul: Kualitas tanah pada sistem silvikultur tebang pilih tanam jalur(TPTJ) di areal kerja IUPHHK/HA PT. Sari Bumi Kusuma provinsi Kalimantan Tengah
Abstrak: Rapid forest exploitations can cause forest degradation, and eventually may cause the global climate change, because of that, the balance of the forest sustainability must be kept as well. The implementation of silviculture system called Selective Cutting and Strip Planting System is one of several forest harvesting method that consider the importance of forest sustainability. Practically, the system has never been tested to the last cycle. So, it is necessary to conduct some evaluation to the method to assure its sustainability. Estimation of soil quality is one of several ways to evaluate the effectiveness of silviculture implementation on a forest area, Since the soil is one of the major factor that influencing the growth of vegetations, then its quality can be used as an indication of conservation of forest productivity. In this research, the soil sampling was done in the forest area of PT. Sari Bumi Kusuma, on class of 1-9 years cultivation age, on May 22-31 2009. The sampling method being used is purposive sampling on the plot with size of 100 m x 100 m, selected purposively based on the same physical characteristic, in each class age on the intermediate block and planting strip to the depth of 0-20 cm and 20-40 cm. The sample is then analyzed with statistic method called ANOVA, to compare the mean value, and then the research data was scored based on Pamoengkas (2006). The result from scoring was then substituted into the formula developed by Pamoengkas (2006), and finally grouped into several categories developed by Pamoengkas (2006). The result of this research is the founding of two categories of soil quality value in the forest area of PT Sari Bumi Kusuma. One is Medium Category (1, 2, 4, 5, 8, and 9 years of cultivation age), and the other is Low Category (3, 6, and 7 years of cultivation age). Those differences might be due to unpredictable factors which have created non-uniform environment conditions of the research area, and those environment conditions have influenced the development of parameters which affecting the soil quality.
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Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model