Judul: Diversity of Undergrowth at Various Ages of Teak Stands in KPH Pati, Central Java
Abstrak: Salah satu unit pengelolaan Perhutani yang mengembangkan hutan jati adalah KPH Pati. Hutan jati yang dikelola KPH Pati terdiri dari berbagai kelompok umur yang berkaitan dengan kondisi lingkungan abiotik di sekitar tumbuhan bawah yang memengaruhi terhadap keanekaragaman tumbuhan bawahnya. Penelitian ini bertujuan untuk mengidentifikasi dan mengukur tingkat keanekaragaman spesies, nilai manfaat dan potensi invasif tumbuhan bawah, serta mendeskripsikan kondisi faktor lingkungan abiotik pada berbagai umur tegakan jati di KPH Pati. Metode pengambilan data dilakukan dengan analisis vegetasi, observasi lapang, dan studi literatur. Hasil penelitian menunjukkan bahwa teridentifikasi 45 spesies tumbuhan bawah dari 24 famili. Keanekaragaman jenis tumbuhan bawah tertinggi pada tegakan jati berumur 43 tahun dengan H’ sebesar 2,54, disusul kemudian pada tegakan jati umur 38 tahun, 33 tahun, dan 48 tahun dengan nilai H’ 2,43, 2,29 dan 2,20. Tumbuhan bawah yang teridentifikasi memiliki nilai manfaat dan beberapa jenis berpotensi invasif. Kondisi lingkungan abiotik pada seluruh lokasi penelitian menunjukkan nilai yang relatif sama., One of the Perhutani management units developing teak forests is KPH Pati. The teak forest managed by KPH Pati consists of various age groups related to the abiotic environmental conditions around the understorey that affect the diversity of the understorey. This study aims to identify and measure the level of species diversity, usefulness value and invasive potential of undergrowth, as well as to describe the condition of abiotic environmental factors at various ages of teak stands in KPH Pati. Methods of data collection is done by analysis of vegetation, field observations, and literature studies. The results showed that 45 species of understorey were identified from 24 families. The highest diversity of understorey species was in teak stands at 43 years old with H' of 2.54, followed by teak stands at 38 years, 33 years, and 48 years with H' values 2.43, 2.29 and 2.20. The understorey identified has a value of benefit and several species are potentially invasive. The abiotic environmental conditions in all research locations showed relatively the same values.
Keyword: jati, keanekaragaman spesies, KPH Pati, tumbuhan bawah, umur tegakan

Judul: Potential Soil Seed Bank of Understorey in KHDTK Cikampek
Abstrak: Kawasan hutan dengan tujuan khusus (KHDTK) Cikampek merupakan hutan untuk kepentingan umum tanpa mengubah fungsinya. Cadangan biji dalam tanah dapat menjaga keanekaragaman tumbuhan lantai hutan dan stabilitas ekosistem di masa depan. Penelitian ini bertujuan menganalisis komposisi vegetasi tumbuhan lantai hutan, mengeksplorasi cadangan biji tanah, dan kemampuan suksesi alami. Tahapan penelitian yang dilakukan meliputi analisis vegetasi, pengambilan sampel tanah, uji perkecambahan, suksesi alami, pengukuran dan pengambilan data lingkungan, dan analisis data. Vegetasi awal memiliki jumlah individu sebanyak 378 individu, uji perkecambahan menumbuhkan 413 individu, dan vegetasi suksesi memiliki 348 individu. Uji perkecambahan dengan kedalaman 5 cm memiliki nilai indeks keanekaragaman yang lebih tinggi (H’=2,30) dibandingkan dengan kedalaman 10 cm dan 15 cm (H’=1,96). Secara keseluruhan, H’ pada uji perkecambahan (H’=2,33) lebih tinggi dibandingkan vegetasi setelah suksesi (H’=1,79) dan vegetasi awal (H’=1,36). Keanekaragaman spesies yang teramati memiliki nilai indeks kemerataan yang tinggi, uji perkecambahan (E=0,80), suksesi (E=0,75), dan vegetasi awal (E=0,53)., Forest area with the special purposes (KHDTK) in Cikampek serves public purposes without altering its primary function. Soil seed banks sustain forest floor plant diversity and future ecosystem stability. This study aims to analyze the vegetation composition of the forest understorey, explore soil seed reserves, and assess natural succession. The research process encompasses vegetation analysis, soil sampling, germination tests, natural succession assessment, environmental measurements and data collection, as well as data analysis. Initial vegetation comprises a total of 378 individuals, germination tests yielded 413 individuals, and succession vegetation had 348 individuals. The germination test at a depth of 5 cm shows higher diversity index (H’=2,30) compared to depths of 10 cm and 15 cm (H’=1,96). The diversity index of germination test (H’=2,33) is higher than in succession vegetation (H’=1,79) and initial succession (H’=1,36). The observed species diversity demonstrates high evenness values in the germination test (E=0,80), succession (E=0,75), and initial vegetation (E=0,53).
Keyword: analisis vegetasi, indeks nilai penting, keanekaragaman, perkecambahan, suksesi

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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