Judul: Habitat Suitability Mapping of Aren (Arenga pinnata Merr.) in Central Bangka Regency, Bangka Belitung Islands Province
Abstrak: Aren (Arenga pinnata Merr.) merupakan salah satu spesies tumbuhan yang berasal dari famili Arecaceae. Salah satu daerah yang memiliki sebaran aren yaitu Kabupaten Bangka Tengah. Penelitian bertujuan mengidentifikasi sebaran spasial aren, kesesuaian habitat, faktor yang memengaruhi distribusi aren, dan strategi pengembangan aren di Kabupaten Bangka Tengah. Data kehadiran aren didapatkan melalui survey dengan stratified sampling. Data titik kehadiran aren dan variabel lingkungan diolah dalam software Maximum Entropy untuk menghasilkan model dan nilai kesesuaian habitat aren. Aren banyak ditemukan pada area dengan kriteria ketinggian 0-50 mdpl, kemiringan lereng 0-8%, nilai NDVI antara 0,42-1, nilai NDMI >1, jarak dari sungai 0-500 m, jenis tanah kambisol oksik, podsolik kromik, dan menyebar di tutupan lahan perkebunan. Model kesesuaian habitat yang diperoleh bersifat baik (AUC = 0,902) dengan pembagian kelas yaitu tidak sesuai (0 ha), kurang sesuai (127.971 ha), cukup sesuai (50.363 ha), sesuai (24.678 ha) dan sangat sesuai (4.7867 ha). Jenis tanah, ketinggian, dan curah hujan menjadi faktor yang berpengaruh dalam kesesuaian habitat aren. Strategi pengembangan budidaya dapat dilakukan menggunakan sistem agroforestri., Aren (Arenga pinnata Merr.) is one of the plant species from the Arecaceae family. One of the regions that have sugar palm distribution is Central Bangka Regency. The study aimed to identify the spatial distribution of sugar palm, habitat suitability, factors affecting sugar palm distribution, and sugar palm development strategies in Central Bangka Regency. Data on sugar palm presence was obtained through a survey with stratified sampling. Data of sugar palm presence points and environmental variables were processed in Maximum Entropy software to produce models and values of habitat suitability of sugar palm. Aren are found in areas with altitude criteria of 0-50 mdpl, slope of 0-8%, NDVI value between 0.42-1, NDMI value >1, distance from river 0-500 m, soil type of oxic cambisol, chromic podsolik, and spread in plantation land cover. The habitat suitability model obtained is good (AUC = 0.902) with class divisions of unsuitable (0 ha), less suitable (127,971 ha), moderately suitable (50,363 ha), suitable (24,678 ha) and very suitable (4,787 ha). Soil type, altitude, and rainfall are factors that influence the suitability of sugar palm habitat. Cultivation development strategy can be done using agroforestry system.
Keyword: aren, habitat, kesesuaian

Judul: Potency and Effect of Organic Bio-fertilizer on Aren (Arenga pinnata Merr.) Stands in Sungkap Village, Central Bangka Regency
Abstrak: Aren memiliki nilai ekonomis dan ekologis tinggi karena hampir semua bagiannya dapat dimanfaatkan. Potensi aren cukup menjanjikan karena dapat hidup di berbagai kondisi tanah asalkan tercukupinya unsur hara. Penelitian bertujuan menduga potensi tegakan aren, produksi nira, pengaruh pupuk terhadap tegakan aren, dan rencana pengembangan aren di Desa Sungkap. Penelitian dilakukan dengan pemberian pupuk organik hayati merek Pupuk Ghaly Organik IPB dengan 45 sampel aren dan diuji dengan ANOVA. Hasil menunjukkan aren di Desa Sungkap menyebar di lahan budidaya dan liar yang keduanya menyebar secara berkelompok. Produksi nira yang tertinggi terjadi di lahan liar. Indikator tumbuhan dengan pemupukan seperti tinggi batang, lilit batang, jumlah daun, dan produksi nira terjadi secara signifikan, sedangkan pH dan brix nira tidak signifikan. Tutupan lahan kebun campuran diasumsikan sebagai habitat aren yang potensial, namun potensi tegakan aren masih belum optimal, sehingga perlu dilakukan budidaya dengan sistem agroforestri. Hasil penelitian dapat digunakan sebagai acuan dalam menduga potensi tegakan dan pengaruh pemupukan terhadap tegakan aren., Sugar palm has high economic and ecological value as almost all of its parts can be utilized. The potential of sugar palm in Sungkap Village is promising because it can thrive in various soil conditions as long as there is sufficient nutrient supply. The research aims to estimate the potential of sugar palm stands, sap production, the influence of fertilizer on sugar palm stands, and development plans for sugar palm in Sungkap Village. The research was conducted by applying organic bio-fertilizer branded Ghaly Organik IPB fertilizer to 45 samples of sugar palm and tested using ANOVA. The results indicate that sugar palm in Sungkap Village are distributed in both cultivated and wild areas, both of which are clustered. The highest sap production occurs in wild areas due to its habitat habitat. The highest sap production occurs in wild land. Plant indicators affected by fertilization such as trunk height, trunk girth, number of leaves, and sap production show significant changes, while pH and brix indicators do not. Mixed garden land cover is assumed to be a potential habitat, but the potential of sugar palm stands is still not optimal, thus cultivation with agroforestry systems are needed. The research results can be used as a reference for assessing the potential of stands and the effects of fertilization on sugar palm stands.
Keyword: budidaya, liar, potensi, pupuk, tegakan

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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