Judul: Tree Health Assessment at Bogor Botanical Garden and  Dramaga Campus Forest Park using i-Tree Eco
Abstrak: Kebun Raya Bogor (KRB) dan Taman Hutan Kampus (TAHUKA) merupakan area konservasi tanaman ex-situ. Tanaman koleksi yang berada di KRB dan TAHUKA perlu dijaga dan dilakukan pemantauan untuk memberikan rasa aman bagi para pengunjung. Forest Health Monitoring (FHM) dan ISA Tree Risk Assessment (ISA TRA) merupakan metode yang dapat digunakan untuk memantau kondisi kesehatan pohon yang menggunakan beberapa parameter, tetapi kedua metode tersebut jarang dikombinasikan dalam penggunaannya. Penelitian ini bertujuan untuk menilai tingkat kesehatan pohon di Kebun Raya Bogor dan Taman Hutan Kampus Dramaga berdasarkan FHM dan ISA serta dilengkapi dengan i-Tree Eco. Hasil penelitian berbasis FHM menunjukkan nilai Visual Crown Ratio (VCR) rata-rata sebesar 3 di VAK XXB Kebun Raya Bogor dan Taman Hutan Kampus Dramaga dengan skor VCR berada pada rentang 7-9. Adapun, penilaian resiko pohon di VAK XXB Kebun Raya Bogor sebesar 49,21% dan Taman Hutan Kampus Dramaga sebesar 44,23% yang berarti persentase risiko tinggi lebih banyak dibandingkan dengan risiko sedang dan rendah. Serapan karbon yang lebih tinggi terdapat di Taman Hutan Kampus sebesar 1.813,75 ton/ha/tahun, sedangkan di Kebun Raya Bogor sebesar 1.301,25 ton/ha/tahun., Bogor Botanical Garden (KRB) and Campus Forest Park (TAHUKA) are ex situ plant conservation areas. Plant collections in KRB and TAHUKA need to be maintained and monitored in order to provide a sense of security for visitors. Forest Health Monitoring (FHM) and ISA Tree Risk Assessment (ISA TRA) are methods that can be used to monitor tree health conditions using several parameters, but the two methods are rarely combined in their use. This study aimed to assess the health level of trees in Bogor Botanical Garden and Dramaga Campus Forest Park based on FHM and ISA and complemented with i-Tree Eco. The results of FHM-based research showed an average Visual Crown Ratio (VCR) value of 3 in VAK XXB of Bogor Botanical Garden and Dramaga Campus Forest Park with VCR scores in the range of 7-9. Meanwhile, the risk assessment of trees in VAK XXB Bogor Botanical Garden is 49,21% and Dramaga Campus Forest Park is 44,23%, which means that the percentage of high risk is more than medium and low risk. Higher carbon sequestration was estimated in the Campus Forest Park at 1.813,75 ton/ha/year, while the Bogor Botanical Garden at 1.301,25 ton/ha/year.
Keyword: Kebun Raya Bogor, kesehatan pohon, penilaian risiko pohon, Taman Hutan Kampus

Judul: Analisis Kondisi Kesehatan Tajuk Pohon pada Petak Tanam XII dan XIII di Kebun Raya Bogor
Abstrak: Kebun Raya Bogor (KRB) merupakan kawasan konservasi ex-situ tumbuhan yang memiliki berbagai koleksi tanaman yang ditanam di atas areal kebun seluas 87 hektar. Pohon sebagai obyek utama yang merupakan daya tarik KRB diharapkan terjamin kesehatannya melalui pengelolaan yang baik. Penelitian ini bertujuan untuk mengetahui kondisi kesehatan tajuk pohon pada petak tanam XI dan XIII di Kebun Raya Bogor menggunakan metode Forest Health Monitoring (FHM). Sebanyak 37 spesies individu diamati menggunakan parameter kondisi tajuk untuk mendapatkan nilai peringkat visual tajuk (VCR), indeks besar tajuk (CSI), dan indeks kerusakan tajuk (CDI). Hasil penelitian menunjukkan nilai skor VCR 5 yang didominasi oleh individu pohon dalam kategori kondisi kesehatan tajuk sedang. Nilai rata-rata CSI dan CDI pada keseluruhan spesies sebesar 22.87 dan 29.14 yang menunjukkan sebagian besar individu pohon termasuk kedalam tingkat kerusakan tajuk sedang., Bogor Botanical Gardens (BBG) is an ex-situ plant conservation area which has a wide collection of plants grown in a garden area of 87 hectares. Trees as the main object and the main attraction of the BBG are expected to be maintained in a healthy condition through proper management. This study aims to determine the health condition of tree crowns in planting plots XI and XIII of Bogor Botanical Gardens using the Forest Health Monitoring (FHM) method. A total of 37 individual species were observed using the canopy condition parameter to obtain crown visual ranking (VCR), crown size index (CSI), and crown damage index (CDI) values. The results showed that the VCR score of 5, indicated that trees crown in the area are mostly categorized moderate canopy health conditions. The average CSI and CDI values for all species were 22.87 and 29.14 which indicated that most of the individual tree’s crown were classified as moderately damaged.
Keyword: Bogor Botanical Gardens, Crown Damage, VCR, CSI, CDI

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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