Judul: Species Composition, Stand Structure, and Carbon Stock in the Wana Lestari Community Forest (HKm) Agroforestry System, West Nusa Tenggara Province
Abstrak: Perubahan iklim merupakan suatu kondisi yang ditandai dengan berubahnya pola iklim yang mengakibatkan fenomena cuaca yang tidak menentu. Dampak dari perubahan iklim adalah menurunnya keanekaragaman hayati dan meningkatnya konsentrasi gas rumah kaca (GRK) terutama karbon. Salah satu upaya konservasi keanekaragaman hayati dan peningkatan cadangan karbon yaitu dengan sistem agroforestri (AF). Penelitian ini bertujuan untuk menganalisis komposisi jenis dan struktur tegakan pohon, serta memperkirakan cadangan karbon di sistem agroforestri (AF) hutan kemasyarakatan (HKm). Metode yang digunakan adalah analisis vegetasi, pengukuran struktur tegakan dengan menggunakan spatially explicit Individual-based Forest Simulator (SexI-FS), serta pendugaan cadangan karbon dengan pendekatan alometrik dan destruktif pada tingkat semai dan tumbuhan bawah. Petak yang digunakan 20 m x 20 m berjumlah 25 petak. Berdasarkan hasil penelitian, komposisi jenis di HKm Wana Lestari terdiri dari 63 jenis tumbuhan dari 40 famili. Indeks Nilai Penting (INP) tertinggi adalah durian (Durio zibethinus) (90,34%) pada tingkat pertumbuhan tiang. Kopi (Coffea robusta) merupakan spesies yang dominan pada sistem agroforestri (AF). Nilai indeks keanekaragaman (H') berkisar antara 0,40 - 2,29 (kategori sedang). Struktur tegakan menunjukkan bukan kurva “J” terbalik. Total biomassa dan cadangan karbon pada semua tingkat pertumbuhan secara berurutan adalah 228,35 ton/ha dan 107,97 ton/ha., Climate change is characterized by changing climate patterns resulting in erratic weather phenomena. The impact of climate change is a decrease in biodiversity and an increase in the concentration of greenhouse gases (GHGs), primarily carbon. One of the efforts to conserve biodiversity and increase carbon stocks is the agroforestry system (AF). This study aimed to analyze the species composition and structure of tree stands as well as to estimate the carbon stock in the agroforestry system (AF) of community forest (HKm). The methods used were vegetation analysis, stand structure measurement using spatially explicit Individual-based Forest Simulator (SexI-FS), as well as carbon stock estimation using allometric and destructive approaches for seedling and understory levels. The plots were 20 m x 20 m with a total was 25 plots. Based on the results, the species composition in HKm Wana Lestari consists of 63 plant species from 40 families. The highest importance value index (INP) is durian (Durio zibethinus) (90.34%) at the pole growth level. Coffee (Coffea robusta) is the dominant species in the agroforestry system. The diversity index (H') value ranges from 0.40 to 2.29 (medium category). The stand structure is not an inverted “J” curve. Total biomass and carbon stock at all growth levels in order is 228,35 tons/ha and 107,97 tons/ha.
Keyword: agroforestry, Above-ground carbon, Coffea robusta, Indonesia’s   FOLU Net Sink, SexI-FS

Judul: Pendugaan Potensi Volume, Biomassa, dan Cadangan Karbon Tegakan di Hutan Pendidikan Gunung Walat Sukabumi Jawa Barat
Abstrak: The current global warming is caused by the increasing of greenhouse gases emitted to the Earth’s atmosphere. Greenhouse gases that affect directly is CO2 (carbon dioxide). If there are too many concentration of CO2 in the atmosphere, it will cause warmer temperature. Increasing the average temperature of Earth's atmosphere over the years led to climate change. The effort to solve climate change is conducting mitigation. One of the sectors that play a role in climate change mitigation is forestry sector. Forest able to absorb the excess carbon in the atmosphere and store it in the form of biomass in various parts of the plant (particularly timber) through the photosynthesis process. One of Indonesia's forests which has the potential carbon stocks is Gunung Walat University Forest (GWUF). This research aims to estimate the potential of volume, biomass, and carbon stocks in the forest which can be use as a basis for making the forest planning, management, and protection. Field data collected at the stands of Agathis lorantifolia (agathis), Pinus merkusii (pine), Schima wallichii (puspa), Maesopsis eminii (kayu afrika), and the others stand with the circle sample plot sized 0.1 ha. The stands volume estimated by using volume table equation and the biomass estimation by allometric models. Carbon stocks estimation obtained from biomass value that is converted to the carbon fraction (0.47). Data analysis in this research uses two methods, estimation without stratification through systematic sampling with random start and estimation with stratification through stratified sampling. Estimation with stratification is performed in two ways, stratification based on potential value and stratification based on the vegetation type. The result of potential estimation with stratification in GWUF more accurate then the method of estimation without stratification. The average volume of estimation with stratification based on its potential value is 399.45 m3/ha and the total volume is 142,832.56 m3; the average and total of biomass potential are 202.37 tons/ha and 72,363.70 tons; and then the of average of carbon stocks is 95.12 tons/ha and the total carbon stocks is 34,085.51 tons. While the estimation results with stratification based on the vegetation type shows the average and total volume are 398.29 m3/ha and 142,416.26 m3; the average of biomass potential is 202.82 tons/ha and the total of biomass potential is 72,522.35 tons; with average of carbon stocks is 95.32 tons/ha and the total carbon stocks is 34,085.51 tons.
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Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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