Judul: Pendugaan Potensi Biomassa Tegakan di Areal Rehabilitasi Hutan Pendidikan Gunung Walat Menggunakan Metode Tree Sampling
Abstrak: Tree sampling is an alternative method to plot sampling for estimating stand potency. Such method, however, has not been commonly used yet for estimating stand biomass of rehabilitated forest areas, particularly in Gunung Walat University Forest (GWUF). The objective of this study was to compare the precision of tree sampling and plot sampling methods in estimating stand biomass in GWUF. The tree sampling method was implemented by measuring only 3, 4, 5, 6, 7, and 8 sample trees nearby the plot centers. The number of sample units was 72, which were located in the field by using a stratified systematic sampling with random start. For each sample unit, tree measurements were conducted to record diameter, height, and distance between the furthest tree and center plot. The results showed that the estimation of stand biomass using 3, 4, 5, and 6 sample trees provided similar precision to that of plot sampling. This means that tree sampling can be used an alternative method for estimating stand biomass in GWUF.
Keyword: Bogor Agricultural University (IPB), tree sampling, stratified sampling, plot sampling, sample unit, biomass

Judul: Prediction Models for Pine Stand Biomass at Rehabilitation Area of Gunung Walat University Forest, Sukabumi, West Java
Abstrak: Kemampuan hutan untuk menyerap CO2 menurun akibat deforestasi dan degradasi hutan. Salah satu upaya untuk meningkatkan penyerapan CO2 adalah dengan merehabilitasi kawasan hutan yang terdegradasi, seperti yang dilakukan di Hutan Pendidikan Gunung Walat (HPGW). Penelitian ini bertujuan untuk mengembangkan model prediksi biomassa tegakan pinus di areal rehabilitasi HPGW. Variabel tegakan diukur di lapangan menggunakan 60 plot contoh yang ditetapkan secara sistematis di setiap areal tahun tanam. Variabel tegakan dianalisis menggunakan beberapa model regresi linier dan non linier. Hasil penelitian menunjukkan bahwa model terbaik pendugaan biomassa tegakan pinus (W, ton/ha) dengan umur tegakan (A, tahun) dan luas bidang tegakan (G, m2/ha) adalah W = 0,38 A0,953 G1,10 dengan nilai R2 sebesar 89,9% dan RMSE 3,02 ton/ha. Jika data umur tegakan dan luas bidang dasar tidak tersedia, maka model alternatif pendugaan biomassa tegakan pinus hanya dengan menggunakan diameter tegakan adalah W = 72,62 (exp (-17,14 / D)) dengan nilai R2 77,5% dan RMSE 4,45 ton/ha., The capability of forests to absorb CO2 decreases due to deforestation and forest degradation. One of the efforts to increase CO2 sequestration is rehabilitating degraded forest areas, such as practised in Gunung Walat University Forest (GWUF). This study was aimed to developed prediction models for pine stand biomass at the rehabiliation area of GWUF. Stand variables were measured in the field using 60 plots that were established systematically in every planting year area. The stand variables were analyzed using some linear and non-linear regression models. The results showed that the best model for estimating pine stand biomass (W, ton/ha) using stand age (A, year) and stand basal area (G, m2 /ha) was W = 0,38 A 0.953 G 1.10 with an R2 value of 89,9% and an RMSE of 3,02 ton/ha. When the stand age and basal area data were not available, an alternative model for estimating the pine stand biomass using stand diameter only was W = 72,62 (exp (-17,14 / D)) with an R2 value of 77,5% and an RMSE of 4,45 ton/ha.
Keyword: biomass, pine, prediction model, rehabilitation

Judul: Characterizations of low alloy steel sae 4422  plated with chromic acid (Cro3)
Abstrak: Characterizations of low alloy steel SAE 4422 plated with chromic acid (CrOrO3) was use Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), RD),Energy Dispersive Analysis of X-Ray (EDAX), Hardness Test and Roughness Test. Microstructures analysis exhibits cracks and grain boundaries microcracks as a characteristics of chrome metal found at plating metal. Perlite and Ferrite as grains of steel found at base metal with grain boundaries around it. Phase analysis of plating metal appropriate to chrome metal with lattice constant (a) is 2.559 Å and phase analysis of base metal appropriate to iron ferrite with lattice constant (a) is 3.318 Å. Both plating and base metal have cubic system. Chemical analysis of plating metal at surface section exhibits that cracks area have highest value of carbon element compare with grains and grains boundaries area. While chemical analysis of base metal at cross section exhibits that perlite have highest value of carbon element compare with ferrite and grain boundaries. The hardness value of plating metal at surface section and cross section are 753 and 637 VHN. While, the hardness value of base metal and interface area at cross section are 205 and 373 VHN. The roughness value at measurement points of chrome surface for as received sample are 0.445 μm. Observation used Optical Microscopy and Scanning Electron Microscopy exhibits surface irregularities combine to form surface texture of plating metal at surface section.
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