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: Perbandingan Ketelitian Metode Pendugaan Biomassa Pinus dan Agathis di Areal Rehabilitasi Hutan Pendidikan Gunung Walat.
Abstrak: An alternative method for estimating biomass is converting tree volume into aboveground tree biomass by using wood density and biomass expansion factor (BEF). This method is commonly used in estimating a tree biomass, especially when allometric biomass models are not available. The objective of this study was to analyze the precision of biomass estimation using the conversion of tree volume for estimating tree-level and stand-level biomass in the rehabilitation area of Gunung Walat University Forest (HPGW). Tree biomass was calculated using three methods, i.e. allometric models, tree volume conversion using a general wood density, and tree volume conversion using a specific wood density. The results showed that generally the volume conversion method using a spescific wood density produced relatively similar biomass estimates to the allometric method. Thus, the volume conversion method using a specific wood density can be used as an alternative method for estimating stand biomass, especially in the rehabilitation area of HPGW.
Keyword: pine, agathis, biomass, volume conversion, precision

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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