Judul: Penyusunan Model Pertumbuhan Biomassa  Tegakan Pinus merkusii di Areal Rehabilitasi Hutan Pendidikan Gunung Walat
Abstrak: Konsep REDD+ dalam menangani perubahan iklim menjadikan tegakan hutan sebagai peran yang sangat penting untuk penyerap CO2. Potensi biomassa Hutan Pendidikan Gunung Walat (HPGW) perlu dihitung untuk mengetahui bagaimana kontribusi areal tersebut terhadap serapan karbondioksida di bumi. Adapun tujuan dari penelitian ini adalah untuk mengetahui nilai riap tumbuh tegakan dan menyusun model pertumbuhan biomassa tegakan. Penelitian dilakukan dengan menggunakan 115 plot contoh dengan metode stratified systematic plot sampling with random start. Penyusunan model dilakukan menggunakan software R 4.3.0 dengan peubah bebas terdiri dari umur, diameter, tinggi, luas bidang dasar (LBDS) dan kerapatan tegakan. Hasil penelitian menunjukkan bahwa model terbaik adalah M8 menggunakan peubah bebas umur dan luas bidang dasar dengan persamaan W = 1,73A0,23G1,12 (R2adj = 99,08%, RMSE = 2,11 ton/ha, AIC = 331,92 dan BIC = 324,11). Alternatif model lainnya yang lebih praktis digunakan di lapangan adalah dengan persamaan W = 0,06A-0,52D2,68 atau W = 0,00057A2,37N1,25. Nilai riap rata-rata pertumbuhan biomassa tegakan Pinus merkusii di HPGW pada umur 14 tahun adalah sebesar 5,77 ton/ha/tahun., The REDD+ concept in dealing with climate change makes forest stands a very important role for CO2 sequestration. The biomass potential of Hutan Pendidikan Gunung Walat (HPGW) needs to be calculated to find out how the area contributes to carbon sequestration on earth. The purpose of this study was to determine the value of stand growth increment and to develop a model of stand biomass growth. The research was conducted using 115 sample plots by stratified systematic plot sampling with random start. Modeling was conducted using R 4.3.0 software with independent variables consisting of age, diameter, height, base area (LBDS) and stand density. The results showed that the best model was M8 using independent variables of age and basal area with the equation W = 1,77A0,21G1,12 (R2adj = 99,27%, RMSE = 2,05 ton/ha, AIC = 292,45 dan BIC = 305,32). Another alternative model that is more practical to use in the field is equation W = 0,06A-0,52D2,68 or W = 0,00057A2,37N1,25. The average growth rate of biomass of Pinus merkusii stands in HPGW at 14 years old was 5,77 tons/ha/year.
Keyword: Biomassa, Model pertumbuhan, Pinus merkusii

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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