Improper tree felling techniques may reduce productivity and log supply. This leads to an increase in production cost. Timber Utilization Efficiency (TUE) in natural forests has not been optimally implemented, thus leaving residual stands with tremendous damages. This study was carried out in late 2015 in PT Inhutani II, North Kalimantan to investigate the implementation of felling techniques and to analyze felling productivity, TUE, production cost, and residual stands damage. Productivity, felling cost, and TUE data were tabulated and averaged. Results revealed that: (1) tree felling techniques implemented on the site were the reduced impact logging (RIL) technique; (2) the average felling productivity and production cost were 38.308 m3/hour and IDR 13, 935.10/m3, respectively; (3) the average TUE was 92%, with only 8% generated-wastes; and (4) the average destruction of residual stands was 13.54%, which comprised of canopy damage, broken/cracked, stem injury, and leaning.

The practice of timber harvesting in natural forests which has been conducted up to now still leaves wood harvesting residue and residual stand damage. Most condition of wood harvesting residue is still good and can be utilized. The objective of this research was to determine the potency of wood harvesting residue and residual stand damage on timber harvesting in natural forests. The data on wood utilization, wood harvesting residue, and residual damage were collected from three sample plots. The sample plots were arranged in a systematic and purposive manner, and the data were processed with tabulation and average analysis. Research results showed that the average volume of wood being utilized was 9.212 m3 tree−1. The average volume of wood harvesting residues was 2.310 m3 tree−1, and the total average volume of wood harvesting residues which were good, defected, and broken was 2.121 m3 (80.952%), with an average volume for good wood harvesting residue condition of 1.038 m3 (34.808%). Proportions of wood harvesting residues were 2.154 m3 (94.444%) consisting of buttress as large as 0.102 m3 (5.159%), stumps as large as 0.375 m3 tree−1 (23.597%), butt as large as 0.855 m3 (35.930%), and end part as large as 0.821 m3 (29.758%). The average number of trees with a diameter of 20 cm which were damaged due to felling and skidding was 5 trees ha−1 (5.40%) and 6 trees ha−1 (6.58%), respectively.

Silica is a functional material with broad benefits, including as a catalyst. It is essential to substitute synthetic silica with natural silica to support green technology and economic development. The silica extraction process from bamboo leaf waste was carried out using an acid-base solution and a cetyltrimethylammonium bromide (CTAB) template structure to get mesoporous biosilica. This mesoporous biosilica was then applied as a biocatalyst for α-cellulose direct pyrolysis. Biosilica was characterized using various analyses including Fourier Transform Infrared Spectroscopy (FTIR), Surface Area Analyzer (SAA), Scanning Electron Microscope (SEM), gravimetric methods, and applications to the cracking process using Pyrolysis Gas Chromatography Mass Spectrometry (Py-GCMS). The CTAB addition is divided into three variations, namely 0.05:1, 0.1:1, and 0.2:1. The data found that the highest yield was produced in the CTAB biosilica 0.2:1, and the silica content in the bamboo ash and CTAB biosilica sample was 60% and 90.5- 93.6%, respectively. The surface acidity of the biosilica ranged from 1.97 and 2.1 mmol/g. The essential groups in the biosilica formed are hydroxyl, silanol, and siloxane groups, with the morphology of the silica being observed to be irregular in shape, forming aggregates like coral. The surface area of biosilica with the ratio of 0.05:1, 0.1:1, and 0.2:1 was 177.068 m2 /g, 661.166 m2 /g, and 684.852 m2 /g, respectively, with a pore size distribution following the mesoporous class. The α-cellulose cracking using py-GCMS with a biosilica catalyst at CTAB variations of 0.05:1, 0.1:1, and 0.2:1 yielded a hydrocarbon content of 44.88%; 61.6%; and 30.4%.

In this work, both pyrochar and activated carbon were prepared by physical activation (i.e., saturation and superheated) by involving a thermal agent as a comparison. The effects of three agents on the pore development of activated carbon from a new material, Calliandra calothyrsus, were observed in detail. The BET surface area and the iodine index of the prepared activated carbon were used as pyrochar selection. Proximate, ultimate, XRD, FTIR, TGA, and SEM were used to characterize the physical and chemical properties of the product. Pyrochar pores were found to develop significantly at 350 °C, indicated by an increase in the BET surface area and iodine index. Pyrochar from a temperature of 350 °C was then selected as a precursor of activated carbon. S–SS and SS–S activated carbon samples were declared to have the highest iodine index (870 mg/g) and the highest BET surface area (642 m2/g), respectively. The pore distribution data showed that the superheated agent widened the pore and provided an active site for iodine adsorption, while the saturation agent resulted in a narrower pore for an increase in the BET surface area. S–SS has a lower C fraction and higher O fraction than SS–S. The SS–S samples have both Vol and Volmic for an increased BET surface area. The number of aromatic layers and –OH functional groups of the S–SS sample is more convenient for iodine enhancement than for increasing the BET surface area. Less water droplets and greater energy from superheated resulting pores widen, increasing the aromatic layer and providing additional functional groups.

Log skidding technique in peatland is different with those practiced in dry land