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Logging concessions in natural forest and industrial plantation forest are the main producers of logs in Indonesia. Several companies of industrial plantation forest have been successfully planted with fast-growing species such as Acacia mangium for pulpwood. These plantation forests have entered their annual harvesting period. Some options of timber harvesting machines such as forwarder, harvester, feller buncher, and excavator are chosen to remove timber from stump to the log landing site. The negative impact of such machines includes the loss of topsoil and soil compaction. The objectives of the research were to analysis soil compaction by excavator with log carrier in forwarding log from stump to landing site. Bulk density, cone index and deep of rut were measured after logging operation at the harvesting site at one of industrial plantation forest of South Kalimantan. The result showed that soil bulk density increase with the increase in the number of excavator with log carrier passes. The rut was formed on several places on the soil surface, particularly near landings and under the log carrier. The ground pressure of the excavator and log carrier caused the formation of the rut on the soil surface. Weight of excavator plus loads had caused pressure on the track of the contact with the ground. Rut formed and high soil bulk density indicated the soil compaction occurred by the harvesting operation.

Rationale For clumped isotope analysis (Δ47), hydrocarbon and organic molecules present an important contaminant that cannot always be removed by CO2 purification through a Porapak‐Q trap. Low‐temperature oxygen plasma ashing (OPA) is a quick and easy approach for treatment; however, the impact of this treatment on the original carbonate clumped isotope values has never been fully studied. Methods We tested the isotopic impact of OPA using three natural samples with a large range of initial Δ47 values. Crushed and sieved (125 μm mesh) samples were placed into a Henniker Plasma HPT‐100 plasma system and treated at a flow rate of 46 mL/min and a power of 100 W at a vacuum of 0.2 mbar for 10, 20, 30 and 60 min before clumped isotope analysis using two MAT 253 isotope ratio mass spectrometers modified to measure masses 44–49. Results OPA treatment for 30 min or more on calcite powder samples has the potential to alter the clumped isotopic composition of the samples beyond analytical error. A systematic positive offset is observed in all samples. The magnitude of this alteration translates to a temperature offset from known values ranging from 4°C to 13°C. We postulate that the observed positive offset in Δ47 occurs because the bonds within lighter isotopologues are preferentially broken by plasma treatment, leading to an artificial increase in the ‘clumping’ value of the sample. Conclusions We recommend that any laboratory performing OPA treatments should reduce the runs to 10–20 min or carry out successive runs of 10 min followed by sample stirring, as this procedure showed no alteration in the initial Δ47 values. Our results validate the use of OPA for clumped isotope applications and will allow future research to use clumped isotopes for challenging samples such as oil‐stained carbonates, bituminous shales or host rocks with very high organic carbon content.

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