Volume 47 No. 1

Identifying effective methods for harvesting wood in short-rotation planted forests has recently become challenging, especially when trying to balance differing perspectives on the issue. In addition, practice in such forests may be highly variable from one place to another, and models are required to better understand the effectiveness of planted forest management and to make better decisions. A simulation experiment was setup in this study to understand how the productive performance of farm tractors, which is a common technical option in Thailand, is affected when extracting small-sized eucalyptus payloads sourced by very short cycles. Two tractors (hereafter T1 and T2) of different class size and fitted with backhoe grapples were selected and monitored via GNSS. Operational events were extracted from GNSS data, and were characterized by their speed, while payload size was estimated based on manual measurement done in the field. Then, simulations were carried out to see how moving speed and payload size may affect the productive performance as a function of extraction distance. Significant differences (α=0.05) in speed and payload size led to substantial variations in performance as the extraction distance increased. For instance, the number of daily work cycles were similar for both machines in a distance range of up to 100 m; daily production (m3), productivity (m3/h), and efficiency (h/m3), on the other hand, have shown important differences, with the higher size class T1 being more performant. Payload size and moving speed had a strong effect on efficiency, tripling the unit time for T2 at a distance of 1000 m. These findings have important consequences, at least for the local practice in South East Asia. Since these machines are frequently used interchangeably, the average extraction distance should be limited to 50 m, a scenario in which the differences in performance are the lowest. T1 maintains higher daily production and a greater number of work cycles at longer distances, highlighting the importance of choosing the appropriate tractor size for varying extraction distances in short-rotation eucalyptus forestry. Furthermore, the extraction distance should also be planned based on the performance of upstream and downstream processes, since the local practice makes use of motor-manual tree felling and cross-cutting, manual delimbing and bunching, and medium capacity trucks.

In the past decades, a considerable body of literature has emerged on timber tracking and tracing in the forest and timber industry supply chain. Therefore, a systematic literature review was conducted using an established method (»PRISMA«). To help define the relevance of timber tracking and tracing, this review addresses the subject areas, objectives and characteristics from scientific studies conducted over the past 25 years. In total 213 papers were included in the qualitative synthesis of the subject areas and objectives, with a 160 of those included in the characteristics synthesis to analyse comparable publication contents.

This study demonstrates the rationale behind the research efforts in the field of timber tracking and tracing. The results showed that the main key objectives were to combat illegal logging and trade, provide sustainable forest management, enable tracking and tracing, enhance efficienc, ensure legal compliance, determine the origin of timber and to identify species. The characteristics of the analysis methods used showed that genetic methods, physical chemistry methods, image methods, geomatics, certification, Radio-Frequency Identification (RFID) and smart technologies and software applications were most common. Most research activities were conducted in Asia and Europe. The majority of tracking and tracing methods were found to be highly practical. The application along supply chain dominated because of the high number of publications in genetic methods where a comprehensive application is possible. Furthermore, the forest, harvesting, and manufacturingwere identified as core application areas. Most studies lacked an economic evaluation of the developed solutions, which is a crucial aspect to consider for future successful implementation. The number of tree/wood species involved was notably extensive with a considerable diversity observed across continents. It will be essential that future research incorporates new technologies such as artificial intelligence (AI) that is currently emerging in the field of timber traceability. This can help achieve the identified objectives and address existing and future challenges through the self-learning property of AI.

This study investigated the greenhouse gas (GHG) emissions associated with various mechanisation levels and extraction methods in Mediterranean chestnut (Castanea sativa L.) coppice forests. Located in central Italy, these forests play a significant role in economic as well as ecological terms. This study addressed a critical gap in emissions data for broadleaf forest operations by examining the productivity and environmental impact of four logging systems. These systems integrate semi-mechanised and mechanised felling methods with skidding and forwarding extraction techniques. The results revealed that mechanised felling significantly boosts productivity by 44–66% compared to semi-mechanised felling but generates over three times the GHG emissions per cubic meter of wood. Notably, extraction operations account for the largest share of total emissions, with skidding emitting nearly three times more than forwarding, primarily due to its lower work productivity. Specifically, forwarding in a Cut-to-Length (CTL) system achieved productivity of over double that of skidding and reduced emissions per cubic meter of extracted wood by up to 63%. Key findings suggested that improving work productivity through optimised extraction methods, operator training, and efficient road network layouts can substantially lower emissions. Among the systems tested, CTL forwarding paired with mechanised felling showed the highest productivity and lowest emissions, presenting a promising model for sustainable chestnut coppice management in Mediterranean regions.

In forest operations, economic advantages can be obtained by increasing the distance between the skid trails. This protects soil by reducing the compacted area, while at the same time increasing the productive timber ground area. These advantages are offset by disadvantages, as fully mechanized timber harvesting is not possible and motor-manual felling is required for the areas that cannot be reached by the harvester. This in turn reduces work safety and increases the workload and personnel requirements, possibly leading to higher timber harvesting costs.

To analyze the consequences of an extended skid trail distance, a timber harvest under real conditions was carried out in north-eastern Germany in the fall of 2023. In a 72-year-old Scots pine (Pinus sylvestris, L.) stand with an area of 23.2 ha, 692 m³ of wood was harvested in a thinning operation. Three different timber harvesting methods with extended skid trail distances of approx. 40 m (ES) were investigated and compared to a fully mechanized system with conventional skid trail distances of approx. 20 m (CS) in a time study with a total of 150 recorded hours. Following the harvest, the residual stand damage was also recorded.

The timber harvesting methods with ES had higher timber harvesting costs than the method with CS, although there are major differences between the three semi-mechanized timber harvesting systems: The productivity of the harvester increases as the number of passes by the harvester decreases (from 13.87 to 14.09 to 15.99 m³/PMH15). Looking at the forwarder productivity, it is higher in ES than in CS. Finally, the costs of the harvesting systems ranged between 29.18 €/m³ for CS to 30.40, 32.41, 34.56 €/m³, respectively, for ES. There is no significant difference in the residual stand damage across the methods. The productivity of semi-mechanized timber harvesting methods can be improved if the motor-manual felling is carried out before the harvester is used and if the trees are not winched with a cable tractor.

In some specific yarding situations ground contact needs to be reduced to an absolute minimum. In such cases, a double-hitch system can serve as an alternative to helicopter logging. In the present investigation, a cable yarding operation using double-hitch carriages for selective thinning in intermediate slope was accompanied by a time and motion study to better understand the working steps and resulting productivity of cable yarding in this unconventional situation. The main aims were to develop a model that can be used to estimate the productivity of comparable yarding operations before their implementation, and to quantify the additional effort relative to the use of a cable yarder with a single-hitch carriage. The results indicated an overall productivity of 5.69 m3ob per productive system hour including delays of up to 15 minutes (PSH15), leading to yarding costs of 97.54 CHF (m3ob)-1 (in addition to costs for installation and felling). Compared to a system with a common single-hitch carriage, the inclusion of a second lateral yarding stage increased time and cost, contributing 13.30 € (m3ob)-1. Key factors affecting productivity were payload size, number of load pieces, and terrain difficulty, while yarding distances had minimal impact. Compared with traditional yarding, double-hitch operations were less productive and more costly, but they can still be considered a suitable alternative to helicopter logging in sensitive areas.