Carbon footprint of forest operations under different management regimes

Different forest management regimes have different carbon footprints due to alternative op- erational strategies and options. Data concerning CO2 emissions (kg m–3) in felling, extraction, comminution and transport operations, performed under two different forest management regime (close-to-nature and plantation), were collected through a systematic literature review involving 162 scientific papers and compiled into a database. Results show that, within limits, forest operations in plantations produce lower emissions due to easier operational conditions, while transportation in both close-to-nature and plantation based forest operations reported the highest levels of emissions. Literature came from a variety of sources and often differed in context due to factors such as technology, work technique, operator skill and environmental conditions. These factors have been shown to highly affect the results obtained from the stud- ies. Nevertheless, it has been possible to summarize most of the information gathered and to highlight the most representative driving factors in CO2 emissions throughout different forest management regime

Carbon Footprint of Forest Operations under Different Management Regimes

Different forest management regimes have different carbon footprints due to alternative operational strategies and options. Data concerning CO2 emissions (kg m–3) in felling, extraction, comminution and transport operations, performed under two different forest management regime (close-to-nature and plantation), were collected through a systematic literature review involving 162 scientific papers and compiled into a database. Results show that, within limits, forest operations in plantations produce lower emissions due to easier operational conditions, while transportation in both close-to-nature and plantation based forest operations reported the highest levels of emissions. Literature came from a variety of sources and often differed in context due to factors such as technology, work technique, operator skill and environmental conditions. These factors have been shown to highly affect the results obtained from the studies. Nevertheless, it has been possible to summarize most of the information gathered and to highlight the most representative driving factors in CO2 emissions throughout different forest management regimes

The Effect of Yarding Technique on Yarding Productivity and Cost: Conventional Single-Hitch Suspension vs. Horizontal Double-Hitch Suspension

Cable yarding is a well establish technology for the extraction of timber in steep terrain. However, it is encumbered with relatively low productivity and high costs, and as such this technology needs to adapt and progress to remain viable. The development of biomass as a valuable byproduct, and the availability of processors to support yarder operations, lend themselves to increasing the level of whole-tree extraction. Double-hitch carriages have been developed to allow for full suspension of whole-tree and tree-length material. This study compared a standard single-hitch to a double-hitch carriage under controlled conditions, namely in the same location using the same yarder with downhill extraction. As expected, the double-hitch carriage took longer to load up (+14%), but was able to achieve similar productivity (10–11 m3 per productive machine hour) through increased inhaul speed (+15%). The importance of this study is that it demonstrates both the physical and economic feasibility of moving to whole-tree extraction using the double-hitch type carriage for longer corridors, for settings with limited deflection, or areas with lower tolerance for soil disturbance

Evaluation of Different Modes for Yarding Windthrown Timber with a Double-Hitch Carriage

Yarding whole trees is the most efficient way of extracting timber in steep terrain and allows reaping the combined benefits of mechanization and biomass recovery. In downhill yarding, however, whole-tree extraction is associated with a greater risk of loosening rocks or debris by the incoming loads as they bounce around along the extraction corridor. That may also cause damage to the cables and anchors by corresponding shock loads, ultimately endangering the yarder and its crew. To avoid these risks, »double-hitch carriages« can be employed. They combine a conventional motorized dropline carriage with a secondary carriage (»trailer«), equipped with a further, independent dropline winch. Thus, loads can be attached at two points and transported fully suspended above the ground in a horizontal position. Operation of these carriages may not be limited to the »horizontal« mode: the main carriage could also be operated without trailer (»single« mode), or separate loads may be attached to the two droplines (»double« mode), but their impact on the efficiency and economy of yarding operations is yet unknown. Therefore, the present study investigated how these modes affect the productivity and cost of downhill whole tree yarding. To this end, a classic time and motion study was conducted during a salvage logging operation in Northern Italy under a strictly controlled experimental design. Average productivity (18.2±7.2 to 24.5±15.4 m³ PSH0-1 merchantable volume per productive system hour excluding delays) and extraction cost (18 to 20 Euro m-³) did not differ significantly between treatments, while load composition and time consumption by task did. More (2.2±0.5) pieces per load were yarded under the »double«, than under the »single« (1.4±0.5) and »horizontal« (1.1±0.3) treatments. Inhaul speed (3.1±0.6 m s-1) was significantly higher under the »horizontal« treatment, which compensated for increased loading time derived from attaching the load at least at one point outside the corridor. Unloading took significantly longer under the »double« treatment, as loads had to be dropped successively due to the confined conditions on the landing. Though slowest (2.5±0.9 m s-1) during inhaul, the »single« treatment exhibited none of the other treatments disadvantages and larger loads could be accumulated due to partial suspension. From an economic viewpoint, the »horizontal« mode may only be warranted over yarding distances substantially beyond average. On shorter ones, it must be justified by other reasons, such as minimizing product contamination, soil disturbance or excessive strain to the skyline when the terrain profile impedes sufficient ground clearance

Carbon Footprint of Forest Operations under Different Management Regimes

Different forest management regimes have different carbon footprints due to alternative operational strategies and options. Data concerning CO2 emissions (kg m–3) in felling, extraction, comminution and transport operations, performed under two different forest management regime (close-to-nature and plantation), were collected through a systematic literature review involving 162 scientific papers and compiled into a database. Results show that, within limits, forest operations in plantations produce lower emissions due to easier operational conditions, while transportation in both close-to-nature and plantation based forest operations reported the highest levels of emissions. Literature came from a variety of sources and often differed in context due to factors such as technology, work technique, operator skill and environmental conditions. These factors have been shown to highly affect the results obtained from the studies. Nevertheless, it has been possible to summarize most of the information gathered and to highlight the most representative driving factors in CO2 emissions throughout different forest management regimes

Skyline tension and dynamic loading for cable yarding comparing conventional single-hitch versus horizontal double-hitch suspension carriages

Wire rope used in cable logging, where a series of cables facilitate the extraction of timber on steep terrain, experiences high tensions that must be managed to ensure safety. Innovations change practices over time and double-hitch carriages, which allow trees to be extracted horizontally, are a recent example. This makes it feasible to harvest across terrain with limited deflection, increases the recovery of biomass, and potentially reduces high-dynamic load events associated with ground contact. In this study, a standard single-hitch carriage was compared against a new double-hitch carriage under controlled conditions. Tension was measured continuously and specific elements, such as tension when the carriage was at midspan, maximum tension at breakout and inhaul, and magnitude of cyclic tension during inhaul were identified, measured and compared against payload. While payload was similar in the treatments, the additional weight of the double-hitch carriage resulted in higher skyline tensions. In both treatments, payload and skyline tension when the carriage was at midspan were strongly correlated. Cyclic tension was reduced by the double-hitch carriage system. While a number of unique high-dynamic loads were identified that were not part of the normal extraction, they represented only 6% of the cycles and the maximum tension was similar to that experienced during break-out and inhaul. This study increased the understanding of skyline tension during logging operations and the effect of carriage type. It showed that, though tension often exceeds the safe working load of the cable, it does not exceed the endurance limit for a well-designed and operated system

Fuel and Time Consumption in Alpine Cable Yarder Operations

A survey was conducted on 12 cable yarding operations in northern Italy, with the purpose of determining fuel consumption and time use. The observation unit was the individual operation, intended as all the activities needed to complete the harvesting of a sale (mean = 500 m3 of timber). All teams were equipped with a tower yarder, an excavator-based loader or processor and a truck or a tractor with trailer, if intermediate transportation to a larger roadside landing (two-staging) was required. The crew size was 3 or 4 operators. Time and fuel use were recorded separately for the following tasks: relocation; set up & dismantle; commuting; yarding; processing and/or loading; major delay events. Fuel consumption averaged 5.1 L m−3, of which 2.2 L m−3 was incurred by two-staging. In general, the yarder accounted for less than half the total fuel consumption of the operation: the processor was indeed the main consumer. Relocation had a very small incidence on time and fuel use. Set up and dismantle did not incur significant fuel consumption but occupied a meaningful share of total time (mean = 22%). Commuting also incurred unexpectedly large (and generally neglected) fuel and time use—with means at 13% and 7%, respectively. Technology developments aimed at reducing fuel consumption should target both main consumers: the yarder as well as the excavator-based processor. Significant benefits would also be achieved through improved planning and infrastructure development, aimed at minimizing the need for intermediate transportation (i.e. two-staging)