Application of a primarily deductive framework describing time consumption for hauling of logs to road-side

Forest management planning decisions are often based on the forest owner’s goals, which typically focus on economic criteria. Logging operation work productivity functions are used when costing forest operations. These functions affect the conclusions drawn during forest management analyses because different logging environments give rise to different harvesting costs. When evaluating new combinations of machines and environments, there is generally a shortage of field data on productivity that can be examined in advance. We applied a previously published deductive framework describing time consumption in forwarding to known environments, in which field studies on forwarding have been conducted and for which extensive data are available. We then adapted the deductive framework to better reproduce the results obtained in the time studies. The deductive framework accurately reproduced the observed forwarding productivities; on average, the adaptation process improved the accuracy of this reproduction. However, it may also have reduced the accuracy of individual predictions. We conclude that the deductive framework can be used as a basis for constructing work productivity functions for forest management analyses, and can serve as a foundation when constructing new productivity functions based on time study results to use when pricing forwarding

Simulation of harvester productivity in selective and boom-corridor thinning of young forests

Forest management practices may change in the future, due to increases in the extraction of forest fuel in first thinnings. Simulation models can be used to aid in developing new harvesting systems. We used such an approach to assess the productivity of innovative systems in various thinnings of young stands with wide ranges of mean breast height diameter (1.5–15.6 cm), stems per hectare (1000–19,100), and mean height (2.3–14.6 m). The results show that selective multiple-tree-handling increases productivity by 20–46% compared to single-tree-handling. If the trees are cut in boom-corridors (10×1 or 2 m strips between strip roads), productivity increases up to 41%, compared to selective multiple-tree-handling. Moreover, if the trees are felled using area-based felling systems, productivity increases by 33–199%, compared to selective multiple-tree-handling. For any given harvesting intensity, productivity increased the most in the densest stands with small trees. The results were used to derive time consumption functions. Comparisons with time study results suggest that our simulation model successfully mimicked productivity in real-life forest operations, hence the model and derived functions should be useful for cost calculations and evaluating forest management scenarios in diverse stands