The effect of harvest tree distribution on harvesting productivity in selection cuts

The study explored the effect of tree-selection pattern on harvesting productivity, under specific site conditions typical of mountain forestry and suitable for mechanized cut-to-length harvesting. In particular, the experiment tested two different single-tree-selection principles, namely, uniform spatial distribution across the whole site and clustered distribution, where selection trees were concentrated along presumed strip roads. The test was conducted on two different sites, representative of two different stand-development stages. Ten plots were located on each site, and randomly assigned to the two spatial distribution treatments (uniform and clustered). Great care was taken to maintain even conditions for the test. Mean tree size and removal intensity were the same on all plots from the same site; all plots were harvested by the same harvester and forwarder team; data were collected by the same researchers in all plots. Under the specific conditions of the study, the spatial distribution of harvest trees had no significant effect on harvesting productivity and cost. In contrast, harvesting performance was affected by tree size and possibly removal intensity. Anecdotal evidence about the effect of spatial distribution on harvesting cost may derive from its possible association with the other above-mentioned factors (e.g. tree size or removal intensity)