FERIC studied fully mechanized cut-to-length systems during commercial thinning treatments in white spruce plantations and natural black spruce stands. The equipment's performance was assessed to better understand the effects of various organizational factors on productivity. The productivity of single-grip harvesters was little affected by variations in the trail layout and removal intensity, and by different sorting strategies. Shortwood forwarders benefited from situations in which large volumes were available for extraction on each trail. As well, it appears that precleaning treatments are not economically justifiable.