The impact of selective logging can be seen in this view of the Tīhoi state forest in 1976. Above the logging road, 55% of the timber has been removed. Just below it, only 30% has been taken. Lower down are unlogged native forest and a clearfelled area. Selective logging was used by the Forest Service from the mid-1970s, in a renewed attempt to manage native forests sustainably. It involved thinning out a forest rather than clearfelling (taking trees of all ages). However, conservationists argued that selective logging damaged the complex structure of the forest. They also drew attention to instances where the logging did not seem at all selective.