The Influence of Soil Conditions, Following Tractor Logging, on the Growth of Planted Douglas‐Fir Seedlings

Growth of planted Douglas‐fir seedlings was investigated on Reddish Brown Latosol soils on two cutover areas in the Cascade Mountains of western Oregon. In April 1955, 2‐0 seedlings were planted on tractor roads, in loose berm material adjacent to the tractor roads, and on undisturbed cutover condition. First‐year survival for all conditions was over 90%. Annual height measurements were made at the end of the 1955 and 1956 growing seasons. Differences in height growth between seedlings on the cutover condition and those on the berm and tractor road conditions were highly significant. Seedling growth differences between berm and tractor road conditions were also statistically significant in several instances. Soil analysis data indicated poor growing conditions on the tractor roads, particularly in regard to aeration, moisture, and N relationships.