Vegetation management on grass-dominated clearcuts planted with Norway spruce in southern Sweden

A field experiment was established between 1989 and 1993 to study the effec ts of competing vegetation on growth of planted Norway spruce (Picea abies (L.) Karst.) seedlings. Effects of clearcut age, scarification (mounding), herbicide treatment, and seedling stock type were investigated 5 years afte r planting. On fresh clearcuts, amounts of vegetation were negligible, wher eas 2.1-3.7 Mg.ha(-1) was found on 4-year-old and older clearcuts. Soil tem peratures were about 10% higher in mounds than in undisturbed ground, while herbicide and clearcut age only marginally affected soil temperatures. See dlings planted on old clearcuts showed significant reductions in growth due to interference from vegetation. Five years after planting, the reduction in growth corresponded to about 1 year's growth. Most of the interaction be tween seedlings and vegetation occurred during the first 2 years after plan ting. Thus, scarification was just as effective as repeated herbicide treat ments in reducing competition from vegetation. Differences in periods of dr ought between years could largely explain variation in leading shoot length . However, leading shoot length was affected in the same way irrespective o f vegetation control treatments. Five years after planting, the relative di fferences in diameter between bare-root and containerized seedlings were th e same as at the time of planting.