Competition by ground vegetation in afforested fields

Competition by ground vegetation has a strong effect on the growth and mortality of birch seedlings in afforested fields. In this study the effects of different preventive controls of vegetation cover on the growth of birch seedlings were studied for 11 years. The study showed that seedlings grew higher when less ground vegetation cover was present. Mortality started to increase when the vegetation cover exceeded 60%. Successful prevention of ground vegetation increased the growth of seedlings and decreased mortality. The largest birch volume from patches treated with herbicides (29 m3/ha) was 2.5 times larger than from the untreated control patches (11.6 m3/ha). Furthermore, seedling mortality on the control patches (21%) was 3.5-fold compared with that in the treated experimental fields.