Regeneration of birch stands in drained peatlands of Ostrobothnia

Thinning of the nurse crop improves the growth of spruce seedlings

The project consisted of regeneration experiments on the drained peatland experimental sites, established since the 1970s, by the Muhos Research Station to determine the height growth of both naturally established and planted spruce seedlings. The density of birch nurse crop proved to be the most significant individual factor affecting the height growth of spruce undergrowth, both for the naturally established and the planted ones. Even a slight thinning of the nurse crop improved the height growth, and the more thinning of the birch, the better the spruce growth. The height growth improved during the first five years following the thinnings, and the effect was even greater during the second half of the study period. The results showed that the spruce undergrowth remained in a vigorous condition for 30-40 years sheltered by the nurse crop. Cultivating the birch nurse crop to pulpwood height to protect spruce seedlings from frost was shown to be justified on medium-fertile drained peatlands.

Additional information on the project: www.metla.fi/hanke/3247/index-en.htm