Impact of different stocking densities of sheep on establishing stands of Larix sibirica in Iceland

The present study was the first in Iceland to investigate the effects of different stocking densities of sheep on planted Siberian larch (Larix sibirica) trees. It covered two years and involved four stocking densities in enclosures with 0.1–3.0 m tall trees, as well as a grazed area on treeless commons. The grazing effect was followed for 75 days each summer. A significant grazing effect was found on the vegetation in both years. None of the sheep stocking densities had a measurable effect on the growth or the survival of the larch trees, however, and no damage was observed on their apical shoots. During the second summer, significant visual and measured browsing effects were recorded on side branches in enclosures with medium and high stocking densities. No trees <0.5 m were browsed, however. Siberian larch is generally not sought after by sheep and the results indicated that it may be generally safe to utilize established monoculture Siberian larch stands for sheep grazing during the summer months, if enough other vegetation is present.