Winter grazing of reindeer in woodland lichen pasture. Effect of lichen availability on the condition of reindeer.

Winter grazing of semi-domesticated reindeer (Rangifer t. tarandus) was investigated at the woodland lichen pasture (lichen approximately 550kg DMha(-1)) in Kaamanen, northern Finland during the winter 1996-1997. Nine female reindeer mainly dug their food in the snow for 122 days (3 December-4 April) in a fenced area of 36.3ha. Over half of the fenced area was lichen dominated dry pine forest. The amount of lichens in lichen forest inside the fence was estimated before and after grazing. Area of grazed and condition of reindeer as well as snow conditions were monitored. Reindeer grazed over the whole area of lichen forest in early winter but from mid-winter they tended to graze on the areas with the greatest lichen abundancy. The amount of lichens measured decreased in the latter areas by 40% and in the other part of the lichen pasture by 17%, respectively. In both of these areas the residual amounts of lichens left after grazing were similar. Of the dominant lichens, the amount of C. stellaris decreased the most and the amount of Cl. uncialis the least. During the study, the estimated average daily area grazed varied from 4 to 87m(2) per reindeer. It was calculated that individual reindeer obtained 2.6kg of lichen DM per day during the most intensive digging period when the body condition score and weight of reindeer increased. Otherwise, the body condition score and weight decreased. Reindeer finished foraging for ground lichens and started to search for arboreal lichens in mid-March when the snow layer was 70-80cm thick and contained some hard snow layers which lifted reindeer. Both the amount of lichens in the pasture and the snow conditions essentially affect the nutritional status of reindeer in the woodland region during winter. Assuming that a reindeer is able to graze around 30m(2) per day in the snow during mid and late winter, there should be, on the basis of energy demand and grazing behaviour of reindeer as well as the nutritive value of lichen, an estimated 1000kg lichen DMha(-1) available in a good condition woodland lichen pasture.