Abstract
In the 1970s, mean lichen biomass ranged by the earmark districts (comprising of 2-9 adjacent herding associations) between 54 kg and 380 kg DM per ha correlating negatively with animal density per lichen ranges (range 1.5 - 14.3 ind. per km2). Biomasses were far below economic carrying capacity of lichen ranges (900 kg DM per ha). The condition of lichen ranges was poorest in the southern half of the area where alternative food to reindeer lichens (Deschampsia flexuosa, arboreal lichens and supplementary feeding) was available. In 1980-86, recruitment (calves per 100 females) was 33% higher than in the 1970's, on an average (65 vs. 49), despite a 90% increase in animal numbers between 1970 and 1986; recruitment has not been dependent on the condition of lichen ranges. The increase in production has been some higher than expected on the basis of animal numbers. The reasons for the increasing trends in animal numbers, recruitment and production remains some unclear, but they may include favorable winter conditions, supplementary feeding, medical treatment against parasites and proper harvesting policy.
Highlights
Economic carrying capacity is referred as an equilibrium where animal density is levelled so that it allows maximum primary production of the range (Caughley, 1976)
From it appears that the proportion of lichen range from the total land area varied between 7% and 84% i increasing towards the north
Condition of lichen ranges The mean height of lichens ranged between 8 and 13 mm by the earmark districts without any clear correlation to animal density per lichen range
Summary
Economic carrying capacity is referred as an equilibrium where animal density is levelled so that it allows maximum primary production of the range (Caughley, 1976). Consumption by animals is in maximum providing in turn maximum sustained yield. Both theoretical and empirical evidence shows that primary production peaks at the biomass value which is about 50% from ecological carrying capacity K (Caughley, 1976; Karenlampi, 1973; Gaare and Skogland, 1980; Skogland 1986). Due to high preference by reindeer but slow growth rate reindeer lichens are vulnerable to over-grazing, i.e. to the reduction of biomass below the 50% limit of K. Over-grazing seems to be closely associated elsewhere to intensive reindeer economy and past (Andreev, 1971; Karenlampi, 1973; Skogland, 1986)
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