Document: ANN-3-42-41

Reindeer population density impact on forage biodiversity.

MARIE ODASZ-ALBRIGTSEN, A.*

Department of Arctic Biology, Institute of Medical Biology, University of Tromsų, N-9037 Tromsų, Norway ¹

Abstract:
How does a quickly expanding reindeer population affect forage biodiversity and soil in an Arctic habitat? After about 100 years of absence, 15 Svalbard reindeer, (Rangifer tarandus platyrhynchus) were reintroduced to Brggerhalvya, western Svalbard, Norway. The total area is ca. 180 km²: 25% glaciers, 50% barren land and 25% potential forage vegetation. The reindeer population increased to ca. 30 animals in l980, ca. 100 animals in l985 and to more than 360 animals by l994 before crashing to less than 70 animals. Impact of the rapidly growing reindeer population, from 2.2 animals/m² in l985 to 8 animals/m² in l994, on Dryas dominated vegetation and soil was analysed. Dryas vegetation on the elevated beach ridges is snow-free in late winter and early spring when reindeer are in search of food after surviving the long winter. Total species biodiversity decreased significantly from l985 to l994. Bryophytes and lichens, including the total cover of preferred reindeer lichens, decreased while vascular plant diversity remained unaffected. The total biodiversity decreased from 23.6 to 11.5 species/m², bryophytes decreased from 9.3 to 1.2 species/m² and lichens decreased from 7.4 to 4.2 species/m². The important reindeer lichens, Cetraria ericitorum and C. nivalis were eradicated. The surviving reindeer population was supported by less-preferred forage and less diverse vegetation. Plant-cover removal and reindeer trampling on the thin Arctic humus layer resulted in a buildup of carbon, smaller soil particles (<2 mm) and higher calcium and magnesium content.

Keywords: forage plants, reindeer grazing, arctic

This abstract is being presented at: 3:30 PM in session:
HERBIVORE EFFECTS ON PLANTS