Climate Change and Caribou

The central objective of this research was to§determine if there is a relationship between§long-term barren-ground caribou (Rangifer tarandus)§abundance and climate patterns. A long-term dataset§indexing caribou abundance was obtained from the§frequency of trampling scars on tree roots of black§spruce (Picea mariana [Mill.] BSP) in the§forest-tundra of the Northwest Territories. Samples§were collected from roots of live trees along§well-used migration trails in the forest tundra. The§scar frequency distributions constructed from two§groups of sites were dated from A.D. 1760-2000 and§both groups of sites showed similar abundance§patterns through time. §§To best determine the relation between long-term§climate and the proxy caribou abundance, local§climate data were needed. A series of tree-ring§chronologies were used to reconstruct summer§temperatures (July-August). This research§demonstrated that the Arctic Oscillation was most§closely correlated to summer temperature. Wavelet§coherence demonstrated that the relation between§caribou abundance cycles and the AOS changed from§inversely related during the first two phases of the§AOS, to in-phase during the final two phases of the AOS.