Rebecca Zalatan

Climate Change and Caribou: the Relation Between Climate and Abundance Cycles Inbarren-ground Caribou Herds of the Northwestterritories, Canada Rebecca Zalatan

The central objective of this research was todetermine if there is a relationship betweenlong-term barren-ground caribou (Rangifer tarandus) abundance and climate patterns. A long-term datasetindexing caribou abundance was obtained from thefrequency of trampling scars on tree roots of blackspruce (Picea mariana [Mill.] BSP) in theforest-tundra of the Northwest Territories. Sampleswere collected from roots of live trees alongwell-used migration trails in the forest tundra. Thescar frequency distributions constructed from twogroups of sites were dated from A. D. 1760-2000 andboth groups of sites showed similar abundancepatterns through time. To best determine the relation between long-termclimate and the proxy caribou abundance, localclimate data were needed. A series of tree-ringchronologies were used to reconstruct summertemperatures (July-August). This researchdemonstrated that the Arctic Oscillation was mostclosely correlated to summer temperature. Waveletcoherence demonstrated that the relation betweencaribou abundance cycles and the AOS changed frominversely related during the first two phases of theAOS, to in-phase during the final two phases of the AOS.