climate change is occurring at an increasingly rapid pace. many tree species, even those with wide seed dispersal and high genetic variability, are long-lived and unable to “keep pace” with these shifting climates. the combination of the longevity of trees and human-caused fragmentation of habitat makes it unlikely that these species will adapt on their own. therefore, local seed sources, though once adapted to local conditions, will no longer be the optimal seed source and will decline in health and rate of growth. instead, seeds adapted to areas with temperature and precipitation conditions typically seen in more southern sources and lower latitudes will be the best solution. this thesis explores the importance of considering climate shift when selecting seed sources for regeneration. a study of data from provenance tests with various ontario seed sources was conducted to identify the optimal growing conditions for each seed source. it was found that, in most cases, optimal growth occurred for sources originating from lower latitude. this growth implies to replant harvested forests that are ideally suited for climatic variables present at that site, seeds should be sourced from these “more suitable” locations.