Climate, fire disturbance regime, and vegetation response of the past 2500 years for central Nova Scotia

Abstract

The interaction between climate change and disturbances affects forest composition and dynamics, but most of our empirical knowledge comes from short-term studies of the past century. Pollen and charcoal analyses of lake sediment cores retrieved from three sites in Nova Scotia were used to produce a landscape-level analysis of long-term forest cover dynamics and fire disturbances of the past ~2500 years. The present-day forests had been established by that time, although a long-term increase in Picea at the expense of northern hardwoods was seen at all sites, consistent with other pollen records found across New England and Eastern Canada. The driving influences of forest change prior to European settlement were a combination of climate and disturbance, acting on site characteristics of each region. Fires were relatively infrequent in this region and did not have a major impact on the evolution of the forests of central Nova Scotia. Changes in the relative abundances of the tree taxa occurred in response to long-term cooling during the past 3000 years and century-scale climate variability such as the Little Ice Age (ce 1450–1850) and Medieval Warm Period (ce 800–1300). The impact of climate variability on the fire regime depends on the landscape and vegetation type. “Borealization” of the Acadian Forest, noted during the period of European colonization, has been occurring for millennia.