Forest Dynamics in Relation to Late-Holocene Climatic Variability, Eastern Ontario, Canada

Abstract

Pollen profiles from two lakes, Tawny Pond (44°48’59”N, 77°10’54”W, 276m) and Stoll Lake (44°58’16”N, 77°17’22”W,303m) in Addington Highlands, eastern Ontario, Canada were analyzed to understand the effects of late-Holocene climate change and European settlement on eastern Ontario’s forests. Both lakes were analyzed at high temporal resolution and record vegetation dynamics over the last 1000 years. Throughout the past 1000 years, Pinus, Tsuga, Betula, Quercus, Acer and Fagus were the dominant taxa in the pollen record. The pollen records show vegetation response in relation to the Medieval Warm Period and the Little Ice Age. From 970-1200 AD the forest was dominated by hemlock, beech and maple trees. From 1200-1870 AD the forest composition changed as pine and boreal trees became more abundant and/or had increased relative pollen production. Most recently, since 1870 AD, herbaceous plants (weeds) increased, whereas softwoods decreased and hardwoods increased, due to landscape changes associated with European settlement. These results show that high resolution studies of unvarved lakes, with an appropriate chronology, can detect multi-decadal climate variability. This thesis was also concerned with making management suggestions to the forestry community. Future climate change will likely create a forest composition more similar to that of the Medieval Warm Period than the time of European colonization, and thus should be the basis for forest planning.