Recent afforestation of the Johnville Peat Bog, southern Québec, Canada, investigated using dendroecological and paleoecological techniques

English Abstract:

Recent dendroecological and paleoecological investigations at the Johnville Peat Bog, in southern Québec, Canada, have provided insight into the evolution of ombrotrophic bogs (those that receive all precipitation and mineral input from the atmosphere) as well as their response to human impacts, such as drainage. Many peat bogs in eastern North America experienced afforestation during the 20^th century due to factors such as fire or landuse changes. The Johnville Peat Bog also underwent afforestation during the 20^th century, possibly related to its drainage for agricultural purposes. The purpose of this study is to examine how Picea mariana (black spruce) responded to this drainage in terms of both its spatial distribution and its annual growth. Eighty black spruce trees, in different areas of the bog, and 20 hemlock trees (Tsuga canadensis), around the margin of the bog, were cored to determine the minimum age of the trees and also their rates of annual growth. The results show that the most rapid expansion of black spruce occurred in the area of the bog close to the area of drainage and that trees in other areas of the bog were relatively unaffected. Annual growth rates were determined by scanning and measuring the rings using WinDENDRO software, but showed more equivocal results. This study indicates that tree growth in ombrotrophic bogs is complex but that there is potential for using tree rings from these systems to infer hydroclimatic variability.