Variations in northern white-cedar (Thuja occidentalis) regeneration following operational selection cutting in mixedwood stands of western Quebec

Abstract

Poorly adapted silvicultural practices and increases in white-tailed deer (Odocoileus virginianus (Zimmerman, 1780)) populations have most likely contributed to the decline of northern white-cedar (Thuja occidentalis L.) in many regions of eastern North America. Selection cutting has been suggested to regenerate northern white-cedar in mixedwood stands, but the approach has not yet been validated in an operational framework. The objective of this study was to determine how local variations in stand condition and treatment application influence northern white-cedar regeneration at an operational scale in mixedwood stands. Seventy treated and control permanent plots, having at least 10% of basal area in cedar, were selected in an operational harvesting site. A regeneration survey was conducted in 2014, 15 to 20 years after harvesting, and data on harvested trees and tree cover, as well as regeneration state and abundance, were collected. Results indicate that selection cutting allows for the establishment of northern white-cedar when deer densities are low, which was the case in the study sites. However, abundance of seed trees nearby, harvesting intensity, competition, and availability of establishment microsites influenced abundance, growth, and recruitment of northern white-cedar seedlings and saplings in the residual stand. Deer browsing had no effect on regeneration.