Effect of Browsing, Seedbed, and Competition on the Development of Yellow Birch Seedlings in High-Graded Stands

Abstract

Many hardwood or mixedwood stands of northeastern North America have been high graded in the past and need restoration treatments to bring them back to an acceptable level of production. Even when early seedling establishment can be secured, further development may be compromised bymany factors. This study looks at the effect of seedbed, browsing, and competition on the growth and survival of yellow birch (Betula alleghaniensis Britt.) seedlings that became established after a brushing and scarification treatment applied in high-graded mixedwood stands of Quebec,Canada. The seedbed types studied include 1-m-wide scarified patches, 2-m-wide scarified patches, and mounds. Browsing impact was assessed by placing fences around half of the plots. Half of the plots were released from competing vegetation. Browsing by hare (Lepus americanus) was seenas a major factor controlling seedling development between 3 and 6 years after scarification. It reduced both survival and growth and obscured the effect of other factors. In the absence of browsing, competition had a major effect on mounds but not on scarified patches. Mounds were found tohave the best growth potential when competition and browsing were controlled. The scarified patches had the best growth when competition and browsing were allowed. Even though mortality was somewhat higher on scarified patches, initial densities were very high and still provide more seedlingsthan required.

Natural Regeneration on Planted Clearcuts—The Easy Way to Mixed Forest?

“…Scarification techniques that expose larger areas of bare mineral soil, like disc trenching in continuous rows, increase the establishment of birch seedlings to densities that might be suitable for establishment of mixed forests. Consistent with earlier studies, the study showed that not only the disturbance rate per se but also the type of scarification affects the regeneration success (Elie et al, 2009;Prevost et al, 2010) and the species composition (Prevosto et al, 2011). However, the scarification effect on a specific site may not be sufficient for predicting the regeneration success.…”