Ten-year response of northern hardwoods to irregular shelterwood in Québec

Abstract

Many outcomes from silvicultural studies suggested that multi-aged silviculture approach, including irregular shelterwood system (ISS), could be an alternative to even and uneven aged silvicultural systems in northern hardwood stands. However, few trials have compared ISS in this type of stands. In 2009 we established an experimental study in Québec to compare hybrid single-tree and group selection cutting, which was the most prescribed treatment, with two novel variants of ISS. These treatments were also coupled with mechanical understory American beech control, soil scarification and deer exclusion. After 10 years net growth was positive and similar for all the cutting treatments despite the difference of stand structure but was negative for the control. Mortality caused by the beech bark disease is an important factor explaining this difference. However, despite high beech mortality, its abundant regeneration in the cutting treatments as well as in the control indicate that this species will probably dominate in the future to the detriment of sugar maple and yellow birch which regeneration was heavily browsed. These results are different from those expected at the beginning of the study and illustrate certain contemporary issues of managing this type of stands.