tractor-pulled drags (barrels and chains) were used on the 30-yearold
stands. The primary herbicide used on 30-year-old INT stands
was 2,4-D (2,4-Dichlorophenoxyacetic acid), whereas glyphosate
herbicides (Round Up and Vision) were introduced in the
mid-1980s and applied aerially using helicopters in many of the
10-year-old INT stands. To ensure that soil types did not systematically
vary among the treatments, we sampled soils with an auger
to a depth of 1 m and classified each sample into a ‘‘soil moisture
regime’’ based on Ontario’s Forest Ecosystem Classification protocol
(Sims et al., 1997).