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Providing evidence to improve practice

Individual study: Threshold effects of variable retention harvesting on understory plant communities in the boreal mixedwood forest

Published source details

Craig A. & Macdonald S.E. (2009) Threshold effects of variable retention harvesting on understory plant communities in the boreal mixedwood forest. Forest Ecology and Management, 258, 2619-2627


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Use clearcutting to increase understory diversity Forest Conservation

A replicated, randomized, controlled study in 1998-2006 in boreal mixed wood forest in Alberta Canada (Craig & Macdonald 2009) found that clearcutting and high thinning intensity increased the cover of understory vegetation, particularly of grasses. The average percentage cover of all species under the canopy was 67% in clearcut and high thinning intensity plots (0-10% retention) and 55% in the three low thinning intensities and uncut plots (20-100% retention). The average percentage cover of grasses was 14% in clearcut and high thinning intensity plots and 4% in the three low thinning intensities and uncut plots. Species richness was unaffected by retention level. In winter 1998-1999, six 10 ha compartments within each of three blocks (∼2 km2) were randomly assigned to six harvesting treatments: clearcutting (0% retention), 10% retention, 20% retention, 50% retention, 75% retention and uncut (100% retention). Sampling was conducted in summer 2006 in twenty 1×1 m plots in each of the 18 compartments.