The influence of partial harvesting and forest floor disturbance on nutrient availability and understory vegetation in boreal mixedwoods

Published source details Frey B.R., Lieffers V.J., Munson A.D. & Blenis P.V. (2003) The influence of partial harvesting and forest floor disturbance on nutrient availability and understory vegetation in boreal mixedwoods. Canadian Journal of Forest Research, 33, 1180-1188.
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This study is summarised as evidence for the following.

	Action	Category
	Use partial retention harvesting instead of clearcutting Action Link
	Use soil disturbance to enhance germination (excluding scarification or ploughing) Action Link
	Use prescribed fire: effect on understory plants Action Link

Use partial retention harvesting instead of clearcutting

A replicated study in 1999-2000 in boreal forest in Alberta, Canada (Frey et al. 2003) found that partial retention harvesting decreased the cover and root-sucker density of Populus spp. compared with clearcutting. Cover of Populus spp. (clearcutting: 9%; thinning: 3%) and density of Populus spp. root-suckers (stems/ha) (clearcutting: 74,800; thinning: 53,900) were higher in clearcut sites. Data were collected in August 2000 in twenty 2 x 2 m plots in each of three replicates of clearcutting (complete removal) and partial removal (50% of basal area removed) treatment units (10 ha). Treatments were applied during the winter of 1998-1999.
Use soil disturbance to enhance germination (excluding scarification or ploughing)

A replicated, controlled study in 1999-2000 in boreal forest in Alberta, Canada (Frey et al. 2003) found that different forest floor disturbance treatments decreased the cover of herbaceous plants and cranberry Viburnum edule and increased the cover of fireweed Epilobium angustifolium and the density of Populus spp. root-suckers but not its cover. Cover of fireweed was higher following soil mounding (20%) than in control plots (5%) and intermediate following soil mixing (9%) or removal of the litter layer, ‘scalping’ (7%). Cover of cranberry was lower in soil mixing (<1%) and soil mounding plots (<1%) than in control plots (2%) and intermediate in litter layer removal plots (1%). Cover of herbaceous plants was lower in soil mixing (1%) and soil mounding plots 2%) than in control (7%) and litter layer removal plots (5%). In litter layer removal plots, populus spp. cover (18%) and density of their root-suckers (122,400 stems/ha) were higher than in the other treatments (3-6% cover, 17,500-36,500 stems/ha). In May 1999, four 2x2 m plots of each of four treatments were established within each of six 10 ha forest units. Treatments were: control, soil mixing (mixing the litter layer with the upper 2-3 cm of mineral soil), soil mounding (mineral soil scooped out to form adjacent mound of mineral soil 15 cm high and 1 m in diameter) and litter layer removal (‘scalping’: litter removal leaving just 2cm of organic matter above the mineral soil). Cover of herbaceous plants was visually estimated in late July 1999. Cover of fireweed, cranberry and Populus spp., as well as the root sucker density of Populus spp., was evaluated in August 2000.
Use prescribed fire: effect on understory plants

A replicated, controlled study in 1999-2000 in boreal forest in Alberta, Canada (Frey et al. 2003) found that prescribed burning increased the cover of fireweed Epilobium angustifolium but not the cover of cranberry Viburnum edule, herbs or populus spp. The cover of fireweed was higher in burned plots (burned: 18%; unburned: 4%), while the cover of cranberry (burned: 2%; unburned: 2%), herbs (burned: 6%; unburned: 7%) and populus spp. (burned: 4%; unburned: 6%), as well as the density of populus spp. root-suckers (burned: 25,400; unburned: 35,500/ha) were similar between treatments. Four burned (in May 1999) and four unburned 2 x 2 m plots were established within each of six 10 ha forest units. Cover of herbaceous plants was visually estimated in late July 1999. Cover of fireweed, cranberry and Populus spp., as well as the root sucker density of Populus spp. was evaluated in August 2000.