The impact of the timing of brush management on the nutritional value of woody browse for moose Alces alces

Published source details Rea R.V. & Gillingham M.P. (2001) The impact of the timing of brush management on the nutritional value of woody browse for moose Alces alces. Journal of Applied Ecology, 38.
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Summary

Early successional woody plants such as birch Betula spp. and willow Salix spp. dominate the diets of moose Alces alces and other ungulates in autumn and winter. Despite their importance to moose, such trees and shrubs are often cleared from young forest stands by managers to enhance the production of conifers. Clearing reduces competition with conifer seedlings and is generally accomplished with the use of forest herbicides and/or by mechanical 'brushing'. An experiment was undertaken in western Canada to examine how the removal of above-ground biomass by mechanical brushing at different times of the year, affected the nutritional value of regenerating shoots of Scouler's willow Salix scouleriana for moose for two winters after brushing.

Study site: The study area was located approximately 20 km north-east of Vanderhoof, British Columbia, Canada (54°05' N, 123°55' W) in the subboreal spruce forest.

Brushing trials: Scouler's willow Salix scouleriana brushing trials were conducted throughout the 1996 and 1997 growing seasons on a 10-year-old regenerating clear-cut area replanted with lodgepole pine Pinus contorta.

The nutritional value of the Scouler's willow browse was assessed in relation to length, diameter, mass, digestible energy, digestible protein, tannin and lignin content of current annual growth shoots in winter, as well as the phenology of plant leafing.

One winter after brushing: One winter after brushing, Scouler's willows brushed in early July had shoots that were lower in lignin, higher in digestible protein and lower or similar in tannin content compared with shoots from earlier brushed or unbrushed willows. Willows brushed in early July also had long, heavy shoots that were high in digestible energy and delayed leaf senescence.

Two winters after brushing: In the second winter after brushing, willows that were brushed in July had larger shoots had lower in digestible energy, digestible protein, tannin and lignin content and delayed leaf senescence compared with several other treatments. Willows brushed after July regenerated negligible shoot material in the first year after brushing. Willows brushed in September delayed leaf flush in the first post-brushing spring.

Conclusions: To increase the nutritional value of woody browse for moose and deer, it is suggested that brushing should be performed in early to mid-July (mid-summer). The authors also recommend that the needs of other fauna potentially affected by changes in shrub architecture, shoot morphology and shoot chemistry be considered when planning the timing of brush management activities.

Note: If using or referring to this published study, please read and quote the original paper. The original paper can be viewed at:
http://www.blackwell-synergy.com/doi/full/10.1046/j.1365-2664.2001.00641.x