Published source details
Thorne M.S., Meiman P.J., Skinner Q.D., Smith M.A. & Dodd J.L. (2005) Clipping frequency affects canopy volume and biomass production in planeleaf willow (Salix planifolia var. planifolia Prush). Rangeland Ecology & Management, 58, 41-50
In the northern hemisphere, willows Salix spp. may be very important component plants of some ecosytems. How browsing frequency and browsing season affects willows (thus indicating appropriate times to allow browsing to occur for conservation management purposes) is poorly known. This study, conducted in a garden at the University of Wyoming, Laramie city (mid-west USA), investigated how frequency of simulated browsing influences above- and below-ground biomass production, and canopy volume, of planeleaf willow Salix planifolia var. planifolia.
Willows were grown from stem cuttings collected at Bighorn National Forest (north Wyoming) on 25 May 1994. The experiment was a randomized block design comprising two willow groups, either unclipped or previous clipping undertaken in 1995 (as part of an earlier study). Within each, willow plants were randomly assigned to one of 11 subgroups (one an unclipped control).
Treatments comprised all combinations of early (May), middle (August), and late (November) clipping season periods (undertaken in 1996 and 1997). In November 1997, destructive harvest was undertaken to measure dry weight; weight of clippings was also measured. Just before and after clipping, canopy volume was calculated.
Clipping frequency (1, 2 or 3 clipping events) alone had little effect on willow biomass. It was specific seasonal combinations that produced greatest variations in production: early season clipping (alone or in combination with other clipping events) was most detrimental to willows with prior clipping histories than mid or late season clippings; willow with prior clipping histories clipped in mid or late season, and the late/middle combination produced more than the controls. Final canopy volume did not vary between groups, but aboveground biomass was significantly greater in willows with no clipping history.
Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://www.srmjournals.org/doi/full/10.2111/1551-5028%282005%2958%3C41%3ACFACVA%3E2.0.CO%3B2