Influence of Fertilization on Feeding Attacks to Lodgepole Pine by Snowshoe Hares and Red Squirrels

Lodgepole pine (Pinus contorta Dougl.) shows favourable growth and yield responses to spacing (thinning) and potentially to fertilization, but is susceptible to feeding injuries by snowshoe hares (Lepus americanus Erxleben) and red squirrels (Tamiasciurus hudsonicus Erxleben). This study was designed to determine the incidence of animal damage to crop trees in a fertilized-spaced stand, compared with those in spaced only and control (unspaced) stands. There was little variation in the percentage of crop trees (range 53.6% to 63.3%) damaged by hares in the three stands. Hares removed an average of 92.2 cm 2 of bark and associated vascular tissues per attack from fertilized stems compared with 46.2 cm 2 in the spaced only stand. This latter value was nearly double that recorded in the control stand (27.4 cm 2 ). Squirrels damaged more fertilized trees (38.9%) than trees in the spaced (30.9%) or control (14.3%) stands. Squirrels removed the largest average amount of bark (66.9 cm 2 ) per attack from fertilized stems with little difference between spaced (41.6 cm 2 ) and control (42.3 cm 2 ) stands. We conclude that hares and squirrels clearly prefer to feed on fertilized lodgepole pine stems over those in non-fertilized or un-managed stands.