Influence of alternative conifer release treatments on habitat structure and small mammal populations in south central British Columbia
This study was designed to test the hypothesis that conifer release treatments would simplify habitat structure and reduce small mammal populations in forest plantations. A secondary objective was to examine some important demographic characteristics, for selected small mammal species, that may be affected by changes in habitat. We examined the effects of manual cutting and cut-stump applications of glyphosate herbicide on vegetation, woody debris, and small mammal populations from 1991 to 1994 in young mixed-conifer plantations of south central British Columbia, Canada. The experimental design consisted of 9 separate and independent plantations: 3 controls, 3 manual treatments, and 3 cut-stump treatments. Total volumes of herbs, shrubs, coniferous trees, and woody debris were not affected by manual or cut-stump treatments for conifer release. Both treatments reduced total volumes of deciduous trees in the first posttreatment year. However, deciduous tree volumes on manual treatments had largely returned to pretreatment levels by the second posttreatment year. There were no significant (P > 0.05) effects of manual or cut-stump treatments on the population size of deer mice (Peromyscusmaniculatus Wagner), yellow-pine chipmunks (Tamiasamoenus J.A. Allen), southern red-backed voles (Clethrionomysgapped Vigors), or long-tailed voles (Microtuslongicaudus Merriam). The response of meadow voles (Microtuspennsylvanicus Ord) was variable. Sex ratios, body weights, reproduction, recruitment, and survival of deer mice remained similar on treatment and control plantations throughout this study. Changes in habitat structure up to 2 years posttreatment did not appear to exceed the tolerance of small mammal populations for early successional change.