Clearcutting and burning of northern spruce-fir forests: implications for small mammal communities

1. This study was designed to test the hypotheses that (i) abundance and re lated demographic parameters of small mammal populations would decline afte r clear-cutting of northern spruce-fir forest, and (ii) prescribed burning, following clearcutting, an approach to emulating natural disturbance, woul d enhance the species richness and diversity of the small mammal community relative to unharvested and clearcut forests. 2. Intensive live-trapping of small mammal populations was conducted in rep licated forest (uncut), clearcut and clearcut-burned sites from 1988 to 199 2 in west-central British Columbia, Canada. 3. Mean abundance of southern red-backed voles Clethrionomys gapperi was si gnificantly higher on forest sites (11.74 ha(-1)) than on clearcut (0.60 ha (-1)) or clearcut-burned (0.02 ha(-1)) sites. Mean numbers of deer mice Per omyscus maniculatus were significantly higher on the clearcut-burned sites (16.88 ha(-1)) than on forest sites (9.04 ha(-1)). Demographic parameters o f reproduction, survival and body weight of deer mice were similar across a ll sites. 4. The long-tailed vole Microtus longicaudus had a strong annual fluctuatio n in abundance, particularly on clearcut sites (14.04 ha(-1)), where there were significantly more animals than on either forest (1.53 ha(-1)) or clea rcut-burned (2.67 ha(-1)) sites. Meadow voles M. pennsylvanicus were relati vely uncommon but occurred more often on clearcut and clearcut-burned sites than on forest sites. 5. The north-western chipmunk Tamias amoenus occurred at significantly high er numbers on clearcut (4.16 ha(-1)) and clearcut-burned (3.88 ha(-1)) site s than on forest sites, where it was rarely captured. Shrews Sorer spp. wer e at similar numbers across forest, clearcut and clearcut-burned sites. Wea sels Mustela spp. were captured more often on clearcut and clearcut-burned sites than on forest sites. A rare species, the western jumping mouse Zapus princeps, was captured on clearcut and clearcut-burned sites only. 6. Mean species richness of small mammals was significantly higher on clear cut sites (3.51) than on forest (2.73) or clearcut-burned (2.72) sites. Spe cies diversity was similar over all sites. Although species composition was altered by clearcutting, abundance of all species, except C. gapperi, was the same or higher than that in uncut forest. 7, Prescribed burning of clearcuts may not be necessary to mimic natural di sturbance regimes. Clearcutting of northern spruce-fir forest may provide d iverse habitats for small mammals through different stages of succession (a long with old growth forest) much as wildfires formerly did.