170 Michael R. Lusk, Michael J. Lacki, and Richard A. Lancia 
1940s or 1950s (National Park Service Uplands Field Research 
Laboratory, 1985, European wild hogs in Great Smoky Mountains 
National Park). Since that time their population has spread through- 
out the Park, damaging its rich flora and fauna (Bratton 1975, Singer 
1981). The upper elevation beech forests have received especially 
heavy impact because of their small total acreage, rich herbaceous 
layer, and preferential rooting by hogs in summer (Bratton 1974, 
Singer et al. 1981). Research has been conducted on the effects of 
rooting on the flora of these areas, but very little work has ad- 
dressed the effects of rooting on the animal communities 
(Bratton 1974, Howe et al. 1981, Lacki and Lancia 1983, Singer et 
al. 1984). 
The objective of our study was to evaluate the responses of 
deer mice and other small mammal populations to wild hog rooting 
in the beech forest in the following ways: (1) compare populations 
of deer mice and other small mammals on rooted and unrooted 
sites, (2) identify important microhabitat variables for trap success 
and failure, and (3) determine if the presence or absence of impor- 
tant microhabitat variables affects population levels at each site. 
METHODS 
Site Selection 
Russell (1953) and Whittaker (1956) defined the Gray Beech 
Forest or “beech gaps” in the Great Smoky Mountains National 
Park. These gaps are beech ( Fagus grandifolia) forests that occur 
between 1,430 and 1,800 m in elevation (Bratton 1975) and are 
usually found on south-facing slopes on the ridge that bisects the 
Park in a northeast-southwest direction (Russell 1953). These gaps 
occur as small islands of deciduous trees in spruce-fir ( Picea rubens 
-Abies fraseri ) forests. 
We grouped our beech gap study sites into rooted or unrooted 
categories based on history and intensity of hog rooting. Selection 
of unrooted (or control) sites and rooted sites was made difficult 
by the high variability of hog densities, the widespread and uni- 
form distribution of the hogs within the Park, and the ephemeral 
nature of some small mammal populations. Because it is impossible 
to say that any beech gaps exist that have never been rooted, we 
use the term “unrooted” to refer to sites that appeared undisturbed 
at the time of our study. We selected three rooted and three unrooted 
trap sites each year. Sites were comparable in elevation, slope, and 
aspect. 
Mammals 
Sampling — We livetrapped small mammals for five trap-nights 
on each site with Sherman live traps arranged in a 6 x 6 grid with 
