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Small Mammals in
Streamside Management
Zones in Pine Plantations1
James G. Dickson2and J. Howard
Williamson3
Many second-growth pine-hardwood
stands in southern forests are being
cut and replaced by pine plantations,
especially on industrial land. From
1971 to 1986, the amount of
Midsouth timberland in pine plantations increased from 6 to 8% (Birdsey
and McWilliams 1986).White-tailed
deer adapt well to young brushy
clearcuts with ample forage and soft
mast. Also, many species of birds are
abundant in this diverse brushy habitat (Dickson and Segelquist 1979).
But the effectsof clearcutting and
planting on all vertebrate species are
not well assessed or defined.
Various environmental concessions are being implemented along
with stand conversion. One practice
used to protect water quality and
enhance wildlife habitat is to retain
mature forest stands along intermittent and permanent streams when
adjacent stands are cut and planted
to pines (Dickson and Huntley 1986,
Seehorn 1986).These areas of mature
pine or pine-hardwoods are called
riparian zones, filter strips, stingers,
streamers, or streamside management zones (SMZ). These areas en'Paper presented at symposium, Management of Amphibians, Reptiles, and
Small Mammals in North America. (Flagstaff. AZ,July 19-21, 1988.1
2JarnesG. Dickson, Supervisory Research
Wildlife Biologist, Wildlife Habitat Laboratory, Southern Forest Experiment Station,
USDA Forest Service, Nacogdoches, Texas.
3J.Howard Williamson,Forestry Technician. WildlifeHabitat Laboratory,Southern
Forest Experiment Station, USDA Forest Service, Nacogdoches,Texas.
Abstract.-Small mammals were captured in live
traps in 6 mature-forested streamside management
zones of 3 widths, narrow ( c 25 m), medium (30-40
m), and wide (50-90 m), which traversed young,
brushy pine plantations. More small mammals were
captured in the narrow zones (165) than in the medium (82), or wide zones (65).
hance habitat diversity and "edge,"
offer suitable habitat for wildlife species associated with mature stands,
serve as travel corridors for animals,
and may permit genetic interchange
between otherwise isolated populations of animals. Retention of SMZ
for reduction of non-point pollution
and for wildlife has been widely recommended.
These mature hardwood strips can
be good squirrel habitat. In Mississippi (Warren and Hurst 1980)and in
eastern Texas (McElfresh et al. 19801,
gray (Sciurus carolinensis) and fox (S.
niger) squirrel numbers were higher
in riparian areas than in adjacent upland stands. In another facet of the
present investigation, gray and fox
squirrels were abundant in SMZ
wider than 50 m but virtually absent
from zones less than 40 m wide
(Dickson and Huntley 1986). A wide
variety of reptiles and amphibians
were abundant in zones greater than
30 m wide, where a closed canopy
offered shaded understory, but were
scarce in SMZ less than 25 m wide,
which were dominated by low,
brushy vegetation (Rudolph and
Dickson In Press). The relationships
of SMZ and other wildlife species are
largely unknown.
The objective of this study was to
determine the relationship of SMZ
width to small mammal communities. We assessed the effects of narrow ( ~ 2 m),
5 medium (30-40m), and
wide (>50 m) SMZ widths on small
mammal captures in 6 SMZ in eastern Texas.
Study Areas and Methods
Study areas consisted of 6 pine plantations on the western edge of the
southern coastal plains in eastern
Texas. Mature pine and hardwood
trees on the areas had previously
been harvested. The plantations had
been planted to loblolly pine (Pinus
taeda) seedlings 5 to 6 years before
this study was begun and were vegetated by diverse flora, dominated by
hardwood and other woody brush.
Oaks (Quercus spp.) and sweetgum
(Liquidambar s tyraciflua) sprouts,
American beautyberry (Callicarpa
arnericana), blackberry and dewberry
(Rubus spp.), and sumac (Rhus spp.)
were abundant.
Each of the 6 study areas was traversed by a SMZ of mature vegetation. Dominant trees (> 13 cm dbh) in
decreasing order of abundance and
stem density (No./ha) were as follows: sweetgum, 63; white oak (Q.
alba), 36; southern red oak (Q.falcata), 28; red maple (Acer rubrum), 19;
black gum (Nyssa sylvatica), 14;
shortleaf pine (P. echinata), 14; and
eastern hophornbeam (Osty a virginiam), 14. Dominant understory vegetation (5-13 cm dbh) and stem density (No./ha) included sweetgum,
140; eastern hophornbeam, 71; black
gum, 40; flowering dogwood (Cornus
porida), 40; loblolly pine, 21; and red
maple, 19.
Assigned treatments were 3 SMZ
widths: narrow (<25 m), medium
(30-40 m), and wide (>50 m). Two
replications of each treatment were
sampled at 2 locations. In each of the
6 study areas two 200-m transects
were established along each of the 6
streamside zones. Distance from
points along the transects to the SMZ
edge was variable because each zone
orientation changed somewhat with
stream meanders. Thirteen Sherman
live traps were placed 12.5 m apart
on each of the 12 transects. Trapping
was conducted 4 consecutive nights
in each of 2 consecutive weeks (8
nights) during February and March
in 1986 and again in 1987 (52 traps/
treatment X 8 nights X 2 years = 832
trap nights). Traps were baited with
oatmeal each morning and checked
the following morning.
Captures per treatment were approximately normally distributed according to the Kolmogorov-Srnirnov
Goodness of Fit Test. Each of the 3
treatments was tested for differences
between years with the T-Test. There
were no significant differences between years (P > .lo); therefore, capture data were combined for both
years. Treatment effects (captures/
treatment) were tested for differences by ANOVA and the Duncan's
Multiple Range Test at the 0.05 level
of confidence.
White-footed mice (Peromyscus leucopus) and cotton mice (P. gossypinus)
were grouped together because of
difficulty in positive field identification. Davis (1974) determined that
white-footed mouse adults were
smaller (15 to 25 g, as opposed to >
30 g for the cotton mouse) and had
brighter colors. Also, adult hind-foot
length was shorter (21 mm, as opposed to 23 mm for cotton mice).
However, numerous sub-adults were
captured during the trapping period,
making identification extremely difficult.
Results and Discussion
Significantly more small mammals
were captured in the narrow SMZ
(165) than were captured in the medium (82) or wide (65) SMZ (table 1).
The absence of tree canopy in the
narrow zones permitted dense,
brushy vegetation growth, abundant
seeds, and dense logging slash cover,
but medium and wide zones were
characterized by shaded sparse
understories under closed canopies.
Other studies have shown higher
densities of small mammals in young
brushy stands than in mature stands.
In an earlier study in eastern Texas,
64 small mammals were captured in
a 6-year-old clearcut, but only 24 in a
pine-hardwood stand more than 35
years old. Small mammal species diversity was also higher in the young
stand (Fleet and Dickson 1984). In
pine plantations in Georgia, small
mammal abundance was higher in 1to 5-year-old pine plantations than in
older stands with closed canopies
(Atkeson and Johnson 1979).Seedeaters were abundant in the 1-yearold plantation, but herbivores were
abundant in older young brushy
stands.
In Pennsylvania, relative abundance of small mammals was greater
in recent clearcuts of both northern
hardwood and oak forests than in
adjacent mature stands (Kirkland
1978). A similar pattern was noted in
deciduous and boreal forests in West
Virginia (Kirkland 1977). After
clearcutting, small mammal abundance and diversity increased and
remained relatively high until stands
returned to forest. In Arizona, rodent
populations were higher in thinned
ponderosa pine (P. ponderosa) stands
with slash than in unthinned stands
(Goodwin and Hungerford 1979).
The most abundant species, the
fulvous harvest mouse (Reithrodontomys fulvescens) and the white footed
mouse/cotton mouse complex, were
much more abundant in the narrow
zone. For the fulvous harvest mouse,
there were 73 captures in the narrow,
4 in the medium, and 3 in the wide
zones.
Apparently, the dense brushy
vegetation with ample down logging
slash provided ideal habitat for this
species. There was abundant vegetative forage, seeds, and dense log and
brush cover. Schmidly (1983) described the best habitats for fulvous
harvest mice in the pineywcmds as
grassland, pine-grass ecotone, and
grass-brush. In an earlier study in
eastern Texas (Fleet and Dickson
1984), fulvous harvest mice were
captured regularly in a young pine
plantation, but were not captured in
the adjacent mature pine-hardwood
stand. In a study of small mammal
populations in 5 pine stands in Louisiana, fulvous harvest mice were
captured most frequently in a pine
seed-tree harvest cut having dense
hardwood brush (Hatchell 1964).
Differences among treatments
were less pronounced for the Peromyscus complex, with captures of 76
in the narrow, 67 in the medium, and
50 in the wide SMZ. In a 1-year-old
pine plantation in Georgia, the whitefooted mouse was the dominant species (Atkeson and Johnson 1979).It
also was the most abundant species
in the mature oak-hickory forest type
in eastern Tennessee (Dueser and
Shugart 1978).Cotton mice were captured regularly in 5 mature pine
stands in Louisiana (Hatchell 1964)
and in a pine-hardwood stand in
eastern Texas (Fleet and Dickson
1984).Neither species was captured
in a pine plantation in the Texas
study. Schmidly (1983) describes preferred habitat of the cotton mouse as
flatland hardwood, flatland hardwood-pine, and lower slope hardwood-pine. McCarley (1954) associated the white-footed mouse with
upland forest habitat.
Six other species were not captured frequently enough for conclusions concerning habitat preference.
Habitat preferences have been documented to some degree in other studies. The hispid cotton rat is often
very abundant and normally is associated with low, dense vegetation
(Atkeson and Johnson 1979, Fleet and
Dickson 1984, Goertz and Long 1973,
Schmidly 1983). It has occasionally
been found in habitats dominated by
early successional grasses and forbs.
The golden mouse is associated
with forested stands having low,
dense vegetation (Fleet and Dickson
1984, Hatchell 1964, McCarley 1958).
The Florida wood rat occupies forested upland and streamside habitat
and thrives in bottomland hardwood
stands with low brushy understories
(Schmidly 1983).Short-tailed shrews
were captured in the medium (2) and
wide zones (4). 0ther investigations
have found them inhabiting a variety
of mature stands (Fleet and Dickson
1984, Ha tchell1964, Schmidly 1983).
In conclusion, more small mammals, especially fulvous harvest
mice, were captured in narrow SMZ
than in medium and wide SMZ. Apparently, this is related to the abundance of low, dense vegetation, with
ample forage, fruits, and seeds; and
down logs and logging slash. But
medium and wide SMZ with closed
tree canopies provide limited mature
habitat for some species associated
with mature stands, such as the
short-tailed shrew, and are positive
for a variety of other wildlife.
Acknowledgments
We thank Jimmy C. Huntley for trapping assistance and James A. Neal
and W. V. Robertson for reviewing
an earlier draft of this manuscript.
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