This study was conducted in the Superior National Forest (fig. 1) in
northern St. Louis, Lake, and Cook Counties of northeastern Minnesota
(92 deg. west longitude, 48 deg. north latitude), an area well described by
Stenlund (1955). Most of the data were collected from within and
immediately south of the Boundary Waters Canoe Area, a special
wilderness region in which travel by motorized vehicles is restricted.
The total study area encompasses approximately 1.5 million acres, and
numerous lakes and rivers comprise about 15 percent of this area (fig.
2). The topography varies from large stretches of swamps to rocky
ridges, with altitudes ranging from 1,000 to 2,300 feet above sea level
(fig. 3). Winter temperatures lower than -30 deg. F. are not unusual, and
snow depths generally range from 20 to 30 inches on the level. However,
an important exception occurred in early 1969 when depths of 45 inches
and more accumulated in much of the area. Further details on snow
conditions in the study area during the period of this investigation
are given by Mech _et al._ (see page 51). Conifers predominate in the
forest overstory, with the following species present: jack pine (_Pinus
banksiana_ Lamb.), white pine (_P. strobus_ L.), red pine (_P.
resinosa_ Ait.), black spruce (_Picea_ mariana (Mill.) B.S.P.), white
spruce (_P. glauca_ (Moench) Voss), balsam fir (_Abies balsamea_ (L.)
Mill.), white cedar (_Thuja occidentalis_ L.), and tamarack (_Larix
laricina_ (DuRoi) K. Koch). However, as a result of extensive cutting
and fires much of the conifer cover is interspersed with large stands
of white birch (_Betula papyrifera_ Marsh.) and aspen (_Populus
tremuloides_ Michx.). Detailed descriptions of the forest vegetation
were presented by Ohmann and Ream (1969).
[Illustration: _Figure 1 (left half)--Map of the study area._]
[Illustration: _Figure 1 (right half)--Map of the study area._
BOUNDARY WATERS CANOE AREA SUPERIOR NATIONAL FOREST]
[Illustration: _Figure 2.--Lakes are common throughout most of the
study area. (Photo courtesy of L. D. Mech.)_]
[Illustration: _Figure 3.--Ridges, islands, swamps, and bays are part
of the variable topography in the Superior National Forest. (Photo
courtesy of L. D. Mech.)_]