8 BULLETIN 1496, U. S. DEPARTMENT OF AGRICULTURE. 
on moderately fresh sandy or loamy soils. Where it is still found, 
white pine grows either in pure second-growth stands or as occa- 
sional trees in the forests of Norway pine or hardwoods. 
Norway pine forests originally occupied sandy soils, drier as a rule 
than those occupied by the white pine, in central Michigan, Wis- 
‘ consin, and Minnesota, and northward. Not many of these Norway 
pine forests now remain in the Lake States, but where they are still 
found Norway pine grows either pure or forms the principal tree in 
mixture with jack or white pine and also occasionally with hemlock 
or oaks. The bulk of the remaining Norway pine timber is on 
national-forest land, on State land such as Itasca Park, or on Indian 
reservations around Red Lake, Minn. In Wisconsin and Michigan 
practically none of it is left. There are, however, small and scattered 
tracts privately owned. 
JACK PINE 
The jack-pine forest is now typical of central Michigan, Wisconsin, 
and west-central Minnesota, northward. It tends to occupy the 
driest, sandiest soils. In this region it occurs either pure or as the 
principal tree in mixture with Norway pine or with scarlet or jack 
oaks (Quercus coccinea and YY. ellipsoidalis), or sometimes in patches 
_with aspen and paper birch in northeastern Minnesota. 
In the most northeastern portions of Minnesota are large stretches 
of jack pine on thin, rocky, but fertile soils. The land, originally 
- occupied by white pine and spruce was taken over by jack pine as a 
result of severe fires, which occurred 60 or 70 years ago. In the older 
jack-pine stands there is a fairly dense undergrowth of black and 
white spruce (Picea mariana and P. glauca), balsam fir (Abies 
balsamea), and white pine. In the younger jack-pine stands there 
is some paper birch, aspen, and only a scattering of spruce and 
balsam reproduction. Occasionally throughout these jack-pine 
stands one still finds a large white pine, a remnant of the original 
forest. 
ASPEN-PAPER BIRCH 
The aspen—paper birch forest is most common in northern Minne- 
sota, Wisconsin, and Michigan, on well-drained upland soils. As a 
rule it follows fires on white pine or hardwocd lands and is made up 
in the earliest stage of aspen, pure or in mixture, and paper birch in 
varying proportions, the birch predominating occasionally over small 
areas. As the stand grows older, white pine, balsam fir, and spruce 
often become conspicuous under the shade of the aspen and birch and 
may eventually replace them. 
Different stages in the development of the aspen—paper birch type 
may be found throughout the northern conifer—hardwoods region, 
ranging from pure stands occupying extensive areas to mixed stands 
in which even jack pine has a place. The aspen found in pure 
stands is practically even-aged. In many stands of aspen 50 or 60 
years old one can still find, charred by old fires, large white-pine 
stumps, snags, and logs, which clearly point to the origin of the aspen 
after cutting of white pine followed by burning. Some pure stands 
of aspen in Minnesota are about 80 years old, but the average age is 
nearer 20 years. Few old stands, moreover, contain more timber than 
at 60 years, for after 60 years aspen usually deteriorates from disease. 
