’ 
LOGGING PRACTICE IN THE LAKE sTATES 9 
The area of the aspen type in the northern parts of the Lake States 
- is extensive and for the last 30 years has been on the increase as a 
result of fires in the better white-pine and hardwood lands. Most 
of this land cut over in Minnesota, Wisconsin, and Michigan has 
been badly burned and now carries only a scrubby growth of aspen 
and paper birch. In a study in St. Louis County, Minn., the 
Cloquet Forest Experiment Station * found 70 per cent of the cut- 
over lands occupied by these species, including stands where aspen 
and birch are mixed with balsam, spruce, or pine. This type of 
tree growth undoubtedly covers more area than any other one type in 
Wisconsin and Minnesota. : 
SWAMP FORESTS 
About 25 per cent of the conifer-hardwood region is classed as 
swamp land. Not all of this swamp land is forest land. Much of it 
is bog which bears no forest, or forest of such poor development that 
it can not be classed with productive forest land. There may be 
recognized four types of swamp forests: 
NORTHERN WHITE CEDAR SWAMPS _ 
These are typical of the northern portions of the region. Cedar 
(Thuja occidentalis) occurs pure or in mixture with balsam fir, 
paper birch, tamarack (Larix laricina), spruce, black ash (Fraxinus 
nigra), red maple (Acer rubrum), and balsam poplar or balm-of- 
Gilead (Populus balsamifera). It develops best in swamps with 
fair drainage. 
TAMARACK SWAMPS 
These are found throughout the region. Tamarack grows either 
pure or in mixture with black spruce, also with some cedar, spruce, 
and fir. It develops in poorly drained acid swamps or bogs. 
BLACK SPRUCE SWAMPS 
These are typical of central Michigan, Wisconsin, and Minnesota, 
and northward. Black spruce occurs either pure or with a little 
tamarack, usually in acid and undrained bogs. 
MIXED SWAMP FOREST 
This is made up of red maple, black ash, balsam poplar, balsam 
fir, cedar, tamarack, spruce, and white pine, and occurs on the better- 
drained swamps bordering upland. It comprises species that occur 
both on the uplands and in the swamps, and for this reason may be 
considered as a transition type between the typical swamp forest and 
the upland forest. 
Distinctions between cedar swamp, tamarack swamp, and spruce 
swamp are based on the predominance of one of the three species, 
all of which usually are present. This predominance is associated 
2 HANSEN, T. S. SECOND GROWTH ON CUT-OVER LANDS IN ST. LOUIS COUNTY. Univ. Minn. 
Agri. Exp. Sta. Bul. 203. 1923. 
73098 °—28———_2, 
