* The species in a “species composition” 
should make up two-thirds of the stand, 
otherwise, a “MIX” (mix) will be added 
in the species composition. 
* Hemlock, white pine, white cedar are the 
species of critical concern for the park 
management. They were placed in the 
third position even though they were 
fourth or lower dominance, so as to 
indicate their presence to any degree. 
Species compositions were subsequently 
aggregated to plant communities and forest 
stands. Plant communities derived from species 
compositions have the same naming conventions 
as the species composition. Instead of three, only 
two species are named. Forest stands represent a 
group of species communities in which a certain 
tree species is dominant or important. In the 
polygon based database, each polygon contains 
not only information of polygon boundaries, but 
also vegetation classification at three levels. 
Air Photography Interpretation 
1992 black-and-white infrared aerial 
photography was interpreted at the species 
composition level. The boundaries and attributes 
were automated into an Arc/Info coverage as an 
initial vegetation coverage. The interpretation 
was made in two ways. First, patches were 
delineated using pictorial characteristics such as 
tone and texture, creating the basic units for 
species composition identification. Then the 
species identification and species composition 
designation for each patch was made by further 
interpretation of the dominant species on air 
photo and consultation of FLORADB and ITU. 
Thus, air photos have been viewed at least twice. 
RESULTS AND DISCUSSIONS 
There were nearly 200 species compositions 
identified and mapped throughout the Apostle 
Island National Lakeshore. (Long Island was not 
mapped as part of our exercise, due to the 
existence of a recently completed vegetation 
inventory and mapping (McEachern, 1991)). 
Thirty-nine plant communities were established 
by the aggregation of species compositions and 
13 forest stands were designated at the top 
classification level (Ventura and He, 1993). 
62 
The results derived from the methods discussed 
above were evaluated independently through 
additional ground-truthing, based on stratified 
random sampling of 4 islands. The 
classification was quite accurate at the highest 
level of the classification and quite variable at 
the species composition level (Hipp, 1994). 
  
Major Forest Types of Apostle Island 
National Lakeshore 
The result and discussion present here is largely 
the summarization of the forest stand level. 
Detailed island by island discussion is beyond 
the scope of this paper and can be found in 
Ventura and He (1993). 
Sugar maple, paper birch, and white cedar are 
the dominant forests of the Apostle Islands 
National Lakeshore. Although it seems that 
white cedar is almost the only dominant forest 
in several areas (e.g., Rocky, Cat, South Twin, 
Ironwood, Raspberry, York, and the northern 
half of Bear and Manitou Islands, Figure 3), 
white cedar is not the leading dominant species 
in many cases. To accommodate a special 
management concern for white cedar in the 
classification system, we included balsam- 
fir/white cedar, paper birch/white cedar, yellow 
birch/white cedar, and sugar maple/white cedar 
in white cedar forest stands, where white cedar 
was only the co-dominant species. Statistics 
from the second classification level (plant 
community) show that white cedar dominated 
forest covers about 11.596 of the Apostle Island 
following sugar maple at 20% and paper birch 
at 17%. Sugar maple forest is dominant on the 
south half of Basswood, Bear, Manitou, and 
Outer Islands, many part of Stockton Island and 
  
% 
most of Oak Island. Paper birch forest is a 
dominant mainly on the Mainland Unit, but it is Sn 
often a locally dominant forest on Oak, Hermit, " 
Sand, and Devils Islands. Paper birch forest is + 
: . dq 
dominant in areas along the coasts of almost all © 
the Apostle Islands. o 
us 
Yellow birch, balsam-fir, and red maple are a 
common forests of the Apostle Islands National E 
Lakeshore. Yellow birch dominated forest 
occupies about 10% of the Apostle Islands, if 
areas where it is co-dominant at the highest 
classification level are included (yellow 
birch/hemlock and yellow birch/white cedar). It