| Last spring the Jo Daviess
Conservation Foundation contracted Michael Jones of the Natural Land
Institute to conduct a baseline survey of the trees and understory
vegetation in Schurmeier Forest. The field work took place during
the 1997 growing season and the final report was completed in
October.
The 56 acre forest contains mesic and dry-mesic
communities. The dry-mesic communities comprise about 40% of the
total area and are located primarily along the ridge top (or along
the south edge of the property) and the remaining 60% consists of
mesic forest communities, which are further divided into mesic-ravine
and mesic-slope communities.
The most frequent canopy level tree you’re
likely to encounter in Schurmeier Forest is Red Elm, followed by Red
Oak, White Oak, and Black Walnut. Frequency is one of three
parameters ecologists use to determine the importance of tree
species in a woodland; density and basal area (based on trunk
diameter) are the other two. These three are combined to determine
the importance value of each species. Another aspect of the study
was to determine the importance of each species in different age
groups. Trees are placed into one of four age groups: canopy trees -
trees with diameter at breast height of 22 cm (9 inches) or greater,
understory trees - trees with diameter at breast height (dbh) less
than 22 cm and taller than 2 meters (6 1/2 feet), saplings -trees
with a dbh less than 5 cm (2 inches) and greater than 1 meter tall,
and seedlings - trees less than 1 meter tall.
The purpose of determining species importance in
different age groups is that it allows us to predict changes in
forest composition in the future. For example, of the four most
important trees in the canopy layer (Red Elm, Red Oak, White Oak,
and Black Walnut) only Red Elm appears in the top four species of
the understory group. In fact, the Oak species become the least
important in the understory group. The changes continue into the
other two age groups as well.
Top Four Species by Age Group
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What these changes suggest is not exactly clear.
There have been comments made that the woodland was logged in the
past but has been left relatively undisturbed for about the last 50
years. The fact that there are very few trees older than 50 to 75
years supports this evidence. Combine this with the results from the
survey and it suggests that the woodland is still immature, that it
is still in the early stages of succession and has not yet reached a
stable self-reproducing community.
What will Schurmeier Forest look like in fifty
years? In a hundred years? What did Schurmeier Forest look like
before it was logged? Before settlement of the region? Will the
forest of yesterday look like the forest of tomorrow?
The common consensus is that most of the
pre-settlement woodlands of the area were dominated by Oak and
Hickory species and indeed the dominant canopy level trees in
Schurmeier suggest this. However, when we look at the younger trees,
we’re left to wonder where the Oaks and Hickories of the future
will come from. Another interesting aspect stems from the
composition of the herbaceous understory plants and flowers. Many of
the plant species identified during the survey are not typical of
the Oak-Hickory woodland but are generally found under more shaded
canopies such as those produced in a Maple-Basswood canopy, yet not
one Maple was found in Schurmeier and the frequency of Basswoods was
very low. So what were the tree species that produced a shaded
canopy sufficient to allow shade tolerant plants to thrive? Probably
the Elm species. Slippery Elm is currently the most important tree
species but American Elm was probably even more important in the
past. The decline of American Elm, due to Dutch Elm Disease, has
undoubtedly impacted the canopy layer of Schurmeier Forest. American
Elm currently ranks fifth in importance in the canopy but drops off
in the younger age groups. What will take the place of American Elm?
and what chance do the Oaks have a replenishing themselves?
The results of the survey may have raised as many
questions as it answered. Actually, the purpose of doing the survey
was to get baseline information so we could begin a management
program; but to manage for what goal is at present unclear. We
should feel lucky to have Schurmeier Forest, not because it is a
pristine old- growth forest worthy of nature preserve status, but
because it isn’t. It is our living laboratory and we, along with
future generations, will be able to observe these changes and learn
from them.
Prepared by JDCF Director Steve Lorig
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