Volume 17 No. 2
One of the biggest problems in tree plantings in Indiana is deer
eating young trees. One way of reducing this browse damage is to plant a mixture
of trees or species which include trees that are less preferred food by deer; or
if the deer pressure is very high, by not planting the most preferred food trees
and shrubs at all. Information about deer preference is not well known and can
vary from county to county, year to year, and from one tree planting to another.
This variability makes the deer problem much more difficult to deal with.
However, I think that there are general trends, which if better known by
foresters and wildlife biologists when making tree planting plans, would be
helpful.
In January I sent a survey to consulting foresters, IDNR
district foresters, and IDNR wildlife biologists asking them to rate deer
preference for different tree and shrub species as they have observed it in
their areas. They were asked to rank each species with a score of 0 through 10.
A score of 0 would mean that they have never seen this species eaten, a score of
1 through 4 would mean less than average preference, 6 through 9 would mean
preferred, and a 10 would mean that this is the most preferred food which is
always eaten first by deer. If they did not have experience with a given species
they were to just leave it blank.
They were also asked to indicate if they were from southern or
northern Indiana to see if there were differences. I had 31 surveys returned
which is over half of those sent out. Some did not respond because they felt
they did not have enough experience to have a good opinion. The table of
responses is on Page 7.
I found several things among
these results to be quite interesting. It appears that southern Indiana has a
more serious deer browse problem than northern Indiana. The average overall
rating for all species from southern Indiana is 6.3 and from northern Indiana it
is 5.3. The biggest difference between northern and southern Indiana seems to be
with persimmon, chestnut oak, scarlet oak, and sweet gum. These are mostly
southern Indiana species that are sometimes planted in northern Indiana, and
they are much more preferred by southern Indiana deer. Southern Indiana deer
also seem to like red pine, bur oak, and chinquapin oak better than northern
Indiana deer. Silver maple is more preferred by deer in the north than in the
south. The oaks seemed to be preferred throughout the state, which I think is an
important reason why we have trouble getting oak regeneration after timber
harvests.
This survey gave black walnut an average rating of 5.4, which I
agree with. However, over the years I have observed sites where walnut
were heavily browsed and sites where they were hardly touched. I know there can
be many reasons for this difference, but I have observed that if the average
score of all species in a planting is less than 6 then the walnut are not
seriously browsed, and if the average score of all trees in the planting is
greater than 6 than the walnut are more seriously browsed. It was this
observation that resulted in this survey. When planning a tree planting, would
keeping the average combined score of species in the planting under a 6 be a
good deer control strategy? Do you have other ideas about how to interpret or
use these survey results? If you have thoughts on these issues, I hope you will
email me at bwakeland@starband.net;
and if the response merits, I will write a
follow-up article.
Bruce Wakeland is a consulting forester in Indiana.