Summer 2000, Volume 9, Number 2
SOME OBSERVATIONS AFTER
THE DROUGHT OF: 1999
by Joe Schuerman, Consulting Forester
By now many of you have probably noticed a difference in your forest or woodlot. The
drought of 1999 lasted long enough to do moderate to severe damage to trees throughout
much of, Indiana. I worried last year as we went with-out adequate rain fall from July to
February, 2000. The problem with drought damage is that it doesn't show up right away.
Unlike damage from wind-storms and tornadoes where we know the extent and can visualize
the damage easily; droughts are insidious in that they leave us not knowing what the trees
are going to look like in a few years. In my work I went through April, May and June and
was not too worried about the health of the trees and then around the 1st of July it
started to show up. The first sign was in one species, tulip poplar. I started to see
unhealthy looking tops and then some poplar with much of the crown missing or dying. As I
continued to work I started to find tulip poplar that were completely dead. Some of these
trees were young regeneration in old openings and others were mature trees that had leafed
out and then died this summer.
With this concern I started to check on my forest and was depressed to see the damage that my tulip poplar had sustained. I have dead and dying tulip poplar trees on my forest land. These are not small trees. They range in size from 16 to 30 inches DBH.
What will happen to these trees? Droughts are nothing new but few of us have lived long enough to see the extent of the damage from a severe drought. In 1997 1 was working in Harrison County, Indiana marking timber for sale when I started encountering dead and dying tulip poplar. These trees were located on a moderately well drained soil with a good stand of black walnut and white ash. The walnut and ash looked fine but the poplar were stressed and dying. I was concerned as I couldn't figure out what was killing these trees. In June of 1997 1 took Phil Marshall; insect and disease specialist with the Indiana Division of Forestry, down to look at these frees and see if he could diagnose the problem. We checked many things looking for a pathogen that might be responsible and found nothing. They were dying from the top down and Phil was puzzled.
I got out the trusty chain saw and cut a couple of the trees so Phil could examine the tops. He couldn't find anything. We started looking at the cut stumps and growth rings. Much to our surprise these trees had not grown since 1988. What happened in 1988? The last severe drought.
It was obvious that these trees were stressed to the limit in 1988 and finally were dying 9 years later.
The odd thing about the drought of 1999 is that there can be major damage on very wet sites especially upland flats.
In my travels I have found dead and dying trees of almost all species. In some cases the entire understory is dead on the driest sites especially South and West facing slopes. On the other hand I have visited some forests expecting to see damage and the trees look fine. It appears that if you were lucky enough to get the couple of rains that helped produce a fair corn or soybean crop lost year your trees didn't suffer as much as trees in the driest areas.
What should you do? At least take a good look at your forest land to check for drought
symptoms. What should you look for? Observe the tops especially tulip poplar. If you see
the outer most leaves are smaller than normal and more than normal foliage being produced
on the main stem of the tree you have a stressed tree. Some of these frees are so weak
that they are sprouting at the base. The most obvious symptom is a dead tree. The most
often used description that folks call me with is; "It looks like someone flew over
my woods with an airplane and sprayed herbicide!" I have seen this and in some cases
that is exactly what the forest looks like.
Also many large open grown white oak have started to show damage that looks identical to herbicide damage. I have watched several of these trees and would have bet money that they were accidentally exposed to herbicide drift or other means. Upon further investigation I find that there has been no herbicide of any kind used near the free. So what is causing the curled up leaves and unhealthy appearance? It appears to be lost years drought just now showing up.
Remember when you stand on the forest floor and look up at a sick free you are usually standing on the problem; the root system. Starvation is a common problem associated with drought damage. The nonwoody fibrous roots do the work of absorbing water and essential elements for the free. When these roots die and can't be replaced the tree gets weaker and can develop other problems or die from out-right starvation. The heavy rains this summer may have done more harm than good in that there is little oxygen in water saturated soil and the tree roots need this oxygen to produce new fibrous roots.
Some of my logger friends are now starting to notice the dying tulip poplar, especially young trees that are growing in openings created during the last 20 years. Was it a mistake to create these openings? The drought of 1999 leaves many unanswered questions.
Were the droughts of the late 1920's and early 30's responsible for some of our pure oak stands? Did they really drive teams of horses with wagons across a dry Ohio Riverbed in the early 1930's. Sometimes we forget that we can't learn everything during our brief stay on Plant Earth.
For further reading on tree physiology I might recommend: 'A New Tree Biology" by Alex L. Shigo. This books deals mainly with urban trees but contains a wealth of information. It is 595 pages printed by: Shigo and Trees, Associates.