Sunday, June 23, 2013

Stressed out?

Explaining how trees react to stress can be difficult.  Trees may take years to react, or show signs, of past damage.  Symptoms of construction activities can take up to 8 years to reveal themselves.  This fact can leave many people skeptical of we arborists.  How can a seemingly healthy tree suddenly, and for no perceived good reason, start falling into decline?

The following small scale example attempts to illustrate how tree stress takes time to manifest.  A willow oak sapling was cut in the 2nd week of June in Charlotte, NC. Let's see what happens:

0.5 hours after being cut on a warm summer day in the afternoon.  The tree still looks green and healthy.
About 25 hours after being cut, still green with little signs of stress.

51 hours after being cut, the tree is beginning to wilt and the leaf edges are beginning to brown.

75 hours after being cut the tree is almost completely necrotic, though the twigs are still pliable. 
Larger trees, with less extreme but compound stresses, take time to show symptoms of damage.  The tree in the above example was dead on day 1, but it took 3 days to show it.  When diagnosing tree problems, a detailed knowledge of site history can be crucial when developing a tree care plan.