By Tim Clancy.
In the world of Urban Forestry one of the concepts we consider is the safe useful life expectancy (SULE) of a tree. There are many components to the equation and some of them are the tree’s age, condition, risk potential and location. These are fairly simple to determine by an experienced tree assessor. Then we consider the economics, potential Eco-benefits (carbon sequestration for example).
There are times when a tree is obviously dead or so close to dead that its SULE can be considered to be complete. This process is intended to assist tree managers with keeping the public safe and keeping the tree population stocked at the desired tree density. After all when a tree is dead it is occupying a planting space that could be re-planted with a new tree that could then contribute the various Eco-benefits and be a source of positive value to the community.
There are times when a dead tree also contributes to the community as well. I have recommended dead tree retention in the population as a valuable source of habitat for our non-human neighbors. Many creatures utilize dead trees for shelter, nesting sites and in the case of the Acorn woodpecker a storage location known as a granary.
And then there is human use of dead standing trees. In Carlsbad, California there is a tree that sits on top of the bluff. I don’t know what the tree species is or was in this case, but it is evident that the tree does serve a clear purpose. The tree is a source of community enjoyment and celebration. It was twisted and contorted by the coastal winds and is in the form of what is known as a krummholz tree. These are trees that due to exposure to various elements grow in an atypical form. Krummholz comes from German and in short means cooked wood.
The Carlsbad tree has been there many years and while I can’t remember exactly the first time I noticed it I do recall that for the last several years the tree gets decorated at Christmas time and it is adorned with attractive Christmas ornaments. I have seen many people stop and admire the tree and pose their family and friends for photo opportunities. Perhaps the photos are to be included in a Christmas greeting to family and friends.
Besides being a home for Christmas decorations, another tree, also in Carlsbad, CA is adorned with Valentine ornaments as well. Once again providing photo opportunities and in both cases a little joy for passing motorists.
On a recent trip to Canada I found another tree that had technically completed its SULE but here again it was a source of community involvement. Some local citizens began attaching old shoes to the tree. It has somewhere north of a hundred pairs of footwear, some attached to the trunk and others hanging off branches.
So while a tree may have technically completed its SULE, there are other benefits trees can offer to our communities that are difficult to put in dollars and cents but are of high value nonetheless.
Contributor Tim Clancy is an International Society of Arboriculture Certified Arborist
No. WE-0806A and Tree Risk Assessment Qualified.