Wednesday 29 November 2006

Old Friends

While walking in a friend’s garden the other day I stepped on a stepping stone with the following inscription; “It takes a long time to grow an old friend”.

Trees are long lived organisms that can easily have life spans across human generations. While not all trees live hundreds of years some can live thousands. Large mature trees are adapted to extreme forest environments and threats. There are many strategies to help trees survive various natural catastrophes. For example fire resistant bark, roots that can regenerate after disasters and seeds that take years to germinate are genetic adaptations for survival. These survival strategies don’t always work for the trees in your front yard.

Changes in nature can be sudden or they can take years. Sudden changes include ice and wind storms that rip and tear branches from trees. Lightning, fires and floods also happen quickly. Long term changes that effect tree survival are soil erosion or deposition, encroachment by grass, and competition for light from other trees.

How does this relate to your front yard trees and their survival?

Simply, change requires adaptation and adaptation in trees is pre programmed. If the tree isn’t able to adapt to changes in it environment it declines and dies. If the tree does not have, within its genetic bag of tricks, the ability to survive fire, the tree will die. A burr oak tree, with thick fire resistant bark, would be able to survive a runaway grass fire without major consequences. A thin barked cherry tree would not survive.

If your tree isn’t able to survive changes in grade or soil compaction it will not survive construction of a new addition to your home.

Trees like American elm will survive changes in grade and soil compaction while white oaks will most likely decline as a result of root disturbance.

In the modern world we are able to affect great changes on our landscapes. Heavy equipment can literally move mountains. Why do we expect trees to survive after the mountain has been moved? Obviously we overestimate the ability of trees to survive construction damage. Trees are alive. Damaging roots has serious impacts on plant health. Tree roots are living plant organs that take moisture and nutrients from the soil environment. The top eight inches of soil contains 90% of all tree roots. Take a look at a storm toppled tree and you will see a broad shallow fan of roots.

So when we think of changing our landscape we should consider the impact that these changes will have on our “Old Friends” before we make the changes. If you’re not well versed in the capabilities of your trees contact your arborist well before construction begins. They will be able to help you minimize the impact of changes in your landscape and maximize the survival of all our green friends.