Thursday 15 December 2011

The Joy of Wood Anatomy

One of the most enjoyable chores is splitting wood. This article could just have well been called things you see while splitting wood.I know many people find this tedious and it can be dangerous. However if you know what you’re looking it can be a fascinating as any forensic drama on television.

Trees do not heal like animals, cells in wood, generally, do not recover when injured.

When compromised, the thick walled cells in wood are closed off from there adjoining cells by rot resistant chemicals like phenols and turpentines. Much the same way watertight doors are closed in a sinking submarine. These are the same chemicals that have been extracted for hundreds of years to produce wood preservatives and are the basis of many paints.

While these have largely been synthesized in modern labs, trees still produce these protective phytochemicals each time they are injured. It still surprises many people that trees are living dynamic beings, even if they are completely immobile in their environment.

Trees and woody shrubs contain or compartmentalize damaged plant tissue behind these strong chemical barriers and continue to grow over the injury. This process of compartmentalization prevents disease from entering the healthy tissue and overwhelming the plant and causing its death. A true case of life over limb, to save its life a tree will lose a damaged limb.

Back to the task at hand, while splitting wood you can find old pruning wounds and injuries that have grown over, encapsulated in new living wood. These barriers are not only resistant to pathogens they can be resistant to splitting as well! With modern hydraulic wood splitters you can power through these tough barriers and see the story contained within. I was splitting a piece of oak that had been removed for construction. The tree was at least sixty years old and very healthy when it was taken down. As I worked through the tree piece by piece I was amazed by the wood’s structure, beautiful rays and grains. As I split one large round I noticed an old branch stub that had been properly pruned many years ago and was now completely grown over. The areas of compartmentalization were clearly defined in all directions from the wound. Above, below and around, you could see the dark staining that prevented rot from entering the trunk of the tree. Whoever made the cut had done so properly and did not injure the branch bark ridge, a key anatomical structure in trees, speeding growth over the wound and preventing the expansion of decay. The most interesting part was that from the outside there was no hint, not a bump or blemish, of the drama, contained within. In fact if you look at the other side of the same piece of fire wood there is not a clue that the limb was removed and the tree had successfully grown over the injury. Any pruning no matter how minor or major is an injury to the tree. Successful limb removal involves knowledge of the art of pruning and the science of plant anatomy. I.S.A Certified Arborists are constantly updated on the latest pruning methods backed up by scientific research on tree wound response. Keep a keen eye on your firewood for these untold arbor-dramas and contact your I.S.A. Certified Arborist to plan and execute your next pruning project.