Sunday, December 16, 2012

The Mystery of the 'Toe'

It's the holidays, and around this time of year I can't help but think about  mistletoe.  That's right, mistletoe.  Mistletoe is the common name for over 20 genera of obligate hemi-parasitic plants of trees in the order Santalales.  Mistletoe still photosynthesizes to create carbohydrates for energy, but it uses structures called haustorium to penetrate tree branches, where it then absorbs water and nutrients directly from the tree. With heavy infestations comes tree decline, and affliction with mistletoe can contribute to tree death.  Branches with mistletoe can also become quite brittle.

Hickory branches afflicted with mistletoe.

The berries of mistletoe are a food source for many species of animals like birds, and is how the plant is distributed through out tree crowns.  Birds either wipe the berries from their beak on to branches, or the seeds survive ingestion and are distributed through bird droppings (poop). The berry itself is extremely sticky when squished.  Most mistletoe flowers are insect pollinated, but some have huge showy flowers which are bird pollinated.

Sticky toe berries.

Now if you thought all of that was interesting, the myth of mistletoe is something else.  Apparently the Norse god Loki tricked the blind god Höðr into killing his brother Baldr with a mistletoe arrow.  This was after Baldr and Höðr's mother, the goddess Frig, failed to get an oath from mistletoe to not harm Baldr.  She never asked mistletoe take the oath as it seemed 'too young.'  Lesson learned.  After bringing Baldr back to life, Frigga declared no harm could come to one standing under mistletoe.  Another myth states mistletoe was the wood that Christ's cross was made of, and after the crucifiction it was destined to live the rest of eternity as a parasite. 

Mistletoe is most famously sacred to the ancient Celtic Druids.  After sacrifices, mistletoe would be passed out, and the recipients were thought to have good fortune.  Mistletoe was thought to be the soul of the oak, and was collected at the summer and winter solstice.  It was also thought of as a sexual symbol.  Druid beliefs were adopted by early Christians and mistletoe was hung in homes to ward off demons.  This is where the modern practice of decorating with mistletoe during the holidays came from.

The Greeks had their own mistletoe tradition, and the plant was used during early marriage ceremonies as a sign of fertility.  This, combined with the Scandinavian tradition of standing under mistletoe as symbol of truce with enemies, is probably were the modern Western European kissing tradition evolved from.    

So mistletoe is pretty interesting on many different levels.  A word of warning though, if your mistletoe is allowed to touch the earth then it looses it's mystical powers.  Happy Toe hunting, and happy holidays.     

Toe harvesting is easiest done by aerial lift truck.

Sunday, December 9, 2012

Conservation Arboriculture

Conservation arboriculture is neat.  It seems their are two main ideas behind conservation arboriculture.  The first, trees (especially urban trees) are of themselves complex ecosystems.  There are obvious and not so obvious examples of this.  Obvious examples are the vertebrates (ie. squirrels and birds) that use trees as their home and food source.  Then there are the not so obvious examples, like the invertebrates and fungi species that only a few may appreciate.  The bark alone can be home to arthropods, lichen, and fungi.   Taking an ecosystem view of a tree forces us as arborists to think of tree management differently.  For example, there are dozens of insect and fungi species that rely upon the dead wood in trees for survival, dead wood that an arborist would traditionally recommend for removal.  Conservation arboricultures teaches us their is an intrinsic value to these forms of life living in the tree.

The other idea behind conservation arboriculture, there is intrinsic value to very old trees.  Trees that we consider, due to structure or health issues, candidates for removal.  Some would call these ancient trees, and in places like the United Kingdom there are organizations dedicated to identifying and preserving these trees.  In my opinion the term 'ancient' is relative.  An ancient white oak may be 600 years old, while an ancient aspen may be 70 years old, but to me the idea is the same.  Older trees have a story to tell us, and the older they are, and the more perceived defects they have, the more likely they are to be the home of a variety of life.

As mentioned earlier conservation arboriculture challenges our tree management strategies.  Our first priority is always safety, but our question becomes how can we manage the perceived risk of our ancient urban/suburban trees while maintaining there vitality as a thriving multifaceted ecosystem?  In some cases it may be easy.  Moving a target or erecting a fence to keep people away from the fall zone.  In other cases it may be making the call on questionable reduction cuts, and leaving pieces of dead or dying branches in the tree that would normally be removed.  Would it be crazy to make reduction cuts on an already dead limb to reduce its chance of failure?  And still on our not so ancient trees, maybe we step back and let some deadwood build up or leave some smaller pieces in there.

This approach may not be for everybody, or every tree, but is an important idea to consider as we learn more about the trees we cherish.  Below is a link to an article written by Neville Fay which was run in Arborist News.  It is a real interesting read.

The Angel Oak of Charleston, SC