Seeing the Trees for the Forest

by Daniel Allen

This message goes out to all the tree-lovers out there…  Or even the ‘tree-likers’.  The remainder of readers can officially stop here, because I’ve never had much to say to someone who is not at least a tree-liker.  

Jokes aside, I’d like to talk today about understanding trees in the context of their nursery.  Now, though it may be helpful to discuss trees in context of the commercial establishments from whence we purchase them, this is not my meaning.  Take a moment, if you will, to answer this question: “where do trees come from?”  Hopefully you’ve already picked up on the clue that we’re not speaking of stores.  The answer, then, of course, is the forest.  The place of nativity for any and all trees.

Our answer is so simple that any 3rd grader, I hope, could answer it.  So simple, in fact, that it may be tempting to overlook its significance.  The fact of the matter is that everything we do in Arboriculture (the professional care of trees) ultimately hinges on this one concept, that a tree’s home is in the forest.  Yes, really.  Don’t worry, this will all make sense in a moment...

But first, I feel a disclaimer is in order: Having both a bachelor’s degree in Forestry and a number of years professional experience as an ISA Certified Arborist, I feel uniquely qualified to speak to this subject.  But, in truth, I’m not unique in my approach, for many subjects are made much easier to understand in their proper context.

        For our first example, let’s take the notion of pruning.  Pruning a tree becomes necessary only for trees who are not in their natural environment, and I don’t just mean this because nobody cares to maintain the form or function of trees in the forest.  I mean this because, when a tree is at home, it does its own pruning.  

Self-pruning has a variety of causes, but they all stem back to the competitive environment that a forest tree is accustomed to.  Shading, by itself or by other trees, can cause a tree to cut off resources to an unproductive limb, or not grow it in the first place.  Damage from animals or severe weather is practically a given in the forest, which is why trees tend to grow more limbs than they’ll actually need.  Take this natural damage away in an urban landscape and we end up with the need to prune because trees grow more limbs than they need, and each limb generally competes for the ‘leadership’ role.

        What’s more, the natural forest environment also gives us cues for how to prune.  In the forest, we most often have a single central leader with branches that are lateral and subordinate.  These are very important characteristics to ‘train’ into our landscape trees (see figure 1).  And, when it comes to making cuts, trees in nature once again show us the way.  When a tree ‘self-prunes’, it almost always leaves its ‘branch collar’ behind.  This is so because that area has specialized tissues for healing over once the limb has been cut off.  The industry standard for pruning is to mimic this phenomenon (see figure 2).

        There are many other attributes of tree care that stem from an upbringing in the forest, but, for the sake of brevity, I will close by naming one of the most important:  Mulch.  Although trees and turf look ‘pretty’ together, unfortunately, they do not play well.  It is very rare in nature to find trees and turf intermixed as we have them in the landscape.  The reason is that the two are competing for the same light, nutrients, and water.  In order for one of these components to be healthy, the other is usually suffering.

So, why not separate the two?  A mulch ring is a highly functional and attractive way to accomplish this.  What’s more, a natural mulch ring of decomposing organic material provides a host of benefits to the tree, among which is ideal soil health.  Just think, it’s what the tree is used to ‘living in’ back at home in the forest.  Mulch is just what the arborist ordered, and what the tree wants, so ideally we will create a ring that’s at least as wide as the drip line (canopy spread) and 4-6” deep (Figure 3).

That’s all for now, but, hopefully, you will from now on start looking at trees in their context, and be able to see the trees for the forest.  For more helpful introductory information on trees, visit www.treesaregood.com (navigate to “tree owner information”).

Figure 1:

        (Bad)                (Good)

Figure 2:

(Proper pruning cuts are made to approximate dashed line)

Figure 3: