The source material for these articles are excerpts from various university research papers, private industry, and  web sites that pertain to the subject matter.

Most tree problems stem from our poor understanding of how trees work. We wouldn't plant trees "good and deep," if we knew more about tree roots and how they work. Planting too deep sets up a tree for severe decay and the death of its root system. 

We would know which trees to remove, and what branches to prune, and how, and if we understood the connections between a tree's structure its life processes, and its natural defenses. We wouldn't clean out cavities and fill them with concrete, or coat wounds with "pruning paint".

We wouldn't try to "rejuvenate" a tree by topping it if we understood that topping is often the first step in the death of the tree; new sucker growth is not a return to youthful vigor, but a distress signal.  

Even learning to identify and call trees by name makes it easier to choose the right tree for the landscape job you have in mind. 
 

Since the mid-1970s researchers such as Dr. Alex Shigo have deepened our understanding of how trees really work. Central to this is recognizing that trees' defenses are fundamentally different from those of animals. We and other animals can run from our enemies, or hide, or actually fight them. But trees 
(since they are rooted in place) depend mostly on shedding weakened parts, and walling off problems that they cannot shed.

Some of a tree's defensive are passive; but others are active, triggered by injury and the advance of decay. All of these defenses have been refined by millions of years of evolution; there are subtle differences between species, but the general principles are the same all over the world.  

The values of trees range from a few dollars for a young ready for planting to several hundred thousand for an important mature tree on a historic property. Benefits such as shade, beauty, a place for children to play, or privacy barriers can be priceless. Yet any tree can be ruined in a few minutes by ignorant acts, no matter how well intended.

But armed with a clear understanding of how trees work, anyone can make good tree-management decisions, if he or she will take time for a little homework.
 

The basic concepts of tree biology are not difficult, and once you have them, they are yours for life, since trees provide generous hints about their problems and their needs. As in most things, the hard part is taking the time to get started.

Once you understand the basic ideas, it's not hard to figure out what needs to be done in a particular situation. You may need help doing it, but you'll know how it should be done. Browse through the topics below, which make up "Tree Biology"

Anatomy -- The Inner Tree Physiology -- The Living Engine 
Defense -- How Trees Survive Practical -- Tree Management Rules
Taxonomy -- The Name Game References --