Pruning is one of the most basic and powerful tools at an arborist's disposal. Cuts can be made to strengthen structure, lengthen structure, and alter the course of growth. A single cut can significantly extend the life of a tree, or doom a tree. When the arborist prunes, they must be able to understand that specific tree in its current life phase, and envision its ultimate structure, weighing the utility of each cut. But a good arborist also understands that when we prune, we are also fundamentally changing the investment strategy of a tree's growth. Pruning can evoke changes in the energy systems of a tree to produce responses that almost resemble a type of magic- Heavier fruit and flower production, better defenses, and stronger growth, to name a few.
Pruning is also a necessity for trees that cohabitate with us.
Trees have evolved to live in forests, densely spaced within large populations of their kind. In this woodland habitat, competition for light produces strong central leaders reaching up into proportionate, healthy crowns as these trees take their place in the sun. As a part of this process, juvenile branches die off as they no longer contribute to carbon production. These branches, lower in the tree, physiologically have weaker connections and are "squeezed off" by the advancing growth of stem tissues.
Urban trees don't have it so easy. Bathed in various casts of light, they are urged to grow by light stimulus, but aren't cautioned to stop by shade. The result becomes trees, unable to stop their biological imperatives, overextending themselves with weak and redundant photosynthesizing structure. Supporting this growth, irregardless of its use, taxes a tree's energies, robbing it's budget for immunoresponses and healthy architecture. For trees to be healthy in our environment, we must be their stewards- and take a portion of nature's responsibility in their growth.
While knowledge is critical in pruning, safety and technique are critical to its execution. Many trees can only be accessed by arborist climbing techniques. Large trees require an accomplished and productive climber. As of January, 2021, no individual performs climbing duties for ArborWise without first passing one of the most rigorous climbing tests in the industry, modeled after the ISA ITCC (International Tree Climbing Championships) Work Climb. A candidate must pass five aerial work stations while observering all ANSI Z133 safety standards within a short time limit to qualify.