Lots of heedless home owners believe that trees prune themselves and they should just leave it at that. Of course, they are quite right, too. Nature does see to it that trees shed members that have become excessive or shaded out or badly damaged. The forest floor is strewn with kindling wood. But the very fact that Nature does so provide only proves that pruning is necessary. Without question, man can do a better job.

When a tree "prunes itself the resultant stub, or an open scar on the parent member, seldom heals entirely unless it is quite small. Left as an entry for insects or fungus is an exposed area of inner tissues through which invasions will spread for years to come. Through such lesions the tree loses moisture by evaporation, or takes in water where it does not belong, causing decay. The only perfect seal is scar tissue, called callus in trees, put out by the cambium layer. Man's surgery can help callus growth close over more quickly and surely than in Nature's casual sloughing-off process.

To some people unfamiliar with them, trees are mysterious to the point of being untouchable. Many a new owner, aware that his tree is a living organism, flinches from cutting any part of it as he would from operating on his child or even his dog. Trees are much more rugged than dogs or children. They feel no pain, and they will survive a few mistakes. Coupled with some understanding of tree physiology, good intentions can soon be translated into good results.

It is not suggested that home owners go up into their big trees with ladders and ropes. Leave the high work to professionals. But by learning, with your feet on the ground, to prune your young trees and mature ones of the smaller species - say, up to fifteen-footers - you can increase and insure your property's value at small cost. All your trees will take on new interest and meaning for you. A light labor of love today will reward you through many tomorrows. If wielding tools does not suit you, study the art and teach it to a helper. Plenty of people "prune" their own trees with a bamboo pole for a pointer.

Let proper tools be the beginning of your new wisdom. Unless you mislay them or let the neighbors borrow, one set can last you a lifetime. You may as well start with the best.

Pruning shears, the kind with heavy-duty blades so opposed that they cut closer on one side than the other. They should be at least eight inches long over-all, with broad handles for a firm grip. Ladylike "snips" are only frustrating. If your arms and fingers are short, get shears with long wooden handles. Take a fair-sized branch with you into the store and settle for no shears that will not make a half-inch cut without effort. The kind without reopening springs is least prone to rust shut. Painted red or orange rather than green, your shears will be found sooner when you drop them into grass.

Tastes differ in handsaws - straight-blade or curved - but one rule prevails for all pruning saws: at least six teeth to the inch. Coarser gauges tend to rip and tear on cuts of less than four inches, which is what most of yours will be. The so-called "speed" saws are for professionals in a hurry. For home-owner use, a 15-inch curved blade with metal or plastic grip is ideal. Good tools, such as a nice handsaw, will pick up where self pruning leaves off.