When you mark your trees for thinning, take a leaf from the Stout study of forest root systems. (See Chapter IV.) Remember that, in a wild grove, each tree has been competing with three or four of its neighbors for nourishment and light. The trees you wish to keep can use all the elbow-room you will give them. Shade-grown trees tend to be spindly, but given air space and root room they can fill out almost like field-grown specimens. Spare the saw and spoil your specimens. As they are spaced, so will they flourish?

When your thinning is undertaken, don't let the bulldozer do it. That blade, those heavy treads, will do more underground damage than you know when they knock the marked trees over and push away the stumps. Do it or have it done by ax and chain saw. Cut the stumps flush to the ground, where they will rot away soon enough. You can speed their dissolution by boring holes and putting in saltpeter or waste crankcase oil and then burning them out. If you are in no hurry to get your final effect, your thinning can be done piecemeal, and often it is better done so. You will not have to find shelter for all the fire logs at once, or burning space for all the brush. If you girdle (ring-cut) one year the trees you plan to take out the next, you can be just as sure of an immediate root-kill—to unshed wanted trees—as if you felled the trees at once. Also, you can thus season your firewood right on the stump instead of having to stack it, which rots the bottom logs.

Vines growing wild on trees will strangle or smother them eventually. Cut them at their roots and they will fall away in time. Not harmful are morning glory, an annual, and trumpet creeper, which climbs free, without throttling, and whose deep-necked blooms the hummingbirds love. If you value the trees you find them on, show no mercy to wild grape, honeysuckle, woodbine, poison ivy, or wisteria (which you can cut back partially and then train to a support all its own). The evergreen ivies English, American, Boston are decorative on tree trunks but should not be allowed to grow much above the first main crotch.