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Watershed plantings do not add to the water table through their upper parts except during fogs, when their contribution can be considerable. Gilbert White, England's first literary botanist, wrote as early as 1770 about the alembic action of trees in his own misty Hampshire. He noted that the best condensers are trees festooned with ivy, whose broad and evergreen leaves will drip puddles while the ground around stays powder-dry. The next chapter, dealing with root systems, will make clear how to feed ailing trees, but your first concern should be with their water supply. Repeated droughts such as the East experienced in the 1950s can set trees back so severely that the effects persist for years. Even when a good growing year like i960 does come around, root systems may be so discouraged and stunted that your trees will respond slowly unless watered on a continuing basis. To safeguard species requiring ample moisture, like the maples and elms, a simple precaution is to set drainage tiles endwise into the ground, five or six around each sizeable tree, well out from the trunk. When the countryside starts to brown, fill these drinking tubes twice a week with the hose or watering can. Around younger trees, grades up a rim to retain the water as in a saucer when you sprinkle them. To do this for larger trees is laborious and unsightly, but a comparable effect can be obtained by putting shallow transverse dips across a tree-bearing slope when your grounds are graded. These will retard runoff water in times of plenty, and check erosion. Too much water is as fatal to trees as too little. But if you have a chronic wet spot in your grounds, don't fill it, drain it. The effects on tree roots under it are suffocation and rot, which filling would only aggravate. |
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