Don't plant too many trees, and we are talking here of trees in general, not just the Leylandii which raise such problems, and in England recently led to legal action because they outgrew the garden hedge stage and led to strife with neighbours. No, just the family that has, say, five or six acres, no longer required for cattle or other purposes and in which the owners wish to do the patriotic thing and help "re-leaf Ireland".
Work out well in advance what size your chosen specimens may grow to - even in your time - and take the conservative view. It is heartbreaking after, say, 20 years to have to cut down a tree that is doing splendidly but is choking two or three others. Douglas Fir is a lovely tree, with its rich foliage and quite remarkable cones. You know, the ones that hang down with, as it were, papery layers of green, then brown bracts or scales, each of which carries a seed. In 20 years, one magnificent specimen has broadened out to smother two lesser trees beside it.
But most painful of all trees planted that must be cut down to make living space for others are the pedunculate oak. In the rush to give the quickest possible cover, pedunculate oaks were planted in great number simply because they were available from another plot. Slowly over the years, they have been thinned, and it doesn't make any sense to cut a 20-year oak. Why, the owner/planter asks, why did I not take professional advice on the layout of the few acres? Then there is the question of the view from the windows. Conifers on the river's edge had to be taken down simply because the view to the horizon, which was rolling pastureland, had become obscured.
The hardest of all to lose this way, of course are the pedunculate oaks, which, given the space, reach out those long, long branches parallel to the ground, then climbing up at right angles, and later continuing the run parallel to the ground. Long ago the stupidity of putting so many of them close together, close for this species that is, though sessile oak could survive and even thrive there, should have been obvious. Trees give pleasure for their beauty and grace; trees give wood for firing and staking. Then there is the industrial use. Go for trees, admire them, love them, but plant them wisely and study the characteristics of each one. Or, get expert advice.