On Planting Trees

President George Bush's promise to plant a billion trees ((ENVIRONMENT, April 30)) sounds impressive. But the mortality of seedlings reduces the total of trees that survive the first few years. And each year older forests are diminished because of fire, insects, disease and harvesting by man. It is not important how many trees are planted, but rather how much forest area is regenerated relative to how much is cut or lost owing to natural causes.

Allan Sugg, Research Assistant

Swedish University of Agricultural Sciences

Umea, Sweden

Having worked as a tree planter in Canada, I would like to put in perspective Union Carbide's commitment to plant half a million trees by the year 2000 ((EARTH DAY, April 23)). In Ontario a crew of 40 workers can plant 50,000 trees in a day. In ten days they can achieve what Union Carbide has promised to do in ten years.

Aart Kraay

Toronto