“A society grows great when old men plant trees whose shade they know they shall never sit in.” – Greek proverb

This is a plea to plant a tree. Not just any tree, but one in a billion. It is a plea to join with millions of other people committed to planting at least 1 billion trees worldwide during 2007.

The idea for the Plant for the Planet: Billion Tree Campaign was inspired by professor Wangari Maathai, Nobel Peace Prize laureate for 2004 and founder of Kenya’s Green Belt Movement, which has planted more than 30 million trees in 12 African countries since 1977. When a corporate group in the United States told professor Maathai it was planning to plant a million trees, her response was: “That’s great, but what we really need is to plant a billion trees.”

The program was launched by the United Nations Environment Programme. Individuals, communities, business and industry, civil society organizations and governments are encouraged to enter tree planting pledges at the campaign’s Web site, www.unep.org/billiontreecam

paign/index.asp. As of this writing, pledges have reached the halfway mark and more than 3 million trees have been planted.

Without trees, human life would be unsustainable. Trees provide essential environmental services, including carbon sequestration and erosion control, a wide range of products such as timber, fruit, medicine, beverages and fodder, and a significant income for more than 1 billion forest-dependent people around the world. Yet in spite of this dependence on trees, deforestation remains a serious issue globally. Between 1900 and 2000, more than 9 million hectares (23 million acres) of global forest were lost, primarily to agricultural expansion in Southeast Asia and Brazil. Other leading global causes of deforestation are logging, urban growth and large developmental projects.

In the United States, individual urban forests are in decline because of urban sprawl and the loss of trees to non-native invasive insect pests such as the Asian long-horned beetle. Knowing that urban trees provide essential ecosystem services, including reducing air pollution, providing wildlife habitat and preventing sediment erosion into streams, the Billion Tree Campaign has targeted the planting of trees in urban environments as a key area of need. And this is where gardeners can have a significant impact.

Plant a tree this spring, one that is both native to Maine and well-suited to the site conditions. If you do not have room in your garden for another tree, consider donating a tree to a local school, church or other institution. Avoid Norway maple and other invasive species. Plant a small tree, one less than 2 inches in trunk diameter; small trees establish faster than large trees with fewer problems and less effort.

If you need help with planting instructions, take a look at the Web site’s link, “How to Plant a Tree.” I was pleased to see the words of caution about planting too deep and the sound advice against staking and fertilizing.

After planting your tree, go to the Billion Tree Campaign Web site and enter your planted tree as one of the billion, remembering these words of J. Sterling Morton, founder of Arbor Day: “Each generation takes the Earth as trustees. We ought to bequeath to posterity as many forests and orchards as we have exhausted and consumed.”

Send queries to Gardening Questions, P.O. Box 418, Ellsworth 04605, or to reesermanley

@shead.org. Include name, address and telephone number.