In praise of raking leaves!
The trees that ornament our lawns and gardens are well worth the once-a-year raking ritual they demand. Trees are a valuable accessory to our lawns and landscaping, and they, like turf and lawns, are natural sound barriers and air filters.
Agents for social change
In some American cities, inner-city tree planting programs such as The Oakland Tree Task Force in California and the Philadelphia Green program are paying community dividends. Supported by local citizens' groups, residents planted trees in their neighbourhoods. Not only did the tree-planting beautify the community, it brought people together, and helped generate a sense of community and shared ownership.
Temperature and trees
It's a natural instinct to take refuge under a shady tree on a hot day. Trees planted around buildings cool in the summer; one large tree can cool the same amount of air as 15 room-sized (4000 BTU) air conditioners. When trees are planted around air-conditioned buildings, they reduce the load on the air-conditioning system by cooling the air before it enters the conditioning system. This can reduce energy costs by 18 to 50 per cent.
Trees planted around buildings also act as a wind break, and can reduce winter heating costs by four to 22 per cent by reducing the speed of winter winds moving around buildings. Using less heating fuel in winter also lessens the atmospheric levels of carbon dioxide and other greenhouse gases given off when heating fuels are consumed.
Trees and air pollution
The American Forestry Association estimates that one mature tree can generate enough oxygen for a family of four, and that an acre of trees will supplies enough oxygen to meet the needs of 18 people.
Trees are also important air purifiers. During the process of photosynthesis, plants absorb carbon dioxide, using the carbon and releasing the oxygen. The American Forestry Association estimates that one mature tree will absorb almost 26 pounds (12 kg) of carbon dioxide annually. That is roughly equal to the pollution created by driving one car 11,000 miles (17,600 km). Researchers have recently confirmed that carbon found in the tissue of a tree comes entirely from the air. The age and vigour of the tree are important factors in its ability to purify the air. A mature and healthy 50-year-old sugar maple will annually convert 120 times more carbon dioxide, than a tree that is 10 years old. It is critical to properly care for trees so that they reach full maturity.
Being kind to trees
Older areas in cities are often graced with stately mature trees that form a beautiful canopy over the streets. In modern subdivision, many trees die early, often within 15 or 20 years, and often the conditions of the root bed are to blame. During construction, the subsoil has been heavily compacted by earthmovers and backhoes, and by the time the building is completed, the soil is like concrete with a few inches of surface topsoil. Trees planted into this soil will not thrive without special care.
If you are planting a new tree, follow the planting instructions carefully. Use a transplanter fertilizer, and water the tree well and frequently until it is established. Water is critically important to all trees, established and newly planted, especially in a new subdivision where the soil's water retention capacity is very low.
One method of fertilizing a tree is to simply apply it in heavier applications under the tree than on the rest of your lawn, remembering that the grass under the tree will capture most of the nutrients. Water soluble and liquid fertilizers must be combined with water before application, and this method insures that some water gets to the tree as well. Always follow the instructions on the label to avoid underfeeding or wasting the fertilizer, and if in doubt, ask for advice at a nursery or garden centre.
Watering and fertilizing a tree is also the best way to prevent insect and disease infestations. If insects become a problem, take a specimen to a nursery or garden centre and ask for advice. In the case of birch borers and leaf miners, an ounce of prevention is often worth several pounds of cure.
Pruning will remove potential sites for disease, and allow strong limbs to develop that will withstand wind and storm damage. It will allow you to shape the tree as you wish, and reduce potential drought stress caused by unnecessary foliage.
Give them some air
To ensure that your trees have the oxygen they need at the root zone, keep parked cars, footpaths, patios, storage sheds and driveways away from trees. These will compact the soil and reduce the availability of oxygen to the tree.
When properly maintained, trees will provide years of beauty and clean air and help cool our homes in summer and protect them in winter. A little kindness (and a little raking) will be much appreciated.
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