Trees have always been a vital part of the landscape. Today, they?re especially valuable as more asphalt and concrete is laid and public concern over environmental issues rises. Thus, the reason behind many communities? codes mandating that trees be planted with new developments.

One example is found at the University of California-Davis, where, according to Ed Mulrean, PhD., director of marketing and sales for Arid Zone Trees, ordinances have been developed that require a certain number of trees to be planted per acre of asphalt in parking structures. The reason: ?To mitigate heat gain from direct sunlight on the parking lots and the effects that has on air quality,? says Mulrean from his Mesa, Arizona nursery.

The United States Department of Agriculture?s Forest Service completed the Chicago Climate Project, which looked at the cost-benefit ratio of planting trees in urban areas.

?Basically they wanted to see if the cost of planting and maintaining trees was financially beneficial,? says Rita McKenzie, an urban forester at Purdue University?s department of forestry and natural resources.

?Through this study they found that there are many beneficial cost-saving reasons to plant trees.?

The study discovered that:

? Due to leaf interception of rainwater, one green ash tree reduced storm water flow by 132 gallons per year. Considering the tree cover currently existent, Chicago saved $494,000 in avoided runoff, and $32,000 at the power plant.
? The carbon sequestration benefit for the city was $547,000 annually, and showed vastly reduced levels of harmful gases like nitrogen dioxide and carbon monoxide.
? Energy savings from one green ash tree equated to cooling savings of 102 kWh and heating savings of 4.5 Btu per year. This translated to a savings for Chicago of $10,162,000.

What can landscape contractors take from this? The reasons behind metropolitan tree-hugging are the same ones to share with your customers. For the homeowner, money talks.

?Investigate the benefits that trees will provide for the family,? says McKenzie. ?If trees are placed properly, there are savings on cooling in the summer and heating in the winter.?

?Deciduous shade trees planted to the south of the house will permit the sun?s rays to reach the house in the winter, providing warmth,? explains Mike Kopas, a consulting arborist based in New Jersey. ?In the summer, the same trees will provide shade, thus cooling that side of the house.?

Trees also provide a wind break and deflect rain and snow. Obviously, the more compact the foliage on the tree or group of trees, the greater the influence of windbreak. Trees intercept water, storing some of it, reducing storm water runoff and the possibility of erosion and flooding. Also, dew and frost are less common under trees because less radiant energy is released from the soil in those areas at night.

Another financially rewarding fact stands out for homeowners: trees increase the value of their property.

?Generally speaking, people will buy a house with trees, or even a lot to build on with trees, rather than one that?s without,? says Lew Bloch, a landscape architect and consulting arborist in Washington, DC. ?There have been surveys that show vacant building lots selling for 15 to 20 percent more if they have trees.?

In fact, the Arbor National Mortgage survey of real estate agents showed the following responses when asked what they believed about a house accompanied by trees:

? Eighty-four percent of the respondents believe a house is 20-percent more salable;
? Sixty-two percent of the agents believe it influences the impression of the neighborhood;
? Sixty percent think it has a big effect on the first impression of a home.

Aesthetic Appeal

There are other reasons to incorporate trees in a landscape, including privacy, noise reduction, and even erosion control. But aesthetic appeal may be the biggest selling point of all.

?Trees enhance properties visually through many means,? says Scott Jamieson, president of Chicago-based The Care of Trees, a tree preservation firm. ?Flowering trees can add color in the spring; trees selected for their brilliant fall color add color at the end of the season. Trees can also be selected for attractive bark characteristics such as peeling bark, deep furrowed bark, or colored bark such as white- or nearly white-barked aspen or birch.?

Besides individual characteristics, groves of trees can add structure to the landscape, and rows or patterns of trees add a natural frame around other landscape elements, such as flower gardens.

?Trees also enhance the health of a property through the psychological benefits they have on people,? adds Jamieson.

Selling customers on the benefits of planting trees can also include ?before and after? photographs of previous properties you?ve serviced. Such images can help the homeowner visualize the striking difference between the effects of a no-tree landscape and the enriching value of a yard complimented with mature trees. There is also software available to show what a property will look like with various tree types and sizes, installed at any given location.

The beneficial aesthetic aspects of trees near commercial structures are also numerous.

?Trees are used to either accentuate or compliment the architecture of a building,? notes Mulrean of Arid Zone Trees. ?When you have these big commercial buildings that are towers of glass, or tilted concrete structures that are pretty geometric, trees?because they operate above eye level?serve to soften those hard angles. Trees give them more of an organic feel than they otherwise would have.?
From the pedestrian?s level, says Mulrean, particularly in the West and Southwest, the trees provide shade, a refuge. ?It makes the building more inviting.?

Tree Tips

To maximize your trees? potential enhancing effect, first consider if the tree will marry well with its surroundings before planting.

?The most important aspect in planting trees is making sure you have the right tree in the right spot,? says Jamieson. ?This is especially important for soil conditions. Make sure the trees can thrive in the existent soil, or make sure you have the capacity to ?create? a better one, such as structural soil.?

It?s worth noting that new soil mixtures are being developed through research, aimed at improving tree health, especially in the more difficult urban growing sites, such as highway and street medians and downtown park areas.

For starters, Jamieson suggests digging a hole wide and shallow, and to properly mulch it. Maintenance isn?t difficult, but Jamieson says that far too often trees are planted, then left to die without proper watering and aftercare in the critical years after planting. Just as healthy, vibrant trees add beauty and value to a landscape, decrepit trees are an eyesore and diminish a property?s perceived value.

A house with trees in such poor condition ?often suggests a lack of interest from the owners,? says Kopas.

Understanding what trees need means digging to the root of the matter. William Fountain, extension professor for horticulture in the University of Kentucky?s College of Agriculture, knows that because ?half of the plant is below ground, what is out of sight is out of mind.

?When soil is compacted during construction, it makes it difficult ? if not impossible ? for plant roots to develop sufficiently.?

In short, take care when working around the immediate area of planting to give newly planted trees a good chance at deep rooting.

Arborists cringe at the thought of poorly planned ? and often rushed ? landscaping jobs involving trees.

?Unfortunately, many new homes are landscaped with inexpensive, fast-growing plants that have been installed without purpose and too close to the house,? says Fountain. ?Within a very few years this becomes a headache for the new homeowner.?

?Trees can be an asset, but they can also be a liability if they?re too close to the house, or if they?re not in good condition,? adds Bloch. ?If they?re old and decayed, and there?s a danger that they may fall on a house or somebody, they should be cut down.?

As a preventative measure against widespread disease, which is often the culprit of decimated trees, Fountain suggests diversifying your tree selection.

?In selecting trees for our landscapes, we must recognize the health and aesthetic value of diversity,? says Fountain. ?There is no such thing as the best tree, or even a short list of ?best? trees. Diversity in the landscape is one of the big keys of a healthy landscape.?

Fountain recalls many urban areas of the past which were planted with a limited number of species, where disease and insects spread rapidly and developed into a ?tree plague.? The American elm, for instance, devastated by Dutch elm disease, has left whole streets void of mature trees. A type of pin oak, which is currently being killed by bacterial scorch, can leave a landscape looking like a barren wasteland.
?Diversity truly is the spice of life,? says Fountain.

Mar 2001