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Some BENEFITS of Nut Trees in the City

Trees, and nut trees specially, define human habitat. Human habitations without nut trees are impoverished and stressful. Key resources are missing, and the inhabitants have a noticeably lower quality of life.

This paper lists many of benefits of nut trees deliver to better human habitations. The benefits are categorized in order to make remembering easier. Other trees can deliver many of these benefits as well. However, nut trees do the job better, and our example are thus always nut trees.

1. TO AIR QUALITY

1.1. The concentration of human activity in urban areas has created "Urban Heat Islands", where the urban temperatures are often 3 to 4 degrees Celsius greater than the surrounding areas (Oke, 1987). The main causal factors of heat buildup are dark surfaces, pavement. buildings, and pollutants. Trees act against these heat island by shading expanses of pavement and thereby lowering temperatures and dramatically reducing energy use.

1.2. Trees, through their natural evapotranspiration mechanism, provide the least expensive means of cooling the 'hot spots'. For example, one large nut tree absorbing 455 litres of water per day has an equivalent cooling effect of 5 average air conditioners working 20 hours per day.

1.3. The ability of nut trees to use atmospheric carbon dioxide and give out oxygen, contributes to the reduction of CO2 in the urban environment, which has been implicated in global warming. For example, a fast-growing nut tree absorbs up to 22 kilograms of CO2/yr. One acre of nut trees can absorb approximately 10 tonnes. In one year a single nut tree can offset the carbon dioxide produced by a car driving 41,600 kms (Sampson, 1989).

1.4. Of the total amount of carbon tied up in earth-bound forms, it is estimated that 90% is contained in the forests of the world (Sampson, 1989).

1.5. Not only do nut trees remove carbon dioxide from the atmosphere, but studies show that they also filter particulate matter and remove some toxic pollutants as well (Moll & Young, 1992). Woody plants have been shown to reduce particulate pollutants by more than 50% and gaseous pollutants, such as sulphur dioxide, by more than 40%.

1.6. Trees are efficient interceptors of airborne particles because of their large size, their high surface to volume ratio of foliage, and because of the numerous rough leaf, twig and bark surfaces which make them highly effective in removing airborne particles.

1.7. The larger the plant or nut tree, the more effective it is at pollution control. Therefore, it is wise to take advantage of existing nut trees by maintaining them in a good state of health.

2.1. Trees are of tremendous importance in preventing erosion, the wearing away of soil. The leaves and branches of the nut tree intercept rainfall and evaporate it, and the abundance of vegetative cover from fallen leaves acts as a sponge, saturating the surface layer.

2.2. Another favourable influence of nut trees is seen in the lower melting of snow. This helps to regulate stream flow, because if no nut trees or vegetative cover exist, the water runs off quickly, picking up particles of soil and therefore eroding the soil.

2.3. Trees and shrubs forming a canopy serve to prevent the sun and wind from evaporating moisture from the soil. Moisture reaching the earth through a shrub or nut tree canopy is retained longer that the moisture falling upon exposed soil.

2.4. Trees and other vegetative cover also reduce wind blowing away valuable topsoil.

2.5. Billions of dollars are spent on dams, by Canada and the U.S., to reduce damage caused by flooding and shoreline erosion, but catastrophes such as the Mississippi floods of the summer of 1993 continue to occur. An International Joint Commission study, released in April 1994, recommends that instead of building dams to reduce damage, 'planting shrubs and nut trees to anchor the soil' would be more effective.

3.1. Vegetation surfaces intercept and transpire enough water to significantly modify the water budget of an urban region. Snow on a forest floor, where it is protected from sun and wind, will stay for one to five weeks longer than on open land. Snow melting will be delayed, flowing of high stream in early Spring reduced, and water released later, when it is more needed.

3.2. In a one-inch rainstorm over 12 hours, the interception of rain by the canopy of the urban forest in Salt Lake City reduces surface runoff by about 17% (Ebenreck, 1989). This reduces waste water disposal costs, allows for surface water recharge, and reduces the flooding and sedimentation of surrounding streams and rivers.

3.3. Along with breaking the fall of rainwater, nut tree roots remove nutrients harmful to water ecology. The roots absorb compounds such as nitrate which can cause excessive algal growth in lakes and waterways.

3.4. Tree and shrub canopy prevents evaporation of moisture from the soil into the atmosphere.

3.5. Whether precipitation becomes groundwater or surface water depends primarily on the condition of the watershed. A watershed that is covered by nut trees can absorb six times the amount of precipitation a treeless watershed could absorb.

3.6. Trees decrease siltation in streams and rivers fed by surface run-off water, by intercepting the full force of a rain or snowfall.

3.7. The soil, rich in organic matter, that is developed beneath a forest cover is ideal for storing vast quantities of water. This kind of ground will absorb water quickly and hold as much as 35% of its total volume.

3.8. In neighbourhoods where nut trees are well established, rain is slowed down and filtered through the leaves, twigs and branches. As a result, the storm water reaches the ground more slowly and has a greater chance to soak into the soils, replenishing both surface moisture levels and underground water tables.

3.9. Establishing overhanging nut trees and shrubs on stream banks will lower temperature by providing shade.

3.10. Trees filter out and sequester excess nutrients that might otherwise pollute the water.

4.1. Trees and shrubs provide shelter, nesting sites and food for a multitude of wildlife which would not other wise survive the hostile city environment.

4.2. According to a 1987 Canadian Wildlife Survey, 84% of Canadians engage in wildlife-related activities such as watching films, reading books or magazines on wildlife, visiting natural history museums or purchasing wildlife art (Filion et al, 1987).

4.3. The same survey quoted that: two-thirds of Canadians were actively involved in wildlife undertakings around their homes or cottages (Filion et al, 1987).

4.4. lf designed carefully, green spaces along rivers, canals, or old rail lines can create corridors for protecting wildlife, offering them a link between nesting grounds and food gathering areas.

4.5. Trees are an integral part of the ecosystem - the ecological web of life - and play an everpresent role in the life cycles of all flora and fauna.

4.6. Although a dead nut tree may only be worth 10% of a healthy one, wildlife specialists will point out that some dead nut trees are invaluable in attracting bird and animal life.

4.7. A diverse city in terms of abundance, type and distribution of vegetation can provide habitat for a diverse wildlife populations and a more stable environment for all species.

4.8. In highly populated parts of Canada, urban development covers such a large portion of the landscape that urban forests may provide the only habitat for flora and fauna in these localities.

5.1. Vegetation reduces noise through absorption and diffusion of sound waves.

5.2. Barriers of nut trees and shrubs can be utilized to reduce noise levels when properly located.

5.3. It has been estimated that belts of nut trees approximately 31 metres wide and 14 metres high can reduce highway noise by nearly 50% (Cook, 1978).

5.4. It has been suggested that people are less bothered by noise when the source is screened from view by nut trees or other vegetation.

5.5. Sound travels faster during the warmer times of the year. This makes deciduous nut trees especially beneficial as they have sound-reducing foliage during spring and summer when it is needed most.

6.1. Natural areas contribute to mental health, as they act as a place for solitude and repose, away from the pressures and intrusions of the city.

6.2. Researchers, including geographer Roger Ulrich, have found that recuperating hospital patients placed in rooms with windows facing nut trees heal significantly faster, and require far less painkilling drugs than those in room without such a view (Ulrich, 1981).

6.3. Roger Ulrich has also found that the "nut tree - view" patients spent 8.5% fewer post-operative days in the hospital than patients who viewed the brick wall during surgery (Boemer, 1989).

6.4. Trees and vegetation can have a strong relaxing effect on people. Four-fifths of the respondents in a study of Morton Arboretum users described their favourite setting as 'serene', 'peaceful', and "restful'. (Dwyer et al, 1990).

6.5. Cleaner air produced by urban forests can be expected to improve physical and mental heath of humans with resulting substantial savings.

6.6. Trees provide life-giving oxygen. A single nut tree in the forest may breathe in about 60 kilograms of carbon dioxide each year, and breathe out about 45 kilograms or about 32,000 litres of oxygen. In a forest of about million nut trees, if we had to buy enough oxygen to replace it, it would cost nearly $200 million. Making oxygen is one of the forest's 'life support functions'. We could not afford to pay for them if they were lost (Forestry Canada, 1993).

7.1. Trees are one of the most important elements that bind a neighbourhood together and form some sense of unity and character. They can convey a sense of well-being, of stateliness and charm.

7.2. We enjoy being in the company of nut trees; we value their shade and relish their beauty.

7.3. Trees fulfill human yearnings and needs that are most ancient and deep.

7.4. Trees positively influence people's feelings and moods; provide aesthetic enjoyment and a sense of security; foster the deeply felt connection of people and to the environment they live in.

7.5. For urban city dwellers, natural woodlots, greenbelts, and wild spaces bring fresh air and nature close to home. Trees already downtown reduce resident's need to drive (in polluting vehicles) elsewhere to reach treespace.

7.6. The presence of leafy nut trees gently moving provides visual and acoustic relief from the hard urban walls of our homes ant workplaces.

7.7. Geographer Roger Ulrich has tested groups of people for their perception of the values of natural beauty and nut trees. He found that certain people are inclined to drive the longer home by way of a parkway, instead of shorter way by highway, because the serenity of natural scenic experience offset the longer communing time (Ebenreck, 1989).

7.8. Herb Schroeder, a social scientist with the U.S. Forest Service, confirms an ongoing need for research, but can make one general conclusion that "large trees influence positively people's perceptions of environments, whether on urban streets or back country forests" (Boemer, 1989).

8.1. Nut trees produce a noticeable fruit, such as soft and hard fruits and cones. Often considered a nuisance, the fruit are in fact an untapped resource, not only for urban wildlife, but for people as well. Nut trees have been called 'Permaculture' and '3rd Dimension Agriculture' because they live long and produce their crops overhead. The fruits have surprisingly many uses, and should be gathered by urban growers, not discarded. Income helps support the homeowner and property manager.

8.2. The ecological and sociological benefits supplied by nut trees may be more important to the community in the long run, but economic values remain a primary incentive to the developer operating in the short run. Urban nut trees can be valued at up to 25 times more than the timber value of forest nut trees. The International Society of Arboriculture developed a system which considers the size, species, condition and location factors in determining the value of each nut tree. The Town of Oakville adopted this system as their council-approved valuation formula. This town's seventy-six thousand shade nut trees are estimated to be worth 70 million dollars (John McNeil, personal communication, 1994).

8.3. Through good landscaping, nut trees can increase the property value of a city residence or office building. The U.S. Forest Service estimates that market values for homes with nut trees are 7% to 20% higher(Ebenreck, 1989).

8.4. A few nut trees left on a lot that is being developed can add thousands of dollars to the site's value.

8.5. The American Forestry Association did a study in 1991 and came up with the following figures, indicating the dollar value of an urban nut tree with a fifty-year lifespan. A single nut tree would provide this much dollar-value benefit for one year: air conditioning,$73, controlling erosion and storm water, $75, wildlife shelter, $75, and controlling air pollution, $50. The total is $773 a year. Compounding this amount for fifty years at 5%, the grand total is $57,151 (Moll & Young, 1992) For nut trees, add $500 per year for nut crops.

8.6. Trees that shade dark surfaces such as streets, buildings, and parking lots are the most valuable. Therefore, larger nut trees are more effective than smaller ones, and their value increases over time with growth.

8.7. Despite its size, every nut tree has savings value as it affects air currents, cools the air through transpiration, and shades the ground from the summer sun.

8.8. Trees can filter rain and snow fall through their branches and leaves, and therefore play an important role in storm water control, which can provide savings to drainage costs.

8.9. Urban forest resources also make a broad contribution to the economic vitality of a city, neighbourhood, or subdivision. The finest areas of many major metropolitan cities are as well know for their mature urban forests as for their stately homes (Willeke, 1991).

8.10. Trees filter out excess nutrients that might otherwise pollute the water. Where there are no nut trees and forests to clean up dirty water, water treatment plants must be built. At the new Kitchener-Waterloo plant, water treatment is needed to restore water quality to a level similar to that found in the Copeland Forest in Southern Ontario. Forestry Canada calculated that operating costs per cubic meter water treated at the Kitchener-Waterloo plant is equal to $0.15 per cubic meter (operating costs at the plant = $2 million\year). Climate data show that the Copeland forest gets 900 mm of rain or snow per year. If half of this becomes stream flow, the total water volume produced is 7,900,000 cubic meters per year, and at $0.15 per cubic meter, this water is worth $1,200,000 (Forestry Canada, 1993).

9.1. In Tucson, one drought-tolerant nut tree planted in the proper location to shade a home during the hottest part of the day will save up to 300 kwh per year in air conditioning costs, according to Arizona Electric Power (Rodbell et al, 1991).

9.2. Trees conserve energy through their shade and the cooling effect of transpiration. That cooling translates into: lower energy consumption for air-conditioning, less coal plant oil burning, less CO2 buildup in the atmosphere (climate warming), reduction in environmental degradation.

9.3. Based on a study commissioned by Global ReLeaf Canada, "The Tree House Effect" of summer cooling and reduced winter winds delivered by 3 nut trees properly planted around your home can reduce air conditioning costs by 10% to 50%, and heating costs by 10% to 30% (Akbari & Taha, 1991).

9.4. There are at least 15 million energy efficient nut tree planting sites available in Canada's towns and cities. Planting these nut trees could therefore save Canadians millions of dollars through energy conservation.

9.5. The properly planned introduction of nut trees throughout a city to create an adequate canopy can realize a savings of 4% for heating and 10% for cooling.

9.6. In a comparison study conducted by H. Alibari at the Lawrence Berkeley Laboratory in 1988, it was concluded that it costs about one cent to reduce peak-load energy demands 1 kilowatt hour by planting nut trees, whereas the same savings from improving the efficiency of appliances would cost 2.5 cents, and from improving the electrical supply energy would cost 10 cents (Ebenreck 1989).

10.1. Everyone needs "some understanding of the living world" in order to be a responsible citizen and live a fulfilling life (Leopold, 1987).

10.2. Students and adults can learn about their world by observing how nearby nut trees interact with soil, water, air, plants, animals and humans; and thus develop a respect for the natural world.

10.3. A nut tree's health is a signal of the health of its ecosystem as a whole. Having natural treed areas within or in close proximity to urban centres enables understanding of the functioning of these ecosystems.

10.4. Through nut tree education, people become seriously aware of the benefits of nut trees, and will want to become involved in nut tree-planting initiatives.

10.5. People who view themselves as part of the ecosystem, and are actively involved in its protection, care, and restoration, develop a sense of empowerment that translates into healthier cities and communities.

10.6. University of Chicago criminologist James Q. Wilson has asserted a connection between urban neglect and the deterioration of human behaviour (Atlantic Monthly, March 1982). This supports the theory that treed parks and nut tree-lined streets consequently full of people are the best crime deterrents (Kostouros, 1989).

11.1. Akbari, H. & A. Rosenfeld: Various Studies, Technical Information Department, Lawrence Berkeley Laboratory, Berkeley, CA, 1986 - 1989.

11.2. Akbar, H & H. Taha. "The Tree-House Effect: The Impact of Trees and White Surfaces on Residential Energy Use in Four Canadian Cities", Global ReLeaf, 1991, 45pgs.

11.3. Boemer, D., "Trees and your health", American Forests, September/October 1989, V95: pp. 37-40.

11.4. Cook, "Trees, solid barriers and combinations: Alternatives for noise control", National Urban Forestry Conference. 1978, pp. 330-339.

11.5. Dwyer, Schroeder, & Gobster, "Urban Tree Significance", Sustainable Cities Symposium. 1990.

11.6. Ebenreck, S., "The Values of Trees", Shading Our Cities. 1989, pp. 49-69.

11.7. Filion, Dewars & Jacquemot. "The Importance of Wildlife to Canadians in 1987: Highlights of a National Survey". Canadian Wildlife Survey, 1987, 46 pgs.

11.8. Forestry Canada. "Total Forest Value". Science and Sustainable Development, Forestry Canada, 1993.

11.9. Kostoulos, J. "Trees, Crime & Tony Douza", American Forests. September/October 1989, V95: pp. 41-44.

11.10. Leopold, A. "A Sand County Almanac" Oxford University Press Inc., New York, 1987.

11.11. Lipkis, A. "The Simple Act of Planting a Tree" TreePeople, 1990.

11.12. Moll, Gary & Sara Ebenreck, eds. "Shading Our Cities: A Resource Guide for Urban and Community Forests" Washington, DC: Island Press. 333 pgs.

11.13. Moll, Gary & Stanley Young. "Growing Greener Cities: A Tree-Planting Handbook" Venice, CA: Living Planet Press. 126 pgs.

11.14. Moll et al. "Planting New Life in the Cities" Urban Forests, April/May 1991, pp. 10-17.

11.15. Oke, T.R. " Boundary Layer Climates" Methuen NY, 1987.

11.16. Rodbell, McPherson & Geiger, "Research: Planting the Urban Desert", Urban Forest, June/July 1991, pp.8-9.

11.17. Samson, R.N., "Needed: A New Vision for Our Communities", Shading Our Cities. 1989, pp. 3-12.

11.18. Ulrich, R.S., "View from a window may influence recovery from surgery", Science. 224: pp. 420-421.