Growing Greener Grass

220px-San_Francisco_Botanical_Garden_Great_Lawn_1

CC BY-SA 3.0

The term sustainability is often used to describe the state an isolated entity, such as a building or a means of producing energy. However, the term intrinsically holds a holistic meaning, and its embodiment is linked not just to those things obviously produced by humans, but to their surroundings as well.

In the context of cities, the LEED system is a means of certifying sustainability, originally at the building scale and, more recently, at the neighborhood level (LEED-ND), where traffic patterns, walkability indices, and other human scale lifestyle factors are included in the equation. The natural landscape in the urban environment however, that which is mainly composed of pristine bright green lawn, is overlooked as a system and is rarely considered part of the sustainability picture as a whole. In certain cases, it is designed for the building which it accompanies, but is considered separately from its neighbors. A closer look at the numbers reveals why careful practices of converting conventional landscaping to cohesive urban ecosystems that function in ways similar to natural systems is essential to the practice of sustainability at the neighborhood, city, and regional scales.

It has already been more than 50 years since Rachel Carson first published her revelatory work, Silent Spring, which exposed the threats of pesticide use to both human health and well-being and to environmental health and vitality—indeed, the two concepts are inextricably coupled and the contamination of our land, air, and water inevitably leads to the deterioration in our health and longevity. As Carson wrote:

Probably no person is immune to contact with this spreading contamination unless [s]he lives in the most isolated situation imaginable.

Though chlorinated hydrocarbons, or DDT, the main focus of Carson’s thesis, have been banned, pesticides remaining on the market still contain toxic substances. Carson spread environmental awareness by dovetailing the human built natural urban environment to contamination of soils and groundwater, but there are additional links between industrial natural landscaping and unsustainability that have since become apparent. Intrinsically, the maintenance of lawns and highly manicured landscapes require high amounts of energy inputs, including mowing, pesticide and fertilizer application, aerating and dethatching and other upkeep; all of these inputs are necessary to maintain lawns in a pristine and tame condition, the opposite of their natural tendency.

According to the Lawn Institute, urban and suburban man-made landscaping covers over 46.5 million acres in the US alone, up from 27.6 million in 1996 (Borman, H., Balmori, T., Geballe, G. and Vernegaard, L. Redesigning the American Lawn: A Search for Environmental Harmony. Yale University Press, 2001). This is equivalent to a land mass area greater than that of Pennsylvania, Delaware, and Rhode Island combined. Approximately 76 percent of this belongs to homes (Borman, Ibid.). To maintain this turf, Americans spend $6.4 billion a year. This maintenance has harmful impacts on air, soil, and water quality caused by gas-powered mechanical equipment use, frequent application of fertilizers and pesticides, and the generation of significant quantities of solid waste. Indirect effects range from increased potential of destructive flooding to noise and air pollution to biodiversity loss through the introduction of invasive species. It is estimated that the gas-powered mowers, trimmers, blowers, and chainsaws used in lawn maintenance activities contribute 5 percent of urban air pollution and emit large amounts of VOCs; as much as 50 tons of VOCs/day during summer months have been reported in the Chicago area. The residential application of pesticides is 20 times that applied in agriculture. The EPA reports that 20 percent of municipal solid waste comes from lawn trimmings, and most of this ends up in landfills.

Much of the cost and energy attributable to current practices in urban landscaping can be offset by conserving natural spaces, minimizing the use of turf, and reclaiming lawns whenever possible and converting them into lower maintenance natural and native systems that would conserve energy and water resources, as well as minimize contamination of soil and groundwater and lower urban air pollution levels. The environmental benefits of natural landscaping are numerous. By aerating the soil, native and other deep rooted grasses and perennial plants increase infiltration and decrease evapotranspiration, resulting in better filtration of pollutants, larger water storage capacity, and reduced non point-source runoff. In a study by Barr Engineering Co., it was found that stormwater runoff could be reduced 82 percent when landscaping with native species. Some studies also show that the carbon sequestration capacity of mature, established native ecosystems increases with the age of the ecosystem, although after a 10-year cycle a recreated ecosystem still only has 45 percent the carrying capacity of virgin prairie. The latter statistic emphasized the importance of conserving existing ecosystems whenever possible.

Appropriate landscaping can add monetary savings for private citizens and municipalities alike. At the individual level, landscaping can be used to minimize energy consumption in the home. By creating landscape designs with context in mind, trees and shrubs can be used as windbreaks in the winter and allow cool breezes in the summer thus lowering heating and cooling costs anywhere from 25-30 percent or in some exceptional cases as much as 50 percent. Planted about one foot from outer walls, shrubs create dead air traps for added insulation. Canopies also help keep outside air cooler through the creation of microclimates and minimize the heat island effect caused by built environments. At the municipality level, appropriate landscaping diverts water from the wastewater system, minimizes runoff and thus contamination of drinking water sources, and lowers the potential for property damage under extreme weather conditions. In addition to lowering the demand on infrastructure services, these implementations are cheaper than large-scale infrastructure solutions; additional savings can be achieved in lower density areas where the expansion of infrastructure services can cost up to three times as much as in core urban areas (Borman, Ibid.). In a recent economic comparison, it was shown that a natural landscape is more cost efficient than a traditional lawn. The first year installation costs of turf are $7,800 to 14,825/acre while those of a natural landscape are $3,400 to 5,975/acre. A ten year average maintenance cost analysis showed that turf was very costly to upkeep at $5,500 to 6,471/acre/year, while the cost for native landscaping was only $1,600 to 1,788/acre/year, 28 percent the cost of maintaining turf.

The opportunity to revise and rebuild the concept of urban landscaping and greenspacing is ripe for the picking. For contemporary cities, one of the largest roadblocks to sustainability is that the overall “urban metabolism” is positive, wherein the city consumes more than it is able to produce (El Khafif, Mona. Coding Urban Metabolism. LandscapeUrbanism.com, 2012). However, by converting green space to perform environmental remediation and provide infrastructure support while simultaneously developing the space into centers of resource production for the city, whether that be in the form of fuels, food, raw materials, social functions or other practical applications, these cities may be able to work their way out of their energy and resource debt. As Mona El Khafif states in her essay, “form should follow ecological function and urban metabolism,” and smart design should not be limited strictly to structures, but should include the entire urban fabric, to create an integrated productive urban organism. By inverting the system and allowing natural areas to become the fabric while the built areas form the patches throughout, we would be maximizing ecosystem services while minimizing our reliance on expensive municipal infrastructure (Ingram, John. When Cities Grow Wild: Natural Landscaping from an Urban Planning Perspective).

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