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Introduction The implementation of environmentally beneficial landscaping techniques can provide long-term monetary and environmental benefits to Air Force installations. Environmentally beneficial landscaping conserves energy and water resources, reduces pollution, and saves money. The strategic planting of trees, shrubs, vines, bushes, and grasses can protect buildings from winter winds and summer sun, control pests with less chemical use, create wildlife habitat, and cut outdoor watering and maintenance costs, all while improving a community's appearance. The purpose of this fact sheet is to provide information about landscaping techniques that can be used by Air Force personnel who wish to take advantage of the many environmental and energy-saving features of environmentally beneficial landscaping.
Applicable Regulations and Policies White House Memorandum, Environmentally and Economically Beneficial Practices on Federal Landscaped Grounds, 26 April 1994. This memorandum directs Federal agencies, where cost-effective and practicable, to 1) use regionally native plants for landscaping; 2) promote construction practices that minimize adverse effects on the natural habitat; and 3) prevent pollution by reducing fertilizer and pesticide use and minimizing runoff. Landscaping practices that reduce the use of toxic chemicals provide an effective approach for reaching reduction goals established in Executive Order 12856, Federal Compliance with Right-to-know Laws and Pollution Prevention Requirements, 3 August 1993. Under Secretary of Defense (Environmental Security) Memorandum, Environmentally and Economically Beneficial Practices on Federal Landscaped Grounds, 23 Sep 1994. This memorandum, in response to the above White House Memorandum, suggests that environmentally and economically beneficial landscaping practices be incorporated as standard policy in installation Integrated Natural Resources Management Plans. Department of Defense Instruction (DoDI) 4715.3, Environmental Conservation Program, 3 May 1996. This instruction prescribes procedures for the integrated management of natural and cultural resources on property under DoD control. The instruction states, in part, that "environmentally and economically beneficial landscape practices shall be used on all DoD lands.[and], each installation shall, to the extent practicable, use regionally native plants for landscaping and other beneficial techniques. Air Force Instruction (AFI) 32-7064, Integrated Natural Resources Management, 1 August 1997. Compliance with Air Force (AF) natural resources programs ensures continued access to the land and air space required to accomplish the AF mission by maintaining these resources in a healthy condition. Chapter 11 states, in part, that "Installations should design and develop landscape on improved grounds to make maximum use of regionally native plants, avoid invasive exotic species, prevent pollution by reducing chemical usage, promote design and construction practices that minimize adverse effects on natural habitat, and reduce maintenance inputs in terms of energy, water, manpower, equipment, and chemicals." The AFI provides an Integrated Natural Resources Management Plan outline and information on natural resources budgeting. In addition, the AFI refers readers to the USAF Landscape Design Guide for additional technical guidance. This guide, developed by the Design and Construction Directorate, Headquarters Air Force Center for Environmental Excellence (HQ AFCEE/DC), is available at http://www.afcee.brooks.af.mil/DC/dcd/land/ldg/index.html.
Important Terms Beneficial Landscaping - an array of landscaping techniques that help retain the natural landscape features and native vegetation of undeveloped land (including wetlands, woodlands, and natural drainage features), reduce the need for pesticides and fertilizers, reduce the heating and cooling needs of buildings (shading, windbreaks), and reduce the need for internal combustion engines to drive landscape maintenance equipment. The term also refers to sites designed to incorporate natural drainage approaches, such as swales and vegetated "filter strips," in contrast to storm sewers and artificial drainage channels. Biological Diversity - the variety of life forms, the ecological roles they perform, and their genetic variability within any defined time and space. Evaporative Cooling - the evaporative process by which air temperatures around vegetation can be lowered by as much as 9 degrees Fahrenheit. Exotic Species - any plant or animal not native (or otherwise well established) to a region, state, or country. Habitat - an area that provides the environmental elements of air, water, food, cover, and space necessary for a given life form to survive and reproduce. Improved Grounds - developed areas of an installation that have lawns and landscape plantings that require intensive maintenance. Integrated Natural Resources Management Plan (INRMP) - a comprehensive management plan based on ecosystem management that shows the interrelationships of the individual component plans as well as mission and land use activities affecting the basic land management plans. Native Plants - for the U.S., all species indigenous to, or that originated in, a region at the time of European settlement. Unimproved Grounds - grounds not classified as improved or semi-improved and usually not mowed more than once a year. These include weapons ranges; forest lands; cropland and grazing lands; lakes, ponds, and wetlands; and areas around airfields beyond the safety zones. XeriscapeTM - from the Greek word xeros, meaning dry, a term coined in 1980 by the Denver Water Department to describe water-efficient landscaping. It involves the strategic selection, placement, and maintenance of plants/soil/irrigation techniques and equipment that minimize water use.
Energy Conservation One of the significant rewards of environmentally beneficial landscaping is the monetary payback realized when summer heat is controlled and winter heat is conserved. Summer cooling and winter heating costs can be significantly reduced using specialized landscaping techniques including shading, ground cover, and wind channeling. The use of the techniques discussed below will depend upon the regional climate and the latitude (distance from the equator) of the building and grounds. Some of the techniques conserve energy year-round, such as planting trees that provide shade in summer and allow light to pass through in winter when the leaves are off the trees.
Controlling Summer Heat
Channeling Wind - Trees, in addition to being providers of shade, also modify air movement. For non-air conditioned buildings, trees may be situated so that breezes are channeled toward open windows. In contrast, air movement on hot days around air-conditioned buildings can cause hot air to infiltrate through windows and door cracks, other small openings, and open crawl spaces. Trees and shrubs planted on the side from which the hot wind blows can divert or "ramp" the hot air over the building.
Ground Covers - Ground covers are low-growing plants that can be used to landscape areas near buildings. Taller and leafier ground covers provide more cooling benefit than shorter ground covers like mowed grass, although grass lawns are more durable under foot traffic. All plants can modify their immediate environment through evaporative cooling. The resulting lowered air temperatures around a building can reduce overall cooling costs.
Conserving Winter Heat
Shading - Plantings can be located to maximize the amount of solar radiation received by a building during winter months. Deciduous trees that lose their leaves in winter can serve as shade trees in the summer and allow increased sunlight infiltration during winter.
Foundation Plantings - Evergreens, due to their dense nature, can create an insulating dead-air space around building foundations, especially along the northern exposures.
Channeling Wind - Buildings lose significantly more heat when buffeted by cold winter winds than when the same cold air is still. The heat is lost via conduction through ceilings and walls. Plantings that serve as windbreaks around buildings and along foundations can substantially reduce the heat-robbing effects of winter winds.
Watering Practices
Xeriscaping
Planning and Design - A well-planned Xeriscape will require far less water than a traditional lawn or garden. Landscape architects can help with the design of Xeriscapes and choose appropriate plants.
Soil Improvement - Certain soil improvements, such as cultivation and the addition of compost, will allow for better water absorption and retention. Some soils require modification of their acidity or alkalinity to restore them to a more natural condition and improve their ability to support native plants.
Appropriate Plant Selection - Trees, shrubs, and groundcovers indigenous to a region's soil and climate conditions will have lower water demand, fewer pest problems, and fewer fertilization needs. Consultation with a local botanist is also recommended when selecting plants for drought-resistant plantings.
Practical Turf Areas - Turfgrasses require more frequent watering and maintenance than most other landscape plants. Turfgrass should be planted only where it will provide functional benefits. Often, grass can be replaced with less water demanding materials, or with decks and patios.
Efficient Irrigation - In addition to wasting water, excessive irrigation can leach nutrients from soils and away from plant roots. Water only when necessary or when wilting and discoloration are observed. Effective irrigation involves watering plants deeply, infrequently, and slowly. This ensures root zones are thoroughly moistened, does not over-water the plants, and eliminates runoff.
Mulching - The placement of decomposed organic matter, or mulch, over a plant's root zone conserves water by reducing moisture evaporation from the soil and reducing weed populations.
Appropriate Maintenance - Xeriscapes require low levels of maintenance. A well-designed xeriscape reduces mowing, requires less fertilization, eliminates weak unadapted plants (which are unattractive and often have disease and pest problems), and uses more efficient watering techniques.
Mowing Frequency
Many installations are undergoing severe budget cuts to their Grounds-Maintenance contracts. It is no longer affordable to keep all available land mowed and in an "improved grounds" condition. Many installations are transitioning these unused/unseen grounds into "unimproved" (unmowed) grounds. Mowing frequency in these areas is only once/twice per year. There are vast areas on many installations where a more natural approach to landscaping maintenance can be applied to the benefit of the environment and budgets. This transition will not only prevent erosion & evapotranspiration problems and over-application of chemicals/fertilizers, but can also reduce Grounds-Maintenance budgets by millions of dollars annually.
Integrated Pest Management
The best method for controlling pests, including insects and rodents, is to use natural controls, either biological or physical. This involves introducing other insects that are beneficial to the landscape, yet are predators to the pests. An example is to introduce certain insects such as praying mantises or ladybugs to feed on, and limit populations of, landscape pests. Another example is to introduce plantings that naturally discourage or repel rodents from designated areas.
In summary, healthy lawns and landscape plants have few pests and disease problems and are more tolerant to environmental stresses (heat, cold, drought).
Personnel should consult with the Installation Pest Management Coordinator before using pesticides, submitting service order requests for pest control, or contracting for pest control services. Headquarters Air Force Civil Engineer Support Agency (HQ AFCESA), Pest Management Program, offers support to installations seeking to prevent pest and disease vectors from adversely affecting military operations or missions - by establishing and maintaining safe, effective, and environmentally sound integrated pest management programs. Visit HQ AFCESA's Pest Management site at http://www.afcesa.af.mil/directorate/ces/mechanical/pest/pest.htm. For more information, contact Mr. Wayne Fordham, Pest Management Program, HQ AFCESA/CESM, Tyndall AFB, FL, DSN 523-6465, wayne.fordham@afcesa.tyndall.af.mil.
Of further interest to readers may be PRO-ACT's May 1997 Fact Sheet Integrated Pest Management, available at http://www.afcee.brooks.af.mil/pro_act/fact/factshet.htm. In addition, the Air Force Model Pesticide Reduction Plan, July 1996, is available at http://www.afcee.brooks.af.mil/EQ/pest.htm and can be used as a guide for conducting base-wide pesticide reduction opportunity assessments and preparing an installation integrated pest management plan.
Return on Investment
Davis-Monthan AFB: Palo Verde Neighborhood, A Cool Community
In October 1994, Davis-Monthan AFB's Cool Communities Program was awarded a grant from the Department of Defense's (DoD) Legacy Program, and a second phase was initiated in the Palo Verde North neighborhood. The mission of the DoD Legacy Program is to safeguard the environment and adopt the concept of ecosystem management. Strategic planting in Phase II was carried out during the spring of 1995. As in Phase I, all plantings were designed to increase direct and indirect shading and cooling for base residents. Lessons learned from Phase I were followed in Phase II; smaller varieties of trees were used, and it was determined that planting closer to homes would increase energy savings without interfering with the buildings themselves. One hundred and fifty trees were planted around 64 homes at the 17 acre Phase II site.
In the Palo Verde North neighborhood, current energy use reduction is estimated at slightly more than 13,000 kilowatt hours (kWh) annually, for an annual savings of approximately $15 per home. Air quality benefits include the annual removal of about 9 pounds of ground-level ozone and over 7 pounds of particulate matter (PM10). Stormwater runoff is being reduced by approximately 1%, translating to about 900 cubic feet of avoided storage space. After thirty years of growth, canopy cover would increase to about 1.57 acres (9%), and it is estimated that annual energy savings would increase to about 38,240 kWh, at a value of about $46 per home in today's dollars. Stormwater reduction would increase to about 5.6%, avoiding the need to construct about 4600 cubic feet of storage space. Annual air pollution benefits would increase to approximately 49 pounds of ground-level ozone and about 40 pounds of PM10.
As part of the project funded by the DoD Legacy Program, strategic tree planting at the Palo Verde North site was analyzed in terms of wildlife habitat benefits by Dr. William Shaw of the University of Arizona. The studies found that the trees probably do not significantly influence the abundance and diversity of birds in the area because they are immature and comprise only a small portion of the total vegetation. Because it is expected that the trees will have greater impact on wildlife habitat as they mature, the study concluded that the neighborhood would be a source of extremely valuable baseline data for future studies. For more information on the Cool Communities project at Davis-Monthan AFB, contact Mr. David Sumner, Community Planner, 355 CES/CECB, DSN 228-2302.
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