   Sustainable Landscapes - August 5, 2009 Jeff Schalau, Associate Agent, Agriculture & Natural Resources University of Arizona Cooperative Extension, Yavapai County While the term “sustainability” can seem overused, the concept is highly applicable to ornamental landscapes. In general, sustainability considers the social, economic, and environmental consequences of the choices we make in our daily lives. These choices are different for each of us because they are based on personal needs and values. In ornamental landscapes, sustainability could examine choices we make related to irrigation, pest management, wildlife habitat, fertilization, energy conservation, maintenance requirements, and more. Landscape sustainability starts with consideration for the soil. Maintaining ground cover in the form of live plants, plant litter, or mulch dissipates energy of raindrop impact and overland flow of water to minimize soil erosion. Natural decomposition of plant materials adds organic matter and leads to the development of soil humus. Vegetative ground cover need not be lush green plants. Perennial grasses and forbs provide ground cover during dormancy. Leaf litter and other plant debris can be left in place to decompose. Mulches have multiple benefits. In addition to mitigating erosion and contributing humus to the soil, organic mulches also cool the soil, reduce evaporation from the soil surface, and reduce annual weed growth. Inorganic mulches (usually gravel or rock) have similar effects, but do not contribute organic matter. Many people use geotextile landscape fabrics to prevent weed growth under mulches. Geotextiles are a great improvement over black plastic because they permit oxygen exchange and water percolation. Geotextiles also have some drawbacks: weeds can become established when soil builds up on top of the fabric and the where the fabric has been exposed over time creating a shabby appearance. I prefer organic mulches placed directly on the soil surface. Thoughtful placement of trees in the landscape can define an outdoor living space, provide privacy, and conserve energy. Evergreen trees provide year-round screening, a windbreak, and shade. Well-placed deciduous trees can screen the area from hot summer sun, while allowing maximum winter sun for solar heat. Use of both evergreen and deciduous trees creates a diverse habitat for birds. Before planting trees, you should analyze space required and be careful not to overplant. People are also attracted to fast-growing tree species such as cottonwoods and willows. These trees tend to require large quantities of supplemental irrigation and can be short lived outside of riparian areas. Create outdoor living spaces that can be used by you and your family. So often, landscapes are created for “curb appeal” and neglect practical living aspects. Small lawns and shady spaces are not unsustainable if they are purposefully created and used by household members. Spiny plants are usually drought-tolerant, but may not be compatible with younger family members and/or pets. Fences and constructed screens can also be used to define space and create privacy. Resist the urge to fertilize ornamental trees and shrubs and learn to tolerate some plant feeding insects. Fertilization is usually unnecessary – some exceptions include lawns, fruit trees, roses, annual flowers, and vegetables. Even these plants may not need as much fertilization as you think. Insects are important to functional ecosystems and your sustainable landscape should be viewed as an ecosystem. For example, wasps and hornets are predators and have many beneficial functions in native ecosystems. If they pose a threat to personal safety or they are nesting near high traffic areas, they may warrant control. Otherwise, exercise tolerance. Water features such as small pools and fountains can add a calming ambiance to outdoor living areas. They will also attract wildlife in water-limited environments. Wild bird feeding is also very popular. Most of the time, we consider these wildlife viewing opportunities to be positive. However, some wildlife species attract other wildlife looking for a meal (mice, wood rats, snakes, javelina, etc.). Placement of water features and wild bird feeding should be done thoughtfully. You must be consistent in the provision of food and not be too surprised by unexpected visitors. To me, sustainable landscaping seeks to meld your horticultural desires with the surrounding native vegetative communities and environmental limitations. Try to work with nature rather than against it and by all means, be flexible. The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at cottonwoodmg@yahoo.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://cals.arizona.edu/yavapai/anr/hort/byg/. |