Construction sites often include the removal of most surface vegetation. A lack of plants in the ground at a construction site is aesthetically jarring to many viewers, and greatly increases erosion and negative impact to the soil ecosystem. Maintaining native plants on the site, or seeding in and installing plants, helps mitigate the regulatory, aesthetic and environmental impact of construction sites.
Runoff from construction sites carries significant quantities of pollutants and sediment into water bodies, according to the University of Missouri Extension Service. The Missouri Extension advises that plants are the single most efficient method of controlling construction site erosion. Plant roots absorb water and hold the soil together, while plant stems--particularly of woodier, more permanent plantings--slow the movement of water across the surface, allowing more time for suspended sediment to settle and water to sink into the ground. Strips of native, pre-existing vegetation should be left where ever possible to stabilize slopes and filter runoff.
Aesthetics and Regulatory Compliance
Construction site disturbance can be visually unpleasant for many people who view the site regularly, such as neighbors and passing commuters. Vegetative cover helps mitigate the aesthetic impact of construction, creating more positive public relations for the construction project proponents.
Keeping existing plant cover to the extent possible can also enhance regulatory compliance and minimize regulatory restrictions on the project. For example, the Fox Point, Wisconsin ordinance regarding construction site erosion control defines a land-disturbing construction activity as any activity which involves removal of surface vegetation. The less surface vegetation removed, the smaller the project is considered to be for regulation purposes. Where vegetation is removed, seeding or sodding in the area is considered an appropriate mitigating activity. Planting larger, site-appropriate flowers, shrubs and small trees is generally looked upon favorably by regulatory authorities.
Minimize Ecosystem Disturbance
Alrie Middlebrook, founder of Middlebrook Gardens, an award-winning California landscape firm specializing in native-plant gardening, notes that construction projects typically involve removing large quantities of topsoil, followed by compacting the remaining soil with heavy equipment. This makes it difficult for vegetation, including the builder's landscaping designs, to survive.
Maintaining as much topsoil as possible, as well as maintaining plants on the construction site to ensure that the soil remains well aerated and soil microbes continue to thrive, will minimize disturbance to the surface and soil ecosystems, which in turn enhances the success of post-construction plantings.