Organizations

Abstract

development was completed. An example of the latter is a wetland mitigation plan that used white alder (Alnus rhombifolia) even though the species is not found in the area of the mitigation. Taking more time to analyze the feasibility of the mitigation at the conceptual stage would help to alleviate these situations. Third, problems occur when a conceptual mitigation plan is given to a landscape architect who lacks familiarity with the species in the revegetation plan or their ecological niches in the landscape. They inevitably produce construction documents (planting plans, irrigation plans, and specifications) that do not reflect the intent of the conceptual plan. This problem is then often confounded by revegetation designers who are unable to correct such mistakes because they cannot read landscape architecture documents. Yet, it is these documents, not the conceptual plans, that are used to install projects. The use of white aider at several wetland mitigation sites in the San Diego area are perfect examples. The plans call for planting this tree six to nine meters (20 to 30 feet) above the water table when it naturally occurs within 0.3 to 1.2 meters (1 to 4 feet) along the stream edge. Likewise, this species is often placed on landscape plans out of all proportion to its presence in natural populations simply because it is the only species the landscape architects are familiar with in the plant palette. To resolve this problem revegetation designers should know planting and irrigation plan symbolism well enough to review and approve all construction documents. In most cases they should either be in a position to produce the initial landscape planting plan or provide the landscape architect in the conceptual mitigation plan with typical habitat planting layouts using landscape architectural symbols. These layouts should show both mature spread of species and describe their ideal ecological locations. Finally, the revegetation designer must be able to modify standard landscape specification packages to suit revegetation project requirements° Fourth, the revegetation designer must be enough of a nurseryman to know what native plants are available and which ones will do well under the environmental regime created at the project site. Plans should not specify a multitude of species not currently in production without making adequate provision for their collection or production. Contract growing should be required to alleviate problems of obtaining plants and revegetation designers should oversee plant production. Designers should aiso severely limit substitutions in the specifications, as such latitude usually leads to an oversimplification of the plant paiette. Designers should write specifications in order to procure or grow important but difficult to obtain species. 236