Mapping and conservation importance rating of the South African coastal vegetation as an aid to development planning

Abstract

In 1989, the opportunity was identified to create a botanical map series which could be used by authorities to make informed decisions and which would highlight the potential impact significance of proposed coastal developments on affected plant community types. In the past, vegetation impact assessments were conducted on a site specific basis and usually included community descriptions and species lists, which contributed little towards objective decision making. Impact significance at a broader, more meaningful spatial scale, for example bio-geographical regions, was rarely established. Based on the needs and the recognised problems, the CSIR developed a protocol for coastal vegetation mapping which included the following: (1) Simplification of the phytosociological complexity by recognising community types rather than communities as the phytosociological units; (2) Development of simple algorithm to determine a relative conservation importance hierarchy for the community types. Variables which are considered to be important for determining conservation importance are used in the algorithm; (3) Creation of a standard colour code to represent relative botanical importance for easy interpretation by non-experts; (4) Division of an approximately 1 km wide strip of the South African coastline into bio-geographical regions so that botanical importance could be established initially at an ecologically meaningful spatial scale; (5) The use of recent, 1:10000 colour aerial photography as a baseline for all mapping and the standardisation of the mapping scale at 1:10000, based on the orthophoto map series, which is a recognised planning scale and which is adequate to identify and map community types; (6) The use of a Geographic Information System to capture and store the vegetation data and to produce high quality maps. The benefits of the vegetation maps are that better decisions can be made with respect to the assessment of the significance of potential development impacts on coastal vegetation. Also, where vegetation importance is a key issue, this is recognised early in the decision making process. The strategy used to express relative botanical conservation importance has greatly facilitated the capability to perform objective first level assessments of potential development impact significance on coastal vegetation.