De botanische waardering van ecotopen als bijdrage tot een globale waardering van het natuurlijk milieu

A method is described for the botanical evaluation of ecotopes as part of a general evaluation of the natural environment. Ecotopes are defined as ecologically uniform landscape units corresponding to larger ecosystems or ecosystem complexes. They are spatial units to be recognized on topographical maps scale 1:50.000.76 Ecotope types are listed in table 1. Per ecotope an estimation is given of a. the degree of naturalness (for completely developed ecosystems) ranging from 0 (cultural) to 9 (natural). b. the international significance, mainly based on the relative importance of the Netherlands for the existence of the vegetation complex in its entire distribution area. c. national significance, mainly based on the rarity within the Netherlands (both scales from 0—9). Ecotopes are distinguished as complexes in larger landscape units, which are taken as a basis for a national environmental survey. The botanical value of each landscape unit is calculated by weighting each ecotope within the unit with its areal dominance and its botanical value (the latter being taken as the highest value of either b or c). The limitations of the method are discussed. Its use is provisional and the method may be abandoned as soon as detailed floristic and phytosociological field work will have been carried out.