HOW TO MAXIMIZE BIOLOGICAL DIVERSITY IN NATURE-RESERVE SELECTION - VASCULAR PLANTS AND BREEDING BIRDS IN DECIDUOUS WOODLANDS, WESTERN NORWAY

One aim in nature reserve selection is to identify a set of reserves that includes all species of interest. Three possible quantitative methods to obtain this goal are presented here, using plant and bird lists from 60 deciduous woods in western Norway. The first method concentrates on the number of so-called endemic species (i.e. those present at only one site). The second repeatedly selects a chosen number of sites al random, aiming at maximising the number of species for that number of sites. The third procedure finds the smallest set of sites that will include each species at least once. Seventy-five per cent of the total area surveyed is needed to preserve all plant species, but only 20% to ensure total representation of the bird species. The existing reserve system in the area (12 woods), selected by traditional non-quantitative procedures has not maximised biological diversity because the sites, to a large extent, duplicate each other. Results from the three methods are discussed and compared with related broad-scale studies in Australia.