IDENTIFYING MINIMUM SETS OF CONSERVATION SITES FOR REPRESENTING BIODIVERSITY IN CANADA: A COMPLEMENTARITY APPROACH

Abstract

OBJECTIVES -To construct an equal-area geo-referenced sampling grid for Canada. -To digitise available range maps for common and COSEWIC species in Canada. -To identify important sites for biodiversity in Canada using a new statistical predictor of conservation value. METHODS -An equal-area grid of 10,000 km2 hexagons was constructed from the truncated icosahedron on a Lambert azimuthal equal-area map projection. -The ranges of 697 common and COSEWIC mammals, birds, reptiles, and amphibians, and COSEWIC fish, plants, lepidoptera and molluscs were digitised within the equal-area grid. -The areas of 217 ecoregions were also digitised within the equal-area grid. -C-Plan, a conservation planning software program, was used to identify important conservation areas and minimum sets of sites required to represent either (i) each taxa once, and/or (ii) 12 % of the area of each ecoregion, using 10 combinations of taxa and ecoregions. RESULTS -An equal-area grid of 1,455 10,000 km2 hexagons was constructed for Canada; 1,275 hexagons either completely or partially covered terrestrial Canada. -There were significant positive correlations between the irreplaceability of sites (hexagons) for most of the focal groups. -We identified four general areas of special importantance for biodiversity conservation in Canada; Okanagan Valley (British Columbia), mid-Prairies (Manitoba and Saskachewan) Niagara Peninsula (Ontario). Other important areas were also located near to the southern United States border. -Minimum set analyses indicated that all mammals could be represented in 16 hexagons, all birds in 14 hexagons, all amphibians and all reptiles in 9 hexagons each, and all COSEWIC species in 55 hexagons. 12 % of all 217 ecoregions could be represented within 188 hexagons. All terrestrial vertebrates could be represented in 31 hexagons, and all terrestrial vertebrates and 12 % of all ecoregions in 187 hexagons. -Of the sub-sets that we used as focal groups, using all mammals or all birds captured the greatest proportion of taxa in other focal groups. CONCLUSIONS -The most important sites for biodiversity conservation in Canada are located near the southern United States border. This is because (i) many non-COSEWIC species that are common in continental North America occur in southern Canada, and (ii) many COSEWIC species are also located in southern Canada. With increasing latitude there are fewer species, and these species have larger distributions (i.e., are generally common). -Since there was high overlap in the distributions of important conservation sites between groups of taxa (birds, mammals, reptiles, and amphibians) deciding the location of protected areas on the basis of just one of these groups alone could also benefit other taxa. -The 12 % area-target for ecoregion alone did not protect all species, indicating that area-based targets may not represent all biodiversity. -The techniques developed during this study show considerable promise for identifying important areas for biodiversity conservation at different scales and in different parts of the globe. The principal limiting factor for the application of this methodology is the availability of suitable species distribution data.