A Comparison of Richness Hotspots, Rarity Hotspots, and Complementary Areas for Conserving Diversity of British Birds

Abstract

Biodiversity conservation requires efficient methods for choosing priority areas for in situ conservation management. We compared three quantitative methods for choosing 5% (an arbitrary figure) of all the 10 × 10 km grid cells in Britain to represent the diversity of breeding birds: (1) hotspots of richness, which selects the areas richest in species; (2) hotspots of range‐size rarity (narrow endemism), which selects areas richest in those species with the most restricted ranges; and (3) sets of complementary areas, which selects areas with the greatest combined species richness. Our results show that richness hotspots contained the highest number of species‐in‐grid‐cell records (with many representations of the more widespread species), whereas the method of complementary areas obtained the lowest number. However, whereas richness hotspots included representation of 89% of British species of breeding birds, and rarity hotspots included 98%, the areas chosen using complementarity represented all the species, where possible, at least six times over. The method of complementary areas was also well suited to supplementing the existing conservation network. For example, starting with grid cells with over 50% area cover by existing “Sites of Special Scientific Interest,” we searched for a set of areas that could complete the representation of all the most threatened birds in Britain, the Red Data species. The method of complementary areas distinguishes between irreplaceable and flexible areas, which helps planners by providing alternatives for negotiation. This method can also show which particular species justify the choice of each area. Yet the complementary areas method will not be fully able to select the best areas for conservation management until we achieve integration of some of the more important factors affecting viability, threat, and cost.

Addressing longitudinal connectivity in the systematic conservation planning of fresh waters

“…Algorithms which incorporate complementarity ensure representativeness, in addition to persistence, which is the other major goal in systematic conservation planning, (Margules & Pressey, 2000;Margules et al, 2002). This guaranties the adequate representation of each species within the reserve, overcoming uncovered deficiencies in other reserve selection methods based in scoring and ranking approaches (Williams et al, 1996;Margules et al, 2002). 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 The figure in the middle corresponds to the trade-off CP value set in Fig.…”

“…While traditional conservation tools relied on crude scoring approaches based on different criteria such as species richness, rarity value, naturalness, or size (Williams et al, 1996), modern conservation planning methods use complementarity-based algorithms and proper problem definition. Complementarity is defined as the gain in representativeness of biodiversity when a site is added to an existing set of areas (Possingham, Ball & Andelman, 2000).…”

Biogeographical patterns of endemic terrestrial Afrotropical birds

“…Approaches vary from the 100% restrictedness in classic definitions of narrow endemism (Williams et al, 1996), to the 50% cutoff of the Braun-Blanquet floristic association method (e.g. Westhoff & van der Maarel, 1973).…”

Patterns of species richness and narrow endemism of terrestrial bird species in the Afrotropical region

“…The 5% criterion is an arbitrary, but frequently used, cut-off level (e.g. Myers, 1988Myers, , 1990Prendergast et al, 1993;Lombard, 1995;Williams, et al, 1996b). However, there was concern that an arbitrary cut-off may bias results of comparisons of hotspot sets.…”