Using higher-taxon richness as a surrogate for species richness: II. Local applications

Abstract

Recent analyses confirm that urgent attempts to catalogue the distribution of biological diversity may be facilitated by focusing at the level of genera or families rather than species. However, questions remain over the application of higher-taxon surveys to identify networks of priority areas for conservation action. Is the close spatial match between species and higher-taxon richness at global and regional scales re-iterated when sites are locally distributed? How much money is saved by the higher-taxon approach? And how does using genus or family information affect the efficiency with which spatial priorities for conservation are identified? We examined these issues using data on the diversity of woody plants in Sri Lankan forests. We found that at this local scale, the family and particularly generic richness of sites was closely linked to their species richness, independently of variation in site size. Moreover, fieldwork in an additional forest showed that targeting woody plant genera and families rather than species reduced survey costs by a minimum of 60% and 85% respectively. Most importantly, while using family data in site-selection algorithms led to the loss from reserve networks of around 7-10% of woody plant species, using genera rather than species had virtually no effect on the representation of species in priority sites. These results thus confirm that judicious use of the higher-taxon approach is indeed a valuable technique for improving the cost effectiveness of field surveys for local conservation planning in the tropics.