Counting Species: Making Choices

Abstract

Imagine that you are charged with going into an ecosystem and assessing its biodiversity. But there's a catch you can only study one plant family. Which should you choose? The legumes, say researchers at the Royal Botanical Gardens in Kew, London. A preliminary assessment of plant diversity and distribution, put together by Kew graduate student Neil Brummitt, suggests that legume diversity most closely mirrors total plant diver? sity. Legumes occur in many dif? ferent habitats in significant numbers, says Kew's science coordinator, plant taxonomist Eimear Nic Lughadha. If you are allowed to count two families, however, grasses and orchids give the best result. They're a comple? mentary pair, explains Lughadha. Orchids are diverse in tropical forests, grasses in open areas. Conservation biologists need such shortcuts. The strategic plan for the Convention on Biological Diversity (CBD) contains a commitment to substantially reduce the rate of biodiversity loss by 2010. Yet for most ecosystems we do not even know what is there, let alone what is being lost and how fast. Monitoring a few represe tative groups such as legumes m ght reveal general trends. To gauge whether the rate of bio? diversi y loss is changing requires data from at least three points in time: the first two to describe the