Narrowing global species estimates

Abstract

In the latter half of the twentieth century, biologists using knockdown insecticides discovered the previously unrecognised and enormous diversity of life, particularly of insects and arthropods, in the canopy of tropical and temperate forests (Erwin 1982; Stork 1988). Such discoveries led to the suggestion that the canopy is ‘the last biotic (or biological) frontier’ (Stork 1995). Some speculated that the Earth held 30 million or more arthropod species and that most of these were undescribed species in the canopy of tropical forests (Erwin 1982, 1988, 1991). These discoveries coincided with revelations that tropical forests were being harvested or cleared at alarming rates around the world and led to many leading biologists suggesting that this might lead to the extinction of a large proportion of tropical species. These issues were highlighted by Wilson and Peter (1988) and were also of critical importance in driving the signing of the Convention on Biological Diversity by 193 countries (subsequently ratified by 168 countries) in 1992.