Biodiversity in the 21st Century: Humanity in a fraying web of life

The diversity of (and interrelationships among) plants, animals and other organisms form the basis of the “web of life” and the biogeochemical processes that circulate matter and energy throughout the biosphere. The "ecosystem services" provided by nature include atmospheric and hydrological regulation, clean water, soil formation, erosion control, food, timber, biological control, genetic resources, waste sinks and a range of social, cultural and aesthetic values. The value of these ecosystem services to humanity in 1997 was estimated to be in the range of US$16-54 trillion per year (Costanza & Arge et al. 1997).

The diversity of life (biodiversity) exists on three levels: ecosystems, species and genetics. The total number of species on earth is unknown. The number of accepted published species varies from year to year, as new species are discovered, and existing species are "lumped" or "split", or become extinct. In 2009, the global count close 1.9 million species and growing at the rate of about 18,000 species per year, while the Australian count was close to 148,000 species (Chapman 2009). Overall, our knowledge of life is biased towards species that are "large", easy to find or are of interest to us.