A healthy world needs lots of species
Effects of biodiversity loss could be worse than previously thought.
Biodiversity loss could impact food production, water quality and carbon dioxide levels more than previously thought, scientists have discovered.
Andy Hector of the University of Zurich, Switzerland, and his colleague Robert Bagchi from the University of Oxford, UK, developed a method to analyse how the number of species in a place affects its combined set of ecosystem processes such as decomposition and soil formation, nutrient and water recycling and plant growth. A 1997 estimate put the value of such ecosystem services to humanity as US$33 trillion a year.
Using data for European grasslands, Hector and Bagchi discovered that as more ecological processes are taken into account, the number of species required to sustain them also increases. Most previous studies have looked at ecosystem processes in isolation.
"Previous analyses have been too narrowly focused and have effectively assumed that the species that are important for one ecosystem process can provide all the other services too," says Hector. "But that doesn't seem to be the case." The results are reported in Nature1.
The groupy effect
The study provides the first evidence that the different ecosystem processes in a place are affected by different groups of species. "People have talked about this before but there has been nothing to support it up to now," says Owen Petchey of the University of Sheffield, UK.
"The work suggests that for a fully functioning ecosystem, with many functions, the maximum number of species must be conserved," says Petchey. "All biodiversity is essential, and none is redundant. This finding has great potential to affect policy, because humanity relies on many essential services from ecosystems."
A 2005 United Nations report concluded that humans have done more damage to biological diversity in the past 50 years than at any other time in history. Unless this trend is halted, the report warned, people will lose vital benefits from the natural world.
- Hector, A. & Bagchi, R. Nature 448, 188-190 (2007).