Content area
Full Text
The most unique feature of Earth is the existence of life, and the most extraordinary feature of life is its diversity. Approximately 9 million types of plants, animals, protists and fungi inhabit the Earth. So, too, do 7 billion people. Two decades ago, at the first Earth Summit, the vast majority of the world's nations declared that human actions were dismantling the Earth's ecosystems, eliminating genes, species and biological traits at an alarming rate. This observation led to the question of how such loss of biological diversity will alter the functioning of ecosystems and their ability to provide society with the goods and services needed to prosper.
In the past 20 years remarkable progress has been made towards understanding how the loss of biodiversity affects the functioning of ecosystems and thus affects society. Soon after the 1992 Earth Summit in Rio de Janeiro, interest in understanding how biodiversity loss might affect the dynamics and functioning of ecosystems, and the supply of goods and services, grew dramatically. Major international research initiatives formed; hundreds of experiments were performed in ecosystems all over the globe; new ecological theories were developed and tested against experimental results.
Here we review two decades of research that has examined how biodiversity loss influences ecosystem functions, and the impacts that this can have on the goods and services ecosystems provide (Box 1). We begin with a brief historical introduction. We then summarize the major results from research that has provided increasingly rigorous answers to the question of how and why the Earth's biological diversity influences the functioning of ecosystems. After this, we consider the closely related issue of how biodiversity provides specific ecosystem services of value to humanity. We close by considering how the next generation of biodiversity science can reduce our uncertainties and better serve policy and management initiatives.
A brief history
During the 1980s, concern about the rate at which species were being lost from ecosystems led to research showing that organisms can influence the physical formation of habitats (ecosystem engineering1), fluxes of elements in biogeochemical cycles (for example, ecological stoichiometry2), and the productivity of ecosystems (for example, via trophic cascades and keystone species3). Such research suggested that loss of certain life forms could substantially alter the structure and functioning...