Content area
Full Text
ECOLOGY
An elaborate microcosm study has a message for the wider world: declining distributional equity among species, where the rare become rarer, and the dominant become more dominant, can put ecosystems at risk.
In the 1770s, Joseph Priestley, the father of biogeochemistry1, conducted his famous experiments in which he placed mice and mint plants in bottles, and discovered the balance between 'putrefying' and 'regenerative' processes. Priestley thus began the tradition of using organisms in microcosms to explore nature. He and his colleagues clearly recognized the global significance of his findings, despite their small scale. On page 623 of this issue, Wittebolle et al.2 describe ecological research in that tradition, but carried out with twenty-first-century tools.
Life on Earth is more than mice and mint, of course, with most ecosystems containing hundreds to thousands of plant, animal and microbial species. The balance between 'putrefying' and 'regenerative' processes in nature is better known today as the balance between respiration, decomposition, photosynthesis, primary production and many other ecosystem functions carried out by species that cycle matter between inorganic and organic forms. In the 1990s, motivated by growing concern over dramatic declines in biological diversity, ecologists began to test experimentally whether declining biodiversity - species richness - could adversely affect ecosystem functions. Early studies consisted of an eclectic mix of experiments, manipulating, for example, the richness of microbial species in Petri dishes or bottles, the richness of plant and animal species in growth chambers or artificial ponds, or the richness of plant species in grassland plots.
These investigations were surrounded by controversy, but most of them indicated that ecosystem functions, such as respiration and primary production, were indeed adversely affected by dramatic declines in biodiversity. Today, evidence that plant, animal and microbial biodiversity influences terrestrial3 and marine ecosystem functions4 has been documented by hundreds of studies. Such research, however, has focused on changes in species richness, in spite of the fact that changes in...