What was done
The authors reviewed 225 pertinent scientific papers in an attempt to synthesize existing knowledge relative to the relationship between ecosystem net primary production and species richness, using data derived from terrestrial, wetland and aquatic environments.

What was learned
Much variability was encountered in terms of both relationships and reasons for the relationships.  It was also discovered that relationships between diversity and productivity were scale-dependent, with the form of the scale-dependence varying from study to study.  On the largest of scales considered, however - the continental to global scale - the most common pattern encountered was a positive one, with ecosystem species richness increasing in response to increases in ecosystem net primary production.  This was dramatically so for plants and marginally so for animals.

What it means
With the CO2 content of the air increasing on the planetary scale, we take these findings to suggest that the aerial fertilization effect of the ongoing rise in atmospheric CO2 concentration is providing a very real impetus for increased net primary production everywhere on earth and, hence, an increased impetus for preserving - and even enhancing - the species richness of both plants and animals over the entire globe.  This conclusion further suggests that we not attempt to restrict anthropogenic CO2 emissions via Kyoto-style interventions (see our Editorial Biodiversity, Productivity and CO2); for with all of the other assaults on the biosphere produced by the activities of our burgeoning population, earth's plants and animals are going to need all the help they can get to maintain enough "critical biomass" to preserve their unique identities in the days and years ahead.