Elevated CO ₂ Reduces Losses of Plant Diversity Caused by Nitrogen Deposition

Mitigating Nitrogen Enrichment? Nitrogen enrichment reduces the species diversity of plants in herbaceous communities. By contrast, the effects of increasing CO 2 on plant species richness is poorly documented, and the interaction of both N deposition and CO 2 elevation are unknown. Reich (p. 1399 ; see the Perspective by Collins ) performed a 10-year open-air field experiment in a North American perennial grassland assemblage. Reductions in plant species richness resulting from N deposition were half as large under elevated CO 2 concentrations as under ambient atmospheric CO 2 . Given that both N and CO 2 are projected to increase globally, these results provide a pointer to the types of ecological change that could be expected, at least in relatively simple plant communities.