Do species and functional groups differ in acquisition and use of C, N and water under varying atmospheric CO₂ and N availability regimes? A field test with 16 grassland species

Authors

• Peter B. Reich, University of Minnesota, St. Paul, MN
• David Tilman, University of Minnesota, St. Paul, MN
• Joseph Craine, University of California, Berkeley, CA
• David Ellsworth, Brookhaven National Laboratory, Upton, NY
• Mark G. Tjoelker, University of Minnesota, St. Paul, MN
• Johannes M. H. Knops, University of Nebraska-LincolnFollow
• David A. Wedin, University of Nebraska-LincolnFollow
• Shahid Naeem, University of Washington, Seattle, WA
• Dan Bahauddin, University of Minnesota, St. Paul, MN
• Jenny Goth, University of Minnesota, St. Paul, MN
• Wendy Bengtson, University of Minnesota, St. Paul, MN
• Tali D. Lee, University of Minnesota, St. Paul, MN

Document Type

Article

Date of this Version

3-30-2001

Comments

Published in New Phytologist (2001) 150 : 435–448.

Abstract

Summary:

• To evaluate whether functional groups have a similar response to global change, the responses to CO₂ concentration and N availability of grassland species from several functional groups are reported here.
• Sixteen perennial grassland species from four trait-based functional groups (C₃ grasses, C₄ grasses, non-leguminous forbs, legumes) were grown in field mono-cultures under ambient or elevated (560 μmol mol^-1) CO₂using free-air CO₂enrichment (FACE), in low N (unamended field soil) or high N (field soil + 4 g N m^-2 years^-1) treatments.
• There were no CO₂ x N interactions. Functional groups responded differently to CO₂ and N in terms of biomass, tissue N concentration and soil solution N. Under elevated CO₂, forbs, legumes and C₃grasses increased total biomass by 31%, 18%, and 9%, respectively, whereas biomass was reduced in C₄-grass mono-cultures. Two of the four legume species increased biomass and total plant N pools under elevated CO₂, probably due to stimulated N-fixation. Only one species markedly shifted the proportional distribution of below- vs aboveground biomass in response to CO₂ or N.
• Although functional groups varied in responses to CO₂and N, there was also substantial variation in responses among species within groups. These results suggest that current trait-based functional classifications might be useful, but not sufficient, for understanding plant and ecosystem responses to elevated CO₂and N availability.