Abstract
Leaf gas exchange responses to elevated CO2 and N are presented for 13 perennial species, representing four functional groups: C3 grasses, C4 grasses, legumes, and nonleguminous forbs. Understanding how CO2 and N effects interact is important to predict plant community response to global change. Plants were field-grown in monoculture under current ambient and elevated (560 μmol mol-1) CO2 concentrations (free-air CO2 enrichment), in combination with soil N treatments, for two growing seasons. All species, regardless of functional group, showed pronounced photosynthetic acclimation to elevated CO2, resulting in minimal stimulation of photosynthesis (A) averaging +15% in C3 grasses, +8% in forbs, +7% in legumes and -2% in C4 grasses. The effects of CO2 and soil N supply did not interact for any leaf traits measured. Elevated CO2 consistently decreased stomatal conductance (gs) leading to 40% increase in A/gs. This substantial acclimation of photosynthesis was greater in magnitude than in most field studies, and was associated with the combined effects of decreased gs and decreased leaf N concentrations in response to growth under elevated CO2.
Original language | English (US) |
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Pages (from-to) | 405-418 |
Number of pages | 14 |
Journal | New Phytologist |
Volume | 150 |
Issue number | 2 |
DOIs | |
State | Published - 2001 |
Keywords
- Elevated CO
- Functional groups
- Nitrogen availability
- Photosynthetic acclimation
- Prairie grassland
- Stomatal conductance