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Title: Leaf Photosynthesis and Plant Competitive Success in a Mixed-grass Prairie: With Reference to Exotic Grasses Invasion

The widespread invasion of exotic cool-season grasses in mixed-grass rangeland is diminishing the hope of bringing back the natural native plant communities. However, ecophysiological mechanisms explaining the relative competitiveness of these invasive grasses over the native species generally are lacking. In this study, we used experimental data collected in south-central North Dakota, USA to address this issue. Photosynthetic potential was obtained from the net assimilation (A) vs. internal CO2 (Ci) response curves from plants grown in a greenhouse. Plant success was defined as the average frequency measured over 25 years (1988 to 2012) on overflow range sites across five levels of grazing intensity. In addition, estimated leaf area index of individual species under field conditions was used to indicate plant success. The correlation between photosynthetic potential based on A/Ci curves and plant frequency was negative. The correlation between leaf photosynthesis and plant success (defined as leaf area within a unit land area) was also negative, although statistically weak. These results suggest that the two cool-season grasses, Poa pratensis and Bromus inermis, do not rely on superior leaf-level photosynthesis for competitive success. Instead, some other traits, such as early and late-season growth, may be more important for them to gain dominancemore » in the mixed-grass prairie. We propose that the negative photosynthesis-frequency relation as observed in this study results from a strong competition for limited soil nutrients in the mixed-grass prairie. In conclusion, it has implications for the stability and productivity of the grassland under various human disruptions influencing the soil nutrient status.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [2]
  1. Texas A & M Univ., College Station, TX (United States)
  2. North Dakota State Univ., Fargo, ND (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Chinese Research Academy of Environmental Sciences, Beijing (China)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Ecosystem & Ecography
Additional Journal Information:
Journal Volume: 4; Journal Issue: 152; Journal ID: ISSN 2157-7625
OMICS International
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES Bromus inermis; Invasive species; Leaf area index; Photosynthetic potential; Poa pratensis; Principal component analysis; Rangeland management