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Hindi Research Article
Leaf Photosynthesis and Plant Competitive Success in a Mixed-grass Prairie: With Reference to Exotic Grasses Invasion
Dong X1,2*, Patton J2, Gu L3, Wang J4 and Patton B21Texas A&M AgriLife Research and Extension Center, Uvalde, Texas-78801, USA
2North Dakota State University, Central Grasslands Research Extension Center, Streeter, N.D. 58483, USA
3Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee-37831, USA
4Chinese Research Academy of Environmental Sciences, No. 8 Dayangfang, Beiyuan, Chaoyang District, Beijing- 100012, China
- *Corresponding Author:
- Xuejun Dong
Assistant Professor of Crop Physiology
Texas A&M AgriLifer Research and Extension Center, Uvalde, Texas-78801, USA
Tel: 830-278-9151
E-mail: xuejun.dong@ag.tamu.edu
Received date: October 19, 2014; Accepted date: November 10, 2014; Published date: November 26, 2014
Citation: Dong X, Patton J, Gu L, Wang J, Patton B (2014) Leaf Photosynthesis and Plant Competitive Success in a Mixed-grass Prairie: With Reference to Exotic Grasses Invasion. J Ecosys Ecograph 4:152. doi:10.4172/2157-7625.1000152
Copyright: 2014 Dong X, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
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. 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. Also, 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 dominance 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. It has implications for the stability and productivity of the grassland under various human disruptions influencing the soil nutrient status.
