Rainfall variability has minimal effects on grassland recovery from repeated grazing
Article first published online: 12 MAR 2013
© 2013 International Association for Vegetation Science
Journal of Vegetation Science
Volume 25, Issue 1, pages 36–44, January 2014
How to Cite
Koerner, S. E., Collins, S. L., Blair, J. M., Knapp, A. K., Smith, M. D. (2014), Rainfall variability has minimal effects on grassland recovery from repeated grazing. Journal of Vegetation Science, 25: 36–44. doi: 10.1111/jvs.12065
- Issue published online: 16 DEC 2013
- Article first published online: 12 MAR 2013
- Manuscript Accepted: 25 JAN 2013
- Manuscript Received: 3 SEP 2012
- USDA CSREES Ecosystem Studies Program
- National Science Foundation Doctoral Dissertation Improvement Grant. Grant Number: DEB-0909912
- University of New Mexico Biology Department Springfield Scholarship
- Climate change;
- Stem density;
- Annual net primary production;
- Grass–forb interaction;
Mesic grasslands experience a complex disturbance regime including frequent fire, grazing by large ungulates and strong inter-annual climate variability. As a result of climate change, growing season precipitation regimes are predicted to become more variable, with larger event sizes and longer dry periods resulting in more temporally dynamic soil moisture regimes. Increased climate variability is likely to interact with other disturbances, such as grazing, in grassland ecosystems. We investigated the individual and combined effects of increased rainfall variability and grazing on plant community composition, structure and function in an annually burned, native tallgrass prairie. Our overarching question was: are grazing impacts modified under a more variable precipitation regime?
Konza Prairie, Kansas, USA.
Plots were established within a long-term rainfall manipulation experiment in which larger, but less frequent, rain events were imposed during the growing season without altering the total rain amount. We then simulated intense grazing pressure during one growing season by repeatedly clipping all graminoids to 5 cm and monitored recovery over 3 yr.
Neither grazing nor rainfall treatments affected species richness; however, grazing decreased total and grass above-ground net primary production (ANPP) and increased forb ANPP relative to ungrazed plots. Grass stem density recovered from intense grazing under ambient rainfall but did not fully recover, even after 2 yr in the altered rainfall treatment.
We found that increased rainfall variability had little effect on tallgrass prairie structure and function, while grazing had large effects. Grazing and increased rainfall variability interacted to suppress grass stem density and delayed recovery relative to controls. Although stem density was reduced, individual stem size increased, resulting in no net change in ANPP. This suggests that ANPP in grazed and ungrazed North American tallgrass prairie may be relatively resilient under more temporally variable precipitation regimes.