Effects of warming and altered precipitation regime on managed grassland structure and function

Managed grasslands cover >12 million hectares of the United States and are particularly predominant within the ‘transition zone' from subtropical to temperate climes in the southeastern region. Despite the large acreage and significant contribution to regional net primary production (NPP) coming from these grasslands, no scientific studies addressing their response to alterations in climate have been performed to date. The primary objective of this study is to determine how alterations in precipitation and temperature impact managed grassland structure and function.

Managed grasslands are dominated by ‘forage' species bred to support high levels of production across broad environmental conditions and to withstand grazing. These species employ different mechanisms to attain these characteristics, some of which may be more responsive to changes in climate than others. For example, a drier environment may favor endophyte-infected tall fescue over other cool season forages because the symbiotic fungal relationship confers drought resistance to the plant. Conversely, a warmer, wetter climate may promote species capable of rapid maturation or producing secondary compounds. Such species shifts and associated changes in litter quality may directly impact nutrient cycling in these ecosystems. This project tests the hypotheses that: 1) climate change (in the form of increased temperature and precipitation) will have predictable consequences on managed grassland structure based on known species-specific traits; and 2) these changes in structure will alter grassland function, specifically NPP and trace gas flux.

 

This project ran from 2009-2013.  Data are currently being analyzed and written up. The infrastructure has been modified to support a new climate change-grass-fungal endophyte project that started April 2016 (see 'Symbiotic Climate Resiliency' page).
 
Associated Manuscripts:
Slaughter, L.C., J.A. Nelson, E. Carlisle, M. Bourguignon, R.D. Dinkins, T.D. Phillips, and R.L. McCulley. 2018. Climate change and Epichloë coenophiala association modify belowground fungal symbioses of tall fescue host. Fungal Ecology 31: 37-46.
Bourguignon, M., J.A. Nelson, A.E. Carlisle, H. Ji, R.D. Dinkins, T.D. Phillips, and R.L. McCulley. 2015. Ecophysiological responses of tall fescue genotypes to fungal endophyte infection and elevated temperature and precipitation. Crop Science 55:2895-2909. doi: 10.2135/cropsci2015.01.0020.
Slaughter, L.C., M.N. Weintraub, and R.L. McCulley. 2015. Seasonal effects stronger than three-year climate manipulation on grassland soil microbial community. Soil Science Society of America Journal 79:1352-1365. doi: 10.2136/sssaj2014.10.0431
McCulley, R.L., L.P. Bush, A.E. Carlisle, H. Ji, J.A. Nelson. 2014. Warming reduces tall fescue abundance but stimulates toxic alkaloid concentrations in transition zone pastures of the U.S.” Frontiers in Chemistry, 10.3389/fchem.2014.00088
Rúa, M.A., R.L. McCulley, and C.E. Mitchell. 2014. Climate drivers, host identity and fungal endophyte infection determine virus prevalence in a grassland ecosystem. Journal of Ecology 102(3):690-699.
Brosi, G.B., R.L. McCulley, L.P. Bush, J.A. Nelson, A.T. Classen, and R.J. Norby. 2011. Effects of multiple climate change factors on the tall fescue – fungal endophyte symbiosis: infection frequency and tissue chemistry. New Phytologist 189:797-805.
Please contact Rebecca for copies
  Raising heaters to evenly heat vegetation and soil.

Raising heaters to evenly heat vegetation and soil.

  Additional precipitation on rainy days to mimic an increase in the intensity of summer storms.

Additional precipitation on rainy days to mimic an increase in the intensity of summer storms.