Contrasting sensitivities of two dominant C4 grasses to heat waves and drought
- 534 Downloads
Heat waves and droughts are predicted to increase in frequency and intensity with climate change. However, we lack a mechanistic understanding of the independent and interactive effects of severe heat and water stress for most ecosystems. In a mesic tallgrass prairie ecosystem, we used a factorial experimental approach to assess ecophysiological and productivity responses of two dominant C4 grasses, Andropogon gerardii and Sorghastrum nutans, to a season-long drought and a mid-summer heat wave at four intensities. We hypothesized that drought would have greater impacts than heat waves, that combined effects would be greater than either factor alone, and that the dominant grasses would differ in their responses to heat and water heat stress. We detected significant reductions in photosynthesis, leaf water potential, and productivity with drought but few direct responses to the heat waves. Surprisingly, there was no additive effect of heat and water stress on any plant response. However, S. nutans was more sensitive than A. gerardii to drought. In this grassland, water stress will likely dominate photosynthetic and productivity responses caused by discrete drought and heat wave events, rather than direct or additive effects of heat stress, with differential sensitivity in these grasses altering future ecosystem structure and function.
KeywordsClimate change Climate extremes Photosynthesis Productivity Mesic grassland
We would like to thank P. O’Neal, J. Taylor, K. Wilcox, K. Duffy, A. Bennett, R. Song, M. Avolio, S. Koerner, K. La Pierre, T. Dugger, C. Blair, J. Blair, J. Briggs, J. Nippert, J. Larkins, and T. Van Slyke as well as the Konza Prairie LTER, Kansas State University Biology Department and the Department of Energy (DE-PS02-07ER0-02-ER63892).
- Arnone JA, Jasoni RL, Lucchesi AJ, Larsen JD, Leger EA, Sherry RA, Luo Y, Schimel DS, Verburg PSJ (2011) A climatically extreme year has large impacts on C4 species in tallgrass prairie ecosystems but only minor effects on species richness and other plant functional groups. J Ecol 99:678–688CrossRefGoogle Scholar
- Ellison AM, Bank MS, Clinton BD, Colburn EA, Elliott K, Ford CR, Foster DR, Kloeppel BD, Knoepp JD, Lovett GM, Mohan J, Orwig DA, Rodenhouse NL, Sobczak WV, Stinson KA, Stone JK, Swan CM, Thompson J, Von Holle B, Webster JR (2005) Loss of foundation species: consequences for the structure and dynamics of forested ecosystems. Front Ecol Environ 3:479–486CrossRefGoogle Scholar
- IPCC (2013) Climate change 2013: the physical science basis. Contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change [Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (eds)]. Cambridge University Press, CambridgeGoogle Scholar
- Knapp AK, Briggs JM, Hartnett DC, Scott SL (1998) Grassland dynamics: long-term ecological research in tallgrass prairie. Oxford University Press, New YorkGoogle Scholar
- Reichstein M, Ciais P, Papale D, Valentini R, Running S, Viovy N, Cramer W, Granier A, Ogee J, Allard V, Aubinet M, Bernhofer C, Buchmann N, Carrara A, Grunwald T, Heimann M, Heinesch B, Knohl A, Kutsch W, Loustau D, Manca G, Matteucci G, Miglietta F, Ourcival JM, Pilegaard K, Pumpanen J, Rambal S, Schaphoff S, Seufert G, Soussana JF, Sanz MJ, Vesala T, Zhao M (2007) Reduction of ecosystem productivity and respiration during the European summer 2003 climate anomaly: a joint flux tower, remote sensing and modelling analysis. Glob Change Biol 13:634–651CrossRefGoogle Scholar
- Sage RF, Monson RK (1999) C4 plant biology. Academic Press, San DiegoGoogle Scholar
- Tilman D, Elhaddi A (1992) Drought and biodiversity in grasslands. Oecologia 89:257–264Google Scholar