Responses of Ecosystem Carbon Cycling to Climate Change Treatments Along an Elevation Gradient
Global temperature increases and precipitation changes are both expected to alter ecosystem carbon (C) cycling. We tested responses of ecosystem C cycling to simulated climate change using field manipulations of temperature and precipitation across a range of grass-dominated ecosystems along an elevation gradient in northern Arizona. In 2002, we transplanted intact plant–soil mesocosms to simulate warming and used passive interceptors and collectors to manipulate precipitation. We measured daytime ecosystem respiration (ER) and net ecosystem C exchange throughout the growing season in 2008 and 2009. Warming generally stimulated ER and photosynthesis, but had variable effects on daytime net C exchange. Increased precipitation stimulated ecosystem C cycling only in the driest ecosystem at the lowest elevation, whereas decreased precipitation showed no effects on ecosystem C cycling across all ecosystems. No significant interaction between temperature and precipitation treatments was observed. Structural equation modeling revealed that in the wetter-than-average year of 2008, changes in ecosystem C cycling were more strongly affected by warming-induced reduction in soil moisture than by altered precipitation. In contrast, during the drier year of 2009, warming induced increase in soil temperature rather than changes in soil moisture determined ecosystem C cycling. Our findings suggest that warming exerted the strongest influence on ecosystem C cycling in both years, by modulating soil moisture in the wet year and soil temperature in the dry year.
Key wordswarming precipitation gross ecosystem photosynthesis ecosystem respiration net ecosystem exchange structural equation model
- Atkin OK, Millar AH, Gardeström P, Day DA. 2000. Photosynthesis, carbohydrate metabolism, and respiration in leaves of higher plants. In: Legood RC, Sharkey TD, von Cammerer S, Eds. Photosynthesis: physiology and metabolism. Dordrecht: Kluwer Academic Publishers. p 153–75.Google Scholar
- Browne MW, Cudeck R. 1993. Alternative ways of assessing model fit. In: Bollen KA, Long JS, Eds. Testing structural equation models. Newbury Park, CA: Sage Publications. p 136–62.Google Scholar
- Christensen JH, Hewitson B, Busuioc A, Chen A, Gao X, Held I, Jones R, Kolli RK, Kwon WT, Laprise R, Magana Rueda V, Mearns L, Menendez CG, Raisanen J, Rinke A, Sarr A, Whetton P. 2007. Regional climate projections. In: Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M, Miller HL, Eds. Climate change 2007: the physical science basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK/New York, NY: Cambridge University Press.Google Scholar
- Garbulsky MF, Peñuelas J, Papale D, Ardo J, Goulden ML, Kiely G, Richardson AD, Rotenberg E, Veenendaal EM, Filella I. 2010. Patterns and controls of the variability of radiation use efficiency and primary productivity across terrestrial ecosystems. Glob Ecol Biogeogr 19:253–67.CrossRefGoogle Scholar
- Intergovernmental Panel on Climate Change (IPCC). 2007. Climate change 2007: the physical science basis-summary for policy makers. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC WGI 4th Assessment Report.Google Scholar
- Luo YQ, Gerten D, Le Maire G, Parton WJ, Weng ES, Zhou XH, Keogh C, Beier C, Ciais P, Cramer W, Dukes JS, Emmett B, Hanson PJ, Knapp A, Linder S, Nepstad D, Rustad L. 2008. Modeled interactive effects of precipitation, temperature, and [CO2] on ecosystem carbon and water dynamics in different climatic zones. Glob Change Biol 14:1986–99.CrossRefGoogle Scholar
- Saleska SR, Miller SD, Matross DM, Goulden ML, Wofsy SC, da Rocha HR, de Camargo PB, Crill P, Daube BC, de Freitas HC, Hutyra L, Keller M, Kirchhoff V, Menton M, Munger JW, Pyle EH, Rice AH, Silva H. 2003. Carbon in Amazon forests: unexpected seasonal fluxes and disturbance-induced losses. Science 302:1554–7.PubMedCrossRefGoogle Scholar
- Silver WL, Jackson RD, Allen-Diaz B. 2005. Soil carbon dynamics of California grasslands under altered soil moisture regimes. Kearney Foundation of Soil Science Final Report: 1–14.Google Scholar
- Soussana JF, Allard V, Pilegaard K, Ambus P, Ammann C, Campbell C, Ceschia E, Clifton-Brown J, Czobel S, Domingues R, Flechard C, Fuhrer J, Hensen A, Horvath L, Jones M, Kasper G, Martin C, Nagy Z, Neftel A, Raschi A, Baronti S, Rees RM, Skiba U, Stefani P, Manca G, Sutton M, Tuba Z, Valentini R. 2007. Full accounting of the greenhouse gas (CO2, N2O, CH4) budget of nine European grassland sites. Agric Ecosyst Environ 121:121–34.CrossRefGoogle Scholar
- Weltzin JF, Loik ME, Schwinning S, Williams D, Fay P, Haddad B, Harte J, Huxman T, Knapp A, Lin G, Pockman W, Shaw R, Small E, Smith M, Smith SD, Tissue D, Zak J. 2003. Assessing the response of terrestrial ecosystems to potential changes in precipitation. Bioscience 53:941–52.CrossRefGoogle Scholar
- Wu Z, Dijkstra P, Koch GW, Penuelas J, Hungate BA. 2010. Responses of terrestrial ecosystems to temperature and precipitation change: a meta-analysis of experimental manipulation. Glob Change Biol. doi:10.1111/j.1365-2486.2010.02302.x.