Main and interactive effects of warming, clipping, and doubled precipitation on soil CO2 efflux in a grassland ecosystem

[1] We conducted two experiments, one long term with a 2°C increase (Experiment 1) and one short term with a 4.4°C increase (Experiment 2), to investigate main and interactive effects of warming, clipping, and doubled precipitation on soil CO2 efflux and its temperature sensitivity in a U.S. tallgrass prairie. On average, warming increased soil CO2 efflux by 13.0% (p < 0.01) in Experiment 1, by 22.9% (p < 0.0001) in Experiment 2, and by 26.6% (p < 0.0001) in the transient study of Experiment 2. Doubled precipitation resulted in an increase of 9.0% (p < 0.05) in soil CO2 efflux in Experiment 2. Yearly clipping did not significantly affect soil CO2 efflux (p = 0.66) in Experiment 1, while clipping decreased soil CO2 efflux by 16.1% (p < 0.05) in the transient study. Temperature sensitivity of soil CO2 efflux significantly decreased from an apparent Q10 value of 2.51 in unwarmed plots to 2.02 in warmed plots without extra precipitation and from 2.57 to 2.23 with doubled precipitation in Experiment 2. No significant interactive effects among the experimental factors were statistically found on soil CO2 efflux or their temperature sensitivities except for the warming × clipping interaction (p < 0.05) in the transient study. Our observed minor interactive effects relative to main ones suggest that results from single-factor experiments are useful in informing us of potential responses of soil CO2 efflux to multifactor global change, at least in our ecosystem.

[1]  Yiqi Luo,et al.  Direct and indirect effects of experimental warming on ecosystem carbon processes in a tallgrass prairie , 2005 .

[2]  K. Nadelhoffer,et al.  Roots exert a strong influence on the temperature sensitivityof soil respiration , 1998, Nature.

[3]  J. Melillo,et al.  Soil warming and trace gas fluxes: experimental design and preliminary flux results , 2004, Oecologia.

[4]  Yiqi Luo,et al.  Changes in microclimate induced by experimental warming and clipping in tallgrass prairie , 2002 .

[5]  David R. Easterling,et al.  Long-Term Trends in Extreme Precipitation Events over the Conterminous United States and Canada , 1999 .

[6]  M. Hart,et al.  A broad analysis of fifteen sites in the tallgrass prairie of Oklahoma. , 1980 .

[7]  Yiqi Luo,et al.  Substrate regulation of soil respiration in a tallgrass prairie: Results of a clipping and shading experiment , 2003 .

[8]  Christopher B. Field,et al.  Grassland Responses to Global Environmental Changes Suppressed by Elevated CO2 , 2002, Science.

[9]  F. Woodward,et al.  Global response of terrestrial ecosystem structure and function to CO2 and climate change: results from six dynamic global vegetation models , 2001 .

[10]  P. Vitousek,et al.  Soil carbon pool structure and temperature sensitivity inferred using CO2 and 13CO2 incubation fluxes from five Hawaiian soils , 1997 .

[11]  K. Pilegaard,et al.  Large seasonal changes in Q10 of soil respiration in a beech forest , 2003 .

[12]  J. Soussana,et al.  Elevated [CO2], temperature increase and N supply effects on the accumulation of below-ground carbon in a temperate grassland ecosystem , 1999, Plant and Soil.

[13]  Yiqi Luo,et al.  Acclimatization of soil respiration to warming in a tall grass prairie , 2001, Nature.

[14]  George M. Woodwell,et al.  Biotic Feedbacks in the Warming of the Earth , 1998 .

[15]  K. Münnich,et al.  Annual variation in soil respiration in selected areas of the temperate zone , 1987 .

[16]  J. Aber,et al.  Soil warming and carbon-cycle feedbacks to the climate system. , 2002, Science.

[17]  J. Soussana,et al.  Elevated [CO2], temperature increase and N supply effects on the turnover of below-ground carbon in a temperate grassland ecosystem , 2004, Plant and Soil.

[18]  A. Knapp,et al.  Responses of Soil Respiration to Clipping and Grazing in a Tallgrass Prairie , 1998 .

[19]  W. Schlesinger,et al.  The global carbon dioxide flux in soil respiration and its relationship to vegetation and climate , 1992 .

[20]  R. Norby,et al.  Below-ground respiratory responses of sugar maple and red maple saplings to atmospheric CO2 enrichment and elevated air temperature , 1999, Plant and Soil.

[21]  P. Fay,et al.  Increased rainfall variability and reduced rainfall amount decreases soil CO 2 flux in a grassland ecosystem , 2005 .

[22]  R. Betts,et al.  Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model , 2000, Nature.

[23]  Jianwu Tang,et al.  How soil moisture, rain pulses, and growth alter the response of ecosystem respiration to temperature , 2004 .

[24]  Helge Toutenburg,et al.  Statistical Analysis of Designed Experiments , 2003 .

[25]  N. Buchmann,et al.  Large-scale forest girdling shows that current photosynthesis drives soil respiration , 2001, Nature.

[26]  S. Kellomäki,et al.  Soil CO2 efflux in a boreal pine forest under atmospheric CO2 enrichment and air warming , 2004 .

[27]  J. Blair,et al.  Increased rainfall variability and reduced rainfall amount decreases soil CO 2 flux in a grassland ecosystem , 2005 .

[28]  Rong Tsao,et al.  Plant growth regulatory effect and insecticidal activity of the extracts of the Tree of Heaven (Ailanthus altissima L.) , 2002, BMC Ecology.

[29]  S. Long,et al.  Primary Production in Grasslands and Coniferous Forests with Climate Change: An Overview. , 1991, Ecological applications : a publication of the Ecological Society of America.

[30]  F. Bowles,et al.  Soil warming in a northern hardwood forest: trace gas fluxes and leaf litter decomposition , 1998 .

[31]  J. Houghton,et al.  Climate change 2001 : the scientific basis , 2001 .

[32]  J. Ehleringer,et al.  Time-dependent responses of soil CO2 efflux components to elevated atmospheric [CO2] and temperature in experimental forest mesocosms , 2001, Plant and Soil.

[33]  P. Kokko-Gonzales,et al.  Soil CO2 efflux of two silver birch clones exposed to elevated CO2 and O3 levels during three growing seasons , 2004 .

[34]  S. Wetzel,et al.  Effect of rainfall patterns on soil surface CO2 efflux, soil moisture, soil temperature and plant growth in a grassland ecosystem of northern Ontario, Canada: implications for climate change , 2002, BMC Ecology.

[35]  P. Vitousek,et al.  Soil carbon pool structure and temperature sensitivity inferred using CO2 and 13C02 incubation fluxes from , 1997 .

[36]  Stephanie A. Bohlman,et al.  Seasonal and topographic patterns of forest floor CO(2) efflux from an upland oak forest. , 1993, Tree physiology.

[37]  Ming Xu,et al.  Soil‐surface CO2 efflux and its spatial and temporal variations in a young ponderosa pine plantation in northern California , 2001 .

[38]  C. Potter,et al.  Global patterns of carbon dioxide emissions from soils on a 0.5-degree-grid-cell basis , 1995 .

[39]  W. Hang,et al.  Soil microbial responses to experimental warming and clipping in a tallgrass prairie , 2005 .

[40]  Yiqi Luo,et al.  Response of soil CO2 efflux to water manipulation in a tallgrass prairie ecosystem , 2002, Plant and Soil.

[41]  E. Davidson,et al.  Soil water content and temperature as independent or confounded factors controlling soil respiration in a temperate mixed hardwood forest , 1998 .

[42]  W. Zhang,et al.  Soil microbial responses to experimental warming and clipping in a tallgrass prairie , 2005 .

[43]  Christopher B. Field,et al.  Elevated CO2 increases belowground respiration in California grasslands , 1996, Oecologia.

[44]  R. Norby,et al.  Evaluating ecosystem responses to rising atmospheric CO2 and global warming in a multi‐factor world , 2004 .

[45]  John Harte,et al.  SUBALPINE MEADOW FLOWERING PHENOLOGY RESPONSES TO CLIMATE CHANGE: INTEGRATING EXPERIMENTAL AND GRADIENT METHODS , 2003 .

[46]  F. Chapin,et al.  Predominance of ecophysiological controls on soil CO2 flux in a Minnesota grassland , 1999, Plant and Soil.