Responses of a C3 and a C4 perennial grass to elevated CO2 and temperature under different water regimes

An experiment was carried out to determine the effects of elevated CO2, elevated temperatures, and altered water regimes in native shortgrass steppe. Intact soil cores dominated by Bouteloua gracilis, a C4 perennial grass, or Pascopyrum smithii, a C3 perennial grass, were placed in growth chambers with 350 or 700 μL L−1 atmospheric CO2, and under either normal or elevated temperatures. The normal regime mimicked field patterns of diurnal and seasonal temperatures, and the high-temperature regime was 4 °C warmer. Water was supplied at three different levels in a seasonal pattern similar to that observed in the field. Total biomass after two growing seasons was 19% greater under elevated CO2, with no significant difference between the C3 and C4 grass. The effect of elevated CO2 on biomass was greatest at the intermediate water level. The positive effect of elevated CO2 on shoot biomass was greater at normal temperatures in B. gracilis, and greater at elevated temperatures in P. smithii. Neither root-to-shoot ratio nor production of seed heads was affected by elevated CO2. Plant tissue N and soil inorganic N concentrations were lower under elevated Co2, but no more so in the C3 than the C4 plant. Elevated CO2 appeared to increase plant N limitation, but there was no strong evidence for an increase in N limitation or a decrease in the size of the CO2 effect from the first to the second growing season. Autumn samples of large roots plus crowns, the perennial organs, had 11% greater total N under elevated CO2, in spite of greater N limitation.

[1]  David T. Tissue,et al.  Response of Eriophorum Vaginatum to Elevated CO_2 and Temperature in the Alaskan Tussock Tundra , 1987 .

[2]  M. B. Kirkham,et al.  Changes in prairie vegetation under elevated carbon dioxide levels and two soil moisture regimes , 1992 .

[3]  F. S. Nakayama,et al.  Effects of increasing atmospheric CO2 on vegetation , 2004, Vegetatio.

[4]  J. Reynolds,et al.  The Influence of Carbon Dioxide and Daily Photon-flux Density on Optimal Leaf Nitrogen Concentration and Root: Shoot Ratio , 1991 .

[5]  Jack A. Morgan,et al.  Consequences of growth at two carbon dioxide concentrations and two temperatures for leaf gas exchange in Pascopyrum smithii (C3) and Bouteloua gracilis (C4) , 1994 .

[6]  John M. Conroy,et al.  Influence of Elevated Atmospheric CO2 Concentrations on Plant Nutrition , 1992, Australian Journal of Botany.

[7]  H. Mooney,et al.  PREDICTING ECOSYSTEM RESPONSES TO ELEVATED CO2 CONCENTRATIONS , 1991 .

[8]  W. Lauenroth,et al.  Response of Native Grassland Legumes to Water and Nitrogen Treatments , 1979 .

[9]  J. Morison,et al.  Plant Growth and Water Use With Limited Water Supply in High CO2 Concentrations. I. Leaf Area, Water Use and Transpiration , 1984 .

[10]  H. L. Hackerott,et al.  Early‐Spring Blue Grama Inflorescences from Fall‐Initiated Spikes 1 , 1969 .

[11]  M. B. Kirkham,et al.  Leaf Photosynthesis Water Use of Big Bluestem under Elevated Carbon Dioxide , 1991 .

[12]  B. Acock,et al.  Crop responses to carbon dioxide doubling: a literature survey , 1986 .

[13]  W. Dixon,et al.  BMDP statistical software , 1983 .

[14]  Paul W. Leadley,et al.  Canopy photosynthesis of crops and native plant communities exposed to long‐term elevated CO2 , 1991 .

[15]  L. H. Allen.  Plant Responses to Rising Carbon Dioxide and Potential Interactions with Air Pollutants , 1990 .

[16]  C. Owensby,et al.  Nitrogen and phosphorus dynamics of a tallgrass prairie ecosystem exposed to elevated carbon dioxide , 1993 .

[17]  F. Clark.  Internal Cycling of Nitrogen in Shortgrass Prairie , 1977 .

[18]  J. Conroy,et al.  Effect of nitrogen and phosphorus availability on the growth response of Eucalyptus grandis to high CO2 , 1992 .

[19]  P. Hocking,et al.  Effects of CO2 Enrichment and Nitrogen Stress on Growth, and Partitioning of Dry Matter and Nitrogen in Wheat and Maize , 1991 .

[20]  H. W. Hunt,et al.  Nitrogen Limitation of Production and Decomposition in Prairie, Mountain Meadow, and Pine Forest , 1988 .

[21]  P. Kemp,et al.  A Physiological Basis for Niche Separation Between Agropyron Smithii (C3) and Bouteloua Gracilis (C4) , 1980 .

[22]  Derek Eamus,et al.  The interaction of rising CO2 and temperatures with water use efficiency , 1991 .

[23]  P. Newton.  Direct effects of increasing carbon dioxide on pasture plants and communities , 1991 .

[24]  J. Morgan,et al.  Gas Exchange and Carbohydrate and Nitrogen Concentrations in Leaves ofPascopyrum smithii(C3) andBouteloua gracilis(C4) at Different Carbon Dioxide Concentrations and Temperatures , 1997 .

[25]  D. Patterson,et al.  Interacting Effects of CO2 and Nutrient Concentration , 1982, Weed Science.

[26]  Edward B. Rastetter,et al.  Global Change and the Carbon Balance of Arctic EcosystemsCarbon/nutrient interactions should act as major constraints on changes in global terrestrial carbon cycling , 1992 .

[27]  Stephen P. Long,et al.  Modification of the response of photosynthetic productivity to rising temperature by atmospheric CO2 concentrations: Has its importance been underestimated? , 1991 .

[28]  C. Körner,et al.  Responses to elevated carbon dioxide in artificial tropical ecosystems. , 1992, Science.

[29]  S V Krupa,et al.  Plant responses to atmospheric CO2 enrichment with emphasis on roots and the rhizosphere. , 1994, Environmental pollution.

[30]  J. Eischeid,et al.  Precipitation Fluctuations over Northern Hemisphere Land Areas Since the Mid-19th Century , 1987, Science.

[31]  M. Stitt.  Rising Co2 Levels and Their Potential Significance for Carbon Flow in Photosynthetic Cells , 1991 .

[32]  Janis Antonovics,et al.  CHAPTER 1 – Concepts of Resource Allocation and Partitioning in Plants1 , 1980 .

[33]  Christopher B. Field,et al.  RESPONSES OF TERRESTRIAL ECOSYSTEMS TO THE CHANGING ATMOSPHERE: A Resource-Based Approach*'** , 1992 .

[34]  S. Huber,et al.  Regulation of photosynthesis by end-product accumulation in leaves of plants storing starch, sucrose, and hexose sugars. , 1992, Plant physiology.

[35]  F. Clark,et al.  Distribution of Nitrogen in Root Materials of Blue Grama , 1976 .

[36]  Alan K. Knapp,et al.  Biomass Production in a Tallgrass Prairie Ecosystem Exposed to Ambient and Elevated CO"2. , 1993, Ecological applications : a publication of the Ecological Society of America.

[37]  F. W. Caldwell,et al.  Root and shoot weight in a tallgrass prairie under elevated carbon dioxide , 1992 .

[38]  Donald A. Klein,et al.  Simulation model for the effects of climate change on temperate grassland ecosystems , 1991 .

[39]  T. Sharkey,et al.  Acclimation of Photosynthesis to Elevated CO(2) in Five C(3) Species. , 1989, Plant physiology.

[40]  Clanton C. Black,et al.  Photosynthetic Carbon Fixation in Relation to Net CO2 Uptake , 1973 .