Interacting effects of soil fertility and atmospheric CO2 on leaf area growth and carbon gain physiology in Populus×euramericana (Dode) Guinier.

Two important processes which may limit productivity gains in forest ecosystems with rising atmospheric CO2 are reduction in photosynthetic capacity following prolonged exposure to high CO2 and diminution of positive growth responses when soil nutrients, particularly N, are limiting. To examine the interacting effects of soil fertility and CO2 enrichment on photosynthesis and growth in trees we grew hybrid poplar (Populus × euramericana) for 158 d in the field at ambient and twice ambient CO2 and in soil with low or high N availability. We measured the timing and rate of canopy development, the seasonal dynamics of leaf level photosynthetic capacity, respiration, and N and carbohydrate concentration, and final above- and belowground dry weight. Single leaf net CO2 assimilation (A) increased at elevated CO2 over the majority of the growing season in both fertility treatments. At high fertility, the maximum size of individual leaves, total leaf number, and seasonal leaf area duration (LAD) also increased at elevated CO2 , leading to a 49% increase in total dry weight. In contrast, at low fertility leaf area growth was unaffected by CO2 treatment. Total dry weight nonetheless increased 25% due to CO2 effects on A. Photosynthetic capacity (A at constant internal p(CO2 ), ((C1 )) was reduced in high CO2 plants after 100 d growth at low fertility and 135 d growth at high fertility. Analysis of A responses to changing C1 indicated that this negative adjustment of photosynthesis was due to a reduction in the maximum rate of CO2 fixation by Rubisco. Maximum rate of electron transport and phosphate regeneration capacity were either unaffected or declined at elevated CO2 . Carbon dioxide effects on leaf respiration were most pronounced at high fertility, with increased respiration mid-season and no change (area basis) or reduced (mass basis) respiration late-season in elevated compared to ambient CO2 plants. This temporal variation correlated with changes in leaf N concentration and leaf mass per area. Our results demonstrate the importance of considering both structural and physiological pathways of net C gain in predicting tree responses to rising CO2 under conditions of suboptimal soil fertility.

[1]  P. Curtis,et al.  Atmospheric CO2, soil nitrogen and turnover of fine roots , 1995 .

[2]  J. Lewis,et al.  Phosphorus supply affects the photosynthetic capacity of loblolly pine grown in elevated carbon dioxide. , 1994, Tree physiology.

[3]  J. P. Grime,et al.  Evidence of a feedback mechanism limiting plant response to elevated carbon dioxide , 1993, Nature.

[4]  A. McDonald,et al.  Effects of elevated carbon dioxide concentration on photosynthesis and growth of small birch plants (Betula pendula Roth.) at optimal nutrition , 1992 .

[5]  P. Curtis,et al.  Seasonal responses of leaf gas exchange to elevated carbon dioxide in Populusgrandidentata , 1992 .

[6]  Stan D. Wullschleger,et al.  Productivity and compensatory responses of yellow-poplar trees in elevated C02 , 1992, Nature.

[7]  James F. Reynolds,et al.  Modelling photosynthesis of cotton grown in elevated CO2 , 1992 .

[8]  S. Wong,et al.  CO2×nitrogen interaction on seedling growth of four species of Eucalypt , 1992 .

[9]  Hendrik Poorter,et al.  A Quantitative-Analysis of Dark Respiration and Carbon Content as Factors in the Growth-Response of Plants to Elevated CO2 , 1992 .

[10]  H. Rouhier,et al.  Changes in dry weight and nitrogen partitioning induced by elevated CO2 depend on soil nutrient availability in sweet chestnut (Castanea sativa Mill) , 1992 .

[11]  B. Drake.  A field study of the effects of elevated CO2 on ecosystem processes in a Chesapeake Bay Wetland , 1992 .

[12]  R. Norby,et al.  Carbon exchange rates, chlorophyll content, and carbohydrate status of two forest tree species exposed to carbon dioxide enrichment. , 1992, Tree physiology.

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

[14]  W. Arp.  Effects of source‐sink relations on photosynthetic acclimation to elevated CO2 , 1991 .

[15]  S. Idso,et al.  Net photosynthesis of sour orange trees maintained in atmospheres of ambient and elevated CO2 concentration , 1991 .

[16]  J. Amthor.  Respiration in a future, higher‐CO2 world , 1991 .

[17]  M. Turner,et al.  How Increasing CO2 and Climate Change Affect Forests , 1990 .

[18]  J. Bunce.  Short- and long-term inhibition of respiratory carbon dioxide efflux by elevated carbon dioxide. , 1990 .

[19]  P. Jarvis,et al.  Effects of CO2 enrichment on four poplar clones. I, Growth and leaf anatomy , 1990 .

[20]  T. Sharkey,et al.  Stromal Phosphate Concentration Is Low during Feedback Limited Photosynthesis. , 1989, Plant physiology.

[21]  R. E. Ferrell,et al.  Design and Performance of a Large, Field Exposure Chamber to Measure Effects of Air Quality on Plants , 1989 .

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

[23]  J. Gaudillère,et al.  Short term effect of CO2 enrichment on leaf development and gas exchange of young poplars (Populus euramericana cv I 214) , 1989 .

[24]  B. Strain,et al.  Effects of Carbon Dioxide Enrichment on the Expansion and Size of Kudzu (Pueraria lobata) Leaves , 1989, Weed Science.

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

[26]  B. Strain.  Physiological and ecological controls on carbon sequestering in terrestrial ecosystems , 1985 .

[27]  E. DeLucia,et al.  Reversibility of Photosynthetic Inhibition in Cotton after Long-Term Exposure to Elevated CO(2) Concentrations. , 1985, Plant physiology.

[28]  R. Loomis,et al.  The Growth and Functioning of Leaves , 1984 .

[29]  J. Goudriaan,et al.  Plant growth in response to CO2 enrichment, at two levels of nitrogen and phosphorus supply. 1. Dry matter, leaf area and development , 1983 .

[30]  Paul J. Kramer,et al.  Carbon Dioxide Concentration, Photosynthesis, and Dry Matter Production , 1981 .

[31]  O. H. Lowry,et al.  Enzymic Assay of 10−7 to 10−14 Moles of Sucrose in Plant Tissues , 1977 .

[32]  D. Bouma.  Effects of nitrogen nutrition on leaf expansion and photosynthesis of Trifolium subterraneum L. 1. Comparison between different levels of nitrogen supply. , 1970 .