LONG-TERM CO2 ENRICHMENT OF A PASTURE COMMUNITY: SPECIES RICHNESS, DOMINANCE, AND SUCCESSION

The present study addresses responses of a pasture community to CO2 en- richment in situ. It focused on two levels of organization. We examined changes in both community properties and species-specific responses during long-term exposure to high CO2 concentration. The underlying hypothesis is that CO2 enrichment could change com- munity composition. At the community level, we observed higher species richness and lesser dominance under enriched than ambient CO2. Two species were apparently central in explaining our results, Agropyron repens and Plantago major. The cover of this first species increased only under ambient CO2. Conversely, the cover of the latter species decreased under ambient CO2 but remained stable under enriched CO2. Species were pooled into dicots and monocots to examine space acquisition. Changes in monocot cover through time were more tightly coupled with that of dicots under ambient than high CO2. Enrichment with CO2 appeared to have a positive effect on the early-successional species, preventing the complete dominance by late-successional species. In fact, under elevated CO2 early- and late-successional species were coexisting. Therefore, our results suggest the possibility that succession patterns might be altered by CO2 enrichment apparently because enriched CO2 stimulates the growth of dicots.

[1]  C. Potvin,et al.  Effects of Elevated CO 2 on an Artificial Grassland Community: Competition, Invasion and Neighbourhood Growth , 1996 .

[2]  F. Chapin,et al.  Future directions of global change research in terrestrial ecosystems. , 1994, Trends in ecology & evolution.

[3]  L. Pitelka.  Ecosystem response to elevated CO(2). , 1994, Trends in ecology & evolution.

[4]  J. Silvertown,et al.  Spatial competition between grasses: rates of mutual invasion between four species and the interaction with grazing , 1994 .

[5]  A. 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.

[6]  C. Chanway,et al.  INTERACTIVE EFFECTS OF NUTRIENTS AND DISTURBANCE: AN EXPERIMENTAL TEST OF PLANT STRATEGY THEORY' , 1993 .

[7]  D. Goldberg,et al.  Patterns and Consequences of Interspecific Competition in Natural Communities: A Review of Field Experiments with Plants , 1992, The American Naturalist.

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

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

[10]  T. E. Thórhallsdóttir,et al.  The dynamics of five grasses and white clover in a simulated mosaic sward. , 1990 .

[11]  D. Hilbert,et al.  Optimization of Plant Root: Shoot Ratios and Internal Nitrogen Concentration , 1990 .

[12]  J. Gurevitch,et al.  Experimental removal of a dominant species at two levels of soil fertility , 1989 .

[13]  B. F. Swindel,et al.  Species diversity and diversity profiles: concept, measurement, and application to timber and range management. , 1988 .

[14]  G. Barrett,et al.  Succession in old-field plant communities : effects of contrasting types of nutrient enrichment. , 1988 .

[15]  Deborah E. Goldberg,et al.  NEIGHBORHOOD COMPETITION IN AN OLD-FIELD PLANT COMMUNITY' , 1987 .

[16]  T. Miller,et al.  Competitive Effects and Responses Between Plant Species in a First‐Year Old‐Field Community , 1987 .

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

[18]  David Tilman,et al.  Secondary Succession and the Pattern of Plant Dominance Along Experimental Nitrogen Gradients , 1987 .

[19]  J. P. Grime,et al.  Plant Strategies and Vegetation Processes. , 1980 .

[20]  E. Odum,et al.  Community and Population Level Responses to Fertilization in an Old‐Field Ecosystem , 1978 .

[21]  J. Diamond,et al.  Avifaunal equilibria and species turnover rates on the channel islands of california. , 1969, Proceedings of the National Academy of Sciences of the United States of America.

[22]  C. Owensby,et al.  24 – Effects of Elevated Carbon Dioxide on Forage Quality for Ruminants , 1996 .

[23]  C. Körner,et al.  11 – Effects of Elevated CO2 on Plant Species Dominance in a Highly Diverse Calcareous Grassland , 1996 .

[24]  A. Lüscher,et al.  19 – Differences between Legumes and Nonlegumes of Permanent Grassland in Their Responses to Free-Air Carbon Dioxide Enrichment: Its Effect on Competition in a Multispecies Mixture , 1996 .

[25]  C. Körner.  CO2 Fertilization: The Great Uncertainty in Future Vegetation Development , 1993 .

[26]  V. Brown,et al.  Grazing and Vegetation Change: Deflected or Modified Succession? , 1992 .

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

[28]  F. Woodward,et al.  Functional Approaches to Predicting the Ecological Effects of Global Change , 1991 .

[29]  David Tilman,et al.  Oscillations and chaos in the dynamics of a perennial grass , 1991, Nature.

[30]  F. A. Bazzaz,et al.  The Response of Natural Ecosystems to the Rising Global CO2 Levels , 1990 .

[31]  C. Potvin,et al.  Sources of variability and experimental designs in growth chambers , 1988 .