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Keywords:

  • climate change;
  • CO2;
  • exotic species;
  • fire;
  • mesocosms

Abstract

This study investigated the effect of elevated CO2 on the post-fire resprouting response of a grassland system of perennial grass species of Cumberland Plain Woodland. Plants were grown in mixtures in natural soil in mesocosms, each containing three exotic grasses (Nassella neesiana, Chloris gayana, Eragrostis curvula) and three native grasses (Themeda australis, Microlaena stipoides, Chloris ventricosa) under elevated (700 ppm) and ambient (385 ppm) CO2 conditions. Resprouting response after fire at the community- and species-level was assessed. There was no difference in community-level biomass between CO2 treatments; however, exotic species made up a larger proportion of the community biomass under all treatments. There were species-level responses to elevated CO2 but no significant interactions found between CO2 and burning or plant status. Two exotic grasses (N. neesiana and E. curvula, a C3 and a C4 species respectively), and one native grass (M. stipoides, a C3 species) significantly increased in biomass, and a native C4 grass (C. ventricosa) significantly decreased in biomass under elevated CO2. These results suggest that although overall productivity of this community may not change with increases in CO2 and fire frequency, the community composition may alter due to differential species responses.