31 research outputs found
Ozone injury on cutleaf coneflower (Rudbeckia laciniata) and crown-beard (Verbesina occidentalis) in Great Smoky Mountains National Park
Seasonal development of ozone-induced foliar injury on tall milkweed (<em>Asclepias exaltata</em>) in Great Smoky Mountains National Park
Seasonal profiles of leaf ascorbic acid content and redox state in ozone-sensitive wildflowers
Interpreting spatial variation in ozone symptoms shown by cutleaf cone flower, <em>Rudbeckia laciniata</em> L.
Stomatal behavior of ozone-sensitive and -insensitive coneflowers (Rudbeckia laciniata var. digitata) in Great Smoky Mountains National Park
Visible foliar injury caused by ozone alters the relationship between SPAD meter readings and chlorophyll concentrations in cutleaf coneflower
Ambient ozone effects on gas exchange and total non-structural carbohydrate levels in cutleaf coneflower (<em>Rudbeckia laciniata</em> L.) growing in Great Smoky Mountains National Park
How much does the presence of a competitor modify the within-canopy distribution of ozone-induced senescence and visible injury?
Many natural vegetation species have been shown to be negatively affected by ozone. This study has investigated how the presence of competing species in a community affects two common responses to ozone: visible injury and senescence. Monocultures and mixtures of Trifolium repens and Lolium perenne were grown in large containers and were exposed in solardomes to either a rural episodic ozone profile (AOT40 of 12.86 ppm h) or control conditions (AOT40 of 0.02 ppm h) for 12 weeks. The proportion of ozone-injured or senesced leaves was different in the different regions of the canopy. The highest proportions of injured/senesced leaves were in the plant material growing at the edge of the canopy and the upper canopy, with a significantly lower proportion of injured leaves in the inner canopy. The presence of L. perenne increased the proportion of ozone-injured leaves in T. repens at the final harvest, whilst the presence of T. repens decreased the proportion of senesced leaves in L. perenne. In L. perenne, the proportion of injured leaves at the edge and inner canopy decreased significantly when grown in competition, whilst for T. repens the reverse effect occurred in the inner canopy only. Different mechanisms appeared to influence the interaction between response to ozone and competitors in these two species. In L. perenne the response to ozone may have been related to nitrogen supply, whereas in T. repens canopy structure was more important