Comparative Ozone Responses of Cutleaf Coneflowers (Rudbeckia laciniata var. digitata, var. ampla) from Rocky Mountain and Great Smoky Mountains National Parks, USA
Neufeld HS, Johnson J, Kohut R. 2018. Comparative Ozone Responses of Cutleaf Coneflowers (Rudbeckia laciniata var. digitata, var. ampla) from Rocky Mountain and Great Smoky Mountains National Parks, USA. Science of The Total Environment. 610-611:591–601
ABSTRACT: Cutleaf coneflower (Rudbeckia laciniata L. var. digitata) is native to Great Smoky Mountains National Park (GRSM) and an ozone bioindicator species. Variety ampla, whose ozone sensitivity is less well known, is native to Rocky Mountain National Park (ROMO). In the early 2000s, researchers found putative ozone symptoms on var. ampla and rhizomes were sent to Appalachian State University to verify that the symptoms were the result of ozone exposure. In 2011, potted plants were exposed to ambient ozone from May to August. These same plants were grown in open-top chambers (OTCs) in 2012 and 2013, and exposed to charcoal-filtered (CF), non-filtered (NF), elevated ozone (EO), NF + 50 ppb in 2012 for 47 days and NF + 30/NF + 50 ppb ozone in 2013 for 36 and 36 days, respectively. Ozone symptoms similar to those found in ROMO (blue-black adaxial stippling) were reproduced both in ambient air and in the OTCs. Both varieties exhibited foliar injury in the OTCs in an exposure-dependent manner, verifying that symptoms resulted from ozone exposure. In two of the three study years, var. digitata appeared more sensitive than var. ampla. Exposure to EO caused reductions in ambient photosynthetic rate (A) and stomatal conductance (gs) for both varieties. Light response curves indicated that ozone reduced A, gs, and the apparent quantum yield while it increased the light compensation point. In CF air, var. ampla had higher light saturated A (18.2 ± 1.04 vs 11.6 ± 0.37 μmol m− 2 s− 1), higher light saturation (1833 ± 166.7 vs 1108 ± 141.7 μmol m− 2 s− 1), and lower Ci/Ca ratio (0.67 ± 0.01 vs 0.77 ± 0.01) than var. digitata. Coneflowers in both Parks are adversely affected by exposure to ambient ozone and if ozone concentrations increase in the Rocky Mountains, greater amounts of injury on var. ampla can be expected.
- Type
- Journal Article
- Authors
- Neufeld, Howard; Johnson, Jennifer; Kohut, Robert
- Units
- GRSM , ROMO
- Keywords
- air quality, APHN, Appalachian Highlands Network, bioindicator, biomass, foliar stipple, Great Smoky Mountains National Park, GRSM, GRSM-00900, injury, ozone impacts, photosynthesis, Rocky Mountain National Park, Rocky Mountain Network, ROMO, Rudbeckia laciniata L. var. ampla, Rudbeckia laciniata L. var. digitata, SER, Southeast Region, stomatal conductance, vascular plants