Submitted to: Southeastern Biology
Publication Type: Abstract Only
Publication Acceptance Date: 11/15/2003
Publication Date: 4/1/2004
Citation: Peoples, S., Neufeld, H.S., Finkelstein, P.L., Davison, A.W., Chappelka, A.H., Burkey, K.O. 2004. Seasonal development of stand structure for cutleaf coneflower (Rudbeckia laciniata) at two sites in Great Smoky Mountain National Park: influences on ozone uptake. Southeastern Biology.
Technical Abstract: We have been investigating cutleaf coneflower (Rudbeckia laciniata) responses to ozone at several stages of organization, including biochemical, physiological, and at the population level. Movement of ozone from atmosphere to leaf is determined in large part by atmospheric and canopy resistances, which are functions of stand height, density, proximity to other vegetation, ozone concentration and wind speed. Our goal was to parameterize an ozone uptake and deposition model being developed by one of us (Finkelstein) as a function of stand development. Canopy structure (height, stem density, leaf position and area, and leaf area index (LAI, m2/m2) was monitored approximately biweekly in five plots at Clingman's Dome and ten at Purchase Knob in Great Smoky Mountains National Park. Plants began to leaf out in late May, and the LAI began to accumulate until values as high as ~7.0 for 1.6 m tall stands were reached in mid-July at Clingman's Dome. Stands were very dense (up to 59 stems/m2) and reduced light and ozone penetration at ground level to ~0.5% of full sunlight and ~40% of above canopy values. LAIs, but not stem densities, were lower at Purchase Knob (~5.5) and even lower if the plants grew beneath a forest canopy (LAI ~2.5, LAI of forest ~2.5). Light and ozone values were reduced to a correspondingly smaller extent than at Clingman's Dome. As LAI increases through the growing season, both light and ozone are progressively attenuated in stands of coneflower, which in turn, affects the magnitude of ozone uptake by leaves.