title: Temporal patterns of foliar ozone symptoms on tall milkweed (Asclepias exaltata L.) in Great Smoky Mountains National Park.
abstract: Incidence and severity of ozone-induced foliar symptoms on tall milkweed (Asclepias exaltata L.) along selected trails in Great Smoky Mountains National Park (GRSM) were determined by two surveys/season conducted from 1992 through 1996. Overall incidence was 73%, and was 84%, 44%, 90%, 58%, and 82% for 1992-1996, respectively for the same clusters. Average incidence was 61% and 84% for the 1st and 2nd surveys, respectively. Seasonal comparisons showed two distinct injury groupings regarding incidence and severity of injury: 1992, 1994 and 1996 (high injury); 1993 and 1995 (low injury). No discernible patterns were observed between symptomatic and asymptomatic plants regarding height, herbivory or flowering. Regression analyses indicated no differentiation in foliar symptoms regarding topographic position, aspect, slope or elevation over the 5-year study period. Our findings indicate other micro-site or genetic factors may control ozone sensitivity of tall milkweed in GRSM.
authors.affiliation: School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36849, USA. chappah@auburn.edu
authors.forename: A H
authors.initials: AH
authors.lastname: Chappelka
authors.forename: G L
authors.initials: GL
authors.lastname: Somers
authors.forename: J R
authors.initials: JR
authors.lastname: Renfro
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000407:Alabama; D000818:Animals; D003247:Conservation of Natural Resources; D017753:Ecosystem; D004781:Environmental Exposure; D004784:Environmental Monitoring / Q000379:methods; D007313:Insecta; D010126:Ozone / Q000032:analysis*; D018515:Plant Leaves; D011998:Recreation; D012621:Seasons; D013714:Tennessee
chemical_list: D000393:Air Pollutants; D010126:Ozone