PARENT SESSION
Oral Session # 33: Pathogens, Toxins, and Disease II: Plants.
Presiding: A Davelos
Tuesday, August 5. 1:30 PM to 5:00 PM, SITCC Meeting Room 201.
Influence of soil, topographic, and stand characteristics on Cornus florida distribution before and after anthracnose.
Jenkins, Michael*,1, Jose, Shibu2, White, Peter3, 1 National Park Service, Gatlinburg, TN2 University of Florida, Milton, FL3 University of North Carolina at Chapel Hill, Chapel Hill, NC
ABSTRACT- In Great Smoky Mountains National Park, heavy losses of Cornus florida (flowering dogwood) have been observed as a result of infection with Discula destructiva, the fungus that causes dogwood anthracnose. We used vegetation, soil, and topographic data from 83 permanent forest plots first established in 1977-79 and resampled in 1995-2000 to examine the influence of soil, topography, and stand structure on the distribution of C. florida before and after anthracnose infection. According to multiple linear regressions, in 1977-79 (prior to anthracnose infection), C. florida basal area increased with increasing soil pH (P < 0.001), percent slope (P = 0.017), and soil potassium saturation (P = 0.025). In 1995-2000 (after anthracnose infection), C. florida basal area increased with increasing soil potassium saturation (P<0.001) and magnesium saturation (P<0.001), but decreased with increasing total stand basal area (P = 0.008). Prior to anthracnose infection (1977-79), soil, topographic, and stand structure variables explained relatively little of the variability in C. florida basal area (adjusted R2 = 0.28). However, after anthracnose infection (1995-2000), these variables accounted for a greater amount of the variability in C. florida basal area (adjusted R2 = 0.44), suggesting that the distribution of C. florida trees was more dependent upon site conditions following heavy morality from anthracnose. Although C. florida has been shown to concentrate large amounts calcium in its foliage, post-anthracnose basal area was not related to soil calcium saturation (P = 0.396).
Key words: dogwood anthracnose, soil cation saturation, Cornus florida, species distribution