PARENT SESSION
Thursday, August 10, 5:00-6:30 pm
Poster Session 20 - Biodiversity
Exhibit Hall, Ballroom Level, Cook Convention Center
The abundance and diversity of plant functional groups in response to a disturbance gradient at Fort Pickett, Virginia.
Emrick , Verl *,, Jones, Robert ,
ABSTRACT- Many disturbance studies focus on the impact of single events and cannot address species responses to repeated long-term disturbance. Fort Pickett, Virginia has experienced both fire and physical disturbance from military training for 60 years, providing a unique opportunity to assess long-term effects of two types of disturbance, and their interaction, on plant community structure, including diversity. The objectives of my research were to identify the relationships between long-term disturbance regimes, plant functional groups, and species diversity and to relate results to disturbance-biodiversity hypotheses. Five variables were collected as measures of vehicle disturbance. Fire frequency for each site was obtained from historical records. Plant functional groups were C4 grasses, C3 grasses, forbs, woody species, and legumes. Total cover and richness of each functional group were calculated on each plot. Data were initially analyzed by canonical correspondence analysis. Functional group response to overall disturbance levels was then examined using a one-way ANOVA. The first canonical axis explained 91.9 percent of the relationship between functional group cover and disturbance. The cover of C4 grasses and legumes were correlated to fire frequency, whereas the cover of woody species and C3 grasses were related to vehicle pass frequency. There were significant differences (P < 0.05) in vegetative cover of C4 grasses, woody species, and legumes among different overall disturbance levels. Disturbance had weaker relationships with species richness within functional groups. However, overall species richness increased in response to disturbance with C4 grasses and legumes showing the greatest effect. Richness was highest for some functional groups at moderate levels of disturbance, thus partially supporting the intermediate disturbance hypothesis.
Key words: Disturbance, Plant Functional Groups, Diversity