PARENT SESSION
Oral Session # 11: Ecological Studies on Military Installations.
Presiding: B Collins
Monday, August 4. 8:00 AM to 11:30 AM, SITCC Meeting Room 203.
Cogongrass (Imperata cylindrica) encroachment into upland pine communities on Camp Shelby Training Site (CSTS), Mississippi.
Yager, Lisa*,1, Jones, Jeanne2, Miller, Deborah3, 1 The Nature Conservancy, Camp Shelby, MS, US2 Mississippi State University, Mississippi State, MS, US3 University of Florida, Milton, FL, US
ABSTRACT- Historically, uplands on CSTS were dominated by longleaf forests with an open understory of scattered hardwoods and bluestem grass-dominated groundcover. Many areas may still be characterized this way. However, fire exclusion over time has resulted in shrub and hardwood encroachment and reduced herbaceous abundance in pine forests on much of CSTS. Differences in light availability and vegetative structure, composition and abundance between these 2 community types (pine/bluestem, pine/shrub) may affect their susceptibility to invasion by cogongrass. Introduced in the early 1900's from Asia, cogongrass is spreading throughout the southeast and can displace native vegetation and alter fire regimes and soil processes in native plant communities. Quantification of rates of spread and possible factors related to rates of spread into pine/bluestem and pine/shrub communities is needed to develop appropriate control strategies. To compare rates of vegetative spread (tiller extension), 20 cogongrass patches growing into pine/bluestem or pine/shrub were selected for each community type. In April 2002, a 1 m section of patch edge selected so that no tillers extended further into the habitat of interest was marked with stakes for each patch. Soil pH, nutrient status and texture for samples collected at these edge plots did not differ between the two community types. Although light availability (PAR) and percent cover of grasses, forbs, shrubs and vines at the edge of the patches differed between the two community types, cogongrass tiller extension measured in October 2002 from the edge plots was not significantly different. Tiller extension from patch edges ranged from 0 to > 0.5 m for both habitat types. Results of fall and spring tiller extension rate and the relationship of spread to environmental variables (PAR, dominant vegetation by type and species) will be evaluated to determine community susceptibility to vegetative encroachment by cogongrass and potential factors influencing its growth.
Key words: invasive, imperata cylindrica, longleaf, cogongrass