PARENT SESSION
Symposium 8: Old-Growth Savannas as Models for Management of Upland Coastal Systems: The Role of Disturbance in a Time of Global Change
Organized by: F Gilliam and W Platt
Tuesday, August 5. 1:30 PM to 5:00 PM, SITCC Chatham Ballroom B.

Using concepts for old-growth pine stands to enhance biodiversity in longleaf pine savanna groundcover.

Platt, Bill, Carr, Susan, Reilly, Matt,

ABSTRACT- Old-growth longleaf pine stands contain variable sized openings without trees. Many second-growth stands contain dense pines with few openings. Restoration logging (group selection of patches of trees) that generates open spaces in such stands could enhance ground cover, but ground surface disruption potentially could produce negative effects and increased invasion by exotic species. We studied effects of restoration logging on groundcover in eastern Louisiana pine savannas. In each of 8 drainages in fertile loess plains savannas at Camp Whispering Pines, we randomly established three permanent plots: 1) restoration logged five years earlier, 2) open with no overstory trees for >30 years, and 3) no overstory trees removed. We sampled numbers of species of three life forms (graminoids, shrubs, forbs) in nested plots from 0.01m² to 100m². Abundance classes (common, intermediate, infrequent) were assigned to species based on relative occurrences in plots. MANOVA analyses indicated that significant treatment effects (overstory trees present or absent; overstory tree removed recently or decades previously) were attributable to forbs; intermediate and infrequent forbs were more abundant when overstory trees were absent, especially if absent for decades. At Abita Springs Preserve, we randomly established nine plots in pine flatwoods, five with overstory pine removal and four with no pine removal. We sampled numbers of species in nested permanent subplots from 0.01m² to 1000m² before and for three years after logging. Repeated measures MANOVA indicated significant effects of overstory removal; effects were attributable to increased numbers of graminoids, primarily sedges. These two studies suggest that ecologically sensitive restoration logging can enhance groundcover biodiversity; less common species increase in abundance, but different life forms may respond in different habitats. Moreover three groups increased biodiversity at both sites: species with a seed pool, species immigrating from surrounding areas of pine savanna, and species invading from different habitats.

Key words: pine savanna, colonization, biodiversity, restoration logging