PARENT SESSION
Poster Session 23: Soil Ecology
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Long-term land use effects on soil invertebrate communities in Southern Piedmont soils.
Callaham , Mac*,1, Richter, Daniel2, Hofmockel, Michael2, 1 USDA Forest Service, Athens, GA, USA2 Nicholas School of the Environment, Durham, NC, USA
ABSTRACT- Historically, a large percentage of land area in the Piedmont of the southern USA was under intensive agricultural management for the production of cotton. This intensive farming resulted in massive erosion, and general degradation of soil resources until insect pests and poor economic conditions forced large-scale abandonment of farmland around the 1930s. In subsequent decades, there have been four predominant land-uses in the region: cultivated fields, pastures, loblolly pine stands, and remnant hardwood stands. We sampled 3 replicates of each of these land-use types for a period of 3 years for soil macroinvertebrates. At each site we dug 3 or 4 soil pits that were 30 x 30 cm to a depth of 15cm, and hand-sorted for invertebrates 5 mm in length or larger. We tallied abundance and biomass data for all invertebrates collected, and we calculated community indices including diversity, richness, evenness and rank abundance in order to identify patterns of community assemblage within each land use type. Preliminary results suggest that soils in hardwood stands support the most taxonomically diverse macroinvertebrate communities followed by pine stands, pastures, and cultivated fields in order of decreasing diversity. For earthworms, Diplocardia spp. (North American megascolecids) were most abundant in the hardwood stands, but sometimes made up a substantial fraction of the community in other land-uses; whereas lumbricid earthworms (introduced Apporectodea spp) were most abundant in the cultivated and pasture soils, or showed no consistent habitat preference (native Bimastos ssp.). Scarab beetle larvae were common in all four systems, but reached high densities only at cultivated and grass sites. Carabid beetle larvae were collected most often from cultivated soils. Several taxa were collected either exclusively or predominantly from forested sites, including diplopods, chilopods, gastropods, and several taxa of Diptera. These results indicate that relative levels of long-term soil disturbance and the attendant differences in vegetation structure have profoundly influenced the community composition of invertebrates in Southern Piedmont soils, and that more intense disturbance results in a less diverse invertebrate community composed of a few, frequently non-native, disturbance tolerant species.
Key words: earthworms, macroinvertebrates