THE ECOLOGY AND SPATIAL DYNAMICS OF ANT-DISPERSED HERBS IN FOUR SOUTHERN APPALACHIAN FOREST COMMUNITIES (MYRMECOCHORY, PATCH

The ecology and spatial dynamics of myrmecochorous herbs were studied at four forested sites which ranged in site moisture from xeric to mesic. In the course of this study, four hypotheses were generated and tested: (1) Ant-dispersed herbs are more important in xeric communities than in mesic communities; (2) Within the forest mosaic, ant-dispersed herbs are more important in patches than in relatively undisturbed areas; (3) Patches differ from relatively undisturbed areas in resource levels such as ant nest density, light intensity, leaf litter depth, and soil nutrients; and (4) Ant-dispersed herbs are not easily typified in terms of "r-" or "K-selection" but instead display a range of life history strategies.;The data collected at the four sites revealed that ant-dispersed species were more important in patches than in relatively undisturbed areas in all four sites. Furthermore, ant-dispersed species were most important in patches in the two most xeric communities. In terms of resource levels in relatively undisturbed areas vs. patches, and nest density was greater in patches than in relatively undisturbed areas. Leaf litter depth was more important than light intensity in explaining the spatial variation in importance values of ant-dispersed species; however, it was also found that light intensity was an important variable in predicting the occurrence of several myrmecochorous species. Soil nutrient levels were of little value in explaining the occurrence of ant-dispersed species. Ant-dispersed species comprised the majority of the dominant herbaceous species at the four study sites. The ant-dispersed species found in the four study sites were predominantly fugitives. A wide range of life history strategies, however, was present among the 22 ant-dispersed species studied.;Finally, based on dispersal experiments carried out here, ant dispersal is more widespread in plant genera in the southeastern United States than was previously thought. Eight species, previously not known to be myrmecochorous, were discovered to be ant-dispersed. Furthermore, phenological studies here indicate that ant-plant mutualisms may not be as non-specific as previous authors have suggested. Some plants may rely on only one or two ant species for dispersal.