Background/Question/Methods Large-scale disturbances (e.g., hurricanes) produce non-uniform distribution of woody (tree stumps, branches) and fine (back, needles) fuels in pine savannas. Non-uniform fuels produce locally heterogeneous fire intensity, creating patchiness in the groundcover, which may in turn facilitate invasion by both native and exotic species. Japanese climbing fern (Lygodium japonicum) is an aggressive, non-native species threatening groundcover plant species in pine savannas. We experimentally examined how changes in fuel distributions, resulting from large-scale disturbances, influence emergence and growth of L. japonicum in a second-growth longleaf pine savanna. We predicted that increased fuel load would negatively influence the growth and emergence of L. japonicum. We randomly selected 18 L. japonicum plots at three sites prior to 2007 prescribed fires. Plants were selected adjacent to and >5m from stumps. One of three treatments (fine-fuel addition, fine-fuel removal, unaltered control) was randomly applied to circular 1m² plots around each plant. Fronds were counted and mapped and frond lengths measured before and after fire.
Results/Conclusions While stumps did not produce a significant effect on L. japonicum, there was a significant difference among fuel treatments. Fine-fuel addition plots had higher consumption of fuel than did either fine-fuel removal or unaltered control plots. Further, frond emergence was reduced in fine-fuel addition plots post-fire. Significant differences were found in frond length among fuel treatments. Responses of L. japonicum differed among fuel treatments, with increased emergence and growth in fine-fuel removal plots. The response of L. japonicum indicates sensitivity to fire intensity. Our results indicate in low intensity fires, more belowground structures may survive and larger above-ground structures are produced. This may facilitate post-fire recovery in areas where fire intensity is low as a result of reduced fuels. Thus, our results suggest that fire suppression may facilitate invasion of L. japonicum. Large-scale disturbance conditions may not have a direct effect on L. japonicum, but may indirectly influence fire intensities around stumps, either facilitating [when fire intensities are lower] or inhibiting [when fire intensities are increased] invasion. Additional studies will be used to explore this relationship.