Helonias bullata (Swamp Pink) Habitat Characteristics under Different Landscape Settings at Fort AP Hill, Virginia

摘要

Helonias bullata (Swamp Pink) is a federally threatened plant found in many of the wetlands throughout US Army Garrison, Fort A.P. Hill, VA. Wetlands that support Swamp Pink are exposed to periodic occurrences of wildland fire. However, much is not yet known about the relationship between this species and wildland fire. This study examines plant-level characteristics (i.e., number of leaves, rosette size) in relation to habitat-level characteristics through comparison of Swamp Pink under 2 land-management regimes in different military training zones. We evaluated the forest compositional differences based on the presence/absence of wildland fire and military-training zone in wetlands supporting Swamp Pink and in adjacent uplands using non-metric multidimensional scaling (NMS), multi-response permutation procedures (MRPP), indicator-species analysis (ISA), and measures of density, dominance, herbaceous cover, and species richness. Swamp Pink rosettes in wetlands exposed to fire were significantly larger and averaged nearly 1 more leaf per rosette as compared to those surveyed in wetlands that were not exposed to fire. There was significantly less upland tree density in burned sites compared to unburned sites. We found no relationship between training zones and Swamp Pink size and the number of leaves. Additional differences in forest composition were revealed by comparing training zone and the presence/absence of wildland fire in conjunction with one another. Compared to other areas, the training zones with lower fire-frequency and recent evidence of fire featured significantly larger rosettes with more leaves. In uplands, overall community composition was significantly different among plots exposed to different fire-management strategies (MRPP; P 0.05), but no such differences occurred in wetlands (P 0.05). This finding suggests that wetlands limit the effects of fire on community composition. ISA showed that in both wetlands and uplands, different species