FACTORS INFLUENCING THE DISTRIBUTION OF PTERIDOPHYTES IN A SOUTHEASTERN OHIO HARDWOOD FOREST

Phytosociological and environmental analyses of the pteridophyte commu nity of a mixed-mesophytic forest in southeastern Ohio were used to ev aluate the influences of major environmental gradients on species dist ribution and community structure. The community was dominated by Adian tum pedatum, Asplenium platyneuron, Botrychium dissectum, B. virginian um, Deparia acrostichoides, Diplazium pycnocarpon, Polystichum acrosti choides, and Thelypteris hexagonoptera. The first two axes of a detren ded correspondence analysis (DCA) captured <30% of the total variation . Correlations between species DCA scores and environmental parameters indicate that species, and associations identified using unweighted p aired-group means analysis (UPGMA), segregate along an environmental p lexus dominated by moisture and soil nitrate; both gradients correlate d well with the first ordination axis. Non-significant correlations be tween canopy cover and the first two ordination axes indicate that the highly fluctuating nature of understory light environments may have l ittle influence on the distribution of long-lived understory perennial s such as pteridophytes. Direct gradient analyses and correlations bet ween species presence/abundance and environmental values were used to generate more detailed information regarding species-specific distribu tional patterns. The data presented here emphasize the complexity of f actors influencing pteridophyte communities and the need for studies t o integrate demographic and environmental analyses of both gametophyte s and sporophytes when studying pteridophyte communities.