Factors Influencing the Distribution of Pteridophytes in a Southeastern Ohio Hardwood Forest

Abstract

GREER, G. K., R. M. LLOYD, AND B. C. MCCARTHY (Department of Environmental and Plant Biology, Ohio University, Athens, Ohio 45701). Factors influencing the distribution of pteridophytes in a southeastern Ohio hardwood forest. J. Torrey Bot. Soc 124: 11-21. 1997.-Phytosociological and environmental analyses of the pteridophyte community of a mixed-mesophytic forest in southeastern Ohio were used to evaluate the influences of major environmental gradients on species distribution and community structure. The community was dominated by Adiantum pedatim, Asplenium platyneuron, Botr-ychiunm dissectum, B. vit-ginianum, Deparia acr-ostichoides, Diplazium pycnocar-pon, Polystichum acrostichoides, and Thelypteris hexagonoptera. The first two axes of a detrended corresporndence analysis (DCA) captured <30% of the total variation. Correlations between species DCA scores and environmental parameters indicate that species, and associations identified using unweighted paired-group means analysis (UPGMA), segregate along an environmental plexus dominated by moisture and soil nitrate; both gradients correlated well with the first ordination axis. Non-significant correlations between canopy cover and the first two ordination axes indicate that the highly fluctuating nature of understory light environments may have little influence on the distribution of long-lived understory perennials such as pteridophytes. Direct gradient analyses and correlations between species presence/abundance and environmental values were used to generate more detailed information regarding species-specific distributional patterns. The data presented here emphasize the complexity of factors influencing pteridophyte communities and the need for studies to integrate demographic and environmental analyses of both gametophytes and sporophytes when studying pteridophyte communities.