Vegetation-Environment Relations in a Conifer Swamp in Central New York

PARATLEY, R. D. AND T. J. FAHEY (Dept. Natural Resources, Cornell University, Ithaca, NY, 14853). Vegetation-environment relations in a conifer swamp in central New York. Bull. Torrey Bot. Club 113:357-371. 1986.-Direct and indirect gradient analysis techniques were employed to quantify the relationships between vegetation and environment in a valley-basin swamp forest in central New York State. It was hypothesized that soil drainage, as indicated by water table position, would be the most important environmental factor ordering vegetation in the swamp, with a secondary influence by site quality as influenced by spatial position with respect to surface and groundwater inflow. The direct gradient analysis, based upon weekly measurements of water table height, sorted the site into five drainage classes and clearly demonstrated the primary control on woody vegetation distribution. However, the indirect gradient analysis, based upon overstory and ground vegetation composition, was more successful in sorting the vegetation into meaningful communities. The overstory vegetation was divided into an upland community occurring on inceptisol, and three swamp communities on histosol (hemlock swamp, and white pine and larch phases of a mixed conifer-red maple swamp). The ground vegetation subdivided the mixed coniferred maple swamp into four communities named for indicator species. Environmental correlation suggested that these divisions were largely the result of site quality differences as influenced by proximity to mineral-rich inflow. The ground vegetation communities were more clearly separated in the ordination space than the overstory, and were more highly correlated with mean depth of water table, ash content and bulk density of peat. Thus, the gradient analyses supported the hypothesis of environmental control of vegetation distribution. Finally, the high species richness (272 vascular plants) resulted from high microsite heterogeneity, the complex hydrology of the basin, and the mixing of boreal relict vegetation with temperate swamp species typical of the region.