PARENT SESSION
Oral Session #104: Plant Communities: Vegetation Analysis.
Presiding: S. Will-Wolf
Friday, August 9. 9:00 AM to 12:00 PM. Grand Ballroom West, Radisson.
Composition of the herbaceous community in a forested watershed in southern New Brunswick, Canada.
ROBERTS, MARK*,1, FREGO, KATHERINE2, HOVEY, ANGELA2, 1 University of New Brunswick-Fredericton, Fredericton, New Brunswick, Canada2 University of New Brunswick-Saint John, Saint John, New Brunswick, Canada
ABSTRACT- Watershed-level vegetation studies provide insights into ecosystem function and provide the basis for designing ecologically based forest management, although few studies have focused on this intermediate scale. Our objective was to examine the variation in species composition in the herbaceous layer within a small forested watershed (ca. 56 ha) in relation to: 1) environmental variables at the individual plot (5m2) scale, and 2) position within the watershed. Detrended correspondence analysis was conducted on species cover data from 167 plots distributed 50m apart on transects running from the stream edge upslope to the ridgetops. There was complete turnover in species composition along the first axis, owing primarily to the unique composition of one portion of the watershed located in a wet seepage. The ordination separated plots under deciduous canopy from those under coniferous canopy. Plots under deciduous canopy had shallower litter, higher soil pH, and lower soil organic matter than plots under coniferous canopy. Partial canonical correspondence analysis indicated that the vegetation pattern was most strongly related to soil chemistry (N, Mg, Ca, P), which was almost five times the contribution of either the canopy or litter characteristics. Coniferous stands and species which are common under a coniferous canopy (i.e., Gaultheria hispidula, Coptis trifolium, and seedlings of Abies and Picea species) occurred near the stream whereas deciduous stands and species common under a deciduous canopy (i.e., Pyrola spp., Aralia nudicaulis, Medeola virginiana, and Chimaphila umbellata) were found on the upper slopes. The small watershed is a convenient unit for studying vegetation variation among adjacent communities and underlying causal factors. Information at this intermediate scale is needed in forest management planning to identify unique communities and habitats for protection or special treatment.
KEY WORDS: environmental variables, forest plants, herbaceous layer, watershed