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Effect of Watershed Disturbance on Pinelands Stream Vegetation
Robert A. Zampella and Kim J. Laidig
The Journal of the Torrey Botanical Society
Vol. 124, No. 1 (Jan. - Mar., 1997), pp. 52-66
Published by: Torrey Botanical Society
Stable URL: http://www.jstor.org/stable/2996598
Page Count: 15
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We related stream channel and stream bank plant species composition to eighteen site specific and regional environmental variables in the New Jersey Pinelands (Pine Barrens). Canonical correspondence analysis (CCA) and detrended correspondence analysis (DCA) related major patterns in species composition to complex watershed disturbance gradients. There were significant correlations between the first axes of both the CCA and DCA stream site ordinations and agricultural and developed land cover in a drainage area, pH, specific conductance, and channel sediment. There was a clear contrast between stream stations found within relatively undeveloped watersheds and those in highly developed or farmed drainage areas. Surface waters of the undisturbed sites displayed lower pH and specific conductance values compared with waters in the more disturbed watersheds. The most heavily impacted sites supported a unique group of peripheral or exotic plant species that replaced characteristic Pine Barrens species. Overall species richness did not change in response to watershed disturbance. The presence of disturbance indicator species, or species found only at disturbed sites, provided a good measure of watershed disturbance. High between-site variability in the species present at relatively undisturbed stations and the persistence of some species at more recently disturbed sites complicated the identification of sensitive species, or species found only at undisturbed sites. A comparison of the number of species historically found within and outside the Pine Barrens, rather than the presence or absence of particular sensitive species, provided an additional measure of ecological integrity.
The Journal of the Torrey Botanical Society © 1997 Torrey Botanical Society