CHAMAECYPARIS-THYOIDES WETLANDS AND SUBURBANIZATION - EFFECTS ON HYDROLOGY, WATER-QUALITY AND PLANT COMMUNITY COMPOSITION

(1) Atlantic white cedar (Chamaecyparis thyoides) wetlands in the New Jersey Pinelands were studied along a gradient of suburban development defined by increasingly intrusive road and house construction close to the site. Water table level, water chemistry, plant species composition and community structure were recorded to assess the effects of increasing levels of upland disturbance on the adjacent wetlands. (2) Some increases in nitrogen, phosphorus, and chloride occurred in both surface and groundwater within wetlands beside septic system drain fields. Much larger increases in these parameters, plus increases in heavy metal concentrations, occurred in sites receiving both septic tank drainage and road run-off. (3) Hydrology was only affected by the presence of dams on the streams traversing the wetlands, and by ditches dug in association with stormwater sewer outfalls. (4) With increasing levels of suburban disturbance, there was an increasing loss of indigenous herbaceous species and an increasing incursion of upland and exotic species. Ground cover by Sphagnum spp. and cedar seedling densities all declined with increasing suburban development. Woody plant community composition and structure showed little change over the gradient. Changes in water quality were more important in determining changes in community composition and structure than were changes in hydrology. (5) The changes in species composition associated with changes in water quality support the theory that species-richness follows an optimization curve with respect to nutritional quality of the wetland. (6) The results suggest that the maximum buffer width provided for by law be required for all upland development adjacent to white cedar wetlands.