Abstract
Two recent studies have documented changes in wetland ecosystems in New England by examining changes in wetland vegetation over time. Both documented shifts in vegetation towards shrub and forest dominated wetlands Both then concluded that natural succession has changed more wetlands than human impact has. The last conclusion does not necessarily follow from the data provided.
There are three important points that emerge from re-considering these studies 1) indirect human impact (for example, water level changes, eutrophication, sedimentation) must be considered when assessing human impact on wetlands, particularly given that subtle indirect impact affects larger areas than direct impact from drainage and infilling, 2) when discussing indirect effects of human activity, it is important to carefully define which indirect effects are being considered, since there is a continuum ranging from infilling through to alteration of global CO2 levels, and 3) given the complexity of indirect effects, it is unlikely that most can be recognized in the field.
Similar content being viewed by others
Literature cited
Auclair, A. N. D., A. Bouchard, and J. Pajaczkowski. 1976a. Plant standing crop and productivity relations in aScirpus-equisetum wetland.Ecology 57:941–952.
Auclair, A. N. D., A. Bouchard, and J. Pajaczkowski. 1976b. Productivity relations in aCarex-dominated ecosystem.Oecologia 26:9–31.
Connell, J. H. 1978. Diversity in tropical rain forests and coral reefs.Science 199:1302–1310.
Dansereau, P. 1959. Vascular aquatic plant communities of southern Quebec. A preliminary analysis. Pages 27–54 in Trans. Northeast Wildl. Conf., 4–7 June 1958, Montreal, Quebec. Department of Game and Fisheries, University of Montreal, Montreal, PQ.
Golet, F. C., and J. A. Parkhurst. 1981. Freshwater wetland dynamics in South Kingston, Rhode Island, 1939–1972.Environ. Manage. 5:245–251.
Harris, S. W., and W. H. Marshall. 1963. Ecology of water-level manipulations on a northern marsh.Ecology 44:331–343.
Huston, M. 1979. A general hypothesis of species diversity.Am. Nat. 113:81–101.
Hutchinson, G. E. 1975. A Treatise on Limnology. Vol. III. Limnological Botany. John Wiley and Sons, New York, NY. 660 p.
Keddy, P. A. 1982. Biological considerations in wetlands management. Pages 183–189 in Proceedings of the Ontario Wetlands Conference, September 18–19, Toronto. Federation of Ontario Naturalists, Toronto, Ont. 193 p.
Keddy, P. A., and A. A. Reznicek. 1982. The role of seed banks in the persistence of Ontario's coastal plan flora.Am. J. Bot. 69:13–22.
Larson, J. S., A. J. Mueller, and W. P. MacConnell. 1980. A model of natural and man-induced changes in open freshwater wetlands on the Massachusetts coastal plain.J. Appl. Ecol. 17:667–673.
Pearsall, W. H. 1920. The aquatic vegetation in the English Lakes.J. Ecol. 8:163–201.
Salisbury, E. 1970. The pioneer vegetation of exposed muds and its biological features. Philosophical Transactions of the Royal Society of London, Series B, 259:207–255.
Spence, D. H. N. 1967. Factors controlling the distribution of freshwater macrophytes with particular reference to the lochs of Scotland.J. Ecol. 55:147–170.
Stuckey, R. L. 1975. A floristic analysis of the vascular plants of a marsh at Perry's Victory Monument, Lake Erie. Mich. Botan. 14:144–166.
Swindale, D. N., and J. T. Curtis. 1957. Phytosociology of the larger submerged plants in Wisconsin Lakes.Ecology 38:397–407.
van der Valk, A. G. 1981. Succession in wetlands: A Gleasonian approach.Ecology 62:688–696.
van der Valk, A. G., and C. B. Davis. 1978. The role of seed banks in the vegetation dynamics of prairie glacial marshes.Ecology 59:322–335.
Walker, B. H., and C. F. Wehrhahn. 1971. Relationships between derived vegetation gradients and measured environmental variables in Saskatchewan wetlands.Ecology 52:85–95.
White, P. S. 1979. Pattern, process and natural disturbance in vegetation.Botan. Rev. 45:229–299.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Keddy, P.A. Freshwater wetlands human-induced changes: Indirect effects must also be considered. Environmental Management 7, 299–302 (1983). https://doi.org/10.1007/BF01866911
Issue Date:
DOI: https://doi.org/10.1007/BF01866911