Scientists' Contributions  
   

Bio-monitoring of environmental change and the use of bryophytes in environmental assessment

M. A. S. Burton

Department of Environmental Sciences, University of Hertfordshire, Hatfield, United Kingdom.

    The widespread distribution of mosses and liverworts and their importance in ecosystems globally, has led to many investigations of their use for assessing environmental change. They respond in a measurable way to climatic factors and to pollutants. The capacity to accumulate metals, organochlorine compounds and radionuclides has been used to detect trends in concentrations of these contaminants, reflecting atmospheric deposition.

    Data on concentrations of contaminants in mosses are available chiefly from many countries in Europe and from North America, and mainly in temperate regions; relatively few data are available for tropical and polar regions.

    The species able to tolerate elevated concentrations can be used to compare the spatial and temporal distribution of contaminants, although there is evidence that differential effects on growth rates in different habitats require caution about interpreting data between and within surveys. Transplanted moss samples at sites of differing levels of contamination can provide information on accumulation rates which can be compared with instrumental measurements.

    Species which are sensitive to acidity and high nutrient input in both terrestrial and freshwater habitats show changes, in the growth rates and species assemblages, which may give an indication of the severity of ecosystem stress. Similar approaches have been applied in metal polluted habitats but to a lesser extent. Various stress parameters have been investigated in endeavours to relate exposure to response, including enzyme activities, photosynthetic rate and pigment composition. Data from both in situ and transplanted bryophytes are discussed. Effects on growth under changing climatic scenarios have also been investigated with regard to species distribution. It is important to assess the relevance of methods applied for detecting different types of environmental change and the consequences for issues related to conservation of sensitive species.

       
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