INVERTEBRATES IN WOODLANDS POLLUTED BY HEAVY-METALS - AN EVALUATION USING CANONICAL CORRESPONDENCE-ANALYSIS

Ground running invertebrates were sampled by pitfall trapping in woodl ands with high and low aerial pollution by heavy metals. Principal com ponent analysis calculated for the environmental variables showed degr ee of metal contamination to be the most important difference between the sites. Calculation of canonical correspondence analysis (CCA) for different groups of animals e.g. Diplopoda, Opiliones, Aranaea and Car abidae was carried out and produced plots which can be interpreted wit h respect to the pollution effect. The effect of different environment al factors on individual species or subgroups delimited by size, breed ing season, diet etc. was determined. Species associating with or disa ssociating from high pollution levels can be identified. No clear patt erns were shown when examining size or breeding season in Carabids in relation to pollution. The highly polluted woods near the main polluti on source at Avonmouth are lacking in lycosid spiders, the vacant nich e may be filled by a large species of ground running agelenid which ma y be more adaptable in habits than the lycosids. CCA plots of both Ara naea and all species pooled together show a triangular shape. This is interpreted as representing a small number of species able to adapt to high pollution levels and a larger potential number found at 'clean' sites.