Ground running invertebrates were sampled by pitfall trapping in woodlands with high and low aerial pollution by heavy metals. Principal component analysis calculated for the environmental variables showed degree 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 Carabidae was carried out and produced plots which can be interpreted with respect to the pollution effect. The effect of different environmental factors on individual species or subgroups delimited by size, breeding season, diet etc. was determined. Species associating with or disassociating from high pollution levels can be identified. No clear patterns were shown when examining size or breeding season in Carabids in relation to pollution. The highly polluted woods near the main pollution source at Avonmouth are lacking in lycosid spiders, the vacant niche may be filled by a large species of ground running agelenid which may be more adaptable in habits than the lycosids. CCA plots of both Aranaea 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. References: 58
展开▼
