ARE PITFALLS BIASED? A COMPARISON OF CARABID COMPOSITION FROM PITFALL TRAPPING AND HAND SEARCHING IN FOREST HABITATS

摘要

There have been concerns over potential biases from the use of pitfall trapping in carabid research. However, few studies have compared the results obtained from pitfall traps with those of other methods. Forty-five paired pitfall traps and hand searching samples were obtained from nine habitats in Thetford Forest, Breckland, for comparison. With much less effort, pitfall traps produced over three times the number of individuals as hand searching, although both methods produced the same number of species. Harpalus rufipalpis Sturm, Amara lunicollis Schiodte and Notiophilus aquaticus L. were over-represented in pitfall traps. Overall, pitfall trapping preferentially captured larger species (>= 8 mm) while hand searching resulted in more individualsof smaller species (<8 mm). Despite these biases, both methods gave a qualitatively similar ordination of community composition across habitats.