The changes in population size of carabid beetles inhabiting an ancient woodland were analysed in a long-term investigation covering a period of nine years (1994-2002). The amplitude of fluctuations of the relative density of these species was estimated and compared with those of carabid beetles inhabiting recent woodlands and more unstable habitats in open landscapes. To analyse this, 8 pitfall traps were set in an ancient beech and oak woodland in the nature reserve "Luneburger Heide" in northern Germany and were emptied every fortnight the whole year round. Catching rates for some species (e.g. Carabus problematicus and Abax parallelepipedus) fluctuated only slightly, whereas those of other species (e.g. C. violaceus and C. auronitens) varied as much as ten-fold. Comparison of these results with those of other long-term investigations of recent woodlands and also of more open habitats showed that in each of the three habitat types some species varied very little in abundance and others, very widely. So it seems that the amplitude of fluctuations in abundance is a feature of each single species rather than a special attribute of their habitats.