Numbers and biomass of centipedes (Lithobiomorpha: Chilopoda) in a Betula-Alnus woodland in N.E. England.

Over a period of 1 year the mean monthly population densities of L. forficatus varied between 7.58 m-2 (February) and 24.07 m-2 (October). The equivalent values for L. crassipes were 17.05 m-2 (February) and 64.17 m-2 (October). The annual mean population density of the two species was estimated at 51 m-2 with a biomass of 0.585 g live wt m-2. Less than 4% of the total lithobiid population was found in decaying logs and tree stumps, most of the population inhabited the soil/litter layers.Seasonal fluctuation in numbers was shown to be unimodal in L. forficatus and bimodal in L. crassipes. A similar pattern was noted in the status of the ovaries, L. forficatus appears to have a single peak breeding period (September) while L. crassipes has two (June and September).In terms of biomass, the relative importance of centipedes among other woodland invertebrate predators is high.