Changes in the lumbricid coenosis during secondary succession from a wheat field to a beechwood on limestone

Abstract

During the autumns of 1986 and 1988 earthworm populations and biomasses were determined at five different sites [a wheat field, a 4 and 11 yr old fallow, ca 50 yr old fallow (ash-dominated wood) and a beechwood], all of which were located on a limestone plateau near Göttingen (northern Germany). The sites were chosen to represent different stages of a secondary succession after cessation of cultivation. The beechwood forms the climax ecosystems on limestone in the submontane belt of Central Europe. The earthworm fauna was determined by a combination of two methods: earthworms inhabiting the litter layer and the upper 6 cm of the mineral soil were extracted by heat. Deeper dwelling species were sampled using formalin expulsion. Changes in populations, biomasses and dominance structure of earthworms during succession are documented and discussed in relation to vegetation and abiotic factors. Earthworm density was low in the field and the 11 yr old fallow and high in the 4 yr old fallow, the ca 50 yr old fallow and the beechwood. Earthworm biomass in the field, the 4 yr old fallow and the beechwood exceeded that of the 11 and the ca 50 yr old fallow considerably. Changes in density and biomass of anecic and endogeic species during succession were different from that of epigeic species. The most important factor for the small populations of endogeic species in the wheat field is assumed to be deeper freezing of the upper soil horizons during winter caused by the absence of a litter layer. Low biomass of earthworms in the ca 50 yr old fallow site is considered to result from the absence of a leaf litter layer between early summer and autumn, i.e. by the lack of food substrate.