- Galbraith, Williams J.
University of Maine Graduate School
Earthworm (Lumbricidae) distribution and abundance were examined in relation to several characteristics of forested land in central and eastern Maine. The purpose of the study was to examine the relationship between earthworm abundance and habitat, in order to improve the evaluation and management of land for woodcock. Thirty-nine forested sites were sampled for earthworms during June, July, and October, 1982. The habitat types examined represented 3 soil drainage and textured classes, 4 forest overstory types, and previously-farmed and never-farmed land.
Agricultural history accounted for the greatest difference in earthworm biomass of any characteristic examined. Earthworms occurred more often, and biomass was markedly greater, at previously-farmed sites (397 of 416 plots had earthworms, mean biomass = 29.1 g/m2) than at never-farmed sites (26 of 144 plots had earthworms, mean biomass = 0.9 g/m2).
The habitat characteristics associated with abundant earthworms were different for the 2 land-use classes. At previously-farmed sites the greatest earthworm biomass was found in moderately drained, fine sandy loam, the least in poorly drained, silt loam. Earthworms were abundant under all forest types, provided that soil and sampling period were favorable. In contrast, 88% of the biomass collected from never-farmed land came from poorly drained, streamside alder or hardwood stands.
The abundance of earthworms on previously-farmed land also varied with sampling period. The greatest biomass was collected in June, the last in July.
A model was developed to estimate predicted earthworm biomass on previously-farmed land using the habitat characteristics of soil type, sampling period and forest type. The model provides a mechanism for evaluating habitat suitability for earthworms using variables that can easily be incorporated into a habitat model or management scheme for woodcock. Recommendations for selecting and managing woodcock habitat with regard to earthworm abundance are presented.