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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 6047

Samuel W. James; Seasonal and experimental variation in population structure of earthworms in tallgrass prairie. Soil Biol.Biochem. 24(12):1445-1449, 1992

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Estimates of the season of reproduction, period of growth to maturity, and patterns of recruitment are presented for six species of the North American earthworm genus Diplocardia and two European Lumbricidae. Reproduction and recruitment is facultatively continuous in D. smithii and D. verrucosa, while D. rugosa reproduces in the autumn and the remaining Diplocardia reproduce in the spring. The period required for growth to maturity is estimated at 1 yr. The lumbricid Octolasion cyaneum has a single spring episode of reproduction, and matures in the second spring after hatching. Aporrectodea turgida reproduction and recruitment are depressed in summer, with the primary episode in the spring. However, hatching may be delayed by climatic factors, rendering estimation of age to maturity difficult. Population structure responses to burning and irrigation were largely manifested as changes in numbers, rather than in proportions, in different stages. It does not appear that population structure is more sensitive to experimental conditions than biomass measures under the experimental regime employed. Consequently there was little to gain by a finer level of analysis.