In Defence of Darwin

Abstract

Some claims made by the authors of a paper on the use of systems analysis in ecology (Reichle, D. E., O'Neill, R. V., Kaye, S. V., Sollins, P., and Booth, R. S., 1973. Systems analysis as applied to modeling ecological processes. Oikos 24: 337-343) deserve comment. This paper deals with the role of earthworms in organic matter decomposition in the soil of a forest ecosystem. The authors, in discussing the results of their analysis, make the following conclusions. With an average organic content of the soil at about 4.5%, earthworms would be processing 5 kg soil m-2 yr-1. Assuming uniform distribution of the population to 35 cm, this would be equivalent to a 70 year turnover time of soil due to earthworm feeding activities. They then go on to say that the synthetic capability of the model these interpretations would have been difficult, if not impossible, to obtain. It seems that Reichle et al. were not aware of the work of an illustrious predecessor in this field. Darwin, C. R., 1881. The formation of vegetable mould through the action of worms with observations on their habits. John Murray, London. does not appear in their list of references. In his treatise Darwin does in fact make certain quantitative interpretations about soil turnover by earthworms and, of course, his conclusions were reached without the aid of a sophisticated mathematical model. It should be conceded that Darwin's interpretations were obtained with difficulty and his methods would certainly not have borne fruit within the confines of a three year research grant. His field work was done over a period of thirty years. It is, however, interesting to compare his results with those of the above authors. Darwin did not study a woodland site but examples of his sites which are closest to a forest situation, i.e. those with soils relatively undisturbed by human activity, have been extracted for comparative purposes. In the table