A POPULATION OF SPIDERS AND THEIR POTENTIAL PREY IN AN OVERGRAZED PASTURE IN EASTERN ONTARIO

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Abstract
The relationships between spiders, their physical environment, and their potential prey are examined. A method of sampling arthropod populations in a short-grass community with a suction sampler and some errors inherent in the method are described. The distribution of individual spiders among the species agreed with Fisher's logarithmic series. The distribution of spiders in space conformed to the negative binomial series, and is ascribed to the distribution of shelters in the community. Though variations in numbers of spiders in parts of the community are ascribed to births and deaths, and to migrations caused by variations of weather, the overall population remained stable. Potential prey species were classified into functional roles and size classes. Size classes of prey conformed to size classes of spiders. Total numbers and biomass of potential prey remained constant over the season, though the constituent elements varied widely with time. No direct relationship between the number of spiders and the number of prey was detected, but a mechanism is suggested whereby the spiders may contribute to stability of prey populations.