Seasonal Changes in an Old-Field Spider Community with Comments on Techniques for Evaluating Zoosociological Importance

Abstract

Seasonal changes in age and species composition were studied in 63 species of spiders collected in the herbaceous stratum of an old-field community. Four species (Tetragnatha laboriosa, Oxyopes salticus, Misumenops asperatus and Metaphidippus protervus) constitute 77.15% of all spiders collected and are discussed in detail. There is no significant seasonal change in species composition (Importance Value). The seasonal pattern of adult/subadult ratios varies from species to species. Mean abundance generally peaks in early and late summer. Three methods of assessing zoosociological importance were compared. Importance Value (Relative Frequency + Relative Abundance) is a better measure of importance than Prominence Value (Abundance x V/Frequency) when comparing similar organisms within a com- munity. PV and IV based on absolute values, unlike IV based on rela- tive values, have no constant sum. Despite other benefits, this charac- teristic makes them difficult to use for comparative purposes.