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Augmentation of basal resources changes microarthropod community structure, the pattern of intraguild predation, and decomposition rate in a soil food web (PhD Dissertation Seminar)  Add To Calendar

Speaker: Monica Farfan
Host: Wise
  • Date(s): Friday, 4/21 12:00 PM to Friday, 4/21 1:00 PM
  • Campus Address: 4289 SEL, 840 West Taylor
Abstract: Predation between generalist predators that consume shared prey on a lower trophic level is termed intraguild predation (IGP). We investigated how augmentation of the resource base of a forest-soil food web alters the dynamics of an IGP module consisting of two size classes of predaceous mites and shared fungivorous prey (fungivorous mites and Collembolan).  Because changes in this IGP module could alter decomposition rates by affecting fungal grazing, we also examined effects of resource enhancement on the rate of decomposition of a standardized substrate. In the two-year experiment, basal resources were augmented by adding artificial detritus to increase saprophytic fungi. During each field season, 150 fenced 1-m2 plots received bi-weekly detrital enhancements at one of three rates: High (4x), Low (1x), or None (0x); 50 unfenced, non-enhanced plots served as a Reference treatment. Detrital enhancement increased densities of fungivorous prey and Parasitidae, a family of predaceous mites. The High rate changed the dominant fungivorous taxon from Tydeidae to Tarsonemidae, a mite family specializing on thin-walled fungal hyphae, which were likely more abundant in that treatment. Path analyses revealed a complex pattern of changes in the IGP module in response to detrital addition. One emergent pattern was the tendency for resource enhancement to increase the degree to which increases in the smaller IG-Prey positively affected densities of the larger IGPredators. Decomposition rate was highest in the High treatment, probably because saprophytic fungi were more abundant in those plots, and because fungivores had a negative impact on decomposition in the Low treatment.
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