Dauer, J., T. Fox and F. Menalled
Presented at the Campus Symposium (2001-04-19 )
The goal of our study was to assess the influence of different management systems on carabid beetle activity/density and weed seed predation. This study was conducted during the 2000 growing season in three annual crop systems at the Kellogg Biological Station –Long Term Ecological Research site: (T1) conventional (high-chemical input, moldboard plowed), (T2) no-till (high-chemical input, no tillage), and (T3) organic (no external chemical input, moldboard plowed). Our approach consisted of a twofold study: 1) assessment of carabid beetle/activity density using pitfall traps and 2) evaluation of invertebrate post-dispersal weed seed predation. Seed removal of fall panicum (Panicum dichotomiflorum) and common lambsquarters (Chenopodium album) was determined using 2 treatments: 1) vertebrate exclosures, which allowed invertebrates to remove seeds, and 2) total exclosures, which prevented both vertebrates and invertebrates from removing seeds. A total of 1616 carabid beetles comprising 33 species were sampled. Three generalist predators (Poecilus chalcites, P. lucublandus, and Anisodactylus rusticus) accounted for 82% of the captures. While 54 % of the beetles were collected in the conventional system, 25% were sampled in the no-till system and 21% in the organic system. A total of 204 seed predators were trapped with 132 captured in the no-till system, 36 in the conventional system and 36 in the organic system. In accordance, weed seed removal was significantly higher in the no-till system than in the conventional and in organic systems.
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