Weeds and ground beetles (Coleoptera: Carabidae) as influenced by crop rotation type and crop input management

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Humble, Shauna Marie
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Weeds and ground beetles are bioindicators of cropping system sustainability. In 1992, a study was initiated near Winnipeg to determine how cropping system diversity and input use affect populations of weeds and ground beetles, and the association between weed and ground beetle populations. Three, four-year rotations (rotation 1 = annual crops only; rotation 2 = annuals plus one green manure crop; rotation 3 = annuals plus two year alfalfa hay crop) were subdivided into four subplots based on fertilizer (f) and herbicide (h) use (all four combinations: f+h+, f+h-, f-h+, f-h- in each rotation type). A prairie grass system was included in each of three replicates. A common test crop (flax ['Linum usitatissimum' L.]) was seeded in all plots at the end of each rotation cycle (1995; 1999). Plant growth, crop yield, weed and ground beetle diversity weed populations and ground beetle activity, were assessed each year and subjected to univariate analysis. Weed populations and ground beetle activity for 1995 to 1999 were analyzed using multivariate redundancy analysis (RDA). (Abstract shortened by UMI.)