Document: HAN-3-42-42

Rodent effects on synthetic tallgrass assemblages.

HOWE, H.*

University of Illinois at Chicago, Chicago, IL 60607, USA ¹

Abstract:
Meadow voles, 320/ha, admitted to 16-species synthetic tallgrass assemblages 26 months after planting in southwestern Wisconsin reduced standing plant biomass 53% over controls within 10 weeks (F_1,33 = 4.105, P = 0.05), with a selective reduction of tick-treefoil, Desmodium canadense, densities by 50% over plots protected from voles (F_1,50 = 5.185, P < 0.05). Because this nitrogen-fixing legume differentially invaded exclosures with nitrogen-deficient soil (1333 - 2968 ppm; regression of legume density on soil nitrogen: F_1,16 = 15.392, P < 0.001), suppression by vole herbivory and anticipated granivory should result in an advantage to unpalatable plants that are competitive on nitrogen-deficient soils, leading to successional divergence in plantings to which rodents are admitted as compared with those from which they are excluded. Voles also eliminated the only dominant grass, Elymus virginicus, while climbing white-footed mice, Peromyscus leucopus, 12/ha) harvested 99% of the heads of large-seeded members of the Asteraceae (early sunflower), Heliopsis helianthoides, and rosenweed, silphium integrifolium. Twelve months after rodent admission to plots, legumes remain suppressed and rye decimated by late summer. Further divergence of plots in plant species composition is expected if, as in previously published experiments, granivory affects seedling recruitment. This is likely to be most apparent after burns scheduled in 2001.

Keywords: meadow voles

This abstract is being presented at: 1:45 PM in session:
Oral Session #17: Mammalian Herbivory.