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Providing evidence to improve practice

Individual study: Effects of community-level grassland management on the rare annual earleaf false foxglove Agalinis auriculata at five wet prairie sites in Illinois, USA

Published source details

Vitt P., Havens K., Kendall B.E. & Knight T.M. (2009) Effects of community-level grassland management on the non-target rare annual Agalinis auriculata. Biological Conservation, 142, 798-805

Summary

A study was undertaken at five wet prairie sites in Illinois (east-central USA) to evaluate whether management of white-tailed deer Odocoileus virginianus and woody brush improved the viability of populations of the rare hemi-parasitic annual, earleaf false foxglove Agalinis auriculata.

Five wet prairie sites, Paintbrush Prairie (24.3 ha), Gensburg-Markham Prairie (38.5 ha), Blodgett Road (121 ha), Foxglove Prairie (20 ha) and West Branch Prairie (0.84 ha) were surveyed for A. auriculata twice a year from 2001 to 2004. How white-tailed deer control (the primary grazer/browser) and brush removal (encroaching onto grassland) affected A. auriculata population structure and viability at the five sites over 4 years was analyzed.

Reducing deer numbers (i.e. reducing grazing/browsing pressure) and removing invading brush both benefitted Agalinis. Brush removal increased the proportion of plants reaching the largest size class (flowering and seeding). Reducing deer browsing increased the fecundity of plants (fecundity of flowering plants was reduced by deer when they consumed leaves, stems or flowers). Both management activities (reducing deer density and brush removal) appear necessary for A. auriculata to persist at the study sites investigated.