Oecologia

, Volume 157, Issue 3, pp 497–508

Drought–herbivory interaction disrupts competitive displacement of native plants by Microstegium vimineum, 10-year results

Authors

    • School of Forest Resources and Environmental ScienceMichigan Technological University
  • Janet H. Rock
    • National Park Service, Great Smoky Mountains National ParkTwin Creeks Science and Education Center
  • Robert E. Froese
    • School of Forest Resources and Environmental ScienceMichigan Technological University
  • Michael A. Jenkins
    • National Park Service, Great Smoky Mountains National ParkTwin Creeks Science and Education Center
    • Department of Forestry and Natural ResourcesPurdue University
Community Ecology - Original Paper

DOI: 10.1007/s00442-008-1085-z

Cite this article as:
Webster, C.R., Rock, J.H., Froese, R.E. et al. Oecologia (2008) 157: 497. doi:10.1007/s00442-008-1085-z

Abstract

Biological invasions are often exacerbated by disturbance or deviations from historic disturbance regimes. Dense understory layers of invasive exotic plants can alter successional trajectories, resulting in consequences that cascade through the biota. However, it is unclear if such layers are self-sustaining or maintained by chronic disturbances that asymmetrically depress native competitors. We examined the role of white-tailed deer (Odocoileus virginianus Zimm.) herbivory and drought on the permeability of recalcitrant understory layers dominated by the invasive exotic Microstegium vimineum (Trin.) A. Camus in 15 exclosures and 15 control plots from 1997 to 2006. This study was conducted in Cades Cove, Great Smoky Mountains National Park, Tennessee, USA. M. vimineum cover exhibited high inter- and intra-annual variation in both exclosures and controls, but displayed a significant correspondence to drought severity. Native species richness and the abundance of woody plants increased within exclosures, but not controls, following a drought-induced nadir in M. vimineum cover that occurred in 2000. By 2003, all height classes of native tree seedlings were present in exclosures and seedlings were advancing into the sapling layer (≥50 cm tall). After 10 years, no tree seedling on a control plot had been able to attain and maintain a height ≥20 cm. Our results suggest that chronic herbivory inhibits state transitions that could occur in response to intermittent disturbances, which reduce the abundance of the invader. Consequently, recalcitrance is likely reinforced by chronic herbivory.

Keywords

Alternate stable states Browse Deer exclusion Invasive exotic species Japanese stilt grass

Copyright information

© Springer-Verlag 2008