The aftermath of an invasion: Structure and composition of Central Appalachian hemlock forests following establishment of the hemlock woolly adelgid, Adelges tsugae

Heather L. Spaulding, Lynne K. Rieske

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


As the highly invasive hemlock woolly adelgid, Adelges tsugae, continues to expand its distribution in eastern North America, affected forests will incur drastic changes in composition and structure. While these changes have been well-studied in dense hemlock forests in the Northeast, relatively little work is known about the effects of the adelgid at the western edge of the range of eastern hemlock, Tsuga canadensis. We evaluated the nature and extent of these changes using vegetation assessments coupled with growth simulations. The woody plant community was assessed in three strata (upper, mid- and lower) and was used to predict forest succession. Using the Forest Vegetation Simulator (FVS), we then projected the growth of hemlock forests 20 years into the future with and without the effects of the adelgid. In forest simulations lacking adelgid invasion, little change in composition or structure is forecast. In contrast, our projections predict a near complete loss of the hemlock forest type within 20 years of adelgid establishment, with widespread conversion to hardwood forest types, most notably white oak-red oak-hickory, chestnut oak-black oak-scarlet oak, and yellow poplar-white oak-red oak. Hemlock loss will result in denser deciduous forests with thinner canopies and multiple gaps, and significant alterations to terrestrial and aquatic wildlife habitat.

Original languageEnglish
Pages (from-to)3135-3143
Number of pages9
JournalBiological Invasions
Issue number9
StatePublished - 2010

Bibliographical note

Funding Information:
Acknowledgments We would like to thank Melanie Antonik, Keith Holmes, Amber Jones, Tommy Kuhlman, Brian Marbert, Aric Payne, and Matt Thomas for their help with vegetation surveys and data entry. Rob Paratley provided taxonomic assistance, Angela Schoergendorfer offered statistical advice, and Talbot Trotter (USDA Forest Service) provided assistance with the Hemlock Woolly Adelgid Event Monitor. We would also like to thank Kyle Napier (Kentucky State Nature Preserves Commission), Merril Flanary (Kentucky Natural Lands Trust Commission), and Rob Watts (Eastern Kentucky University) for help in selecting our study sites. John Obrycki and two anonymous reviewers provided comments on an earlier version of this manuscript. This research was supported by funds from the USDA Forest Service Southern Research Station and the Kentucky Agricultural Experiment Station, and is published as Experiment Station Project 09-08-047.


  • Adelges tsugae
  • Forest vegetation simulator
  • Hemlock
  • Modeling
  • Tsuga

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology


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