Plant Ecology

, Volume 202, Issue 1, pp 103–111 | Cite as

High white-tailed deer densities benefit graminoids and contribute to biotic homogenization of forest ground-layer vegetation



Biotic homogenization, with its emphasis on invasions, extinctions, and convergence in taxonomic similarity, provides an important framework for investigating changes in biodiversity across scales. Through their selective foraging, large populations of white-tailed deer are altering population sizes, driving extirpations, and facilitating invasions of plants throughout the eastern United States. I hypothesize that deer can drive biotic homogenization in forest understory communities by shifting species composition to one dominated by grasses, sedges, and ferns (all wind-pollinated plants). I report the effects of 16 years of deer exclusion in a hemlock-northern hardwood stand in N Wisconsin using a block design. Species composition showed greater convergence in control plots than exclosure plots, indicating deer can drive biotic homogenization at the stand level. Total percent cover is nearly 4 times greater in exclosure plots. Percent cover by woody plants, broadleaf herbs, and ferns is 150, 63, and 20 times greater in exclosure plots, respectively, while cover by sedges and grasses is 3.8 and 2.2 times greater in control plots. Cover by species with showy, insect-pollinated flowers is 79 times greater in exclosures. Graminoid-dominated control plots represent a novel state not observed fifty years ago, and could reflect the emergence of a grazing lawn. The increase in graminoids at this study area and throughout the region could under some global change scenarios be an early stage of conversion from forest to savanna or wood pasture.


Log response ratio Northern hardwood forest Wisconsin Bray–Curtis similarity Grazing lawn Deer browsing 



This project would not have been possible without help from the following: D. Marquart for overseeing the construction and maintenance of exclosures, R. Hewitt for maintaining exclosure records, and H. Ruder, T. Hanson, and the governing board of Dairymens Inc. for continued in-kind support and access to the property. I am indebted to Dave Rogers, Emmet Judziewicz, and Ted Cochrane for help identifying woodland sedges, and Rogers again for introducing me to PRIMER-E software. An anonymous reviewer made helpful suggestions on an earlier draft of this manuscript.


  1. Allombert S, Gaston AJ, Martin JL (2005) A natural experiment on the impact of overabundant deer on songbird populations. Biol Conserv 126:1–13CrossRefGoogle Scholar
  2. Augustine DJ, McNaughton SJ (1998) Ungulate effects on the functional species composition of plant communities: herbivore selectivity and plant tolerance. J Wildl Manage 62:1165–1183CrossRefGoogle Scholar
  3. Bazely DR, Jefferies RL (1989) Leaf and shoot demography of an Arctic stoloniferous grass, Puccinellia phrayganodes, in response to grazing. J Ecol 77:811–822CrossRefGoogle Scholar
  4. Biesmeijer JC, Roberts SPM, Reemer M, Ohlemüller R, Edwards M, Peeters T, Schaffers AP, Potts SG, Kleukers R, Thomas CD, Settele J, Kunin WE (2006) Parallel declines in pollinators and insect-pollinated plants in Britain and the Netherlands. Science 313:351–354PubMedCrossRefGoogle Scholar
  5. Boucher S, Crête M, Ouellet J-P, Daigle C, Lesage L (2004) Large-scale trophic interactions: white-tailed deer growth and forest understory. Ecoscience 11:286–295Google Scholar
  6. Bradshaw RHW, Hannon GE, Lister AM (2003) A long-term perspective on ungulate-vegetation interactions. For Ecol Manage 181:267–280CrossRefGoogle Scholar
  7. Carson WP, Banta JA, Royo AA, Kirschbaum C (2005) Plant communities growing on boulders in the Allegheny National Forest: evidence for boulders as refugia from deer and as a bioassay of overbrowsing. Nat Areas J 25:10–18Google Scholar
  8. Clarke KR (1993) Non-parametric multivariate analyses of changes in community structure. Aust J Ecol 18:117–143CrossRefGoogle Scholar
  9. Clarke KR, Gorley RN (2006) PRIMER v6: user manual/tutorial. PRIMER-E, PlymouthGoogle Scholar
  10. Conover MR (2001) Effect of hunting and trapping on wildlife damage. Wildl Soc Bull 29:521–532Google Scholar
  11. Côté SD, Rooney TP, Tremblay JP, Dussault C, Waller DM (2004) Ecological impacts of deer overabundance. Annu Rev Ecol Evol Syst 35:113–147CrossRefGoogle Scholar
  12. Coughenour MB (1985) Graminoid responses to grazing by large herbivores: adaptations, exaptations, and interacting processes. Ann Mo Bot Gard 72:852–863CrossRefGoogle Scholar
  13. Curtis JT (1959) The vegetation of Wisconsin. University of Wisconsin Press, MadisonGoogle Scholar
  14. deCalesta DS, Stout SL (1997) Relative deer density and sustainability: a conceptual framework for integrating deer management with ecosystem management. Wildl Soc Bull 25:252–258Google Scholar
  15. de la Cretaz AL, Kelty MJ (2002) Development of tree regeneration in fern-dominated understories after reduction of deer browsing. Restor Ecol 10:416–426CrossRefGoogle Scholar
  16. Dublin HT, Sinclair ARE, McGlade J (1990) Elephants and fire as causes of multiple stable states in the Serengeti-Mara woodlands. J Anim Ecol 59:1147–1164CrossRefGoogle Scholar
  17. Ferraro DO, Oesterheld M (2002) Effect of defoliation on grass growth. A quantitative review. Oikos 98:125–133CrossRefGoogle Scholar
  18. Fuller RJ (2001) Responses of woodland birds to increasing numbers of deer: a review of evidence and mechanisms. Forestry 74:289–298CrossRefGoogle Scholar
  19. Gaston AJ, Stockton SA, Smith JL (2006) Species-area relationship and the impact of deer browse in the complex phytogeography of the Haida Gwaii archipelago (Queen Charlotte Islands), British Columbia. Ecoscience 13:511–522CrossRefGoogle Scholar
  20. Griggs JA, Rock JH, Webster CR, Jenkins MA (2006) Vegetative legacy of a protected deer herd in Cades Cove, Great Smoky Mountains National Park. Nat Areas J 26:126–136CrossRefGoogle Scholar
  21. Groom MJ (1998) Allee effects limit population viability of an annual plant. Am Nat 151:487–496PubMedCrossRefGoogle Scholar
  22. Handa IT, Harmsen R, Jefferies RL (2002) Patterns of vegetation change and the recovery potential of degraded areas in a coastal marsh system of the Hudson Bay lowlands. J Ecol 90:86–99CrossRefGoogle Scholar
  23. Hedges LV, Gurevitch J, Curtis PS (1999) The meta-analysis of response ratios in experimental ecology. Ecology 80:1150–1156Google Scholar
  24. Horsley SB, Marquis DA (1983) Interference by weeds and deer with Allegheny hardwood reproduction. Can J For Res 13:61–69CrossRefGoogle Scholar
  25. Horsley SB, Stout SL, deCalesta DS (2003) White-tailed deer impact on the vegetation dynamics of a northern hardwood forest. Ecol Appl 13:98–118CrossRefGoogle Scholar
  26. Kanda N, Yokota T, Shibata E, Sato H (2005) Diversity of dung-beetle community in declining Japanese forest caused by an increasing Sika deer population. Ecol Res 20:135–141CrossRefGoogle Scholar
  27. Kirby KJ (2001) The impact of deer on the ground flora of British broadleaved woodland. Forestry 74:219–229CrossRefGoogle Scholar
  28. Kirby KJ, Thomas RC (2000) Changes in the ground flora in Wytham Woods, southern England from 1974 to 1991—implications for nature conservation. J Veg Sci 11:871–880CrossRefGoogle Scholar
  29. Knight TM (2003) Floral density, pollen limitation, and reproductive success in Trillium grandiflorum. Oecologia 137:557–563PubMedCrossRefGoogle Scholar
  30. McCullough DR (1985) Variables influencing food habits of white-tailed deer on the George Reserve. J Mammal 66:682–692CrossRefGoogle Scholar
  31. McKinney ML (2004) Measuring floristic homogenization by non-native plants in North America. Glob Ecol Biogeogr 13:47–53CrossRefGoogle Scholar
  32. McKinney ML, Lockwood JL (1999) Biotic homogenization: a few winners replacing many losers in the next mass extinction. Trends Ecol Evol 14:450–453PubMedCrossRefGoogle Scholar
  33. McNaughton SJ (1984) Grazing lawns: animals in herds, plant form, and coevolution. Am Nat 124:863–886CrossRefGoogle Scholar
  34. McShea WJ, Rappole JH (2000) Managing the abundance and diversity of breeding bird populations through manipulation of deer populations. Conserv Biol 14:1161–1170CrossRefGoogle Scholar
  35. Myers JA, Vellend M, Gardesu S, Marks PL (2004) Seed dispersal by white-tailed deer: implications for long-distance dispersal, invasion, and migration of plants in eastern North America. Oecologia 139:35–44PubMedCrossRefGoogle Scholar
  36. Noy-Meir I (1975) Stability of grazing systems: an application of predator-prey graphs. J Ecol 60:459–481Google Scholar
  37. Olden JD (2006) Biotic homogenization: a new research agenda for conservation biogeography. J Biogeogr 33:2027–2039CrossRefGoogle Scholar
  38. Olden JD, Poff NL (2003) Toward a mechanistic understanding and prediction of biotic homogenization. Am Nat 162:442–460PubMedCrossRefGoogle Scholar
  39. Olden JD, Rooney TP (2006) On defining and quantifying biotic homogenization. Glob Ecol Biogeogr 15:113–120CrossRefGoogle Scholar
  40. Osenberg CW, Sarnelle O, Cooper SD (1997) Effect size in ecological experiment: the application of biological models in meta-analysis. Am Nat 150:798–812PubMedCrossRefGoogle Scholar
  41. Palmer TM, Stanton ML, Young TP (2003) Competition and coexistence: exploring mechanisms that restrict and maintain diversity within mutualist guilds. Am Nat 162:S63–S79PubMedCrossRefGoogle Scholar
  42. Porter WF, Underwood HB (1999) Of elephants and blind men: deer management in the U.S. National Parks. Ecol Appl 9:3–9CrossRefGoogle Scholar
  43. Potvin F, Beaupré P, Laprise G (2003) The eradication of balsam fir stands by white-tailed deer on Anticosti island, Québec: a 150 year process. Ecoscience 10:487–495Google Scholar
  44. Putman R, Edwards PJ, Mann JCE, How RC, Hill SD (1989) Vegetational and faunal changes in an area of heavily grazed woodland following relief of grazing. Biol Conserv 47:13–32CrossRefGoogle Scholar
  45. Rahel FJ (2000) Homogenization of fish faunas across the United States. Science 288:854–856PubMedCrossRefGoogle Scholar
  46. Rahel FJ (2002) Homogenization of freshwater faunas. Annu Rev Ecol Syst 33:291–315CrossRefGoogle Scholar
  47. Rooney TP (2006) Deer density reduction without a 12-gague shotgun (Wisconsin). Ecol Restor 24:205–206Google Scholar
  48. Rooney TP, Dress WJ (1997) Species loss over sixty-six years in the ground-layer vegetation of Heart’s Content, an old-growth forest in Pennsylvania USA. Nat Areas J 17:297–305Google Scholar
  49. Rooney TP, Waller DM (2003) Direct and indirect effects of deer in forest ecosystems. For Ecol Manage 181:165–176CrossRefGoogle Scholar
  50. Rooney TP, Wiegmann SM, Rogers DA, Waller DM (2004) Biotic impoverishment and homogenization in unfragmented forest understory communities. Conserv Biol 18:787–798CrossRefGoogle Scholar
  51. Ruhren S, Handel SL (2003) Herbivory constrains survival, reproduction, and mutualisms when restoring nine temperate forest herbs. J Torrey Bot Soc 130:34–42CrossRefGoogle Scholar
  52. Sauvé DG, Côté SD (2006) Winter forage selection in white-tailed deer at high density: balsam fir is the best of a bad choice. J Wildl Manage 71:911–914CrossRefGoogle Scholar
  53. Scheller RM, Mladenoff DJ (2005) A spatially interactive simulation of climate change, harvesting, wind, and tree species migration and projected changes to forest composition and biomass in northern Wisconsin, USA. Glob Chang Biol 11:307–321CrossRefGoogle Scholar
  54. Siemann E (1998) Experimental tests of effects of plant productivity and diversity on grassland arthropod diversity. Ecology 79:2057–2070CrossRefGoogle Scholar
  55. Stockton SA, Allombert S, Gaston AJ, Martin J-L (2005) A natural experiment on the effects of high deer densities on the native flora of coastal temperate rainforests. Biol Conserv 126:118–128CrossRefGoogle Scholar
  56. Stromayer KAK, Warren RJ (1997) Are overabundant deer herds in the eastern United States creating alternate stable states in forest plant communities? Wildl Soc Bull 25:227–234Google Scholar
  57. Taylor EB (2004) An analysis of homogenization and differentiation of Canadian freshwater fish faunas with an emphasis on British Columbia. Can J Fish Aquat Sci 61:68–79CrossRefGoogle Scholar
  58. Tilghman NG (1989) Impacts of white-tailed deer on forest regeneration in northwestern Pennsylvania. J Wildl Manage 53:524–532CrossRefGoogle Scholar
  59. Tremblay JP, Huot J, Potvin F (2006) Divergent nonlinear responses of the boreal forest layer across an experimental gradient of deer densities. Oecologia 150:78–88PubMedCrossRefGoogle Scholar
  60. Webster CR, Jenkins MA, Rock JH (2005) Long-term response of spring flora to chronic herbivory and deer exclusion in Great Smoky Mountains National Park, USA. Biol Conserv 125:297–307CrossRefGoogle Scholar
  61. Westoby M, Walker B, Noy-Meir I (1989) Opportunistic management for rangelands not at equilibrium. J Range Manage 42:266–274CrossRefGoogle Scholar
  62. Wiegmann SM, Waller DM (2006) Fifty years of change in northern upland forest understories: identity and traits of “winners” and “loser” plant species. Biol Conserv 129:109–123CrossRefGoogle Scholar
  63. Wilcock C, Neiland R (2002) Pollination failure in plants: why it happens and when it matters. Trends Plant Sci 7:270–277PubMedCrossRefGoogle Scholar
  64. Woodward A, Schreiner EG, Houston DB, Moorhead BB (1994) Ungulate-forest relationships in Olympic National Park—retrospective exclosure studies. Northwest Sci 68:97–110Google Scholar

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  1. 1.Department of Biological SciencesWright State UniversityDaytonUSA

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