Abstract Detail

Interactions of White-Tailed Deer and Invasive Plants in Forests of Eastern North America

Nuzzo, Victoria [1], Dávalos, Andrea [2], Blossey, Bernd [3].

Assessing plant community composition fails to capture impacts of white-tailed deer on native and invasive plant species.

Managing white-tailed deer impacts is creating major challenges for foresters, land managers and conservationists. Deer exclosures, often used to document impacts, may be of questionable utility as impacts may materialize as a function of size, time since construction, other stressors and metrics used. We examined interactive effects of deer, earthworms, and invasive plants using paired plots (30 x 30 m; one fenced and one unfenced) in 12 forests in West Point NY. Sites differed in initial earthworm density, non-native plant cover, and native cover and diversity. Permutational and ordination analyses indicated that plant community composition is associated with earthworm density (and soil pH), with higher understory plant diversity at sites with high earthworm abundance and these differences were maintained over the five year study period (2009-2012). Plant community composition was not affected by fencing but non-native plant cover (Alliaria petiolata and Microstegium vimineum) decreased while native plant cover increased in fenced plots keeping overall plant cover similar across years. In our indicator analyses we expected, but failed, to identify plant species associated with high deer browse pressure (unpalatable or resistant species). Instead we identified two plant species to be indicators of low earthworm density, five species to be indicators of high earthworm density (two of them non-native), and one species each indicative of high earthworm density in open plots and fenced plots, respectively. We also found that a combination of Acer saccharum and Polystichum acrostichoides or A. saccharum and Viola sororia were indicators of deer exclusion at sites with low earthworm density. Even five years appears insufficient time to detect changes in plant community composition following deer exclusion, particularly at sites with a prolonged deer browse history. Additional time is needed for colonization and/or for remaining individuals to reproduce and offspring recruitment to be detected in community monitoring. A more promising approach appears assessment of individual plants for their growth, flowering and reproductive success. At our sites individual measurements of Eurybia divaricata, Maianthemum racemosum and Polygonatum pubescens indicated that after five years of fencing plants were larger and had a higher probability of flowering in fenced plots. Deer exclusion interacted with earthworm density and effects on plant community composition were weak, but we found strong effects on performance of plant individuals and in cover of native and non-native species. We recommend a revision of tools to assess deer impacts with a focus on plant individuals and their performance.

1 - Natural Area Consultants, 1 West Hill School Road, Richford, New York, 13835, United States
2 - Cornell University, Natural Resources, Fernow Hall, Ithaca, NY, 14853, United States
3 - Cornell University, Natural Resources, Fernow Hall, Ithaca, NY, 14853, USA

Keywords:
deer
Plant Commmunties
browse impact.

Presentation Type: Colloquium Presentations
Session: C1, Interactions of white-tailed deer and invasive plants in forests of eastern North America
Location: Chatham Ballroom - C/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 4:45 PM
Number: C1012
Abstract ID:377
Candidate for Awards:None