Item Details

title

LIMITATIONS TO UNDERSTORY VEGETATION AND TREE SEEDLING RECRUITMENT IN A PIEDMONT MONADNOCK FOREST

author

Lopez, Christopher L

abstract

White-tailed deer are the most common large mammalian herbivore in temperate forests of the eastern United States. At high densities, deer decrease the diversity and abundance of understory vegetation and exert strong negative effects on tree recruitment through chronic browsing of seedlings. To investigate the influence of deer on understory vegetation and tree seedling mortality in eastern deciduous forests, we established 10 deer exclosures at Pilot Mountain State Park in 2018 and studied the resulting vegetation changes inside and outside of fenced plots. After four years, vegetation percent cover and biomass were consistently higher inside exclosures, but the biological effect sizes were small. In addition to deer, we hypothesized that small mammalian herbivores also affect understory vegetation and tree seedling mortality. The impacts of small herbivores on temperate forest understory community dynamics are often ignored, and whether their effects on tree seedling mortality are additive or compensatory to deer herbivory is not well-understood. To study the influence of multiple herbivore guilds on tree seedling survival, we experimentally transplanted 720 white oak and shortleaf pine seedlings into plots that either (i) permitted access to all herbivores, (ii) excluded deer, or (iii) excluded deer and small mammals and monitored them over two hundred and nineteen days. Mortality of oak seedlings was 32.5% in plots permitting all herbivores, 18.3% in plots permitting only small mammals, and 12.5% in plots excluding all herbivores. Our results initially suggest that small mammals cause significant additive mortality of white oak seedlings. However, this effect was driven by a small subset of sites where rabbit activity, based on high scat density, evidence of rabbit herbivory on seedlings, and camera trap imagery, was higher than in most of the park. The pattern was similar for pines, but survivorship was much higher. These results highlight the species-specific responses of seedlings to high deer densities in temperate forests and indicate that forest understory communities may require additional management beyond the removal of deer to see a significant recovery of native species diversity and abundance.

subject

Herbivory

Mortality

Piedmont

Recruitment

Seedling

Understory

contributor

Anderson, T. Michael (advisor)

Silman, Miles (committee member)

Anderson, Dave (committee member)

date

2023-09-08T08:35:23Z (accessioned)

2023-09-08T08:35:23Z (available)

2023 (issued)

degree

Biology (discipline)

identifier

http://hdl.handle.net/10339/102608 (uri)

language

en (iso)

publisher

Wake Forest University

type

Thesis