Aspen Bibliography

Deer density effects on vegetation in aspen forest understories over site productivity and stand age gradients

Document Type

Article

Journal/Book Title/Conference

Forest Ecology and Management

Volume

261

Issue

3

First Page

408

Last Page

415

Publication Date

2011

Abstract

Studies examining the interacting effects of ungulate herbivore pressure and site productivity on vegetation are mostly on grassland–grazing systems and have shown conflicting patterns. Here we examine the effects of deer density (>30 years differences in density between two landowners), site productivity (site index, SI) and stand age on subcanopy vegetation characteristics in 60 closed canopy, clear-cut originPopulus tremuloides dominated stands, Michigan, USA. Stand age effects were included because age varied among stands and can affect subcanopy vegetation patterns. Compared with fewer deer, stands with more deer had greater total forest floor vegetation mass, and its major components bracken fern (Pteridium aquilinum), sedge (mostly Carex pensylvanica) and trees/shrubsPopulus stands (1) strongly limits the recruitment of woody stems to larger (>0.9 m tall) size classes, which could affect long-term successional trajectories, and (2) diminishes forb density and species richness, especially at higher site productivity, but increases total forest floor vegetation mass (mostly bracken fern and sedge), especially at lower site productivity. Given associations of bracken fern and sedge with poorer and/or more open sites and assuming high palatability of forbs, this pattern may result from the combination of selective herbivory and higher light availability caused by limited recruitment of trees and shrubs to taller strata.

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