Category Archives: forest regeneration

Hunting gives deer-damaged forests in state parks a shot at recovery

Hunting gives deer-damaged forests in state parks a shot at recovery
Phys.org, July 9, 2014

A research team led by Michael Jenkins, associate professor of forest ecology, found that a 17-year-long Indiana Department of Natural Resources policy of organizing hunts in state parks has successfully spurred the regrowth of native tree seedlings, herbs and wildflowers rendered scarce by browsing deer.

“We can’t put nature in a glass dome and think it’s going to regulate itself,” he said. “Because our actions have made the natural world the way it is, we have an obligation to practice stewardship to maintain ecological balance.”

Indiana state parks historically did not allow hunting. But by the 1990s, white-tailed deer populations in parks had swelled to such size that many species of native wildflowers such as trillium and lilies largely disappeared, replaced by wild ginger and exotic species such as garlic mustard and Japanese stiltgrass, plants not favored by deer. Oak and ash tree seedlings gave way to highly deer-resistant or unpalatable trees such as pawpaw.

Excessive deer populations hurt native plant biodiversity

Excessive deer populations hurt native plant biodiversity
PhysOrg, March 11, 2014

To study the effect of rampant deer on trillium and garlic mustard populations, Kalisz and colleagues established multiple 196-square-meter plots in the forest. Half were fenced to exclude deer. Years of observation and hours of statistical analysis later, Kalisz and her colleagues have found that in plots where deer were excluded, the trillium population is increasing and the garlic mustard population is trending toward zero.

Deer Browsing Delays Succession by Altering Aboveground Vegetation and Belowground Seed Banks

Deer Browsing Delays Succession by Altering Aboveground Vegetation and Belowground Seed Banks
PLOS ONE, March 2014

Abstract
Soil seed bank composition is important to the recovery of natural and semi-natural areas from disturbance and serves as a safeguard against environmental catastrophe. White-tailed deer (Odocoileus virginianus) populations have increased dramatically in eastern North America over the past century and can have strong impacts on aboveground vegetation, but their impacts on seed bank dynamics are less known. To document the long-term effects of deer browsing on plant successional dynamics, we studied the impacts of deer on both aboveground vegetation and seed bank composition in plant communities following agricultural abandonment. In 2005, we established six 156 15 m fenced enclosures and paired open plots in recently fallowed agricultural fields near Ithaca, NY, USA. In late October of each of six years (2005–2010), we collected soil from each plot and conducted seed germination cycles in a greenhouse to document seed bank composition.

These data were compared to measurements of aboveground plant cover (2005–2008) and tree density (2005–2012). The impacts of deer browsing on aboveground vegetation were severe and immediate, resulting in significantly more bare soil, reduced plant biomass, reduced recruitment of woody species, and relatively fewer native species. These impacts persisted throughout the experiment. The impacts of browsing were even stronger on seed bank dynamics. Browsing resulted in significantly decreased overall species richness (but higher diversity), reduced seed bank abundance, relatively more short-lived species (annuals and biennials), and fewer native species. Both seed bank richness and the relative abundance of annuals/biennials were mirrored in the aboveground vegetation. Thus, deer browsing has long-term and potentially
reinforcing impacts on secondary succession, slowing succession by selectively consuming native perennials and woody species and favoring the persistence of short-lived, introduced species that continually recruit from an altered seed bank.

Identification and Management of Multiple Threats to Rare and Endangered Plant Species

Identification and Management of Multiple Threats to Rare and Endangered Plant Species
RC-1542, SERDP and ESTCP
Dr. Bernd Blossey, Cornell University
Sept 2013

Density and species composition of monitored stressor organisms (earthworms, slugs, and B. pellucidus) varied across field sites and years. Unexpectedly, it was found that earthworm density and biomass decreased in the fenced plots, indicating a possible, but unforeseen, interaction between earthworms and deer. In just five years, it was found that all three target non-native plants had significantly lower abundance (frequency, cover, and/or density) in fenced plots, in response to deer exclusion. This is particularly true for the short-lived M. vimineum and A. petiolata, which are annual and biennial, respectively. Simultaneously, native vegetation responded positively to deer exclusion. Results indicate that it may be possible to reduce abundance of non-native plants simply by substantially reducing deer density.

Historically browsed jewelweed populations exhibit greater tolerance to deer herbivory than historically protected populations

Historically browsed jewelweed populations exhibit greater tolerance to deer herbivory than historically protected populations
Journal of Ecology, 2013

Browsing by overabundant white-tailed deer has altered ecological relationships in forest communities across eastern North America. Recent but limited work suggests that deer browsing also selects for particular plant defensive traits.

Report – 2011/2012 Deer Management Plan Implementation

Report – 2011/2012 Deer Management Plan Implementation, Report to Board of Commissioners
HURON-CLINTON METROPOLITAN AUTHORITY, Meeting of September 13, 2012

It is the consensus of natural area managers that controlling excessive deer populations is critical to the long term health and viability of the native ecosystems that these animals are a component of. The management efforts the Metroparks established has had a direct impact on insuring that the parks’ high quality natural areas remain intact for future generations to enjoy.

“Dramatic” response by flora & fauna to climate change

“Dramatic” response by flora & fauna to climate change, USGS WUWT, Jan 11, 2012

The U.S. Geological Survey and University of Montana study not only showed that the abundance of deciduous trees and their associated songbirds in mountainous Arizona have declined over the last 22 years as snowpack has declined, but it also experimentally demonstrated that declining snowfall indirectly affects plants and birds by enabling more winter browsing by elk. Increased winter browsing by elk results in trickle-down ecological effects such as lowering the quality of habitat for songbirds.

Climate impacts on bird and plant communities from altered animal–plant interactions

Climate impacts on bird and plant communities from altered animal–plant interactions
Thomas E. Martin & John L. Maron
Nature Climate Change, Jan 10, 2012

Effects of climate on plant communities may provide an alternative, but particularly powerful, influence on animal populations because plants provide their habitats. Here, we show that abundances of deciduous trees and associated songbirds have declined with decreasing snowfall over 22 years of study in montane Arizona, USA. We experimentally tested the hypothesis that declining snowfall indirectly influences plants and associated birds by allowing greater over-winter herbivory by elk (Cervus canadensis). We excluded elk from one of two paired snowmelt drainages (10  ha per drainage), and replicated this paired experiment across three distant canyons. Over six years, we reversed multi-decade declines in plant and bird populations by experimentally inhibiting heavy winter herbivory associated with declining snowfall. Moreover, predation rates on songbird nests decreased in exclosures, despite higher abundances of nest predators, demonstrating the over-riding importance of habitat quality to avian recruitment.

Long-term effects of deer browsing: Composition, structure and productivity in a northeastern Minnesota old-growth forest

Long-term effects of deer browsing: Composition, structure and productivity in a northeastern Minnesota old-growth forest
Mark A. White
The Nature Conservancy, Minnesota and the Dakotas, Forest Ecology and Management 269 (2012)

Continued high browsing pressure is one of many factors contributing to the restructuring of northern Great Lakes forests away from historical variability conditions towards a novel and more homogeneous forested landscape. These simplified forests may be less resilient to the suite of emerging stressors such as climate change and less able to provide ecosystem services such as carbon storage, biological diversity and forest products. Sustained restoration efforts, along with reductions in deer density will be needed to restore species and structural diversity.