Category Archives: vegetation

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.

Ann Arbor Government, Urban & Community Forest Management Plan

Ann Arbor Government, Urban & Community Forest Management Plan, adopted June 2, 2014

VISION: Ann Arbor’s urban and community forest is a prominent feature of the city valued by its citizens for the positive contributions it makes to the quality of life and character of the community. The urban and community forest is a vital part of the city’s green infrastructure system and is managed sustainably through sound practices, policies and community stewardship to provide environmental,
social and economic benefits today and into the future.

other information

In a long-term experimental demography study, excluding ungulates reversed invader’s explosive population growth rate and restored natives

In a long-term experimental demography study, excluding ungulates reversed invader’s explosive population growth rate and restored natives
Proceedings of the National Academy of Sciences of the United States of America, vol. 111 no. 12, Mar 25, 2014
Susan Kalisz, p. 4501–4506.

In a long-term experimental demography study, excluding ungulates reversed invader’s explosive population growth rate and restored natives.

The study was long-term, over six years in a PA woodland with a deer population of 20-42 deer per km-sq (51-107 mi-sq), a population similar to some areas of Washtenaw County. There’s a lot of data and statistics in the report, and it shows that the garlic mustard population “explodes” (their “technical” term) where deer had access, but declines where deer were excluded. The ability of native plants to successfully compete with garlic mustard was dependent on the extent of deer browse. Deer never browsed on the garlic mustard, but selectively browsed the native plants.

For our natural areas to sustain the native plants that support a community of other wildlife, the PA study shows that the deer need to be managed at a level where the native flora can survive.

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.

Broadening the ecological context of ungulate–ecosystem interactions: the importance of space, seasonality, and nitrogen

Broadening the ecological context of ungulate–ecosystem interactions: the importance of space, seasonality, and nitrogen
Ecology, June 2013

Where deer were present, patch sizes of ammonium availability, cover, and diversity were smaller compared to deer exclosures, whereas mean site-level effects were not significant. Within deer exclosures cover and solar radiation were more similar in patch size than were cover and nitrogen availability. Our results suggest that browsing ungulates affect spatial patterns of herb-layer cover and diversity through the excretion of nitrogenous wastes in small, discrete patches. Ungulate-excreted nitrogen deposition and herbivory were concentrated in the dormant season, allowing herb-layer plants a greater opportunity to benefit from nitrogen additions. Therefore, the impact of ungulates on nitrogen cycling in forest ecosystems varies with spatial scale and the seasonal timing of ungulate impacts. In this way, ungulates may function as a seasonally dependent link between fine-scale and landscape-level ecological processes.

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.