Ecological Balance

P0000009 (2)An ecosystem is a community of living and non-living things that work together. Plants are pollinated and grow; animals eat plants or other animals, microbes decompose the leftovers. Our ecosystem balance in Washtenaw County is askew, in part through our killing off of large predators. This lack of predators has led to an overpopulation of a certain species that negatively affects the rest of the ecosystem. See Bees, Feral Cats, Deer, Mice, state of the Forest, Waterways

Bees

Another aspect of ecological imbalance of increasing interest is the struggle bees face for survival and their critical role in the environment. Michigan State University researchers point out that bees are responsible for one out of every three bites of food we eat. Most crops grown for their fruits, nuts, seeds, fiber, and hay, require pollination by insects. Pollinating insects also play a critical role in maintaining natural plant communities and ensuring production of seeds in most flowering plants.

The main insect pollinators, by far, are bees, and while European honey bees are the best known and widely managed pollinators, there are also hundreds of other species of bees, mostly solitary ground nesting species, that contribute some some level of pollination services to crops and are very important in natural plant communities.

Bee communities, both wild and managed, have been declining over the last half century as pesticide use in agricultural and urban areas increased. Changes in land use have resulted in a patchy distribution of food and nesting resources. We must consider practices that will benefit pollinators by providing habitats free of pesticides, full of nectar and pollen resources, and with ample potential nesting resources. For further information, see http://nativeplants.msu.edu/

EPA’s bee decisions are sweet for growers, but they sting environmentalists, LA Times, Jan 14, 2017The U.S. Environmental Protection Agency backed away from tough restrictions on how pesticides can be used while honeybees are pollinating crops, and it declared that three of the pesticides most closely associated with bee deaths are safe in most applications. The assessments, released late Thursday, conclude that clothianidin, thiamethoxam and dinotefuran can kill bees and their larvae individually, but that in “most approved uses” they “do not pose significant risks to bee colonies” at the exposure levels expected to be found on fields.

This bumble bee was everywhere. Now it’s on the endangered species list., Washington Post, Jan 10, 2017For the first time in American history, a bumble bee species has been placed on the endangered species list. The rusty patched bumble bee was so prevalent 20 years ago that pedestrians in Midwest cities fought to shoo them away. Now, even trained scientists and experienced bee watchers find it difficult to lay eyes on them.

Feral Cats

Cats imperil species around the world, including our own, with which their relations have become—at least on the surface—more symbiotic. A century ago, when they were still viewed as a quasi-domesticated form of vermin control, cats were also regularly deemed vermin themselves—a germ-carrying danger to be treated as such. The New York SPCA, for instance, gassed 300,000 strays during a 1911 polio scare. The invention of kitty litter in 1947 heralded the thoroughly housebound cat, and a new identity, or rather, disguise: The pampered pet had arrived, but the semi-pest still lurked.

A 2013 study co-authored by Marra estimated that outdoor cats in the U.S. kill—not by disease—somewhere between 1.3 billion and 4 billion birds and between 6.3 billion and 22.3 billion mammals each year. It’s fair to say, as Tucker does, that cats may be considered “nightmarish invaders, capable of ransacking whole ecosystems and annihilating feebler life-forms in their path.”

Read more: The Atlantic, Dec 2016, The Case Against Cats

Deer

Here, now, deer have become that destructive species; changing the composition and structure of forests by feeding on select plant species, denuding the forest of its shrubs and saplings, jeopardizing future regeneration. Birds that nest in shrubs or in the intermediate layers of the forest, have declined. The native white trilliums that once dominated the forest floor have all but disappeared. The forest floor is presently dominated by garlic mustard, an invasive exotic that the deer avoid eating.

Deer change the landscape indirectly, Phys.org, Feb 7, 2017It is widely known that the white-tailed deer is a nonstop eater. Unless it is sleeping or fleeing from a predator, the keystone North American herbivore is nearly always nibbling. Ecologically, deer herbivory is a fairly well understood phenomenon. The presence, abundance and reproductive success of many plant species are directly affected by deer, whose populations are orders of magnitude greater in some regions than they were before European settlement. “Deer are affecting understory communities in many different ways,” explains Autumn Sabo, a University of Wisconsin–Madison plant ecologist and the lead author of a new study that teases out some of the secondary impacts of white-tailed deer on forest ecosystems. Writing this week (Feb. 6, 2017) in the Journal of Ecology, Sabo and her colleagues detail how deer affect forest plant composition by altering facets of the forest environment, including light availability, soil compaction, and the thickness of a particular layer of soil.

Why we manage deer, Cornell Botanic Gardens, 2016Managing the deer population is essential to maintaining or improving forest health. As deer populations have increased at our natural areas and beyond, so have their impact on forest health. Many of our natural areas exhibit reduced forest structure, decreased native plant populations such as trilliums, orchids and various rare plants, increased invasive species growth, and higher rates of Lyme disease, as compared to documented conditions of these sites twenty or thirty years ago.

Deer Discovery: Invasive Plants Get Boost from too Many Deer, Smithsonian Insider, May 6, 2016A survey of the two study plots after 25 years revealed the density of Japanese barberry, wine raspberry and Japanese stiltgrass was much higher in the open plot. The presence or absence of deer, they found, was an excellent predictor of the abundance of exotic plant species.

White-tailed Deer and Their Influence on Forest Vegetation, Long Island Natural History Conference, Tom Rawinski of the U.S. Forest Service, April 2015

How many deer is too many deer?

From: Actionbioscience (below)

In an ideal world, biologists would have a simple common practice to guide deer management. In recent years, some biologists have regarded 8 deer per square kilometer as the maximum number a habitat can support long-term. This is complicated greatly by habitat quality, however. It is likely some habitats could support much more than 8 deer km-2, whereas other habitats could not support 4 deer km-2 in the long-term. Biologists instead try to determine whether a deer population is overpopulated in a particular region. From a management perspective, deer populations can be considered overpopulated if any of the following six conditions are met:

  • Deer negatively impact vegetation structure and composition, local fauna, or soils or other physical features of the environment.
  • Deer populations exhibit a poor average body condition in terms of body mass, reproductive rate, or trophy scores.
  • Individual deer have unusually high parasite loads or infectious disease prevalence.
  • Deer are transmitting disease to humans, livestock, or other species.
  • High deer population densities cause significant economic losses in agriculture, horticulture, forestry, or residential gardens and landscaping, as well as other property damage, like vehicle damage from deer collisions.
  • Deer population densities are associated with a significantly increased risk of injury or death to humans—primarily via deer-vehicle collisions.

See recent Exhibit at Smithsonian Museum of Natural History

Resources

This “before and after” photo–2001 vs 2013–of a Southold, NY property demonstrates the dramatic destruction of the understory by the deer over the last decade. Featured in Al Cambronne’s national blog

    Deer-mediated changes in environment compound the direct impacts of herbivory on understorey plant communities, Wiley Online [abstract], March 2, 2017In forests of eastern North America, white-tailed deer (Odocoileus virginianus) can directly affect, via herbivory, the presence, abundance and reproductive success of many plant species. In addition, deer indirectly influence understorey communities by altering environmental conditions.

  • Deer change the landscape indirectly, Phys.org, Feb 7, 2017Now, scientists are looking beyond herbivory to better understand the indirect effects of deer on eastern North American forest landscapes. In particular, scientists are interested in how the animal’s presence and behaviors affect the composition and overall health of the wildflowers and other herbs—what scientists call understory communities—that blanket the forest floor.
  • The Dangers of Too Many Deer, Izaak Walton League of Conservation, 2016To Williams and DeNicola, these woods could scarcely look uglier. The barberry (an invasive non-native) and ferns are thriving because deer shun them. The native understory is gone because deer browsed it away. There is no tree regeneration because seedlings are eaten before they’re boot-high.

    Many hunters in these parts (and in much of the East and Midwest) expect to take clear, 150-yard shots through woods like these because they’ve never known anything else. But where you can do that, something is dreadfully, drasti­cally wrong. That something is too many deer.
  • Deer make collision-free escapes thanks to inbuilt ‘compasses’, Phys.org/June 7, 2016Researchers believe that the tendency of deer to align their bodies with respect to a north-south magnetic field line confirm that they are magnetosensitive and magnetoreceptive. They also speculate that escape in a known direction eases spatial orientation and helps the animals to return later to the same place from which they fled. This might for example be important for a lactating female roe deer that has been hiding her fawn in tall grass or crops nearby.
  • When Animal Rights Backfire, Richard Conniff, Takeapart, April 8, 2016Saving the ‘furry’ animals—despite science—can devastate ecosystems.
  • Tracking deer by NASA satellite, ScienceDaily, March 30, 2016“This kind of applied research is very important for making remote sensing data relevant to wildlife management efforts,” said Jyoteshwar Nagol, a researcher at the University of Maryland. Deer have a huge economic impact in the United States, from hunting to crop damage to car accidents. As regional climates shift or droughts occur, deer distributions could change in response to changes in the timing of vegetation green-up.
  • When the Killing’s Done, Island Wildlife Roars Back, Takeapart, March 21, 2016New research shows that eradicating invasive species lets unique and imperiled wildlife recover. Jones, who teaches at Northern Illinois University, is the lead author on a study published Monday in Proceedings of the National Academy of Sciences that looks at the long-term effects of eradicating cats, rats, goats, pigs, and other invasive mammals from islands. On the 181 islands where biologists have conducted follow-up studies, Jones and her coauthors found that eradication turns out to be one of the most effective strategies “for protecting the world’s most threatened species.”
  • DNR releases update on health of Michigan’s forest land, MI Dept Natural Resource, Feb 22, 2016The report breaks down forest health threats by examining insects and diseases, forest decline and ongoing forest health research. Accompanying photos and maps illustrate the pests and show the effects they have had on Michigan’s forest system.2015 Forest Health Highlights report 
  • Dread is vanishing from the animal world. Here’s why that’s a bad thing., Washington Post, Feb 24, 2016“I think it does suggest that fear is in some respects a critical component of ecosystems,” he said. “When you remove the top level of the food chain as humans have done across the globe … you don’t just remove the actual predation but you remove the behavioral effects as well.”

    Bringing fear back, he continued “restored a balance to the food chain that had been lost when the top level was taken away.”
  • Ball State study: Deer ready to overrun some urban areas, Fox News, Feb 4, 2016A new analysis by a Ball State University researcher has found many Midwestern communities could soon be overrun with white-tailed deer because more than twice as many fawns survive in urban areas compared to rural.

    Tim Carter, a biology professor, says young deer are more than twice as likely to survive in an urbanized area as compared to rural. Ball State researchers spent 2013-14 tracking deer around the area of the Bloomington, Indiana.
  • Oh, deer: Study uses GPS to explore animals’ relationship with forest, Penn State News, Jan 18, 2016According to Christopher Rosenberry, supervisor of deer and elk management with the Pennsylvania Game Commission, deer snacking like the kind that wipes out Ray’s apple harvest is normal behavior, and it presents a danger to the entire forest. “Deer are browsers. They will browse on woody vegetation, and too much browsing may eliminate the small trees in the forest. If there’s a timber harvest or an ice storm or something that removes the canopy, and those young trees do not exist under the canopy, you can potentially lose your forest.”

    Thanks to geospatial technologies like GPS, one Penn State research study may soon have a better understanding of how to balance these woodland creatures’ effect on forest vegetation.
  • Deer and the Numbers Explosion, Local in Ann Arbor, Feb 24, 2015 The tendency of deer to increase their numbers well beyond the carrying capacity of their environment is termed an “irruption”. This early (1943) paper by Aldo Leopold, one of the fathers of environmental conservation, lays out the story. A reserve owned by the University of Michigan was stocked with 4 does and 2 bucks. Within 6 years, there were 160 deer, and they had exceeded the food supply in a 1200 acre reserve.
  • Guest Spot: How deer have decimated our woodlands, Suffolk Times, Nov 29, 2014Deer have a large and varied diet. There’s little they won’t eat at one time or another. Twigs, leaves, bark, grasses, weeds and soft-stemmed plants, acorns, other nuts, fruits, mushrooms, algae and mosses are all on their menu. But at their base, deer thrive on the seedlings of most species and, over a short period of time, strip the understory bare. In its current state, it could take decades or even hundreds of years to restore our woodlands.

    The loss of the understory, of new trees and of tree and plant diversity, has altered food sources, mating, nesting and nursery sites for insects, birds and small mammals. In addition, as older trees are lost to disease and storm damage, with no new trees coming to replace them, birds like the woodpecker, chickadee and tree swallow have no place to nest. And with no ground cover, towhee and bobwhite numbers have plummeted.
  • History of Deer Population in Indiana, City of Bloomington, IN, 2014?Causes of high deer populations, indicator species to assess impacts of deer
  • White-tailed Deer in Northeastern Forests: Understanding and Assessing Impacts, Thomas J. Rawinski, Northeastern Area State and Private Forestry, Forest Service, U.S. Department of Agriculture, Newtown Square, PA, www.na.fs.fed.us, November 2014Forest habitat degradation by white-tailed deer is not a new problem. Durward L. Allen wrote about it in his book, Our Wildlife Legacy, originally published in 1954: “The beginning of range deterioration usually is evident only to the specialist. It involves gradual reduction of the most palatable woody plants and their replacement with species that deer do not like. An insidious destruction of habitat takes place while people delay and bicker.”
  • Hunting gives deer-damaged forests in Indiana state parks a shot at recovery, Purdue Agriculture News, July 9, 2014
  • Effects of abundant white-tailed deer on vegetation, animals, mycorrhizal fungi, and soils, Angela L. Shelton et al, Forest Ecology and Management, May 2014Here, we simultaneously examine effects of excluding white-tailed deer on responses of woody and herbaceous vegetation, terrestrial and subterranean animals, mycorrhizal fungi, and soil characteristics. This study was conducted in a forest preserve with high deer densities in the central hardwoods region of the Midwestern US, using a series of replicated deer exclosures (15×15 m) and adjacent unfenced controls that ranged in age from two to seven years. Despite significant tree recruitment inside exclosures, we recorded no native tree seedling recruitment in control plots. In addition, the growth rate of existing tree seedlings was significantly greater in exclosures than in controls, and the growth rate of invasive shrubs was approximately 30 times higher inside exclosures.
  • DEER FORAGING MOST DAMAGING AFTER FOLIAGE FALLS, Fairfield County Deer Management AllianceDr. Georgina Scholl, Vice Chairman of the Alliance, stated “Residents have forgotten that it is not normal to look through the forest and see the rise and fall of our topography hundreds of feet out. The shrubs and saplings that once comprised the leafy understory used to block your view. Today, such lower areas look more like manicured parklands”.
  • Status and Ecological Effects of the World’s Largest Carnivores, Science Magazine, Jan 2014Current ecological knowledge indicates that large carnivores are necessary for the maintenance of biodiversity and ecosystem function. Human actions cannot fully replace the role of large carnivores. Additionally, the future of increasing human resource demands and changing climate will affect biodiversity and ecosystem resiliency. These facts, combined with the importance of resilient cosystems, indicate that large carnivores and their habitats should be maintained and restored wherever possible. Preventing the extinction of these species and the loss of their irreplaceable ecological function and importance will require novel, bold, and deliberate actions.
  • Overgrazing by deer is changing the face of U.S. forests, Earthsky, March 18, 2014
  • Deer proliferation disrupts a forest’s natural growth, Cornell Press Release, March 7, 2014Expanding deer populations in the Northeast, however, stall forest development and promote the growth of thorny thickets of buckthorn, viburnum and multiflora rose bushes. If deer leave the forests alone, such trees as cottonwood, locust and sumac can sprout and grow unimpeded.
  • Deer Browsing Delays Succession by Altering Aboveground Vegetation and Belowground Seed Banks, PLOS One, March 7, 2014Deer also altered the general structure of the plant community, causing a 31% increase in short-lived monocarpic plants in the seed bank, a 5% decrease in the number of native relative to introduced species, and a 12% decrease in the abundance of native species in the seed bank. Very few woody plants emerged from the soil seed bank (10 individuals in total)
  • An Economic Assessment of the Impacts of White-Tailed Deer Overabundance in Town of Hamilton, New York, Digital Commons @ Colgate, Fall 2013This paper’s main objective will be dealing with the stakeholders— focusing on the economic burdens/advantages they incur. We will identify the stakeholders a priori, and thus get into a discussion of their burdens/advantages. Deer cause economic problems at all levels of the community; people are aware that they must protect themselves, their families, and their homes/gardens from the effects of deer. Stakeholders we deem most affected by deer are homeowners, farmers, hunters, and drivers.
  • Deer in Balance, covering New Jersey deer population issues
  • Too Many Deer: A Bigger Threat to Eastern Forests than Climate Change?, Cool Green Science, The Science Blog of The Nature Conservancy, August 22, 2013
  • Worth Reading: DEERLAND – America’s Hunt for Ecological Balance and the Essence of Wildness, Wisconsin writer Al Cambronne, 2013
  • Impacts of White-tailed Deer on Forests, OSU, October 26, 2015The loss of plants and plant diversity due to over browsing by deer can reverberate up through the food chain, especially to insects and birds. The loss of plants and diversity can have adverse effects on the diversity and abundance of insects, which serve as prey for many forest songbirds. The loss of plants can also mean loss of shelter for small mammals, reptiles, and amphibians, and nesting sites for songbirds. Finally, a loss of native vegetation can open the forest up to colonization by invasive species, such as garlic mustard and honeysuckle.
  • Impact of Deer Management Inaction on Natural Ecosystems, Anne Hairston-Strang, Ph.D., MD DNR Forest ServiceThis powerpoint presentation discusses the impact of deer on Forests. Heavy deer browse reduces tree seedlings and can change species composition in forests: succession, plant diversity, wildlife habitat quality and water quality. Deer can accelerate invasive species spread, further reducing native tree regeneration. The longer the heavy browse, the greater the effects (browse line becomes loss of mid-canopy)
  • America Gone Wild, Wall Street Journal, Nov 2, 2012Welcome to the nature wars, in which Americans fight each other over too much of a good thing—expanding wildlife populations produced by our conservation and environmental successes. We now routinely encounter wild birds and animals that our parents and grandparents rarely saw. As their numbers have grown, wild creatures have spread far beyond their historic ranges into new habitats, including ours. It is very likely that in the eastern United States today more people live in closer proximity to more wildlife than anywhere on Earth at any time in history.
  • Estimating Deer Populations on Your Property: Population Dynamics, University of Missouri Extension, March 2012
  • Fifteen Years of Urban Deer Management: The Fontenelle Forest Experience, Wildlife Society Bulletin 35(3):126–136; 2011We engaged in a public process to establish a deer management program in this developed landscape and learned from 15 years of experience. Formation of the Bellevue Deer Task Force led to implementation of controlled deer-hunting seasons from 1996 to present. Total annual harvest of white-tailed deer by archery and muzzleloader hunters at FF ranged from 28 in 1996 to 140 in 2006. Mean success rates of archery (52%) and muzzleloader hunters (93%) at FF were high compared to other areas. Densities of white-tailed deer in the study area declined from 27 deer/km2 in 1995 to 15 deer/km2 in 2006, though harvest and deer were not evenly distributed across the landscape. By 2006, densities of deer were near overwinter goals in the hunted FF lowlands, FF uplands, and GP lowlands (7 deer/km2, 5 deer/km2, and 13 deer/km2 , respectively), but they remained relatively high in the adjacent unhunted BR area (30 deer/km2). Native plant communities were severely overbrowsed in the study area through 1995, influencing their structure and composition, but signs of recovery were apparent in areas where controlled hunting reduced densities of deer to

    From the Fontenelle Forest Website:
    Deer Management

    Since the 1980s, the deer population has exploded, due in part to the lack of larger predators and the abundance of food. To mitigate the issue, we embarked on what has been a decades-long process: conducting research, forming and enacting a plan, and constantly evaluating results. Since the official deer hunt program began in 1996, it has become arguably the most successful conservation program in the history of the forest.

  • Legacy of top-down herbivore pressure ricochets back up multiple trophic levels in forest canopies over 30 years, Ecosphere, Jan 2011Removal of top-down control on herbivores can result in a trophic cascade where herbivore pressure on plants results in changes in plant communities. These altered plant communities are hypothesized to exert bottom-up control on subsequent herbivory via changes in plant quality or productivity. But it remains untested whether top-down perturbation causes long term changes in plants that ricochet back up the new food chain that depends on them. In a large-scale, 30-yr controlled field experiment, we show that 10 yr of top-down control of an ungulate herbivore (white-tailed deer, Odocoileus virginianus) created contrasting forest tree communities exerting bottom-up effects that ricochet back up 3 trophic levels 20–30 yr later. Higher ungulate densities during stand initiation caused significant reductions in tree species diversity, canopy foliage density, canopy insect density, and bird density in young (ca. 30 yr old) forests. Because recruitment of trees from seedlings to the canopy occurs over a relatively brief period (ca. 10 yr), with membership in the canopy lasting an order of magnitude longer, our results show that even short-term perturbations in ungulate density may cause centuries-long disruptions to forest ecosystem structure and function. In documenting this five-step trophic ricochet, we unite key concepts of trophic theory with the extensive literature on effects of ungulate overabundance. As predators decline and ungulate herbivores increase worldwide, similar impacts may result that persist long after herbivore density becomes effectively managed.
  • White-tailed Deer Biology and Management, Fact Sheet, Clemson Cooperative Extension 34, 2009Since vast stands of virgin forest and large predators are gone, few natural factors, except deer themselves, now act to limit deer populations. If factors are not present to limit a population’s growth, deer herds become their own worst enemy. The most valuable and preferred food plants are browsed out or eliminated. Deer are then forced to utilize lower preference foods with lower nutritive quality. The problem becomes more complicated with each successive fawn crop. Natural mortality may increase significantly and the population often experiences a reduction in overall health. Unfortunately, when die-offs occur, the habitat has usually been severely damaged and may require many years to recover. This sequence of events occurs as a cycle where factors are not present to regulate a deer population’s growth.
  • Impacts of White-Tailed Deer Overabundance in Forest Ecosystems: An Overview, US Forest Service, Thomas J. Rawinski, June 2008The Forest Service recognizes that white-tailed deer overabundance has become a serious forest health issue, especially in the 20 Northeastern and Midwestern States.
  • A perfect storm: two ecosystem engineers interact to degrade deciduous forests of New Jersey, Biol Invasions, 2008We look at how two ecosystem engineers, the white-tailed deer and the invasive plant Japanese stilt grass, interact to completely alter the structure and composition of the subcanopy within northern deciduous forests. This interaction has wide-ranging repercussions on forest food webs which we explore through a case study of breeding woodland birds in the state of New Jersey. We show that the guilds of birds that rely on the subcanopy have experienced greater declines from 1980 to 2005 than birds that specialize on the intact upper canopy of impacted forests.
  • What Do We Do with Too Many White-tailed Deer? Actionbioscience, May 2010
  • Negative Effects of White-tailed Deer on Native Wildflowers at Indiana Dunes National Lakeshore (INDU), National Park Service, 2010 In all plots, the researchers collected data on focal forest understory wildflowers that deer prefer as food termed palatable, and wildflowers that deer avoid eating, termed unpalatable. Native plant populations of the understory herbs constantly grazed by abundant deer are unable to regenerate, become less viable, and can decline to extinction. This can result in the loss of biodiversity in our forests . The research findings suggest a need to decrease the deer herd size at INDU to sustain regeneration of native plants in the understory of forested habitats.
  • Nonconsumptive effects of a generalist ungulate herbivore drive decline of unpalatable forest herbs, Ecology, 2010 Analyses of individual size in five unpalatable forest plant species in long-term experimental paired deer exclosure/deer access plots corroborate the natural site results; all five species were smaller in deer access plots. Analyses of abiotic variables in natural and experimental sites suggest one potential mechanism for indirect effects of deer. Deer-mediated soil quality declines included increased soil penetration resistance and decreased leaf litter depth, which are known to hinder plant growth. Unpalatable plant species in forests experiencing high deer numbers may be in decline along with their palatable neighbors. Our study implicates deer overabundance in the cascade of forest species decline and the urgency of this conservation issue in North America
  • Too Many Whitetails?, Northern Woodlands, Winter 2010How many deer are too many? Is it when the population density reaches a certain number, like 16 or 20 deer per square mile? Is it when hunters complain that the deer are too skinny and that there are no trophy bucks? Is it when the deer population exceeds the habitat’s carrying capacity? Or when environmental impacts, like loss of wildflowers, become noticeable?
  • Ecology and Management of White-tailed Deer in Missouri, Robert A. Pierce II, Jason Sumners, Emily Flinn, University of Missouri Extension, Nov 2011
  • Biology and Management of White-tailed Deer, David Hewett, CRC Press, 2011?
  • Bluff Point Deer Exclosure, Deer Deforestation, Oct 5, 2010
  • Deer Facilitate Invasive Plant Success in a Pennsylvania Forest Understory, Natural Areas Journal, 2009We suggest that deer-mediated disturbance to understory communities facilitates the success of invaders in forests. Many North American forests experience both exotic plant invasion and deer overabundance, but the two problems have never been empirically linked. In this paper, we quantify deer effects on native and exotic understory herbs in a western Pennsylvania forest.
  • Biodiversity, exotic plant species, and herbivory: The good, the bad, and the ungulate, Marty Vavra, Catherine G. Parks, Michael J. Wisdom, Forest Ecology and Management, 2007s. Herbivory by both wild and domestic ungulates exerts considerable impact on structure and composition of native plant communities. Intensive herbivory by ungulates can enhance exotic plant invasion, establishment, and spread for three reasons: (1) many exotic plants are adapted to ground disturbances such as those caused by ungulate feeding, trampling, and movements; (2) many exotic plants are adapted for easy transport from one area to another by ungulates via
    endozoochory and epizoochory; (3) many exotic plants are not palatable or are of low palatability to ungulates, and consequently, their survival is favored as ungulates reduce or eliminate palatable, native plants. Ungulate herbivory is a chronic, landscape-scale disturbance capable of influencing plant communities as much as episodic events such as fire.
  • Deer vs. the Environment, On Earth, November 8, 2008
  • Oh Deer!, Piedmont Environmental Council
  • Deer, Communities & Quality of Life, Ecosystem Management Project, 2006Scientific research published in respected journals documents that the destruction is well underway in Pennsylvania’s woodlands. Dr. Gary Alt, former supervisor of the Game Commission’s Deer Management Section, described the situation involving deer and forests this way:
    “If the deer population is not controlled, we will lose the composition of forests; we’ll lose the ability to grow wildlife, and we’ll grossly change the commonwealth and be poorer because of it.
  • Biologist doubts hunter’s ability to control deer numbers”, Deer Management Conference, 2005?Like they are in Wisconsin,overabundant deer populations in Pennsylvania are raising concerns about forest regeneration.
  • Managing White-tailed Deer in Forest Habitat From an Ecosystem Perspective, Pennsylvania Case Study, Report of the Deer Management Forum, 2005This report, using Pennsylvania as an example, addresses the seriously degraded ecological condition of forests across much of the East, which has resulted in large part from high deer densities.
  • Linking Wolves and Plants: Aldo Leopold on Trophic Cascades, BioScience, 2005Aldo Leopold, perhaps best known for his essays about nature, was also an eloquent advocate during the 1930s and 1940s of the need to maintain wolves and other large carnivores in forest and range ecosystems. He indicated that their loss set the stage for ungulate irruptions and ecosystem damage throughout many parts of the United States. We have synthesized the historical record on the potential effects of wolf extirpation in the context of recent research. Leopold’s work of decades ago provides an important perspective for understanding the influence of large carnivores, via trophic cascades, on the status and functioning of forest and range plant communities. Leopold’s personal experiences during an era of extensive biotic changes add richness, credibility, and even intrigue to the view that present-day interactions between ungulates and plants in the United States have been driven to a large degree by the extirpation of wolves and other large carnivore.
  • Ecological Impacts of High Deer Densities, Teaching Issues and Experiments in Ecology, 2004Decision-making for deer management involves many challenges beyond insufficient data and incomplete understanding of the role deer play in complex ecosystem interactions. A major issue is that interpretation of deer numbers and impacts varies with scale.
  • ECOLOGICAL IMPACTS OF DEER OVERABUNDANCE, Annu. Rev. Ecol. Evol. Syst. 2004Deer inflict major economic losses in forestry, agriculture, and transportation and contribute to the transmission of several animal and human diseases. Their impact on natural ecosystems is also dramatic but less quantified. By foraging selectively, deer affect the growth and survival of many herb, shrub, and tree species, modifying patterns of relative abundance and vegetation dynamics. Cascading effects on other species extend to insects, birds, and other mammals. In forests, sustained overbrowsing reduces plant cover and diversity, alters nutrient and carbon cycling, and redirects succession to shift future overstory composition. Given the influence of deer on other organisms and natural processes, ecologists should actively participate in efforts to understand, monitor, and reduce the impact of deer on ecosystems.

    See also michigansaf.org/Tours/05Deer/05-TremblaySlides.pdf

  • The Forest Nobody Knows, US Forest Service, Forest Science Review, Winter 2004“Deer have the capability of changing forest ecology, by changing the direction of forest vegetation development. It doesn’t matter what forest values you want to preserve or enhance — whether deer hunting, animal rights, timber, recreation, or ecological integrity — deer are having dramatic, negative effects on all the values everyone holds dear.”
  • Long-term effects of white-tailed deer on the structure and composition of heavily browsed boreal plant communities on Anticosti island, Viera, Vanessa, Maître ès sciences (M.Sc.), Université Laval, 2003Deer browsing affected species abundance and composition on Anticosti island. It is unlikely that the differences between the vegetation of Anticosti and Mingan are due to factors other than deer browsing. Indeed, herbaceous and woody species rapidly recovered in exclosures, which clearly demonstrates the effects of deer browsing on vegetation communities. Moreover, since 1930, many studies have already reported deer impacts on vegetation on Anticosti (Pimlott 1963, Huot 1982, Chouinard and Filion 2001, Hébert and Jobin 2001, Potvin et al. 2003).
  • Proceedings of the State of the Forest Symposium: Ecological Issues Regarding Highlands Forest Degradation & Restoration held Oct 3, 2002, New Jersey Audubon Society, Conservation Foundation, Nature ConservancyThis symposium report provides information from numerous experts and covers many issues. Keynoter Marc Matsil, for the NJ Department of Environmental Protection, stressed the importance of maintaining healthy forests for reducing air pollution and preserving water resources. Other speakers addressed specific ecological stressors and challenges in preserving the Highlands forests, as well as methodologies for restoring the forests to a healthy state.
    The threats posed by invasive plant species and by herbivory by superabundant deer were two key topics featured in the panel discussions.
  • Deer impacts on forest ecosystems: a North American perspective, T.P. ROONEY, Department of Botany, University of Wisconsin, 2001.
  • Managing the Abundance and Diversity of Breeding Bird Populations through Manipulation of Deer Populations, Conservation Biology, 2001Deer densities in forests of eastern North America are thought to have significant effects on the abundance and diversity of forest birds through the role deer play in structuring forest understories. We tested the ability of deer to affect forest bird populations by monitoring the density and diversity of vegetation and birds for 9 years at eight 4-ha sites in northern Virginia, four of which were fenced to exclude deer. Both the density and diversity of understory woody plants increased following deer exclosure. The numerical response of the shrubs to deer exclosure was significantly predicted by the soil quality (ratio of organic carbon to nitrogen) at the sites. Bird populations as a whole increased following exclosure of deer, particularly for ground and intermediate canopy species.
  • Direct and indirect effects of white-tailed deer in forest ecosystems, Forest Ecology and Management 181 (2003) 165–176
  • Eating Themselves Out of House and Home, National Wildlife Federation, Oct 1998
  • The Influence of White-Tailed Deer on the Biodiversity of Indiana State Parks (PDF 3.56 MB), Report submitted to Martin Foundation, 1998?
  • Relative deer density and sustainability: a conceptual framework for integrating deer management with ecosystem management, David S. deCalesta and Susan L. Stout, Wildlife Society Bulletin 1997Relative deer density (RDD) provides managers with a way to broaden their
    approach to issues of deer overabundance from single-species management and carrying capacity to multiple-species management and ecosystems
  • Interview with Mary Mathias, who is leading the drive to increase NWF certified wildlife habitat in Washtenaw County., The Green Room, May 13, 2014

Mice

  • As rodent populations grow, ticks — and Lyme disease — are coming indoors, BangorDailyNews, Julyu 7, 2017The recent appearance of vermin and pests in Wood’s bedroom coincides with the warming temperatures related to climate change. The past three years have been the planet’s hottest on record, and it is in this changing climate that many pests thrive, negatively affecting human health. Forty to 90 percent of white-footed mice carry Borrelia burgdorferi, the spirochete bacterium that causes Lyme disease, and they provide the first blood meals for blacklegged ticks, also known as deer ticks, which can transmit the disease to humans.
  • One sign that 2017 will be a bad year for Lyme disease, CNBC, March 6, 2017Its rise results in part from rising deer populations, but also in the changing landscape of the country. Land development for farming, housing and commerce has chewed through the once vast forests and wild lands of the U.S., leaving smaller patches of forest interspersed with human settlements. Mice thrive in these smaller forests, in large part because the larger animals who prey on them cannot.
  • Lyme Disease Is Spreading, And It’s Partly This Mouse’s Fault, FiveThirtyEight, July5, 2017Black-legged ticks in forests of the Northeast and Midwest have a variety of options for the three blood meals they consume in their lifetime: In their earlier stages, the ticks feed on at least 41 species of mammals, from chipmunks to black bears, plus 57 species of birds and 14 species of lizards. In adulthood, they will hop onto at least 27 species of mammals and one type of lizard. Ticks aren’t born with the pathogens that cause the main tick-borne diseases in humans; they get them from feeding on animals that act as reservoirs of the bacteria and parasites. Scientists are especially interested in the host that seems to be by far the best at harboring Lyme disease: the white-footed mouse.

The State of our Forests

  • Urban trees save cities millions of dollars, new research says, Christian Science Monitor, Aug 3, 2017The multifaceted benefits of urban trees were detailed in a new study finding that cities with more trees reduce air pollution and protect people from heatwaves.
  • Trees in Eastern U.S. Head West as Climate Changes, Scientific American, May 18, 2017Ecologists have long predicted that climate change will send plants and animals uphill and towards the poles in search of familiar temperatures. Such movements have increasingly been documented around the world. But a study now shows that changing rainfall patterns may be driving some tree species in the eastern United States west, not north. The team measured shifts in the centres of abundance for the 86 types of tree and found that over the past 30 years or so, 34% showed statistically significant poleward shifts at an average rate of 11 kilometers per decade. Forty-seven per cent made statistically significant westward shifts at an even faster rate — 15.4 kilometers per decade. Hardly any types of tree moved south or east.
  • 2016 Forest Health Highlights Report, MI, DNR, 2017Department of Natural Resources forest health professionals work with other state and federal agencies and universities to prevent, evaluate and manage the occurrence and impacts of both native and exotic forest insects and diseases.

The State of our Lakes and Waterways

  • State finds new invasive weed, FreePress, Sept 2, 2017According to a news release from the Michigan Department of Natural Resources, Japanese stiltgrass has been positively identified on private property in Scio Township, near Ann Arbor in Washtenaw County. “This annual grass is considered highly invasive, taking hold in areas of disturbed soil along banks, roadways and woods,” said Greg Norwood, invasive species coordinator for the DNR’s Wildlife Division. “Seeds can be transported by water or on animals, and seeds can remain viable in the soil for three to five years. Because deer don’t feed on Japanese stiltgrass, it often takes over in areas where deer browse on native plants and leave open patches of soil.”
  • Fighting phragmites a never-ending battle, MLive, Aug 8, 2017Phragmites (frag-MY-teez) is an aggressive, invasive plant that grows to 15 feet in height and has had a massive impact on the ecological health of Michigan’s wetlands and coastal shoreline. Ever-expanding stands of the grass have crowded out thousands of acres of native plants across the state in recent decades, destroying food and shelter for wildlife, blocking natural shoreline views, and reducing access for swimming, fishing and hunting.

Comments are closed