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Forest Stewards Guild Can we grow trees with today’s deer densities? Aldo Leopold became deeply concerned with over-abundant deer in Wisconsin in the 1940's after taking a trip to Germany in 1935 and seeing the impacts of over-intensive game & forest management 1 Forest Stewards Guild Can we grow trees with today’s deer densities? Why deer are a concern to forest managers and landowners? Talk Outline: The problem! • Forest regeneration • Biodiversity of plants, birds, insects • Spread of invasive species • Deer are killing us: • Car and motorcycle collisions • Lyme and other tick borne diseases • Primary effects • Secondary effects: no child in the woods 2 Forest Stewards Guild Can we grow trees with today’s deer densities? Bradshaw and Waller 2016 • Forest regeneration Sample 13,105 FIA Plots, “Impacts of white-tailed deer 1983 to 2013. 48 Deer on regional patterns Module 5, Lecture 2 Management Units. of forest tree recruitment” Forest Ecology and Management August 2016 Study area (shaded) is all of northern Wisconsin mixed hardwood region but NOT the Apostle Islands 3 Variation in estimated deer densities (deer per km2) among Deer Management Units (DMUs) from 1983 to 2011. Note the high level of variation in estimated deer densities 4 Distributions of red maple and northern white cedar sapling numbers among stands. Frequency histograms show the logarithm of the mean number of small saplings (+ 1) in all stands. Note the approximately log-Normal distribution of sapling abundances in red maple, a prolific seeder of intermediate palatability to deer 5 Distributions of northern white cedar sapling numbers among stands. Frequency histograms show the logarithm of the mean number of small saplings (+ 1) in all stands. Note the highly skewed distribution in cedar (b) which is highly palatable and susceptible to deer browse 6 Forest Stewards Guild Can we grow trees with today’s deer densities? Palatability classes Class 1, low: Picea spp. and Abies balsamea Class 2, low intermediate: Acer rubrum Acer saccharum Populus tremuloides Class 3, high intermediate: Pinus strobus Quercus rubra Class 4, high: Betula alleghaniensis, Tsuga canadensis, Thuja occidentalis. High means very palatable to deer 7 8 Forest Stewards Guild Palatability Class 2 Can we grow trees with today’s deer densities? (yellow line, maples and aspen) • Forest regeneration strongly declines depending on deer densities 10 years prior 9 Forest Stewards Guild Can we grow trees with today’s deer densities? A path analysis (statistics using partial regression coeffiecients catching cumulative effects) 10 11 Study conclusions: “Deer have considerably reduced regeneration in many tree species of intermediate palatability and eliminated it altogether at most sites in several conifer species known to be sensitive to deer browsing. This is highly relevant for deer management in that stands of these conifers provide key habitats for overwintering deer. These stands will likely disappear given this regional failure in regeneration. These effects are not local, temporary, or restricted to a few sensitive species. Rather, they extend across all of northern Wisconsin, cover a 30 year period, and affect most (8 of 10) of the tree species examined. These effects have also begun to modify the composition and structure of the mid-stories of these forests. It will not be simple to limit or reverse these impacts…” 12 Forest Stewards Guild Can we grow trees with today’s deer densities? 13 Forest Stewards Guild Can we grow trees with today’s deer densities? Why deer are a concern to forest managers and landowners? Talk Outline: The problem! • Forest regeneration • Biodiversity of plants, birds, insects 14 Impact on plants An old-growth forest in Pennsylvania that had been sampled in 1929. Dr. Rooney returned in 1995 and duplicated the sampling of 1929. During that interval the deer population of that area of Pennsylvania has skyrocketed to about the same level as southern Wisconsin. A startling 80% of the understory species had disappeared. There had been 42 species and now there were 8. Dr. Rooney attempted to explain this disappearance by other causes but concluded that deer were primarily responsible. Module 5, Lecture 1 Rooney, T.P and W.J. Dress. 1997. Species Loss Over 66 Years in the Ground Layer Vegetation of Heart’s Content, an Old-Growth Forest in Pennsylvania. Natural Areas Journal 17-297-305. 15 Impact on Birds Deer are opportunistic feeders. The photo on the right shows deer eating sparrow nestlings. In a study in Pennsylvania in 1994, intermediate canopy nesting birds declined 37% in abundance with a 27% drop in species diversity at high deer densities, similar to what we have here in Wisconsin. This was due References: White-tailed deerpredators of grassland birds-USGS mostly to the change in plant life brought on by the deer, rather than DeCalesta, D.S. 1994. Effect of White-Tailed Deer on Songbirds Within Managed Forests direct predation of nestlings. in Pennsylvania. Journal of Wildlife Management 58:711-717 Module 5, Lecture 1 16 Forest Stewards Guild Can we grow trees with today’s deer densities? Why deer are a concern to forest managers and landowners? Talk Outline: The problem! • Forest regeneration • Biodiversity of plants, birds, insects • Spread of invasive species, and differential browsing favors invasives over natives: Natural Areas Journal 29(2):110-116. 2009 “Deer Facilitate Invasive Plant Success in a Pennsylvania Forest Understory” Tiffany M. Knight1,2 Jessica L. Dunn1 Lisa A. Smith3 JoAnn Davis4 Susan Kalisz 17 Forest Stewards Guild Can we grow trees with today’s deer densities? Why deer are a concern to forest managers and landowners? Talk Outline: The problem! • Forest regeneration • Biodiversity of plants, birds, insects • Spread of invasive species • Deer are killing us: 18 In 2008, over one million deer collided with cars and motorcycles in the US. The Insurance Institute for Highway Safety stated this resulted in the death of approximately 150 people, injuries to 29,000 others, and an estimated $1.1 billion in vehicle damage 19 20 21 Secondary effects: no child in the woods 22 But wait, there’s more! 23 Don’t forget Anaplasmosis, which has the same increase over time and about half the fatality rate! 24 Deer are killing themselves 25 Forest Stewards Guild Can we grow trees with today’s deer densities? Talk Outline: Solutions and ideas. • Understanding history—how we got to where we are • Understanding and being able to detect deer browse and effects • Missing evidence when deer are feeding on acorns • Once a decade shifts due to harsh winter • Your own exclosures, trail cams • Getting hunters on your land • The Quabbin experience • The Weston experience 26 Forest Stewards Guild Can we grow trees with today’s deer densities? Talk Outline: Solutions and ideas. • Understanding history—how we got to where we are 27 Big predators of the Northwoods Cougar Gray Wolf 28 Dark blue areas show 20 to 67 percent decrease in Hemlock! Our Hemlock is disappearing! slide from D.Mladenoff Module 5, Lecture 2 29 new habitat created 30 31 Forest Stewards Guild Can we grow trees with today’s deer densities? Talk Outline: Solutions and ideas. • Understanding history—how we got to where we are • Understanding and being able to detect deer browse and effects 32 How do deer affect plant species? Intense hardwood browse in the Chippewa National Forest. Photo by Christina Isenring 33 Are trees sensitive to deer damage? Study this photo for a minute. This is called a “sandwich tree,” in this case an eastern hemlock in the Ottawa National Forest. The bottom of the tree, around the lower clipboard, is more or less intact as it is protected below deep snow in the winter. The middle of the tree is gone, eaten by deer. The top of the tree, by the upper clipboard, is also intact as it is around 7 feet above ground. Photo by Bob Wernerehl 34 Are trees sensitive to deer damage? Here’s another shot, this time with Dr. Rooney beside a balsam fir sandwich tree. This indicates severe browse as balsam fir is low on the list of deer menu choices. This tree will have a very hard time making it to the canopy with all this browse holding it back. 35 Browse lines are evident on Northern White Cedar 36 How do deer affect plant species? Impacts on Reproduction. Deer often graze off flowers & fruits first. These are often conspicuous and exterior, they stick out from the rest of the plant. Flowers and fruits are, of course, vital for reproduction and represent the next generation. Grazed plants persist vegetatively, but often fail to reproduce. Effects of failed reproduction on population growth often are delayed and obscure relative to the more conspicuous and immediate effects of vegetative browsing (scarce or absent seedlings). Deer browsing can represent a threat to population persistence even when the plants themselves persist. Flower top nipped off of Solomon’s Plume 37 deer vs rabbit browse 38 39 How to recognize deer browse browsed wild sarsaparilla Photos by Bob Wernerehl 40 Look closely to see the slightly ragged ends of the stems of the browsed wild sarsaparilla 41 Deer Exclosures Another way to study the effect of deer browse is through deer exclosures— fenced areas that keep deer out. These require 8 to 10 foot high fences maintained so that treefall doesn’t bring down the fence and let in deer. In the Chequamegon-Nicolet National Forest at Foulds Creek, biologists erected an exclosure more than 30 years ago (left). The other photo is of an exclosure that has been in place for 15 years at the Dairymen’s Club of Vilas County. Fence down the middle, deer excluded from L-side. 42 Approaches to studying deer impacts III. Island comparisons C. Balgooyen and Don Waller surveyed variation across 12 locations in the Apostle Islands and adjacent Bayfield peninsula. They found reductions of many species at sites with higher deer densities, including: mountain maple (Acer spicatum) and sugar maple (Acer saccharum), yellow birch (Betula allegheniensis), mountain ash (Sorbus decora), and Canada yew (Taxus canadensis) (r2 = .91 !). Note that the Ojibwa word for yew: ‘that which grows everywhere’ 43 44 What are the long-term effects of browsing? If trees repeatedly fail to reproduce, the understory thins out. Eventually, canopy trees that fall are not replaced. This produces savanna-like conditions, and allows invasions by ferns. Eventually, ‘Fern Parks’ develop, as in parts of Pennsylvania. >20 deer / km2 for 30+ yrs Is this the future for Wisconsin's forests? Allegheny plateau, PA 45 46 47 Forest Stewards Guild Can we grow trees with today’s deer densities? Talk Outline: Solutions and ideas. • Understanding history—how we got to where we are • Understanding and being able to detect deer browse and effects • Missing evidence when deer are feeding on acorns • Once a decade shifts due to harsh winter • Your own exclosures, trail cams • The Quabbin experience 48 THE QUABBIN EXPERIENCE: White-Tailed Deer Population Reduction and the Ecological Response Dan Clark MA Department of Conservation and Recreation Division of Water Supply Protection Natural Resources Section Quabbin Reservation • Created in the 1930’s • Water flows from Quabbin into Wachusett reservoir then on to Boston • Quabbin holds 412 billion gallons • Treated, but unfiltered water Quabbin Reservation DCR owns 56,000 acres 93% forested 99% of forest is older than 50 years 59% is older than 90 years 50% of forest is hardwood 23% is softwood 27% is mixed Deer at Quabbin Closed to hunting from 1930’s until early 1990’s Signs of over browsing first seen in 1946 Deer densities estimated from 1983-1992 Deer densities ranged from 45-60 deer/mi2 Petersham: 60 deer/mi2 804 deer Forest conditions with lots of deer Forest conditions with lots of deer Forest conditions with lots of deer Forest conditions with lots of deer Mean Stem/Acre at Quabbin from 1989 - 2014 12000 11134 Stems/acre 9000 8395 8239 8031 6000 4531 4109 3372 3780 3275 3000 2389 1344 910 130 417 0 1989 Total Regen 1994 2004 Regen >4.5 Ft 2006 2009 Linear (Total Regen) 2013 2014 Linear (Regen >4.5 Ft) Current Forest Conditions Current Forest Conditions Roadside breeding bird data Towhee Ovenbird Yellowthroat Chestnut 120 90 60 30 0 1988 1989 1990 1998 2006 2010 2014 Return of herbaceous plants Brambles: blackberry and raspberry Sumac Flowers: lady slipper Trout lily Trillium Cardinal flower Poison ivy Ecological diversity Grape vines Milkweeds Joe pye weed Asters Marsh marigold Alder Ruffed grouse & rabbits Conclusions Deer densities at Quabbin substantially reduced and maintained at much lower levels Excellent response from the forest Able to regenerate trees Diversity is still lacking but moving in right direction Increased ecosystem diversity Herbaceous plants Wildflowers Bird communities Small mammals Recovery is relatively slow and ongoing 66 67 Forest Stewards Guild Can we grow trees with today’s deer densities? Talk Outline: Solutions and ideas. • Understanding history—how we got to where we are • Understanding and being able to detect deer browse and effects • Missing evidence when deer are feeding on acorns • Once a decade shifts due to harsh winter • Your own exclosures, trail cams • Getting hunters on your land • The Quabbin experience • Resources for quantifying deer effects • The Weston experience 69 Free online (downloadable pdf booklet), great resource! 70 71 72 73 74 Forest Stewards Guild Can we grow trees with today’s deer densities? Recommendations for landowners and managers • Understand and be able to detect deer browse and effects • Don’t seek evidence when deer are feeding on acorns • Once a decade shifts due to harsh winter • Set up your own exclosures and trail cams • Get good hunters on your land and educate them! • Get the public, especially mothers, on your side. • In a “political” debate, bring the animals rights groups in early on rather than after the fact. Know how to respond. Be ready to handle the media. 75