White-tailed Deer Browsing Research Articles

Environmental drivers and species traits of mesophication and xerophication in forests of western New York State

Forests of the eastern US have exhibited widespread taxonomic shifts involving decreasing abundances of many species of Quercus, Pinus and Carya and increasing abundances of many species of Acer, Fagus, Prunus as well as other genera. These taxonomic changes have been called mesophication and explained variously as decreased tolerance of fire, drought, and heat; decreased palatability for deer browsing; and increased tolerance of shade. The major driver of those shifts in taxonomy and ecological traits has been attributed to decreased surface burning due to Native American depopulation, cessation of settler-colonial land clearance, larger deer populations, and decreased drought, among other drivers. We endeavored to test which traits exhibited the most mesophication and which environmental factors best predicted that mesophication. We collected size-stratified taxonomic data for 2488 trees from 160 plots, converted that into measures of mesophyticness for each trait in each plot, and then inferred mesophication in each plot as the difference between the mesophyticness of small trees and large trees. Mesophyticness of each trait ranged from zero for a xerophytic trait to one for a mesophytic trait. We also collected site-specific data for 22 potential environmental predictors of trait changes (including abiotic, biotic, anthropogenic, and spatial predictors). All traits exhibited strong mesophication; these are, in descending order of percent of sites with strong mesophication: fire tolerance, white-tailed deer browse preference, Native American diet tree, cold tolerance, shade tolerance, drought tolerance, and general browse preference. For all traits, mesophication of small relative to large trees was greatest in plots where large trees were xerophytic, and least where large trees were mesophytic. We further found that mesophication was similar for plots regardless of the abundance or presence of Quercus, indicating that mesophication is not the same as oak decline. A diverse set of predictors best explained mesophication of taxonomic and ecological traits, but three were consistently chosen: cooler summer temperature, higher small tree density, and shorter distance to pre-1700 Native American towns. In addition to mesophication, there was also some evidence of xerophication, most strongly for an increase in heat tolerance as might be expected due to recent climate change. Our results show that forest mesophication is a complex syndrome involving changes in independent species traits that are driven by many environmental factors, creating a challenge for land managers.

Experimental evaluation of four protocols for assessing white-tailed deer browse intensity

Native and introduced deer populations have expanded on many continents and are now considered primary drivers of ecosystem degradation. Large herbivore management can be controversial, requiring appropriate tools to gauge impacts and guide management decisions. While many different protocols have been proposed to measure deer impacts to vegetation, few have been experimentally validated to assess whether they respond reliably to changes in deer browse intensity.Here we used a network of large (2 ha) long-term deer exclosures in New York State to assess utility and reliability of AVID (Assessing Vegetation Impacts of Deer), the Ten-Tallest, and Twig-Age protocols to capture changes in white-tailed deer (Odocoileus virginianus) browse intensity. We also assessed whether three herbaceous species: blue-stemmed goldenrod (Solidago caesia), white wood aster (Eurybia divaricata), and zigzag goldenrod (Solidago flexicaulis) could expand upon a red oak (Quercus rubra) Sentinel protocol. Finally, we evaluated whether these four protocols adhered to criteria defined for ecological indicator selection.AVID, Ten-Tallest, and Twig-Age protocols rely on existing vegetation to measure deer browse intensity, which limited their ability to adhere to basic sampling principles and be standardized across different forest types, especially in areas with little vegetation remaining in browse height. The Ten-Tallest protocol did not consistently detect differences in deer browse intensity, calling into question its scientific validity. The Sentinel protocol utilizes propagated and planted species, which standardizes impact assessments across sites and captures annual changes in deer browse intensity. Sentinel met nearly all criteria required to function as a reliable deer browse indicator. Validation and selection of additional sentinel species is necessary to build out a portfolio of regionally relevant species that can gauge deer browse intensity across vegetation and habitat types. Of the herbaceous species evaluated, S. caesia showed promise as a new sentinel species, but further evaluations are necessary. Evidence-based deer management will require scientifically rigorous and validated impact monitoring approaches and metrics. We caution against adopting protocols that have not been thoroughly vetted to avoid misguided deer management and policy.

Economic returns and the perceived obstacles to adopting active management in the forest-grassland transition ecoregion in south-central USA

Forest-grassland ecotones are a mosaic of grassland, savanna, and upland forest. As such, landowners may have opportunities to choose to manage their lands for multiple objectives. We estimated the economic returns from managing forest and rangeland in southeastern Oklahoma, USA to produce different combinations of timber, cattle forage, and white-tailed deer (Odocoileus virginianus Zimmermann) browse for a 40-year period. We further conducted a survey to understand landowner perceptions of obstacles to adopting active management that involve timber harvest and prescribed fire. The highest net return was obtained from the treatment with harvested timber that was burned every four years (uneven-aged woodland/forest) because it had the greatest gross return from a combination of timber (46%), cattle forage (42%), and deer browse (11%). The return from this treatment was greater than that for managed for timber only (closed-canopy forest) or prioritizing cattle and deer (savanna). Survey results suggested that landowners were aware of the benefits of active management but that the majority (66%) considered cost a major obstacle in the management of their forest or rangeland. In particular, women forestland owners and older landowners considered cost an obstacle. Our findings advocate integrated timber, cattle, and deer management as the best economic strategy within the forest-grassland ecotone and for targeted outreach and landowner education related to the benefits of active management.

Linked disturbance in the temperate forest: Earthworms, deer, and canopy gaps.

Despite the large body of theory concerning multiple disturbances, relatively few attempts have been made to test the theoretical assumptions of how and if disturbances interact. Of particular importance is whether disturbance events are linked, as this can influence the probability and intensity of ecological change. Disturbances are linked when one disturbance event increases or decreases the likelihood or extent of another. To this end, we used two long-term, multi-disturbance experiments in northern Wisconsin to determine whether earthworm invasion is linked to canopy gap creation and white-tailed deer browsing. These three disturbances are common and influential within North American temperate forests, making any interactions among them particularly important to understand. We expected both deer and canopy gaps to favor invasive earthworms, particularly species that live close to or on the soil surface. However, we found only partial support of our hypotheses, as both deer exclosures and canopy gaps decreased earthworms in each experiment. Further, earthworm density increased the most over time in areas far from the gap center and in areas with deer present. Deer exclosures primarily decreased Aporrectodea and Lumbricus species, while gaps decreased Dendrobaena and Lumbricus species. Our findings show that earthworm invasion is linked to deer presence and gap-creating disturbances, which provides new insight in multiple disturbance theory, aboveground-belowground dynamics, and temperate forest management.

Comprehensive Assessment of White-Tailed Deer Browse in the Presence of Beech Bark Disease at a Great Lakes National Park

In northern hardwood forests, white-tailed deer (Odocoileus virginianus) impact both tree regeneration and groundlayer composition, leading to a dominance of American beech (Fagus grandifolia), an unpalatable species, as well as a reduction of preferred groundlayer species. Deer become especially problematic in areas with beech bark disease, such as at Sleeping Bear Dunes National Lakeshore. We analyzed datasets from Sleeping Bear Dunes, collected in 2009 and 2018, to assess vegetation change in three management units: a mainland unit with a long history of deer occupancy, and two islands, one with high deer pressure and one with no known history of permanent deer presence. For each unit, we tested for change in species richness and mean coefficient of conservatism. We also examined the groundlayer, testing for change in indices of abundance and size of preferred and avoided species. Finally, we compared regeneration of palatable and unpalatable tree species. We found increased nonnative species richness, decreased number and abundance of preferred herbaceous species, as well as decreased height of a preferred species. We also detected increased sapling density of beech while that of palatable species declined. Our data provide further evidence of the impacts of white-tailed deer on the forest understory. Management goals should focus on maintaining deer densities at or below 5 deer km–2 in order to promote growth of the full suite of herbaceous species typical of the region and habitat and to allow adequate regeneration of the overstory.

Evaluating the impacts of white-tailed deer (Odocoileus virginianus) browsing on vegetation in fenced and unfenced timber harvests

Ensuring the recruitment of desired tree species is a primary goal when considering successful regeneration of timber harvests. Deer populations that are overabundant relative to forage availability within their local landscapes pose a considerable challenge to successful forest regeneration. We evaluated the short-term (<10 years) impact of white-tailed deer browsing on woody structure and composition in northcentral Pennsylvania. Specifically, we compared woody plant species density, height, and cover within 10 pairs of fenced and unfenced regenerating timber harvests. Percent of browsed stems was higher in unfenced harvests for red maple (Acer rubrum), oaks (Quercus spp.), Rubus spp., sassafras (Sassafras albidum), and witch hazel (Hamamelis virginiana). Stem density did not differ between fenced and unfenced harvests for any species except Rubus spp., which was greater in the former. However, height of serviceberry (Amalanchier spp.), sassafras, northern red oak (Quercus rubra), Rubus spp., and red maple was taller in fenced harvests. Both vertical and horizontal vegetation density were greater in fenced harvests, suggesting a more structurally complex understory in fenced harvests. Rubus spp. and tall (>1.5 m) sapling cover were greater in fenced harvests, while unfenced harvests had greater forb, fern, and blueberry/huckleberry (Vaccinium spp./Gaylussacia spp.) cover. Our results suggest that browsing by deer in the years initially (<10 years) following timber harvest may not immediately impact woody species density, but can considerably reduce seedling height, overall horizontal and vertical structure, and composition of vegetation strata. Reduced sapling height and greater prevalence of blueberry/huckleberry, forbs, and ferns in unfenced harvests threaten the successful recruitment of desired species into the future overstory. Our results from large, operational-scale timber harvests combined with those from previous small-scale studies stress the potential value of deer exclusion fencing to achieve successful forest regeneration. Future research should examine the timing of fence removal to achieve forest regeneration success, while also providing deer access to available foraging opportunities during the later portion of stand initiation.

Impacts of invasive earthworms and deer on native ferns in forests of northeastern North America

Forest understory plants in eastern North America experience heavy white-tailed deer browse and impacts associated with invasive species, including of non-native earthworms. Deer and earthworms are well-recognized ecosystem engineers due to their ability to alter understory plant dynamics. We examined interactive effects of earthworms and deer on four woodland ferns (Adiantum pedatum, Polystichum acrostichoides, Dryopteris marginalis, and Dennstaedtia punctilobula) using field and common garden experiments. In the field we planted ferns into fenced and deer-accessible plots in areas with and without earthworms. In a common garden, we assessed both fern responses to different earthworms and fern effects on earthworm survival and biomass. Venue was important in determining experimental outcomes. In the field, A. pedatum and P. acrostichoides showed higher survival and P. acrostichoides grew taller or produced more fronds in worm-invaded areas. Deer presence/absence was not a significant explanatory variable. In the common garden, earthworms had no discernible effect on ferns, but fern species identity varied in its effect on earthworm survival and leaf litter decomposition. Our findings indicate that, contrary to many other understory species, common ferns benefit or are unaffected by earthworms. That we obtained different and even contradictory results in different venues should encourage investigators to validate common garden findings in the field.

Timing is Not Everything: Assessing the Efficacy of Pre- Versus Post-Harvest Herbicide Applications in Mitigating the Burgeoning Birch Phenomenon in Regenerating Hardwood Stands

Sweet birch (Betula lenta L.) is aggressively recruiting in temperate forest understories of the eastern United States and often dominates the post-disturbance seedling community, diminishing diversity and hindering sustainable silviculture. The type and timing of silvicultural actions affect birch recruitment via their effects on seedling recruitment, survival, and growth. Here, we examine birch regeneration under two contrasting treatment sequences: pre- versus post-shelterwood harvest herbicide application (H–S vs. S–H) in combination with white-tailed deer (Odocoileus virginianus Zimmerman) browsing (fenced vs. unfenced) at 22 sites in northwestern Pennsylvania, USA. Additionally, we examine how treatments interact with additional site factors, including potential propagule sources and site productivity (i.e., integrated moisture index). We found the S–H sequence initially reduced birch density by 71% relative to the H–S sequence; however, the magnitude of this reduction waned over five growing seasons. Furthermore, birch proliferated following the H–S sequence only where mature birch were present. Deer browsing reduced birch height by 29% relative to fenced areas protected from browsing; however, by the fifth growing season birch seedlings were over twice as tall as other hardwood species across all treatments. Finally, increasingly mesic sites enhanced birch height growth. In sum, although post-harvest herbicide (S–H) provides short-lived control over birch, land managers should also consider browse pressure, seed source, and site productivity, as these may enhance or diminish the efficacy of post-shelterwood herbicide sequence effects on birch.

Invasive shrub removal benefits native plants in an eastern deciduous forest of North America

AbstractIn eastern deciduous forests of North America, invasive shrubs are increasing in richness and abundance at the expense of native species across taxa. Invasive shrubs create an understory that is more dense than both recent and historical preinvasion conditions. Interest in invasive shrub removal to restore native habitat is growing, but our understanding of natural regeneration following treatment of a diverse invasive shrub community is lagging. Using an invasive shrub removal experiment, we provide insight into the effect of repeated removal of a suite of 18 invasive shrub species dominated by border privet (Ligustrum obtusifolium Siebold &amp; Zucc.). In 2009, invasive shrubs were removed from five 20-m-diameter treatment plots, each with a paired control plot. Seven years later, we find an increase in plant diversity, native understory species abundance, and overstory tree species regeneration for individuals under a meter in height. For plants 1 to 4 m in height, the removal treatment has a positive effect on understory woody species, but there has been no change in regenerating overstory trees. A lack of overstory tree regeneration to greater heights is not surprising, given the time frame and the closed-canopy conditions. However, other factors, such as white-tailed deer (Odocoileus virginianus Zimmermann) browse, could be serving as an impediment to taller tree regeneration in the forest understory. An ambient sampling approach in unmanaged, invaded, and uninvaded forest has been used in other studies to estimate the potential impacts of invasive shrub species to native plant communities. However, in this study the ambient sampling approach underestimated the impacts of invasive shrubs compared to their experimental removal. Overall, invasive shrub removal increased plant diversity and allowed passive natural regeneration of native plants that exceeded native cover in the unmanaged, ambient forest under minimal invasive shrub abundance.

White-tailed deer browse preference for an invasive shrub, Amur honeysuckle (Lonicera maackii), depends on woody species composition

AbstractSelective browsing by abundant, generalist herbivores on preferred species could allow less-preferred invasive species to flourish. We tested such an effect by examining rates at which white-tailed deer (Odocoileus virginianus Zimmermann) consume Amur honeysuckle [Lonicera maackii (Rupr.) Herder], an invasive shrub, relative to native woody species across eight forested sites in southwestern Ohio. We tested three hypotheses: (1) deer prefer to browse on L. maackii versus other woody plants; (2) L. maackii is not a preferred source of browse, but is consumed where preferred foods are scarce; and (3) L. maackii provides an important food resource for deer in early spring when other foods are scarce. We used counts of browsed and unbrowsed twigs of each species to calculate, for each site, both the proportion of each species’ twigs browsed and the degree to which deer selectively favor each species (“electivity”) during early to mid-growing season. Across the eight sites, electivity of L. maackii correlated with the proportion of its twigs browsed, and both measures were negatively associated with the density of L. maackii twigs. Lonicera maackii electivity was negative at most sites, indicating it is generally not preferred, undermining hypothesis 1. The hypothesis that deer consume L. maackii when more-preferred foods are depleted was not supported, as there was no negative relationship between L. maackii browse and the density of twigs of more-preferred species. We found a negative relationship between the proportion of L. maackii twigs browsed and the density of L. maackii among sites, which supports the third hypothesis. This finding, combined with seasonal patterns of deer browse on L. maackii, indicates that this invasive shrub is an important source of browse for deer during early spring, regardless of its abundance.

Evaluating Inter-Rater Reliability and Statistical Power of Vegetation Measures Assessing Deer Impact

Long-term vegetation monitoring projects are often used to evaluate how plant communities change through time in response to some external influence. Here, we evaluate the efficacy of vegetation monitoring to consistently detect changes in white-tailed deer browsing effects. Specifically, we compared inter-rater reliability (Cohen’s κ and Lin’s concordance correlation coefficient) between two identically trained field crews for several plant metrics used by Pennsylvania state agencies to monitor deer browsing impact. Additionally, we conducted a power analysis to determine the effect of sampling scale (1/2500th or 1/750th ha plots) on the ability to detect changes in tree seedling stem counts over time. Inter-rater reliability across sampling crews was substantial for most metrics based on direct measurements, while the observational based Deer Impact Index (DII) had only moderate inter-rater reliability. The smaller, 1/2500th ha sampling scale resulted in higher statistical power to detect changes in tree seedling stem counts due to reduced observer error. Overall, this study indicates that extensive training on plant identification, project protocols, and consistent data collection methods can result in reliable vegetation metrics useful for tracking understory responses to white-tailed deer browsing. Smaller sampling scales and objective plant measures (i.e., seedling counts, species richness) improve inter-rater reliability over subjective measures of deer impact (i.e., DII). However, considering objective plant measures when making a subjective assessment regarding deer browsing effects may also improve DII inter-rater reliability.

Quantifying impacts of white-tailed deer (Odocoileus virginianus Zimmerman) browse using forest inventory and socio-environmental datasets.

Elevated population levels of white-tailed deer (Odocoileus virginianus Zimmerman) can drastically alter forest ecosystems and negatively impact society through human interactions such as deer vehicle collisions. It is currently difficult to estimate deer populations at multiple scales ranging from stand, county, state, and regional levels. This presents a challenge as natural resource managers develop silvicultural prescriptions and forest management practices aimed at successfully regenerating tree species in the face of deer browsing. This study utilized measurements of deer browse impact from the new tree regeneration indicator developed by the United States Department of Agriculture Forest Service Forest Inventory and Analysis (FIA) program. Seedling and sapling abundance and other plot-level characteristics were analyzed across three states (Michigan, Minnesota, and Wisconsin) in the Great Lakes Region of the United States. Socio-environmental datasets (Lyme disease cases, deer vehicle collisions, and deer density estimates) were used in conjunction with FIA data to determine their predictive power in estimating deer browse impacts by county. Predictions from random forests models indicate that using Lyme disease case reports, the number of deer-vehicle collisions, deer density estimates, and forest inventory information correctly predicted deer browse impact 70–90% of the time. Deer-vehicle collisions per county ranked highly important in the random forests for predicting deer browse impacts in all three states. Lyme disease cases ranked high in importance for the Lake States combined and for Minnesota and Wisconsin, separately. Results show the effectiveness of predicting deer browse impacts using a suite of freely available forest inventory and other socio-environmental information.

Timing of white-tailed deer browsing affects wetland plant communities

White-tailed deer (Odocoileus virginianus Zimm.) have the potential to alter plant community composition and successional trajectory by browsing differentially on forb, graminoid, and woody species. The objective of this study was to determine if seasonal elimination of deer browsing changed wetland plant community composition and structure. We established 66 deer exclosure plots in two wetland vegetation communities in Canaan Valley, West Virginia, USA. Plots were established in April 2005 and monitoring was conducted in June and October, 2005–2007 to obtain data on both early and late species. Composition differed between control and treatment plots in Solidago spp.–Rubus hispidus L. communities in late-protected plots (enclosed July–October) when data were gathered in October. Community composition also varied in early-protected plots (enclosed April–July) when data were gathered in June. Forb cover increased in treatment plots in Solidago spp.–Rubus hispidus communities. Composition differed in Populus tremuloides Michx. communities in late-protected and continuously protected plots. There was no increase in cover by any wetland indicator status categories after 2 years of protection. Timing of browse played an influential role in the effect that white-tailed deer have on wetland plant communities. Our results suggest that reducing browsing pressure seasonally can increase forb species cover.

White-tailed deer (Odocoileus virginianus) and fire effects on flowering diversity of tallgrass prairie forbs

We studied the effect of white-tailed deer (Odocoileus virginianus Zimmermann) browsing and fire on diversity and number of prairie-forb flowering stems in a remnant tallgrass prairie in northern Illinois. Our study included two plots protected from deer browsing since 1992 and two unprotected plots. All plots were burned twice in late April of 1990 and 1991. Deer densities of 32–50 km−2 (1992–96) declined to 7–9 km−2 in 1998 and 1999 after controlled hunting. Similarity between protected and unprotected plots was initially 82%, declined to 49% during the period of high deer density, and increased to 68% in 2001 with managed hunting. Flowering stems for all forbs were tallied in 1998–2001. Diversity (Shannon index [H′] and effective number of stems [HO]) of flowering stems was higher on protected than on unprotected plots for all study years. Differences in composition and diversity between protected and unprotected plots were associated with interactions between fire and protection from deer browsing as measured by total number of flowering stems, which was significantly higher on protected than on unprotected plots in nonburn years (3.4–3.5-fold) but not in burn years (1.0–1.2-fold). The two leading species on protected plots (ashy sunflower [Helianthus mollis Lam.] and Culver's root [Veronicastrum virginicum (L.) Farw.]) tended to have fewer flowering stems in burn years and always had them in protected plots (54-fold and 70-fold higher in protected plots for the two species, respectively). For the second leading species on unprotected sites (wild quinine [Parthenium integrifolium L.]), the number of flowering stems was significantly higher in burn years (27-fold); however, there was no significant difference in the number of stems between protected and unprotected plots. These results show strong interactions between fire and deer-browsing disturbances in communities recovering from deer overabundance.

White-tailed deer browse on an invasive shrub with extended leaf phenology meets assumptions of an apparent competition hypothesis.

It has been hypothesized that invasive plant species with extended leaf phenology (ELP) elevate generalist herbivore populations, increasing herbivory on native plants (apparent competition). This hypothesis assumes that consumption of the invasive is associated with periods of ELP, the invasive is a major component of the herbivore's diet, and that it is more nutritious than native plants during periods of ELP. We tested these assumptions by estimating the proportion of the white-tailed deer diet comprised of Lonicera maackii, an invasive shrub with ELP, quantifying the seasonal pattern of deer browse on this invasive shrub, and comparing its nutritional quality to leafless woody stems. In the Miami University Natural Areas in southwest Ohio we quantified the frequency of leafy twigs of woody species 0.3-2.1 m high in three habitats (deciduous forest, Juniperus virginiana forest, and forest-field edge). Monthly we quantified deer browse on marked L. maackii twigs, and estimated the mass of leaf and stem tissue consumed with allometric relationships using diameter and length of unbrowsed twig portions. We estimated the percent of the annual deer diet comprised of L. maackii by dividing the sum of these estimates by the product of deer abundance (estimated by pellet-based distance sampling) and consumption estimates from the literature. Crude protein of L. maackii stems and leaves was determined by C:N analyser. In each habitat the frequency of L. maackii was greater than all other woody species combined. We estimated L. maackii comprised 14-47 % of the annual deer diet. Deer browsed L. maackii each month, but consumption was high in early spring and late summer. Crude protein of leafy twigs of L. maackii in early spring was 12.9 %, much higher than leafless twigs of native species on-site. These findings support the assumptions of the hypothesis that invasive plants with ELP impact native plants via deer-mediated apparent competition.

White-Tailed Deer Browsing of Soybeans Significantly Changes Plant Morphology and Reduces Yield, Contributing to Large Financial Losses

White-tailed deer (Odocoileus virginianus) densities in North America have increased significantly in the last 100 years, contributing to extensive agricultural losses. Smaller farming operations are more likely to be impacted by these losses since they generally are not as financially buffered against poor harvests. This study explores changes in plant growth patterns, percent damage, harvest biomass, and yield of a soybean crop from deer browsing at three exposure levels on a small research farm in southwestern Ohio. Experimental soybean plots protected from deer browsing were placed in 0.5 hectare fields during the entire 2010 growing season. Similar, but unprotected, control plots were adjacent to these exclosed areas. The exclosure/control areas were assigned a browse exposure level (high, medium, low) based on their proximity to a wooded area. Individually identified plants were sampled by exposure level and treatment (protected vs. unprotected) in July and August measuring height, width, and percent damage. Yield and above-ground biomass were assessed upon harvest in October. Soybean plants protected from deer browsing were 25 percent taller, 87 percent less damaged, yielded 74 percent more seed, and had 47 percent more above-ground biomass than unprotected plants. Browsing exposure level was not significantly different between enclosed and open plots for any plant parameter. Given per-plant yield results and an average planting density, this farm experienced a loss of $68 (±$32) per hectare to deer. Overall, that represents a $405 (± $214), or 43 percent, financial loss over one growing season.

Scale-Dependent Effects of Coyote-Predation Risk on Patterns of White-Tailed Deer Browsing along Linear Forest Edges

Abstract Browsing by Odocoileus virginianus (White-tailed Deer) plays an important role in shaping forest structure in the northeastern US. Predation can influence patterns of browse through decreasing White-tailed Deer abundance and influencing patterns of habitat selection. Canis latrans (Coyote) is the dominant predator of White-tailed Deer in our focal region in northern New York. Optimal foraging theory suggests that White-tailed Deer browse in locations that maximize energy intake while minimizing predation risk. Linear forest edges provide abundant woody browse for White-tailed Deer, but are also used as travel-ways by Coyotes in our focal region. These locations therefore provide a venue for testing the extent to which predation risk influences patterns of White-tailed Deer browsing. We quantified White-tailed Deer browse use for edge and interior sites and the density of Coyote scats along seventeen 500-m transects to evaluate the scale at which White-tailed Deer herbivory was affected by Coyote ...

Use of a Native Matrix Species to Facilitate Understory Restoration in an Overbrowsed, Invaded Woodland

AbstractThe interactive effects of herbivory, exotic species, and other human-mediated changes to the biosphere are reducing species diversity and altering ecosystem services globally. In this study, we tested whether facilitation could be used as a management technique to restore a degraded northeast Wisconsin forest understory facing high white-tailed deer (Odocoileus virginianus) browse pressure and high abundance of the exotic herb garlic mustard [Alliaria petiolata (Bieb.) Cavara &amp; Grande]. Specifically, we attempted to facilitate native understory restoration by planting or seeding native herbs into three different matrix densities of the native, browse-tolerant grass Virginia wildrye (Elymus virginicus L.), which were either protected from (fenced), or accessible to, deer browsing. Deer had minimal impacts on E. virginicus but significantly reduced the cover, survival, and flower production of white snakeroot [Ageratina altissima (L.) King &amp; H.E. Robins.] transplants, largely independent of the density of E. virginicus plantings in open-access plots. In contrast, the richness and abundance of native-seeded species were not affected by deer access but were reduced by increasing E. virginicus densities. Alliaria petiolata cover was significantly higher in plots accessible to deer but declined significantly with increasing E. virginicus planting density in both open-access and fenced plots. These results were largely corroborated by results from an associated observational study, with the exception that natural E. virginicus stands supported slightly higher native-species richness than did adjacent areas lacking E. virginicus. Thus, although we found little support that establishing E. virginicus facilitated browse-susceptible native understory herbs during our short-term experimental study, restored E. virginicus successfully established, thereby increasing native species cover and significantly reducing the cover of the exotic A. petiolata. We suggest the planting of browse-tolerant native species, such as E. virginicus, as a viable restoration technique in heavily browsed, A. petiolata–invaded woodlands.

Does Balsam Fir (Abies balsamea) Facilitate the Recruitment of Eastern Hemlock (Tsuga canadensis)

Abstract Eastern hemlock (Tsuga canadensis) was a major component of mesic forests in the Upper Great Lakes region, but presently persists in only a few locations. Many of these stands experience poor regeneration due to herbivory by white-tailed deer (Odocoileus virginianus), suggesting that hemlock will become progressively less common in these stands. We tested the hypothesis that balsam fir (Abies balsamea) facilitates establishment of eastern hemlock at 11 sites in northern Wisconsin. Hemlock saplings are three times as dense and twice as tall when growing within patches of balsam fir compared to growing outside such patches. Hemlock saplings growing outside balsam fir patches are also four times as likely to exhibit deer browsing damage as those growing inside. These results suggest that patches of balsam fir create a physical or visual barrier to deer and thus provide a refuge for hemlock saplings from white-tailed deer browsing. Because balsam fir saplings are much more abundant than hemlock in no...

Establishment of natural regeneration under severe browsing pressure from white-tailed deer after group seed-tree cutting with scarification on Anticosti Island

The use of large clearcuts with protection of advance regeneration is inappropriate for regeneration of balsam fir ( Abies balsamea (L.) Mill.) under severe browsing from white-tailed deer ( Odocoileus virginianus (Zimmermann)). However, little is known about the effects of tree-retention methods along with scarification on the establishment of balsam fir in a context of severe herbivory. Consequently, we hypothesized that seed-tree-group cutting in conjunction with soil scarification creates favourable conditions for balsam fir regeneration. In 1998 and 1999 we set up three circular forest groups of different sizes (40, 60, and 80 m in diameter) surrounded by three different intensities of scarification (no treatment, single pass, double pass) in two balsam fir stands on Anticosti Island, Quebec, Canada. Moreover, we used a network of fenced and unfenced regeneration plots to evaluate the impact of white-tailed deer browsing. The results showed that up to 7 years after harvest, seed-tree-group cutting did not improve the establishment of conifer species. Scarification had a negative impact on the abundance of conifer species, whereas white birch ( Betula papyrifera Marshall) density was significantly higher in areas scarified twice than in unscarified areas. Overall, the development of palatable tree species appears unlikely at deer densities &gt;20 individuals/km2.