Overabundant Deer Research Articles

Aboveground biomass and structural characteristics of poisonous Pieris japonica shrub stands dominating under deer pressure

ABSTRACT Canopy tree seedlings rarely grow in regions with overabundant deer in Japan, whereas Pieris japonica, a shrub species that is unpalatable to deer, has been expanding its habitat and occasionally forms dense pure stands in disturbed locations. Although this species could be the key to understanding vegetation structure and function under intense deer pressure, little information is available regarding the structural and functional aspects of P. japonica stands. Here, we examined aboveground mass (M A) and several structural parameters for 13 P. japonica stands of various developmental stages (3–64 years old as estimated from the number of growth rings of component plants); the stand M A and leaf area were estimated by developing relevant allometric equations for individual plants. The M A of P. japonica stands (≤50 Mg ha−1) were less than a fifth of that recorded for neighboring forests consisting of deciduous broad-leaved trees and conifers. Leaf area index (≤4.9 m2 m−2) and basal stem area (≤62 m2 ha−1, determined at 5 cm from the ground) of the stands reached the level comparable to tree forests, whereas canopy height (≤4.4 m) was much shorter and plant density (≥7,300 stems ha−1) was fairly high compared with those of average tree forests in neighboring regions. The stand structure lacked thick and long boles, resulting in low biomass accumulation in P. japonica stands. Thus, one possible consequence of the long-lasting deer pressure is the reduction of the carbon sequestration capacity to a fraction of that of the present forests.

The long‐term drive count and culling data of the sika deer (Cervus nippon) population introduced on Nakanoshima Island in Lake Toya, Hokkaido, Japan, during 1980–2023

AbstractCervid populations introduced to favorable habitats in confinement often increase excessively without predators and hunting. Overabundant deer populations impact the ecosystems and may cause damages to agriculture and forestry. Long‐term count data on the changes in a deer population is essential to understand the relationship between the population dynamics and the natural vegetation. The introduced sika deer (Cervus nippon Temminck, 1836) population without predators on Nakanoshima Island, Hokkaido, Japan, showed repeated irruptions and declines with mass mortality and irregular culling between 1980s and 2000s. The overabundant deer significantly altered the natural vegetation, and density‐dependent changes in population parameters such as body size and reproduction were observed. Here, we present the drive count and culling data to examine the population dynamics during 1980–2023. Deer were counted by 20–30 walking drivers and 2–3 observers on boats once per year in February or March. The number of counted deer rapidly increased from the original three introduced around 1960 to >270 deer (the first peak) in two decades and decreased by half due to starvation and the first culling. Thereafter, the number of counted deer continued to increase with a lower growth rate, reached a higher peak (>400, the second peak) than the first irruption in two decades, and decreased again by half due to starvation and the second culling. Although the number of counted deer increased again up to >300 in several years, it decreased and was maintained at around 100 deer with the annual culling program since 2012. The complete data set for this abstract published in the Data Article section of the journal is available in electronic format in MetaCat in JaLTER at http://db.cger.nies.go.jp/JaLTER/metacat/metacat/ERDP-2024-06.1/jalter-en.

Regional‐scale effects of deer‐induced forest degradation on river ecosystem dynamics

AbstractAlmost all ecosystems are open systems, meaning that significant changes in one ecosystem can lead to unexpected changes in others. Deer overabundance has become a problem worldwide, leading to forest degradation that has impacts on not only terrestrial, but also aquatic ecosystems. This study aims to investigate the regional‐scale importance of large herbivores in inter‐ecosystem interactions by examining the effects of deer‐induced forest degradation on fish populations. We selected similar‐scale catchments from river systems in Hyogo, Japan, that differed in the time since deer‐induced forest degradation. Conventional surveys for fish densities and microhabitat environments were conducted in 23 catchments, and surveys using quantitative eDNA metabarcoding were conducted in 95 catchments. We examined the relationships between fish population densities, microhabitats, and time since forest degradation, considering confounding effects. Data from 8 and 17 fish taxa detected by snorkeling and eDNA methods, respectively, were available for statistical analysis. Snorkeling‐counts (Individuals/1 m transect) and eDNA concentrations (Copies/L) in river water were strongly correlated. Fine sediments on riverbeds were increased in the 3–15 years following forest degradation and decreased after 16 years. Population densities of sand‐preferring fishes, as inferred from both eDNA and snorkeling, reasonably followed this pattern. These patterns may be caused by the depletion of fine sediments on mountain slopes. The results of this study suggest that deer‐induced worldwide alternation may also occur in aquatic ecosystems.

Browsing by non-native invasive sambar deer dramatically impacts forest structure

Large herbivores introduced to novel habitats can cause major ecosystem impacts. While impacts of overabundant deer have been documented around the world, there are few examples from Australia, where deer are non-native and natural predators are absent.Here, we outline the impacts of sambar deer in wet eucalypt forest understoreys of the Yarra Ranges National Park, south-eastern Australia. Using data obtained from a full and partial (permitting native herbivores) exclusion experiment over four years, we (i) demonstrate differences between native herbivore and introduced deer browsing, (ii) identify plant species commonly browsed by deer, and (iii) provide evidence that vegetation condition can recover in the absence of deer.While species richness and composition were unaffected, the exclusion of deer led to substantial recovery of several attributes of forest understorey vegetation. Treatments excluding deer (partial and full exclosures) saw increases in the cover of understorey trees, shrubs, ferns and climbers. Within the 1–2 m height class (the primary deer browse zone), vegetation cover-abundance increased 3–4 fold over time in full and partial exclusion plots compared to non-exclusion controls.Tree ferns (Dicksonia antarctica and Cyathea australis) were particularly impacted by deer, and browsing impacts to tree ferns were dramatically reduced from ∼50% of fronds browsed to negligible levels with deer exclusion. Deer exclusion also saw substantial reductions in browsing to individual trees, shrubs and ground ferns. The growth of commonly browsed trees, e.g. Pomaderris aspera, were demonstrably higher in partial and full exclosures than unfenced control plots. The low levels of browsing on trees and shrubs that persisted in partial exclosures probably indicates the background levels of browsing pressure attributable to native herbivores in these forests.In the absence of effective deer control, commonly browsed understorey trees, shrubs and tree ferns are likely to decrease substantially in cover over coming decades, potentially leading to increased light availability, drying of the understorey, and increased susceptibility to wildfire. The potential cascading ecological effects of unabated and increasing deer impacts may be substantial and pose major challenges to forest management.Despite management culls and recreational hunting in recent years, deer populations are increasing across Australia. As sambar populations increase, ecological impacts are likely to exacerbate. It is therefore critically important to reduce sambar numbers, before negative and potentially irreversible changes occur to forest structure, composition and function.

Homogenization of understory vegetation by an overabundance of deer (Cervus nippon) in a temperate forest in central Japan

ABSTRACT Deer browsing is a form of selective disturbance that homogenizes plant community composition and structure. In mountainous regions, disturbance intensity, together with topographical factors, affect plant communities. However, studies on the multiple effects of deer browsing and topographical factors on plant communities are limited. Here, we investigated the effects of deer exclusion on understory vegetation across the upper and lower slopes of a temperate deciduous forest in a mountainous area of Japan. We established six pairs of exclosure and control quadrats, with three pairs at each topographical position. We assessed changes in vegetation and plant structure (coverage and height), species composition, numbers of flowering/fruiting species, and damage to the plant species caused by deer browsing between 2009–2016. Vegetation coverage and the number of flowering/fruiting plant species increased in the exclosure quadrats during the study period, indicating that browsing prevents herb-layer species from reaching the flowering and fruiting stages in this site. Moreover, dissimilarity in species composition between the exclosure and control quadrats increased on the upper slope. However, the dissimilarity between upper and lower slopes in the control quadrats tended to decrease. Large herbs, which mainly include forbs and perennial species, were characteristically abundant on the lower slopes and decreased in the control quadrats on the lower slope. Our results indicate that the exclusion of deer had different effects on the understory vegetation of upper and lower slopes, suggesting that deer overbrowsing weakens the correlation between plant functional traits and topographic factors, resulting in homogenized plant communities.

Overabundant deer and invasive plants drive widespread regeneration debt in eastern United States national parks.

Advanced regeneration, in the form of tree seedlings and saplings, is critical for ensuring long-term viability and resilience of forest ecosystems in the eastern United States. Lack of regeneration and/or compositional mismatch between regeneration and canopy layers, called regeneration debt, can lead to shifts in forest composition, structure, and in extreme cases, forest loss. Here we examined status and trends in regeneration across 39 national parks from Virginia to Maine, spanning 12 years to apply the regeneration debt concept. We further refined the concept by adding new metrics and classifying results into easily interpreted categories adapted from the literature: imminent failure, probable failure, insecure, and secure. We then used model selection to determine the potential drivers most influencing patterns of regeneration debt. Status and trends indicated widespread regeneration debt in eastern national parks, with 27 of 39 parks classified as imminent or probable failure. Deer browse impact was consistently the strongest predictor of regeneration abundance. The most pervasive component of regeneration debt observed across parks was a sapling bottleneck, characterized by critically low sapling density of native canopy species and significant declines in native canopy sapling basal area or density for most parks. Regeneration mismatches also threaten forest resilience in many parks, where native canopy seedlings and saplings were outnumbered by native subcanopy species, particularly species that are less palatable deer browse. The devastating impact of emerald ash borer eliminating ash as a native canopy tree also drove regeneration mismatches in many parks that contain abundant ash regeneration, demonstrating the vulnerability of forests that lack diverse understories to invasive pests and pathogens. These findings underscore the critical importance of an integrated forest management approach that promotes an abundant and diverse regeneration layer. In most cases, this can only be achieved through long-term (i.e. multi-decadal) management of white-tailed deer and invasive plants. Small-scale disturbances that increase structural complexity may also promote regeneration where stress from deer and invasive plants is minimal. Without immediate and sustained management intervention, the forest loss we are already observing may become a widespread pattern in eastern national parks and the broader region.

Effect of Deer and Forest Edge on Understory Plant Communities

White-tailed deer (Odocoileus virginianus) impact the ecological integrity of eastern deciduous forests by modifying plant community composition and structure. Previous studies have shown that overabundant deer can negatively impact the recruitment and persistence of both woody and herbaceous plants. However, the strength and nature of these interactions can depend on habitat context. Forest edges provide favorable habitat for deer along with many introduced plant species, and have the potential to modify the nature of deer impacts. Here, we explore whether forest edges shape the impacts of deer on plant communities within the forest landscape. Specifically, we excluded deer, or, alternatively, allowed deer access, in plots along the edge and within the interior of two northern hardwood forests. Background deer abundance in these forests was approximately 6–12 individuals per km2. After eight years of exclusion, we surveyed plant communities within plots to assess the impacts of deer on plant community composition across the forested landscape. We found that the impacts of deer were robust across habitat context within the forest, with relatively weak impacts on cover and richness of both native and introduced species. Edge habitat, on the other hand, had strong impacts on cover of both native and introduced species, as well as woody and herbaceous species, but the magnitude of these impacts was variable across the two forest sites. This work suggests that deer can have modest impacts when at relatively low densities, and that these effects can be consistent across forest habitat types, while forest fragmentation and subsequent generation of edge habitat can be an important driver of composition in the forest understory.

A 17-Year Study of the Response of Populations to Different Patterns in Antlerless Proportion of Imposed Culls: Antlerless Culling Reduces Overabundant Deer Population.

Increasing populations of large herbivores have caused environmental damage around the world, and it is necessary to improve population management strategies. Culling is a traditional management method. Antlerless deer proportions, consisting of adult female deer and fawn in Cervidae in wildlife statistics, are directly related to population increases; thus, the culling-based removal of individuals from habitats and the removal of these antlerless individuals by game hunting and nuisance control might be effective approaches for reducing population sizes. We evaluated the effectiveness of antlerless culling on 17-year density trends in the sika deer (Cervus nippon) population across an area of 1175 km2 in Fukuoka Prefecture (Japan). In 11 out of 47 grids (area measuring 5 by 5 km), the densities of sika deer tended to decline; meanwhile, in the remaining 36 grids, the densities increased. These density trends were explained by changes in the proportion of antlerless culling, as the densities declined with increasing proportions of antlerless deer. The results affirm the theory that antlerless culling is effective in population management; it is posited that antlerless-biased culling could be a crucial measure in managing overabundant populations of herbivores, contributing to more effective conservation of forest environments.

Exclusion of Overabundant White-tailed Deer (Odocoileus virginianus) Results in Shifts in Soil Microbial Communities and Abiotic Soil Condition in a Northeastern Deciduous Forest

Past and current anthropogenic practices have resulted in dramatic alterations to ungulate population densities worldwide. When ungulate populations are overabundant, they can alter the dynamics, structure, and function of ecosystems. White-tailed deer (Odocoileus virginianus), specifically, can occur at densities far greater than their historical records in parts of their native range, which includes forests in the northeastern U.S. They have been shown to alter community structure of native plants, indirectly impact animal communities, and promote the success of invasive species. Despite much research into the effects of overabundant ungulates and deer in particular, less is known about the effects of deer on soil microbial communities. Here, we utilized soil samples from inside and outside of six deer exclosures located in a regional second growth mixed hardwood forest on the Binghamton University campus in Vestal NY, U.S.A. A metagenomic analysis was conducted on DNA extracted from the soil to identify the microbes present. Soil characteristics, including soil organic matter, soil moisture, pH, and electrical conductivity were also measured. Soil samples from inside exclosures had on average lower pH, higher soil moisture and organic matter, and higher electrical conductivity. The microbial communities across all samples were dominated by Proteobacteria, Acidobacteria, and Actinobacteria. However, the structure of the microbial soil community appeared to differ between samples taken inside and outside the exclosures, with those taken outside more closely resembling other outside samples and those sampled inside soils showing more variability in community structure. Overall, our results suggest that overabundant deer may have a homogenization effect on the soil abiotic environment and the soil microbial community.

Soil nutrient and moisture environments and shoot growth of Quercus crispula canopy trees in two areas that experienced contrasting effects of deer overabundance over an 11-year period

ABSTRACT To elucidate the effects of modification of the understory aboveground plant biomass and soil nutrient and moisture environments on canopy tree growth in deer overabundance sites, we compared the canopy shoot growth of oak trees (Quercus crispula), which are not a target for bark stripping or bark feeding by deer, understory aboveground plant biomass, and components of soil nutrient and moisture between inside (protected) and outside (exposed) a large fenced area. We found that canopy shoot growth in the exposed area was reduced compared with that in the protected area. Net nitrogen (N) mineralization rates did not differ between areas, although understory aboveground plant biomass, total carbon (C) and N, and total soil inorganic N content were significantly lower in the exposed area than in the protected area. Indices of canopy shoot growth correlated significantly with soil water content, but due to the limited scope of our study this result does not confirm an effect of soil moisture on canopy shoot growth. Further study is required to clarify the effects of deer overabundance on canopy tree growth.

Meta-analysis shows that overabundant deer (Cervidae) populations consistently decrease average population abundance and species richness of forest birds

AbstractLocal-scale studies have shown that an overabundance of Cervidae species (deer, elk, moose) impacts forest bird communities. Through meta-analysis, we provide a generalized estimate of the overall direction and magnitude of the indirect effects overabundant cervids have on avian species. We conducted 2 distinct meta-analyses that synthesized data on 130 bird species collected from 17 publications. These analyses compared bird species’ population abundance and/or species richness at sites with overabundant cervids to sites with lower cervid abundance or without cervids. We evaluated whether the impacts of overabundant cervids are generally in the same direction (positive, negative) across avian species and locations and if effects vary in magnitude according to avian nesting location and foraging habitat. We found that where cervids were overabundant, there was a significant decrease in mean bird population abundance and species richness. Species that nest in trees, shrubs, and on the ground showed the largest decreases in abundance, as did species whose primary habitat is forest and open woodland and species that are primarily insectivores or omnivores. We did not find significant decreases in abundance for avian species that nest in cavities, whose primary habitat is grassland or scrub, nor for species that mainly eat seeds. Our results indicate that overabundant cervids, likely through their direct effects on vegetation and indirect effects on insects and forest birds, negatively impact individual bird populations and decrease overall avian species richness.

Evaluating the construction and effectiveness of slash walls at the perimeter of regeneration harvests to exclude deer

Deer impacts on forest vegetation have complicated attempts at forest regeneration in many parts of the Northeast, Mid-Atlantic States, and other regions. Deer overabundance limits the success of forest regeneration. One strategy is to reduce deer browsing by temporarily excluding them from regeneration harvests. Because of the costs of fence installation, maintenance, and removal, we developed and tested the feasibility and effectiveness of slash walls. In 2017, 4 regeneration harvests ranging from 4.5 to 30 ha were cut. Slash and trees of marginal value proximate to the perimeter were piled into a slash wall that averaged 3.7 m to the tallest branch and 7.2 m wide. Slash walls occupied from 0.5 to 1.5 ha of the harvest area and used approximately 28,000 kg of slash and low-grade logs per 30 m section. The rate of construction depended on topography along with access to slash and low-grade trees. Construction rates for slash walls varied from 32 m/hr to 77 m/hr. The average cost of construction was $4.82/m ($1.47/ft) based on machine and operator costs of $200 (US)/hr for a weighted average cost of $541/ha ($219/ac). Fence installation can cost 3–4 times as much as slash wall construction, plus additional costs for maintenance and removal. The cost to monitor and maintain slash walls was negligible. Slash wall heights slumped approximately 8–14% per year, which reduced slash wall height by 37 cm per year. Four years after creating the slash walls, the heights of tagged seedlings of palatable species remained significantly greater inside the slash wall where deer were excluded than in adjacent control areas that were accessible to deer. We recommend slash walls minimally be constructed 3.1 m tall to the highest 5-cm-diameter branch, 7 m wide at the base, and sufficiently dense to prevent deer from being able to crawl through. This study is the first documentation of slash walls as a feasible and effective technique during regeneration harvesting to exclude deer from impacting forest vegetation. Subsequent to this study, multiple logging crews have created additional slash walls in CT, MA, NH, NY, and RI as part of commercial harvests.

Forest Vegetation Response to White-Tailed Deer Population Reductions in a Large Urban Park

Overabundance of white-tailed deer (Odocoileus virginianus) constitutes a threat to the biological diversity and ecosystem function of forested natural areas. Managers of Eagle Creek Park, a large forested park in Marion County, Indiana, that is surrounded by densely populated residential housing, implemented a deer population reduction program in 2014 to reduce negative impacts to park ecosystems. Starting in 2013, we instituted a monitoring program within two nature preserves imbedded within Eagle Creek Park to track the response of vegetation communities to population reductions. We found positive response in the heights of two published indicator species, Arisaema triphyllum (jack-in-the-pulpit) and Actaea pachypoda (white baneberry). We also observed increased richness and density of native woody species and an overall reduction in the proportion of twigs browsed at both preserves. The reduction efforts coincided with heavy mortality of overstory Fraxinus (ash) trees from emerald ash borer (Agrilus planipennis). Consequently, while we observed recovery of native woody species at both sites, one of the preserves also experienced a large increase in the abundance of nonnative woody plants in response to increased light availability and reduced browse pressure. Overall, our monitoring showed that deer population reductions have allowed the recovery of vegetation communities in the park. However, continued monitoring is needed to track vegetation community response to continued management of the deer population in conjunction with other human pressures on biological communities in the park.

Leaf trait variability explains how plant community composition changes under the intense pressure of deer herbivory

AbstractThere is growing evidence indicating that intraspecific trait variation (ITV) plays a prominent role in determining plant community composition. In this study, we investigated the significance of ITV in identifying the processes that shape the development of forest understory plant communities in an area in which excessive herbivory by overabundant deer populations has been an issue. We measured functional traits (height, leaf area, leaf mass per area, leaf dry matter content, and leaf toughness) of 13 forest floor plant species growing in two contrasting sites in which deer were overabundant or had been completely excluded, respectively, and examined the relationships between species dominance and interspecific trait variation and ITV. We detected variations in the trait plasticity of size and morphological features among species, reflecting species‐specific strategies in response to herbivory and consequently observed marked differences in species composition and diversity at the two sites. Notably, small stature and less costly leaves were identified as important traits that enable plants to persist under conditions of intense deer herbivory probably because such plants are less exposed to herbivory and simultaneously optimize carbon assimilation. In contrast, large‐sized plants with costly leaves tended to dominate the plant community in the absence of deer herbivory, as these plants would tend to gain a competitive advantage with respect to the acquisition of space and light. The findings of this study indicate that a focus on ITV represents a promising approach for determining the general ecological patterns of plant communities responding to environmental disturbance.

The Forest of Unintended Consequences: Anthropogenic Actions Trigger the Rise and Fall of Black Cherry

AbstractThe twentieth century confluence of clear-cutting, deer overabundance, and rising nitrogen deposition favored dominance by the shade-intolerant, unpalatable, and nitrogen-demanding black cherry (Prunus serotina) throughout the Allegheny Plateau of the eastern United States. The abundance of this species conferred unique and valuable ecological and economic benefits that shaped regional biodiversity and societies. Sustaining these values is increasingly difficult because black cherry, seemingly inexplicably, has experienced diminished establishment, growth, and survival in the twenty-first century. In the present article, we chronicle the change and assess underlying drivers through a literature review and new analyses. We found negative plant–soil microbial feedback loops and lowered nitrogen deposition are biologically, temporally, and geographically consistent with observed declines. The evidence suggests that black cherry dynamics are the unintended consequence of actions and policies ostensibly unconnected to forests. We suggest that these shifts are a bellwether of impending changes to forests, economies, and ownership patterns regionally and beyond.

History of Deer Herd Reduction for Tick Control on Maine’s Offshore Islands

The incidence of Lyme disease in Maine is associated with high abundance of blacklegged (deer) ticks, which in turn has been partly attributed to local overabundance of white-tailed deer. With evidence from Monhegan Island that the complete removal of deer reduced ticks and risk of contracting Lyme disease, nine other offshore communities initiated efforts to cull deer. We reviewed and summarized available histories of deer management on Maine’s offshore islands. Concern about Lyme disease provided the overarching impetus for deer culls. Culls mostly occurred on islands that have no regular firearms hunting season, island communities have been challenged to control deer numbers, and social acceptance of deer culls varied. Integrated tick management (ITM) is the key to controlling ticks, but statewide ITM policy is lacking. Formation of vector control districts with statewide ITM policy would support all communities in Maine.

Support for deer herd reduction on offshore Islands of Maine, U.S.A

Over the past three decades, citizens of Maine in the northeastern United States have experienced increasing blacklegged tick (Ixodes scapularis) abundance and rising incidence of Lyme and other tick-borne diseases. White-tailed deer (Odocoileus virginianus) overabundance has been considered one cause of the high incidence of tick-borne diseases on offshore islands of New England. Most of Maine’s 15 offshore, unbridged island communities have a history of concern about ticks, Lyme disease, and white-tailed deer overabundance, but have been challenged to keep deer numbers down through hunting or culls. This history has led to perennial, often divisive community debates about whether and how to reduce the size of their deer herds. In 2016 we conducted a convenience sample survey of year-round and summer residents of Maine’s offshore islands to quantify the level of concern about Lyme disease, and assess the motivations and level of support for deer herd reduction. Among respondents, 84 % agreed Lyme disease was a problem on their island and 61 % supported deer herd reduction. Agreement that Lyme disease was a problem was associated with having acquired tick-borne disease as well as with tick bites without disease. Respondents ranked deer overabundance as a top cause of tick abundance and tick-borne disease and supported deer herd reduction as an approach to reduce the risk of Lyme disease. Other problems associated with deer overabundance (vehicle collisions, damage to landscaping, and damage to forests) also motivated support for deer reduction. Approval of doe permits, an expanded archery season, and sharpshooting as reduction methods was greater than an expanded firearms season. Respondents felt responsibility for tick control fell to the town for the most part, and recognized that multiple factors have contributed to the tick problem in Maine, not just deer.

Long-term effects of white-tailed deer overabundance, hybrid poplar genotype and planting stock type on tree growth and ecosystem services provision in bioenergy buffers

Populus hybrids are increasingly planted in multifunctional bioenergy buffers bordering crop fields. However, such small agroforestry systems are vulnerable to damage caused by overabundant deer populations. We measured after 8 years the effects of white-tailed deer (Odocoileus virginianus), genotype and planting stock type on tree growth and ecosystem services provision (biomass production; energy, nutrient and carbon storage; and phytoaccumulation of soil nitrate and phosphorus) in 15-m wide buffers located downslopes of hayfields in southern Québec (Canada). Two deer protection treatments (fenced and unfenced), two genotypes (P. deltoides × P. nigra, genotype D×N-3570 and P. maximowiczii × P. balsamifera, genotype M×B-915311) and two stock types (bare-root stocks: ±1.8 m in height and whips: 2.5 m in height) were studied. In unfenced plots, deer heavily browsed poplars (increase in the height of the first branch by 59 cm), repeatedly rubbed tree bark (36% of trees with rubs for genotype D×N-3570, and 59% for genotype M×B-915311), slightly decreased survival (by 2.9%), which reduced tree-level and stand-level productivity. Proportion of trees with rubs, first branch height and survival were correlated (p < 0.001) with woody biomass yields. Fenced poplars increased wood volume, biomass and energetic content by 20–21%, and C, N and P stocks in aboveground biomass by 13–20%. Higher soil phosphorus bioavailability was also found in unfenced plots. Genotype D×N-3570, which allocates less biomass to branches, grows its first branches farther from the ground and rapidly develops a rough and thick bark, was the least affected by deer, despite its high palatability. Genotype M×B-915311, which had higher biomass allocation to branches, a smooth and thin bark, but low palatability, was the most affected by deer. Soils in plots of genotype M×B-915311 had the lowest macronutrients availability, except for nitrate. Biomass feedstock quality (i.e. low nutrient concentrations and high heating value of woody biomass) was highest for genotype M×B-915311. In both fenced and unfenced plots, whips were more productive than bare-root stocks, especially for genotype D×N-3570. Optimizing ecosystem services provision in bioenergy buffers can be achieved by fencing, and by genotype and stock type selection.

History and Evolution of the North American Wildlife Conservation Model

The first section of this monograph describes the NAWCM and the difficulties it faces confronting circumstances very different from those that created it, namely the local overabundance of whitetail deer, wild hogs, and other wild game animals. It describes scientific wildlife management and argues that it constitutes the sole necessary cause of sustainable consumptive use of living natural resources. It concludes by showing that scientific wildlife management and markets for wild game meat can be compatible when commercial influences on wildlife managers are adequately checked. Section two reviews the history of wildlife management in North America, from American Indians through the development of the NAWCM in the late nineteenth century, and surveys the interplay between biology, ecology, markets, range, and population size of a dozen important types of wild animals. The key takeaway is that common pool problems and species-specific characteristics, like herding and flocking behaviors, endanger wild game populations far more than the scientifically-managed commercialization of their flesh does. The third section warns that the facile application of “democracy” to wildlife management poses grave risks for wildlife, especially wild game species, by threatening the authority of scientific wildlife management and further eroding the wildlife dollars volunteered by consumptive users. The fourth section suggests several ways that wildlife managers, short of reinstating markets for wild game meat, can increase the number of consumptive users and political support for the sustainable, consumptive use of wildlife. The most important suggestion is for the legalization of proxy hunting as a way, short of full-blown commercialization, of increasing wild game harvests where needed to meet local scientific wildlife management goals. The conclusion argues that by stressing the importance of scientific wildlife management over its other components, instead of making a fetish of prohibitions on wild game markets, the NAWCM can continue to protect North America’s wildlife throughout the twenty-first century.

Seasonal and annual fluctuations of deer populations estimated by a Bayesian state-space model.

Deer overabundance is a contributing factor in the degradation of plant communities and ecosystems worldwide. The management and conservation of the deer-affected ecosystems requires us to urgently grasp deer population trends and to identify the factors that affect them. In this study, we developed a Bayesian state–space model to estimate the population dynamics of sika deer (Cervus nippon) in a cool-temperate forest in Japan, where wolves (Canis lupus hodophilax) are extinct. The model was based on field data collected from block count surveys, road count surveys by vehicles, mortality surveys during the winter, and nuisance control for 12 years (2007–2018). We clarified the seasonal and annual fluctuation of the deer population. We found a peak of deer abundance (2010) over 12 years. In 2011 the estimated deer abundance decreased drastically and has remained at a low level then. The deer abundance gradually increased from April to December during 2013–2018. The seasonal fluctuation we detected could reflect the seasonal migration pattern of deer and the population recruitment through fawn births in early summer. In our model, snowfall accumulation, which can be a lethal factor for deer, may have slightly affected their mortality during the winter. Although we could not detect a direct effect of snow on population dynamics, snowfall decrease due to global warming may decelerate the winter migration of deer; subsequently, deer staying on-site may intensively forage evergreen perennial plants during the winter season. The nuisance control affected population dynamics. Even in wildlife protection areas and national parks where hunting is regulated, nuisance control could be effective in buffering the effect of deer browsing on forest ecosystems.