Search Results (35)

Ungulate browsing is a major driver of forest regeneration dynamics and habitat structure in managed temperate forests, influencing species composition, regeneration success, and long-term stand development. Traditional assessments of browsing impacts often rely on field-based indicators such as regeneration density or visual cover, but these metrics provide limited insight into three-dimensional habitat structure. Mobile handheld LiDAR offers highly detailed measurements of forest structure, enabling objective and reproducible quantification of structural complexity that complements and extends conventional field-based methods. In this study, we applied handheld LiDAR as an innovative indicator for habitat structure within the ungulate browsing zone (<2 m height) to evaluate structural development across sites differing in management context. Paired fenced and unfenced plots (12 × 12 m) were surveyed within the WiWaldI project framework in 2019 and 2023 and compared across three hunting regimes representing different degrees of ungulate population management. Structural complexity was quantified by deriving box-counting dimensions from LiDAR point clouds, providing a measure of spatial arrangement and density relevant to ungulate–vegetation interactions. To support interpretation and ecological context, we complemented LiDAR indicators with streamlined field assessments. Based on this framework, we assessed whether forest structural complexity and visual cover differ among regions and over time, and whether ungulate browsing induces detectable structural differences between fenced whether structural differences between fenced and unfenced plots are detectable. We further examined the relative importance of tree species composition, plant architecture, and hunting regime as drivers of three-dimensional habitat structure. A simplified octant method characterized the spatial distribution of woody regeneration, while a silhouette-based approach quantified visual cover from the perspective of a standard ungulate profile. These auxiliary measures contextualize visual and spatial aspects of structure that LiDAR metrics capture with minimal observer bias. LiDAR studies have previously demonstrated potential for linking high-resolution structural data to ungulate habitat use, and our approach extends this by focusing on structural complexity as a habitat indicator. Results show a consistent increase in LiDAR-derived structural complexity between 2019 and 2023 across all regions. This increase occurred across management contexts and was not consistently explained by fencing or hunting regime effects, suggesting that site conditions, forest composition, and successional processes were dominant drivers during the observation period. Hunting regime showed no statistically significant and no consistent effect on structural complexity across regions or years. Visual cover metrics varied strongly among regions and species and declined over time. These findings suggest that three-dimensional habitat structure information has the potential to enhance the evaluation of ungulate impacts and may support evidence-based forest and wildlife management, particularly when interpreted in the context of site conditions and successional dynamics. Beyond ungulate impact assessment, the presented handheld LiDAR approach provides a scalable remote sensing framework for precision forestry by capturing three-dimensional structural attributes that are directly linked to forest stability, resilience, growth dynamics, and stand-level species mixing, thereby supporting evidence-based forest management recommendations. Full article

Assessing the extent and magnitude of wildlife impact on forest regeneration (e.g., % browsed seedlings or reduction in regeneration density) remains a central challenge. This study explores the potential of unmanned aircraft systems (UAS) to quantify wildlife impact through the integration of drone-based thermal surveys and vegetation assessments. Specifically, it evaluates whether UAS-derived wildlife density estimates can be linked to browsing intensity and regeneration structure, thereby enabling an indirect assessment of silviculturally relevant forest dynamics. By combining remotely sensed wildlife data with field-based vegetation inventories, the study aims to identify measurable relationships between structural forest characteristics and browsing effects. This approach contributes to the development of spatially efficient, objective, and reproducible monitoring methods at the forest–wildlife interface. Ultimately, the study provides a novel framework for integrating modern remote sensing technologies into wildlife–ecological monitoring and for improving adaptive, evidence-based management in forest ecosystems increasingly affected by high ungulate densities and climate-related stressors. Two silviculturally contrasting study areas were selected: a broadleaf-dominated mixed forest in Hesse, where high ungulate densities were expected, and a pine-dominated site in Brandenburg, anticipated to experience lower browsing pressure. Thermal surveys were conducted using a DJI Matrice 30T drone equipped with a high-resolution infrared camera to detect and geolocate wildlife. In parallel, browsing impact was assessed using a modified circular transect method (“Neuzeller method”). Regeneration was recorded by tree species, height class, and browsing intensity. Statistical analyses and GIS-based spatial visualizations were used to examine the relationship between estimated ungulate densities and browsing levels. Results revealed clear differences in wildlife abundance and browsing intensity between the two sites. In the Heppenheim forest, roe deer densities exceeded 40 individuals per 100 ha, correlating with high browsing pressure—particularly on ecologically and silviculturally valuable species such as sycamore maple and sessile oak. In contrast, the Rochauer Heide exhibited lower densities and a comparatively moderate browsing impact, although certain tree species still showed signs of selective pressure. This study demonstrates that drone-based wildlife monitoring offers an innovative, non-invasive means to indirectly evaluate forest structural conditions in regeneration layers. The findings highlight the relevance of UAV-supported methods for evidence-based wildlife management and the adaptive planning of silvicultural measures. The method enhances transparency and spatial resolution in forest–wildlife management and supports evidence-based decision-making in times of ecological and climatic change. Full article

The global forestry discourse frequently highlights the issue of ungulate browsing, which can significantly impact tree regeneration and tree species composition by inhibition of growth and elimination of certain, particularly ecologically valuable, tree species. The forestry field often utilizes the percentage of browsed trees within a specific area, ranging from single hunting grounds to broader provincial scales, as a metric of browsing intensity. This measure correlates with ungulate density, which is known to vary across landscapes, rendering spatially averaged browsing percentages less useful for silvicultural decisions even with accurate results. Addressing this gap, we utilized a GLMM with random effects to assess tree specific browsing pressure more appropriately. We incorporated data from two adjacent areas in the northeastern limestone Alps, focussing on the four important tree species in the region (Abies alba, Acer pseudoplatanus, Fagus sylvatica, and Picea abies). We analyzed data collected with distinct methodologies for the two regions, respectively, Austrian Federal Game Impact Monitoring and Austrian Regeneration and Browsing Monitoring of Federal Forests. Overall, the data documented browsing occurrence on 8933 trees over 632 sampling plots totalling 55,000 hectares. By comparing various models, including those with spatial considerations, we found that treating sampling plot location as a latent state variable improved the model fit and allowed prediction of browsing probability on a landscape scale. This study underlines the value of incorporating spatial elements into models for assessing browsing pressure and its spatial variations, thereby facilitating more informed silvicultural decisions. Full article

Human activities are increasing the occurrence of megafires that alter ecological dynamics in forest ecosystems. The objective of this study was to understand the impacts of a 610 km² megafire on patterns of tree regeneration and herbivory across three forest types (aspen/fir, oak/maple, and pinyon/juniper). Seventeen transect pairs in adjacent burned/unburned forest stands (6 aspen/fir, 5 oak/maple, and 6 pinyon/juniper) were measured. Sapling density, meristem removal, and height were measured across the transect network over a three-year period from 2019 to 2021. Tree species able to resprout from surviving roots (oak and aspen) generally responded positively to fire while species that typically regenerate by seeding showed little post-fire regeneration. Browse pressure was concentrated on deciduous tree species and was greater in burned areas but the effect diminished over the three-year study period. Meristem removal by herbivores was below the critical threshold, resulting in vertical growth over time. Our results indicate that forest regeneration within the megafire scar was generally positive and experienced sustainable levels of ungulate browsing that were likely to result in forest recruitment success. Full article

Ungulate browsing represents a contemporary issue for forest development, influencing forest regeneration, composition, and management practices across the world, especially in North America. This review synthesizes findings from 101 studies conducted between 1980 and 2025 to examine patterns of herbivory damage through browsing by moose, elk, white-tailed deer, black-tailed deer, and bison. Despite regional variation, high ungulate density consistently emerges as the primary factor driving browsing intensity and ecological and economic impact, leading to decreased social acceptance of coexistence with ungulates. This review highlights the selective suppression of palatable species such as balsam fir, red oak, and white cedar, leading to shifts toward less-preferred conifers. Preventive and control measures, ranging from fencing and repellents to regulated hunting, are widely implemented but vary in effectiveness and social acceptability. Although predator presence is an evident controlling factor, it was not statistically associated in this review with reduced browsing, nor with behavioral or trophic cascade effects. Ultimately, this study underscores the importance of integrated management strategies that combine silvicultural adaptation, population control, and, where feasible, predator reintroduction to ensure forest resilience and sustainability in the face of increasing pressure from climate change. Full article

Improved forage and living conditions in certain parts of Europe over the past few decades have led to alarming levels of ungulate densities. Consequently, the overabundance of red deer, roe deer, and fallow deer in the Western Plains of Romania has begun to generate issues in the development of young oak stands. In addition to causing damage to the agricultural sector and increasing the risk of vehicle collisions, ungulates are increasing pressure on the forestry sector, mainly through the browsing of young saplings. This study quantifies the levels of ungulate browsing in oak stands using a permanent sample grid of 42 plots in both natural and artificial regeneration areas. A total of 3223 individual saplings were measured, revealing browsing intensities of 49.65% in clearcut systems and 12.8% in continuous forest cover systems. With high ungulate densities identified as the main cause, the Sustainable Population Threshold was calculated using a complex set of indices and compared to the actual numbers of ungulates, both of which were translated into stock unit equivalents. A logistic regression model was developed based on silvicultural and wildlife indices to identify other factors influencing browsing occurrence. The findings indicate that the proportion of forested areas in the hunting ground and the type of silvicultural system are significant factors in the occurrence of browsing. The problem of ungulate overabundance clearly influences forest development, and new solutions should be identified in terms of both forestry and wildlife management. Full article

(1) Background: Human–wildlife conflict can lead to adverse consequences for both parties, particularly in areas with a high concentration of wild ungulates. Ungulates cause frequent, severe plant damage by stripping the bark or browsing on the youngest plants. In the latter case, they damage vegetative sprouts and leaves, which can cause a delay in growth or the plant’s death. Tuscany is notable for its significant population of wild boar, which cause substantial damage to vineyards and cereal crops, costing farmers millions annually. In Tuscany, given the highly cultivated landscape of olive trees, damage has also been recorded in these plants. Balancing human and wildlife needs is crucial for minimizing damage and ensuring coexistence. (2) Methods: This study tested innovative electronic playback devices using long-range radio technology (LoRa) to deter wild ungulates and prevent crop damage. These devices use sounds and lights to induce wild animals to be afraid and thus run away from the cultivated plot to be protected. The experiment was conducted on a farm in Chianti, Tuscany, involving four plots of land planted with olive trees: in two test areas, four playback devices and four camera traps were installed, and in the two control areas, only camera traps were installed. Playback devices aimed to deter wild ungulates and camera traps aimed to test their effectiveness. Data from the camera traps were analyzed statistically and behaviorally. (3) Results: Playback devices significantly reduced wild animal activity in the equipped areas. Statistical analysis revealed that the use of acoustic–luminous deterrent devices (PDs) significantly reduced wildlife visits to the olive groves. (4) Conclusion: The study’s findings, supported by heatmaps and frequency analyses, provide insights into wildlife activity patterns and guide the development of targeted, effective wildlife management strategies. Full article

Herbivory by ungulates is a seminal driving force in Mediterranean landscapes, where habitat diversity contributes to supporting high population densities. We investigated the influence of grazing and browsing, primarily by red deer (Cervus elaphus), on herbaceous and woody plant species, using a twin-plot design with herbivory exclusion. The prompt detection of herbivory cessation in vegetation was measured in multiscale plots by calculating Hill’s numbers (0, 1, and 2) as diversity indices over two years. The results revealed an increased diversity gradient by habitats (Pine reforestation→Mediterranean woodland→dehesas of Quercus spp.) with an initial increase in overall species and herbaceous species richness in the fenced plots. Woody vegetation did not change significantly in species richness, or typical or dominant ones. In addition to the early changes detected in the richness of herbaceous species (⁰D_her), medium–long term variations in woody species (presence and abundance) would represent good indicators of herbivory pressure for a diverse array of Mediterranean habitats. Full article

Forest–steppe ecosystems represent a heterogeneous small-patch landscape important as a biodiversity hotspot and habitat for many endangered species. In this work, we examine threatened forest–steppe communities using structural indices, browsing intensity and indices that consider herbivorous game preferences. The study aims to assess the abundance of natural regeneration and the browsing intensity in relation to different stand structures and to identify woody species threatened by selective browsing at three study sites on the Krupina Plateau in the southern part of central Slovakia. At each study site, three circular permanent research plots (PRPs), each 500 m² in size, were established for stand structure analysis. Within each PRP, nine circular subplots with a radius of 2 m were established for detailed analysis of natural regeneration. The results of this study suggest that forest patches in the forest–steppe mosaic suffer from a long-term lack of natural regeneration, which is induced mainly by increasing aridity and ungulate pressure. Positive effects on the amount of natural regeneration were noted in association with the aggregated structure of forest patches and the presence of dead wood. Differentiated stand structure influenced the regeneration number in a negative way and at the same time significantly increased browsing intensity. In relation to a more advanced regeneration, shrubs had a protective effect against browsing. The feeding preferences of the animals can positively modulate the species composition and eliminate the imbalances in the regeneration in favor of the increasingly rare Quercus pubescens Willd. Full article

In recent decades, ungulates have expanded in number and range in Europe. This review aims to analyze the impact of ungulate browsing in different forest ecosystems and identify the main driving factors and trends. In total, 155 studies were analyzed in preparing this review, across 19 European countries. In Europe, the main browsers are represented by roe deer (Capreolus capreolus L.), red deer (Cervus elaphus L.), moose (Alces alces L.), chamois (Rupicapra rupicapra L.), and fallow deer (Dama dama L.). Regarding browsing severity, they frequently exceeded 50%, meaning that over half of the saplings were browsed. Ungulate density was the main driving factor of browsing severity, with areas exhibiting high browsing pressure often having more than ten individuals per square kilometer. The type of silvicultural system used played a vital role in the severity of browsing, and trends in foraging for preferred tree species were identified. Fencing was the most common non-harmful protection method used, while hunting management was the most efficient method for controlling deer numbers and browsing intensity. Large carnivores were missing in most study areas, but in the areas where they were present, they played a significant role in creating a chain reaction of ecological impacts. Considering the significant impact of ungulate browsing on forest ecosystems, there is a pressing need for more research to comprehend and effectively mitigate the effects of deer presence comprehensively. Full article

Quaking aspen (Populus tremuloides Michx.) landscapes are valued for their biodiversity, water retention, fire mitigation, aesthetics, and recreation opportunities. Across North America, some aspen populations are experiencing population declines as they face uninhibited ungulate browsing, drought, fire suppression, insects, disease, and inappropriate management. Increased human development and recreational use within aspen landscapes can serve as additive stressors, though there is a dearth of literature examining these elements. At a popular recreational area in Utah, USA, identifying the cause of apparent decline within a larger aspen community is complicated by development upstream and recreation-related activities. We sought to (1) assess the overall condition of the aspen at the site, (2) understand key variables that influence aspen conditions, and (3) elucidate how aspen fitness varies across the site. We collected data from forty-five plots using established aspen sampling methods, including ungulate presence, tree characteristics, soil chemistry, and environmental descriptors. Results suggest that a combination of higher levels of browsing and elevated soil sodium may be causing premature mortality and limiting aspen recruitment in a portion of the study area. These findings will inform future management at this site, as well as similar recreational forest settings experiencing compound stressors. Full article

This study examines the impact of ungulate browsing on the understory dynamics of the Cansiglio Forest, the only European beech high forest in the Southern Limestone Alps. Utilizing seven pairs of fenced versus unfenced forest stands established over two decades, we assessed how fencing affects understory structure and tree regeneration. Significant differences were found in cover, height and vascular species composition in both tree regeneration and shrub layers. Fenced areas showed a significantly higher number and greater average height of young trees, supporting the hypothesis that ungulate browsing negatively impacts tree regeneration. Despite previous studies attributing the lack of silver fir (Abies alba Mill.) regeneration primarily to red deer (Cervus elaphus Linnaeus, 1758) browsing, our findings did not show a significant association of this species with fenced conditions. While Rubus abundance was higher inside fenced areas, overall vascular species richness did not differ. Our results highlight the evident effects of ungulate browsing and suggest the need to consider other factors influencing forest regeneration and understory development. Future research should establish additional study replicates, balanced across diverse site and stand structure conditions, to further explore these dynamics. Full article

The impact of ungulate browsing on tree saplings has been found to have a negative effect on the regeneration of temperate forests. However, it remains ambiguous whether a relationship exists between browsing intensity and soil quality in natural forests. Therefore, we conducted a study in Roztoczańskie National Park to investigate the relationship between soil quality and browsing intensity for tree saplings. The aim was to gain a better understanding of how soil quality affects the browsing of ungulates on tree species. Baseline data (sapling height, basal diameter, crown length and width, browsed-shoot diameter, and soil samples) were collected from the 22 belt transects established in the permanent research plots. The soil quality index was calculated using physical and chemical soil properties. Twig dry mass was determined using allometric equations. Species relative density and browsing intensity were assessed through field measurements. Relationships between the variables were established using a linear regression model. The results suggest that browsing intensity is influenced by the gradient of the soil quality index and that it varies between tree species. Along the increasing soil quality gradient, tree species’ relative density (p = 0.012) and twig dry mass m⁻² (p = 0.005) significantly decreased for A. pseudoplatanus. In contrast, browsing intensity increased significantly with an increasing species relative density for A. pseudoplatanus (p = 0.00) and C. betulus (p = 0.001) and with an increasing twig dry mass for F. sylvatica (p = 0.034) and C. betulus (p = 0.004). Browsing intensity increased significantly with an increasing soil quality index for F. sylvatica (p = 0.027) and decreased significantly for A. pseudoplatanus (p = 0.036). Notably, there was a significant positive relationship between browsing intensity and species relative density and twig dry mass, indicating that ungulate browsing is concentrated where browsing is abundant. These results provide insights that can be used to improve management and conservation strategies to protect tree species vulnerable to ungulate herbivory. Full article

The foraging behavior of ruminating ungulates significantly impacts forest ecosystems due to their nutritional requirements. This study focuses on inter-specific comparisons of bark browsing (stripping) between Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and silver fir (Abies alba Mill.). Field measurements were conducted at the previously established research demonstration site “Husárik” in the Javorníky Mountains, north-western Slovakia. We measured the sizes of wounds on stems and assessed the dimensions of unrecovered parts of wounds, subsequently calculating areas of recovered bark patches. Then, the total areas of wounds recovered patches, and unrecovered parts were measured. Additionally, the percentages of wound areas, recovered areas, and unrecovered areas were expressed as proportions relative to the total bark surface. Influencing factors such as the position of wounds along the vertical stem profile and stem diameter class were analyzed using two- and three-way ANOVA followed by Fisher’s LSD test. The results demonstrate the susceptibility of both tree species to bark browsing by ruminating ungulates, primarily red deer (Cervus elaphus L.) in our study site. Douglas fir exhibited slightly less intense browsing compared to silver fir, while silver fir had a slightly higher recovery rate. Specifically, 17.0% of the bark surface in Douglas fir and 21.5% in silver fir were browsed. The proportions of recovered areas on wounds were 62.5% and 69.6% in Douglas fir and silver fir, respectively. Regarding the vertical stem profile, the most intense browsing occurred at a height of 101–125 cm from the ground level, with rates of 40.7% in Douglas fir and 47.0% in silver fir. Browsing intensity showed negligible variation among diameter classes, which were classified as up to 35 mm, 35–50 mm, and over 50 mm. Our findings suggest that, as an introduced species, Douglas fir is not a suitable substitute for other commercially significant tree species in supporting sustainable forestry in European countries where ruminating ungulates are overabundant. Full article

Ungulate populations have surged to unsustainable levels in multiple areas in recent decades due to human intervention, making forestry and conservation practices arduous. The population of ungulates is also currently displaying a rising trend in Hungary, prompting decision-makers to commence substantial reduction efforts. Our study examined the ungulate impact in three forested regions of Hungary, employing field survey sampling plots on almost 50,000 hectares. Our findings revealed that regeneration browsing and soil disturbance were evenly high in these areas, while the cover of the regeneration layer was extremely low. Ungulate pressure was suspected as the cause of the lack of regeneration. Based on habitat and vegetation conditions, we divided our sample as favourable and unfavourable for regeneration. The cover of the regeneration categories was not significantly different between the two sets. The evidence of the direct indicators, including browsing and soil disturbance, coupled with the lack of regeneration, leads us to infer indirect signs of ungulate pressure. The absence of older and taller vegetation in the area also suggests long-standing ungulate pressure. Our investigation suggests that the high ungulate population can cause low abundance, even the lack of regeneration, not only locally but also at a regional scale. Full article