The blame game: Using eDNA to identify species-specific tree browsing by red deer (Cervus elaphus) and roe deer (Capreolus capreolus) in a temperate forest

Increasing deer populations in many temperate regions can affect tree regeneration, resulting in severe long-term impacts on forest structure, composition and diversity. Of the most common deer species in Europe — red deer (Cervus elaphus) and roe deer (Capreolus capreolus) — roe deer are generally thought to have the highest impact on palatable tree species owing to their feeding niche. Although browsing and its potential consequences are well researched, less is known about the influence of specific deer species within multi-species ungulate communities on specific tree species. Environmental DNA (eDNA) allows the determination of species-specific browsing habits without the need for direct observations, facilitating effective targeting of management interventions. In this study eDNA was used to elucidate the browsing patterns of these two deer species in the temperate forest of the Bavarian Forest National Park, Germany and analysed the influence of tree species, management type and height of browsing, on the success rate of the method. Samples were collected from twigs used in feeding trials from enclosures containing red deer or roe deer and from naturally browsed twigs in three different management types within the national park. eDNA was successfully amplified from 98% of the feeding trial samples, and the correct deer species was identified for all samples. eDNA was successfully amplified from approximately 50% of the naturally browsed samples. Neither management type, tree species, nor height of browsing had any significant influence on the success of the method. For silver fir and rowan, no significant difference was found in the proportion of browsing events attributable to roe or red deer, when the two deer species occur at similar densities. These results indicate that roe deer might not always be disproportionately responsible for the browsing of palatable tree species as expected from its food niche. Roe deer were significantly more responsible for browsing at lower heights than red deer. Although not statistically significant, roe deer were more responsible for browsing in intact forest compared to bark-beetle-impact forest, with the opposite relationship for red deer

Data from: Does wolf presence reduce moose browsing intensity in young forest plantations?

Large carnivores can be a key factor in shaping their ungulate prey’s behavior, which may affect lower trophic levels. While most studies on trade-offs between food acquisition and risk avoidance by ungulate prey species have been conducted in areas with limited human impact, carnivores are now increasingly returning to highly anthropogenic landscapes. Many of these landscapes are dominated by forestry, and ungulate-forestry conflicts are an increasing issue. The aim of this study was to test if the indirect effects of a re-colonizing large predator, the wolf (Canis lupus), results in a change in browsing intensity by moose (Alces alces) in young forest plantations in a boreal forest in Sweden. We selected 24 different forest plantations, with 12 located in low-wolf and 12 in high-wolf utilization areas. In each plantation, we measured browsing intensity, tree height, tree density, distance to the closest forest edge and we counted the number of moose pellet groups. In contrast to our predictions, wolf utilization was not the main driver of moose browsing patterns. Instead, moose browsing intensity declined with tree density and height. Separate analyses on the main tree species showed that wolf utilization had an influence, but browsing intensity was in fact higher in the high-wolf utilization areas for three out of five tree species. This pattern seemed to be driven by a strong confounding relationship between wolf utilization, tree density and height, which were both lower in the high-wolf utilization areas. We argue that this confounding effect is due to wolves being pushed towards the less productive parts of the landscape away from human activity centers. Therefore, we concluded that in order to better understand carnivore driven risk- mediated effects on herbivore behavior in anthropogenic landscapes we need to better understand the complexity of human-carnivore-prey-ecosystem interactions

The blame game: Using eDNA to identify species-specific tree browsing by red deer (Cervus elaphus) and roe deer (Capreolus capreolus) in a temperate forest

Increasing deer populations in many temperate regions can affect tree regeneration, resulting in severe long-term impacts on forest structure, composition and diversity. Of the most common deer species in Europe — red deer (Cervus elaphus) and roe deer (Capreolus capreolus) — roe deer are generally thought to have the highest impact on palatable tree species owing to their feeding niche. Although browsing and its potential consequences are well researched, less is known about the influence of specific deer species within multi-species ungulate communities on specific tree species. Environmental DNA (eDNA) allows the determination of species-specific browsing habits without the need for direct observations, facilitating effective targeting of management interventions. In this study eDNA was used to elucidate the browsing patterns of these two deer species in the temperate forest of the Bavarian Forest National Park, Germany and analysed the influence of tree species, management type and height of browsing, on the success rate of the method. Samples were collected from twigs used in feeding trials from enclosures containing red deer or roe deer and from naturally browsed twigs in three different management types within the national park. eDNA was successfully amplified from 98% of the feeding trial samples, and the correct deer species was identified for all samples. eDNA was successfully amplified from approximately 50% of the naturally browsed samples. Neither management type, tree species, nor height of browsing had any significant influence on the success of the method. For silver fir and rowan, no significant difference was found in the proportion of browsing events attributable to roe or red deer, when the two deer species occur at similar densities. These results indicate that roe deer might not always be disproportionately responsible for the browsing of palatable tree species as expected from its food niche. Roe deer were significantly more responsible for browsing at lower heights than red deer. Although not statistically significant, roe deer were more responsible for browsing in intact forest compared to bark-beetle-impact forest, with the opposite relationship for red deer

Ungulate management in European national parks

1. Primary objectives of national parks usually include both, the protection of natural processes and species conservation. When these objectives conflict, as occurs because of the cascading effects of large mammals (i.e., ungulates and large carnivores) on lower trophic levels, park managers have to decide upon the appropriate management while considering various local circumstances. 2. To analyse if ungulate management strategies are in accordance with the objectives defined for protected areas, we assessed the current status of ungulate management across European national parks using the naturalness concept and identified the variables that influence the management. 3. We collected data on ungulate management from 209 European national parks in 29 countries by means of a large-scale questionnaire survey. Ungulate management in the parks was compared by creating two naturalness scores. The first score reflects ungulate and large carnivore species compositions, and the second evaluates human intervention on ungulate populations. We then tested whether the two naturalness score categories are influenced by the management objectives, park size, years since establishment, percentage of government-owned land, and human impact on the environment (human influence index) using two generalized additive mixed models. 4. In 67.9% of the national parks, wildlife is regulated by culling (40.2%) or hunting (10.5%) or both (17.2%). Artificial feeding occurred in 81.3% of the national parks and only 28.5% of the national parks had a nonintervention zone covering at least 75% of the area. Furthermore, ungulate management differed greatly among the different countries, likely because of differences in hunting traditions and cultural and political backgrounds. Ungulate management was also influenced by park size, human impact on the landscape, and national park objectives, but after removing these variables from the full model the reduced models only showed a small change in the deviance explained. In areas with higher anthropogenic pressure, wildlife diversity tended to be lower and a higher number of domesticated species tended to be present. Human intervention (culling and artificial feeding) was lower in smaller national parks and when park objectives followed those set by the International Union for the Conservation of Nature (IUCN). 5. Our study shows that many European national parks do not fulfil the aims of protected area management as set by IUCN guidelines. In contrast to the USA and Canada, Europe currently has no common ungulate management policy within national parks. This lack of a common policy together with differences in species composition, hunting traditions, and cultural or political context has led to differences in ungulate management among European countries. To fulfil the aims and objectives of national parks and to develop ungulate management strategies further, we highlight the importance of creating a more integrated European ungulate management policy to meet the aims of national parks