Uncovering widespread Anthropocene dietary shifts in Chinese large mammalian herbivores.

The Anthropocene's human-dominated habitat expansion endangers global biodiversity. However, large mammalian herbivores experienced few extinctions during the 20th century, hinting at potentially overlooked ecological responses of a group sensitive to global change. Using dental microwear as a proxy, we studied large herbivore dietary niches over a century across mainland China before (1880s-1910s) and after (1970s-1990s) the human population explosion. We uncovered widespread and significant shifts (interspecific microwear differences increased and intraspecific microwear dispersion expanded) within dietary niches linked to geographical areas with rapid industrialization and population growth in eastern China. By contrast, in western China, where human population growth was slower, we found no indications of shifts in herbivore dietary niches. Further regression analysis links the intensity of microwear changes to human land-use expansion. These analyses highlight dietary adjustments of large herbivores as a likely key factor in their adaptation across a century of large-scale human-driven changes.

Rewilding by large ungulates contributes to organic carbon storage in soils.

The concept of rewilding, which focuses on managing ecosystem functions through self-regulation by restoring trophic interactions through introduced animal species with little human intervention, has gained increasing attention as a proactive and efficient approach to restoring ecosystems quickly and on a large scale. However, the science of rewilding has been criticized for being largely theory-based rather than evidence-based, with available data being geographically biased towards the Netherlands and Scandinavian countries, and a lack of objective data on rewilding effects on soil processes and C sequestration. In response to a call for data-driven experimental rewilding projects focused on national contexts, we collected unique data on the effects of large herbivore rewilding on soil properties from eight sites in the Czech Republic. These include sites with a wide range of edaphic characteristics that were grazed by Exmoor ponies, European bison, and back-bred Bos primigenius cattle (singly or in combination) for 2-6 years on areas ranging from ≈30 to ≈250 ha. Despite the relatively short duration of rewilding actions and considerable variability in the response rate of soil properties to grazing, our results indicate improved nutrient availability (evidenced by higher nitrification rate or higher soluble nitrogen concentration) and accelerated ecosystem metabolism (higher soil microbial biomass and dissolved carbon content). On longer-grazed pastures, rewilding contributed to soil carbon sequestration associated with increased water holding capacity and improved soil structure. However, other soil properties (reduced dissolved P concentration or total P content) showed signs of low P availability in the soils of the rewilding sites. Therefore, carcass retention should be considered where possible. Our data, although limited in number and geographic coverage, allow us to conclude that large ungulate rewilding has the potential to enhance soil carbon sequestration and related ecosystem services in rewilding areas. At the same time, we urge similar monitoring as an essential part of other rewilding projects, which will ultimately allow much more robust conclusions about the effects of this management on soils.

Understanding spatial patterns of poaching pressure using ranger logbook data to optimize future patrolling strategies.

Poaching is driving many species toward extinction, and as a result, lowering poaching pressure is a conservation priority. This requires understanding where poaching pressure is high and which factors determine these spatial patterns. However, the cryptic and illegal nature of poaching makes this difficult. Ranger patrol data, typically recorded in protected area logbooks, contain information on patrolling efforts and poaching detection and should thus provide opportunities for a better understanding of poaching pressure. However, these data are seldom analyzed and rarely used to inform adaptive management strategies. We developed a novel approach to making use of analog logbook records to map poaching pressure and to test environmental criminology and predator-prey relationship hypotheses explaining poaching patterns. We showcase this approach for Golestan National Park in Iran, where poaching has substantially depleted ungulate populations. We digitized data from >4800 ranger patrols from 2014 to 2016 and used an occupancy modeling framework to relate poaching to (1) accessibility, (2) law enforcement, and (3) prey availability factors. Based on predicted poaching pressure and patrolling intensity, we provide suggestions for future patrol allocation strategies. Our results revealed a low probability (12%) of poacher detection during patrols. Poaching distribution was best explained by prey availability, indicating that poachers target areas with high concentrations of ungulates. Poaching pressure was estimated to be high (>0.49) in 39% of our study area. To alleviate poaching pressure, we recommend ramping up patrolling intensity in 12% of the national park, which could be achievable by reducing excess patrols in about 20% of the park. However, our results suggest that for 27% of the park, it is necessary to improve patrolling quality to increase detection probability of poaching, for example, by closing temporal patrolling gaps or expanding informant networks. Our approach illustrates that analog ranger logbooks are an untapped resource for evidence-based and adaptive planning of protected area management. Using this wealth of data can open up new avenues to better understand poaching and its determinants, to expand effectiveness assessments to the past, and, more generally, to allow for strategic conservation planning in protected areas.

Effects of stand structure and ungulates on understory vegetation in managed and unmanaged forests.

Conventional conservation policies in Europe notably rely on the passive restoration of natural forest dynamics by setting aside forest areas to preserve forest biodiversity. However, since forest reserves cover only a small proportion of the territory, conservation policies also require complementary conservation efforts in managed forests in order to achieve the biodiversity targets set up in the Convention on Biological Diversity. Conservation measures also raise the question of large herbivore management in and around set-asides, particularly regarding their impact on understory vegetation. Although many studies have separately analyzed the effects of forest management, management abandonment, and ungulate pressure on forest biodiversity, their joint effects have rarely been studied in a correlative framework. We studied 212 plots located in 15 strict forest reserves paired with adjacent managed forests in European France. We applied structural equation models to test the effects of management abandonment, stand structure, and ungulate pressure on the abundance, species richness, and diversity of herbaceous vascular plants and terricolous bryophytes. We showed that stand structure indices and plot-level browsing pressure had direct and opposite effects on herbaceous vascular plant species diversity; these effects were linked with the light tolerance of the different species groups. Increasing canopy cover had an overall negative effect on herbaceous vascular plant abundance and species diversity. The effect was two to three times greater in magnitude than the positive effects of browsing pressure on herbaceous plants diversity. On the other hand, a high stand density index had a positive effect on the species richness and diversity of bryophytes, while browsing had no effect. Forest management abandonment had few direct effects on understory plant communities, and mainly indirectly affected herbaceous vascular plant and bryophyte abundance and species richness and diversity through changes in vertical stand structure. Our results show that conservation biologists should rely on foresters and hunters to lead the preservation of understory vegetation communities in managed forests since, respectively, they manipulate stand structure and regulate ungulate pressure. Their management actions should be adapted to the taxa at stake, since bryophytes and vascular plants respond differently to stand and ungulate factors.

Conservation overstretch and long-term decline of wildlife and tourism in the Central African savannas.

When in 2010 the world's governments pledged to increase protected area coverage to 17% of the world's land surface, several Central African countries had already set aside 25% of their northern savannas for conservation. To evaluate the effectiveness of this commitment, we analyzed the results of 68 multispecies surveys conducted in the seven main savanna national parks in Central Africa (1960-2017). We also assembled information on potential drivers of large herbivore population trends (rainfall and number of rangers) and on tourist numbers and revenues. In six out of the seven parks, wild large herbivore populations declined dramatically over time, livestock numbers increased severalfold, and tourism, the pillar under a once thriving local wildlife industry, collapsed. Zakouma National Park (Chad) stood out because its large herbivore populations increased, an increase that was positively correlated with rainfall and number of rangers (a proxy for management inputs). With increasing insecurity and declining revenues, governments find themselves confronted with too few resources to protect vast areas. To deal with this conversation overstretch, we propose to extend the repeatedly promoted solutions--scaled up funding, enhanced management--with a strategic retreat, focusing scarce resources on smaller areas to save wildlife in the Central African savannas.

Sobredimensionamiento de la Conservación y la Declinación a Largo Plazo de la Fauna y el Turismo en las Sabanas de África Central Resumen Cuando los gobiernos del mundo se comprometieron en 2010 a incrementar la cobertura de áreas protegidas al 17% de la superficie terrestre del planeta, varios países del centro de África ya habían dispuesto el 25% de sus sabanas ubicadas al norte de la región para la conservación. Para evaluar la efectividad de este compromiso, analizamos los resultados de 68 censos multiespecies realizados en los siete parques nacionales principales de la sabana en África Central (1960-2017). También ensamblamos información sobre los causantes principales de las tendencias poblacionales de los grandes herbívoros (lluvias, número de guardaparques) y sobre las cifras e ingresos del turismo. En seis de los siete parques, las poblaciones de los grandes herbívoros silvestres declinaron dramáticamente con el tiempo, el número de cabezas de ganado incrementó varias veces y el turismo, el pilar de una industria faunística próspera en su momento, colapsó. El Parque Nacional Zakouma en Chad resaltó debido a que las poblaciones de herbívoros grandes incrementaron en esta localidad, un incremento que estuvo relacionado positivamente con las lluvias y el número de guardabosques (un sustituto para las aportaciones de manejo). Con el incremento en la inseguridad y la declinación de los ingresos, los gobiernos se encuentran de frente con muy pocos recursos para proteger áreas extensas. Para afrontar este sobredimensionamiento de la conservación, proponemos ampliar las soluciones que se promueven repetidamente - incrementos al financiamiento, manejo mejorado - con un repliegue estratégico, el cual enfoque los recursos escasos en las áreas más pequeñas para rescatar a la fauna de las sabanas del centro de África.

Ungulates increase forest plant species richness to the benefit of non-forest specialists.

Large wild ungulates are a major biotic factor shaping plant communities. They influence species abundance and occurrence directly by herbivory and plant dispersal, or indirectly by modifying plant-plant interactions and through soil disturbance. In forest ecosystems, researchers' attention has been mainly focused on deer overabundance. Far less is known about the effects on understory plant dynamics and diversity of wild ungulates where their abundance is maintained at lower levels to mitigate impacts on tree regeneration. We used vegetation data collected over 10 years on 82 pairs of exclosure (excluding ungulates) and control plots located in a nation-wide forest monitoring network (Renecofor). We report the effects of ungulate exclusion on (i) plant species richness and ecological characteristics, (ii) and cover percentage of herbaceous and shrub layers. We also analyzed the response of these variables along gradients of ungulate abundance, based on hunting statistics, for wild boar (Sus scrofa), red deer (Cervus elaphus) and roe deer (Capreolus capreolus). Outside the exclosures, forest ungulates maintained higher species richness in the herbaceous layer (+15%), while the shrub layer was 17% less rich, and the plant communities became more light-demanding. Inside the exclosures, shrub cover increased, often to the benefit of bramble (Rubus fruticosus agg.). Ungulates tend to favour ruderal, hemerobic, epizoochorous and non-forest species. Among plots, the magnitude of vegetation changes was proportional to deer abundance. We conclude that ungulates, through the control of the shrub layer, indirectly increase herbaceous plant species richness by increasing light reaching the ground. However, this increase is detrimental to the peculiarity of forest plant communities and contributes to a landscape-level biotic homogenization. Even at population density levels considered to be harmless for overall plant species richness, ungulates remain a conservation issue for plant community composition.

Fire history influences large-herbivore behavior at circadian, seasonal, and successional scales.

Recurrent environmental changes often prompt animals to alter their behavior leading to predictable patterns across a range of temporal scales. The nested nature of circadian and seasonal behavior complicates tests for effects of rarer disturbance events like fire. Fire can dramatically alter plant community structure, with important knock-on effects at higher trophic levels, but the strength and timing of fire's effects on herbivores remain unclear. We combined prescribed fire treatments with fine-scale location data to quantify herbivore responses to fire across three temporal scales. Between 2001 and 2003, 26 stands of fir (Abies spp.) and Douglas-fir (Pseudotsuga menziesii) were thinned and burned; 27 similar stands were left untreated as experimental controls. Analyzing female elk (Cervus canadensis) locations across 21 yr (1996-2016), we found crepuscular, seasonal, and successional shifts in behavioral responses to fire. Elk displayed "commuting" behavior, avoiding burns during the day, but selecting them at night. Elk selection for burns was strongest in early summer and the relative probability of elk using burns peaked quickly (5 yr post burn) before gradually returning to pre-treatment levels (15 yr post burn). Our results demonstrate that fire history has complex, persistent effects on herbivore behavior, and suggest that herbivores benefit from heterogeneous landscapes containing a range of successional stages.

Determinants of blood water δ 18O variation in a population of experimental sheep: implications for paleoclimate reconstruction.

Mammalian body, blood and hard tissue oxygen isotope compositions (δ 18O values) reflect environmental water and food sources, climate, and physiological processes. For this reason, fossil and archaeological hard tissues, which originally formed in equilibrium with body chemistry, are a valuable record of past climate, landscape paleoecology, and animal physiology and behavior. However, the environmental and physiological determinants of blood oxygen isotope composition have not been determined experimentally from large herbivores. This class of fauna is abundant in Cenozoic terrestrial fossil assemblages, and the isotopic composition of large herbivore teeth has been central to a number of climate and ecological reconstructions. Furthermore, existing models predict blood water, or nearly equivalently body water, δ 18O values based on environmental water sources. These have been evaluated on gross timescales, but have not been employed to track seasonal variation. Here we report how water, food, and physiology determine blood water δ 18O values in experimental sheep (Ovis aries) subjected to controlled water switches. We find that blood water δ 18O values rapidly reach steady state with environmental drinking water and reflect transient events including weaning, seasons, and snowstorms. Behavioral and physiological variation within a single genetically homogenous population of herbivores results in significant inter-animal variation in blood water δ 18O values at single collection times (1 s.d. = 0.1-1.4 ‰, range = 3.5 ‰) and reveals a range of water flux rates (t1/2 = 2.2-2.9 days) within the population. We find that extant models can predict average observed sheep blood δ 18O values with striking fidelity, but predict a pattern of seasonal variation exactly opposite of that observed in our population for which water input variation was controlled and the effect of physiology was more directly observed. We introduce to these models an evaporative loss term that is a function of environmental temperatures. The inclusion of this function produces model predictions that mimic the observed seasonal fluctuations and match observations to within 1.0 ‰. These results increase the applicability of available physiological models for paleoseasonality reconstructions from stable isotope measurements in fossil or archaeological enamel, the composition of which is determined in equilibrium with blood values. However, significant blood δ 18O variation in this experimentally controlled population should promote caution when interpreting isotopic variation in the archaeological and paleontological record.

Combining familiarity and landscape features helps break down the barriers between movements and home ranges in a non-territorial large herbivore.

Recent advances in animal ecology have enabled identification of certain mechanisms that lead to the emergence of territories and home ranges from movements considered as unbounded. Among them, memory and familiarity have been identified as key parameters in cognitive maps driving animal navigation, but have been only recently used in empirical analyses of animal movements. At the same time, the influence of landscape features on movements of numerous species and on space division in territorial animals has been highlighted. Despite their potential as exocentric information in cognitive maps and as boundaries for home ranges, few studies have investigated their role in the design of home ranges of non-territorial species. Using step selection analyses, we assessed the relative contribution of habitat characteristics, familiarity preferences and linear landscape features in movement step selection of 60 GPS-collared Mediterranean mouflon Ovis gmelini musimon × Ovis sp. monitored in southern France. Then, we evaluated the influence of these movement-impeding landscape features on the design of home ranges by testing for a non-random distribution of these behavioural barriers within sections of space differentially used by mouflon. We reveal that familiarity and landscape features are key determinants of movements, relegating to a lower level certain habitat constraints (e.g. food/cover trade-off) that we had previously identified as important for this species. Mouflon generally avoid crossing both anthropogenic (i.e. roads, tracks and hiking trails) and natural landscape features (i.e. ridges, talwegs and forest edges) while moving in the opposite direction, preferentially toward familiar areas. These specific behaviours largely depend on the relative position of each movement step regarding distance to the landscape features or level of familiarity in the surroundings. We also revealed cascading consequences on the design of home ranges in which most landscape features were excluded from cores and relegated to the peripheral areas. These results provide crucial information on landscape connectivity in a context of marked habitat fragmentation. They also call for more research on the role of landscape features in the emergence of home ranges in non-territorial species using recent methodological developments bridging the gap between movements and space use patterns.

Refaunation and the reinstatement of the seed-dispersal function in Gorongosa National Park.

Large animals are important seed dispersers; however, they tend to be under a high extinction risk worldwide. There is compelling evidence that the global biodiversity crisis is leading to the deterioration of several ecosystem functions, but there is virtually no information on how large-scale refaunation efforts can reinstate seed dispersal. We evaluated the effectiveness of a 62-km2 wildlife sanctuary, which was established to recover populations of large mammals in Gorongosa National Park (Mozambique), in restoring seed dispersal. We collected animal scats during the dry season of 2014 (June-August) along 5 transects inside and 5 transects outside the sanctuary fence (50 km total) with the same type of plant community, identified animal and plant species in the transects, and quantified the number of seeds in each scat. Based on these data, we built bipartite networks and calculated network and species-level descriptor values, and we compared data collected inside and outside the sanctuary. There were more scats (268 vs. 207) and more scats containing seeds (132 vs. 94) inside than outside the sanctuary. The number of mammal dispersers was also higher inside (17) than outside the sanctuary (11). Similarly, more seeds (2413 vs. 2124) and plant species (33 vs. 26) were dispersed inside than outside the sanctuary. Overall, the seed-dispersal network was less specialized (0.38 vs. 0.44) and there was a greater overlap (0.16 vs. 0.07) inside than outside the sanctuary. Both networks were significantly modular and antinested. The high number and richness of seeds dispersed inside the sanctuary was explained mostly by a higher abundance of dispersers rather than by disperser identity. Our results suggest conservation efforts aimed at recovering populations of large mammals are helping to reestablish not only target mammal species but also their functional roles as seed dispersers in the ecosystem.

Large herbivores surf waves of green-up during spring.

The green wave hypothesis (GWH) states that migrating animals should track or 'surf' high-quality forage at the leading edge of spring green-up. To index such high-quality forage, recent work proposed the instantaneous rate of green-up (IRG), i.e. rate of change in the normalized difference vegetation index over time. Despite this important advancement, no study has tested the assumption that herbivores select habitat patches at peak IRG. We evaluated this assumption using step selection functions parametrized with movement data during the green-up period from two populations each of bighorn sheep, mule deer, elk, moose and bison, totalling 463 individuals monitored 1-3 years from 2004 to 2014. Accounting for variables that typically influence habitat selection for each species, we found seven of 10 populations selected patches exhibiting high IRG-supporting the GWH. Nonetheless, large herbivores selected for the leading edge, trailing edge and crest of the IRG wave, indicating that other mechanisms (e.g. ruminant physiology) or measurement error inherent with satellite data affect selection for IRG. Our evaluation indicates that IRG is a useful tool for linking herbivore movement with plant phenology, paving the way for significant advancements in understanding how animals track resource quality that varies both spatially and temporally.

Incorporating anthropogenic effects into trophic ecology: predator-prey interactions in a human-dominated landscape.

Apex predators perform important functions that regulate ecosystems worldwide. However, little is known about how ecosystem regulation by predators is influenced by human activities. In particular, how important are top-down effects of predators relative to direct and indirect human-mediated bottom-up and top-down processes? Combining data on species' occurrence from camera traps and hunting records, we aimed to quantify the relative effects of top-down and bottom-up processes in shaping predator and prey distributions in a human-dominated landscape in Transylvania, Romania. By global standards this system is diverse, including apex predators (brown bear and wolf), mesopredators (red fox) and large herbivores (roe and red deer). Humans and free-ranging dogs represent additional predators in the system. Using structural equation modelling, we found that apex predators suppress lower trophic levels, especially herbivores. However, direct and indirect top-down effects of humans affected the ecosystem more strongly, influencing species at all trophic levels. Our study highlights the need to explicitly embed humans and their influences within trophic cascade theory. This will greatly expand our understanding of species interactions in human-modified landscapes, which compose the majority of the Earth's terrestrial surface.

Time-scale dependency of host plant biomass- and trait-mediated indirect effects of deer herbivory on a swallowtail butterfly.

Despite recent attempts to quantify the relative strength of density- and trait-mediated indirect effects, rarely has the issue been properly addressed at the population level. Most research is based on short-term small-scale experiments in which behavioural and/or physiological responses prevail. Here, we estimated the time-scales during which density- and trait-mediated effects manifest, as well as the strength of these effects, using an interaction chain with three organisms (deer-plant-butterfly). A hierarchical Bayesian model was performed by using a long-term data set of deer density in the Boso Peninsula, central Japan (where local densities differ spatially and temporally) as well as densities of the swallowtail butterfly Byasa alcinous and its host plant Aristolochia kaempferi. The time-scale effect of deer on plant quantity and quality was estimated according to the degree of carry-over effects. The negative influence on leaf density showed a temporal saturation pattern over the long term, while the positive influence on leaf quality due to resprouting of leaves after deer browsing showed no clear temporal trend. The net indirect effect changed from positive to negative with time, with the negative density-mediated effect becoming prominent in the long term. Our novel approach is widely applicable in assessing the dynamic impacts of wildlife if the spatio-temporal variability of expansion and/or invasion history is known.

Upscaling the niche variation hypothesis from the intra- to the inter-specific level.

The "niche variation hypothesis" (NVH) predicts that populations with wider niches should display higher among-individual variability. This prediction originally stated at the intra-specific level may be extended to the inter-specific level: individuals of generalist species may differ to a greater extent than individuals of a specialist species. We tested the NVH at intra- and inter-specific levels based on a large diet database of three large herbivore feces collected in the field and analyzed using DNA metabarcoding. The three herbivores (roe deer Capreolus capreolus, chamois Rupicapra rupicapra and mouflon Ovis musimon) are highly contrasted in terms of sociality (solitary to highly gregarious) and diet. The NVH at the intraspecific level was tested by relating, for the same population, diet breadth and inter-individual variation across the four seasons. Compared to null models, our data supported the NVH both at the intra- and inter-specific levels. Inter-individual variation of the diet of solitary species was not larger than in social species, although social individuals feed together and could therefore have more similar diets. Hence, the NVH better explained diet breadth than other factors such as sociality. The expansion of the population niche of the three species was driven by resource availability, and achieved by an increase in inter-individual variation, and the level of inter-individual variability was larger in the generalist species (mouflon) than in the specialist one (roe deer). This mechanism at the base of the NVH appears at play at different levels of biological organization, from populations to communities.

Future changes in society and climate may strongly shape wild large-herbivore faunas across Europe.

Restoring wild communities of large herbivores is critical for the conservation of biodiverse ecosystems, but environmental changes in the twenty-first century could drastically affect the availability of habitats. We projected future habitat dynamics for 18 wild large herbivores in Europe and the relative future potential patterns of species richness and assemblage mean body weight considering four alternative scenarios of socioeconomic development in human society and greenhouse gas emissions (SSP1-RCP2.6, SSP2-RCP4.5, SSP3-RCP7.0, SSP5-RCP8.5). Under SSP1-RCP2.6, corresponding to a transition towards sustainable development, we found stable habitat suitability for most species and overall stable assemblage mean body weight compared to the present, with an average increase in species richness (in 2100: 3.03 ± 1.55 compared to today's 2.25 ± 1.31 species/area). The other scenarios are generally unfavourable for the conservation of wild large herbivores, although under the SSP5-RCP8.5 scenario there would be increase in species richness and assemblage mean body weight in some southern regions (e.g. + 62.86 kg mean body weight in Balkans/Greece). Our results suggest that a shift towards a sustainable socioeconomic development would overall provide the best prospect of our maintaining or even increasing the diversity of wild herbivore assemblages in Europe, thereby promoting trophic complexity and the potential to restore functioning and self-regulating ecosystems. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'.

Movements of European bison (Bison bonasus) beyond the Bialowieza Forest (NE Poland): range expansion or partial migrations?

The European bison is the largest terrestrial mammal in Europe. After extinction in the wild at the beginning of the twentieth century, it was re-introduced to Bialowieza Forest and other woodlands in Eastern Europe. In this paper, we analysed the movements of European bison beyond the continuous woodlands of the Bialowieza Forest (NE Poland) between 1964 and 2010. In total, 1,117 direct observations of bison were collected. The number of males moving out of the forest fluctuated during the study period, whilst the number of females steadily increased. The number of male observations outside of the forest per annum was dependent on the population size and snow depth, whilst the number of cows in mixed groups moving outside of the forest was correlated with the population size only. Males were observed mainly alone (50 % of observations) or in small groups of two to three individuals (25 %); however, distribution of group size differed from those observed in the population. There was a significant difference between the direction of movement of males and females out of the forest-males moved mainly west and southwest, whilst females moved to the north. This was also significantly different from the expected movement direction. The mean distance of bison observations from the forest border was 1.8 ± 0.13 km and did not differ significantly between sexes. After 1990, males were observed significantly farther away from the forest (2.2 km) than in the previous years (0.9 km). Most observations (94 % of bulls and 93 % of cows) were up to 5 km from the forest edge. The range of bison in the vicinity of the Bialowieza Forest was strictly seasonal. Most observations (78 % in males and 88 % in females) were recorded from November to April. Increasing utilisation of areas beyond the forest habitats may be driven by different factors but most probably it is related to range expansion and the bison's preference for open habitats. The strong seasonal pattern of bison movements indicate that the partial seasonal migrations were initiated in the Bialowieza population.

Large herbivores trigger spatiotemporal changes in forest plant diversity.

Large herbivores can exert top-down control on terrestrial plant communities, but the magnitude, direction, and scale dependency of their impacts remain equivocal, especially in temperate and boreal forests, where multiple disturbances often interact. Using a unique, long-term, and replicated landscape experiment, we assessed the influence of a high density of white-tailed deer (Odocoileus virginianus) on the spatiotemporal dynamics of diversity, composition, and successional trajectories of understorey plant assemblages in recently logged boreal forests. This experiment provided a rare opportunity to test whether deer herbivory represents a direct filter on plant communities or if it mainly acts to suppress dominant plants, which, in turn, release other plant species from strong negative plant-plant interactions. These two hypotheses make different predictions about changes in community composition and alpha and beta diversity in different vegetation layers and at different spatial scales. Our results showed that deer had strong effects on plant community composition and successional trajectories, but the resulting impacts on plant alpha and beta diversity patterns were markedly scale dependent in both time and space. Responses of tree and non-tree vegetation layers were strongly asymmetric. Deer acted both as a direct filter and as a suppressor of dominant plant species during early forest succession, but the magnitude of both processes was specific to tree and non-tree vegetation layers. Although our data supported the ungulate-driven homogenization hypothesis, compositional shifts and changes of alpha diversity were poor predictors of beta diversity loss. Our findings underscore the importance of long-term studies in revealing nonlinear temporal community trends, and they challenge managers to prioritize particular community properties and scales of interest, given contrasting trends of composition and alpha and beta diversity across spatial scales.

Forest floor plant diversity drives the use of mature spruce forests by European bison.

The distribution of large ungulates in space is in large extent driven by the availability of forage, which in temperate forests depends on light availability, and associated plant diversity and cover. We hypothesized that the increased number of GPS fixes of European bison (Bison bonasus L.) in usually avoided spruce forests was an effect of higher plant species richness and cover of the forest floor, which developed owing to increased light availability enhanced by spruce mortality. We carried out 80 forest floor plant surveys combined with tree measurement on plots chosen according to the number of GPS locations of GPS-collared European bison. The mean plant species richness per plot was higher on intensively visited plots (IV) than rarely visited (RV) plots (30 ± 5.75 (SD) versus. 26 ± 6.19 (SD)). The frequency of 34 plant species was higher on IV plots, and they were mainly herbaceous species (32 species), while a significant part of 13 species with higher frequency on RV plots was woody plants (5 species). The species richness of forbs was higher on IV plots, while other functional groups of plants did not differ. Tree stem density on the IV plots was lower than on the RV plots (17.94 ± 6.73 (SD) versus 22.9 ± 7.67 (SD)), and the mean value of Ellenberg's ecological indicator for light availability for all forest floor plant species was higher on IV plots. European bison visiting mature spruce forests was driven by higher forest floor plant cover and species richness, and high share and species richness of forbs. The two latter features may be translated into higher quality and diversity of forage. In spite of morphological characteristics suggesting that European bison is a species of mixed (mosaic) habitats, it seems to be well adapted to thrive in diverse forests.

Trophic Rewilding Advancement in Anthropogenically Impacted Landscapes (TRAAIL): A framework to link conventional conservation management and rewilding.

A variety of rewilding initiatives are being implemented across Europe, generally characterized by a more functionalist approach to nature management compared to the classic compositional approach. To address the increasing need for a framework to support implementation of rewilding in practical management, we present TRAAIL-Trophic Rewilding Advancement in Anthropogenically Impacted Landscapes. TRAAIL has been co-produced with managers and other stakeholders and provides managers with a framework to categorize rewilding initiatives and to link conventional nature management and rewilding by guiding steps towards a higher degree of self-regulation. Applying TRAAIL to data obtained in a Danish survey of rewilding-inspired initiatives we find that out of 44 initiatives there is no "Full rewilding" initiatives, 3 "Near-full rewilding" initiatives, 23 "Partial rewilding" initiatives, 2 "minimal rewilding" initiatives and 16 "Effort-intensive conservation management" initiatives. This study shows how TRAAIL can guide and inform trophic rewilding on a local and national scale.

Trophic rewilding as a climate change mitigation strategy?

The loss of megafauna at the terminal Pleistocene has been linked to a wide range of Earth-system-level changes, such as altered greenhouse gas budgets, fire regimes and biome-level vegetation changes. Given these influences and feedbacks, might part of the solution for mitigating anthropogenic climate change lie in the restoration of extant megafauna to ecosystems? Here, we explore the potential role of trophic rewilding on Earth's climate system. We first provide a novel synthesis of the various ways that megafauna interact with the major drivers of anthropogenic climate change, including greenhouse gas storage and emission, aerosols and albedo. We then explore the role of rewilding as a mitigation tool at two scales: (i) current and near-future opportunities for national or regional climate change mitigation portfolios, and (ii) more radical opportunities at the global scale. Finally, we identify major knowledge gaps that complicate the complete characterization of rewilding as a climate change mitigation strategy. Our perspective is urgent since we are losing the Earth's last remaining megafauna, and with it a potential option to address climate change.This article is part of the theme issue 'Trophic rewilding: consequences for ecosystems under global change'.