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.

Plant dispersal syndromes are allocated based on diaspore morphology and used to predict the dominant mechanisms of dispersal. Many authors assume that only angiosperms with endozoochory, epizoochory or anemochory syndromes have a long‐distance dispersal (LDD) mechanism. Too much faith is often placed in classical syndromes to explain historical dispersal events and to predict future ones. What is usually recorded as the ‘endozoochory syndrome' is in reality a ‘frugivory syndrome' and this has often diverted attention from endozoochory by non‐frugivores (e.g. waterbirds and large herbivores) that disperse a broad range of angiosperms, for which they likely provide the maximum dispersal distances. Neither the endozoochory nor the epizoochory syndromes provide helpful predictions of which plants non‐frugivores disperse, or by which mechanism. We combined data from previous studies to show that only 4% of European plant species dispersed by ungulate endozoochory belong to the corresponding syndrome, compared to 36% for ungulate epizoochory and 8% for endozoochory by migratory ducks. In contrast, the proportions of these species that are assigned to an ‘unassisted syndrome' are 37, 31 and 28%, respectively. Since allocated syndromes do not adequately account for zoochory, empirical studies often fail to find the expected relationship between syndromes and LDD events such as those underlying the colonization of islands or latitudinal migration rates. We need full incorporation of existing zoochory data into dispersal databases, and more empirical research into the relationship between plant traits and the frequency and effectiveness of different dispersal mechanisms (paying attention to unexpected vectors). Acknowledging the broad role of non‐frugivores in facilitating LDD is crucial to improve predictions of the consequences of global change, such as how plant distributions respond to climate change, and how alien plants spread. Networks of dispersal interactions between these vertebrates and plants are a vital but understudied part of the Web of Life.

We here describe the multiple mechanisms by which ungulates distribute diaspores across landscapes. There are three primary and three secondary seed dispersal mechanisms by which ungulate dispersal agents contribute to the spread of plant diaspores, both with and without the intervention of other biotic and abiotic agents. These dispersal mechanisms may be combined in successive inter-dependent steps. Native, introduced and domestic ungulates co-occur in many ecosystems and frequently interact with numerous plant species, which facilitates long-distance dispersal of both native and exotic plants. However, ungulate taxonomic diversity conceals a much higher diversity in terms of the functional traits involved in ungulate-mediated dispersal (e.g., feeding regime, fur morphology). These traits may strongly affect emigration, transfer and immigration in the animal-mediated plant dispersal, and consequently; they may also impact overall seed dispersal effectiveness, both quantitatively and qualitatively. In this review, we compare internal mechanisms, where seeds must survive digestive treatments (regurgitation, endozoochory), with external mechanisms, where diaspores are carried on the outside of the vectors (epizoochory). We include both primary epizoochory (direct adhesion to fur essentially) and secondary epizoochory (diaspore-laden mud adhering to hooves or the body and, transfer through contact with a conspecific). We addressed the overlap/complementarity of ungulates for the plant species they disperse through a systematic literature review. When two ungulate species co-occur, there is always an overlap in the plant species dispersed by endozoochory or by fur-epizoochory. Further, when we consider the proportion of plant species dispersed both internally and externally by an ungulate, the overlap is higher for grazing than browsing ungulates. We identify two challenges for the field of dispersal ecology: the proportion of all diaspores produced that are carried over long distances by ungulates, and the relative importance of ungulates on the whole as the main dispersal agent for plants. Furthermore, the fact that numerous plants dispersed by fur-epizoochory do not feature any specific adaptations is intriguing. We discuss unsolved methodological challenges and stress research perspectives related to ungulate-mediated dispersal: for example, taking animal behavior and cognition into account and studying how ungulates contribute to the spread of invasive exotic plants and altitudinal plant dispersal.