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Steven L. Chown - One of the best experts on this subject based on the ideXlab platform.
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The extent and impacts of ungulate translocations : South Africa in a global context
Biological Conservation, 2009Co-Authors: Dian Spear, Steven L. ChownAbstract:Despite the apparent risks of the introduction of non-indigenous Ungulates to biodiversity, relatively little is known globally about the pathways of introduction, propagule pressure and realized impacts of ungulate introductions. These issues were examined here by investigating ungulate introductions to South Africa within a global context. Across countries globally, introduced ungulate richness is not related to indigenous ungulate richness, and several countries are clear outliers. South Africa is second only to the USA in the number of ungulate species introduced to date. Zoos have traded more ungulate species and individuals to non-zoo recipients than to other zoos, highlighting the tensions that exist between in situ and ex situ conservation goals. Introductions to, and extralimital introductions within South Africa have increased through time, with propagule pressure being highest in areas with high human population density. The long distances Ungulates have been translocated raise concerns for genetic homogenization. Translocations of indigenous ungulate species extralimitally have significantly altered range sizes, typically to a greater extent than is expected from range shifts associated with global climate change. Although ungulate introductions and translocations are likely to have impacts on biodiversity, evidence for such impacts in South Africa, and elsewhere, is limited. Whilst arguments may be made for a precautionary approach to ungulate introductions, an evidence-based one is much more likely to deliver efficient and convincing conservation decision-making.
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Non-indigenous Ungulates as a threat to biodiversity
Journal of Zoology, 2009Co-Authors: Dian Spear, Steven L. ChownAbstract:Non-indigenous ungulate species pose a problem for conservation. They can be socially and economically valuable, but are also potentially harmful to biodiversity. Therefore, their introduction requires an explicit assessment of risk relative to benefit. To conduct such risk assessments, information regarding the impacts of non-indigenous Ungulates on biodiversity is required. Here, we review the available evidence for the biodiversity impacts of non-indigenous Ungulates. Hybridization, exploitation and apparent competition, vegetation impacts, predation, facilitation, trophic cascades and soil system functioning were assessed using a hierarchical set of criteria for the strength of the evidence. Strong evidence was lacking for risks posed by competition. Numerous reports exist of hybridization in captivity between ungulate species that normally do not co-occur, but conclusive evidence for introgression in the wild was restricted to one case. Strong evidence (using exclosure experiments) for the impacts of introduced Ungulates on vegetation structure and composition was found and in some cases introduced Ungulates caused the extirpation of plant species. Predation by Sus scrofa is a substantial threat to island faunas and systems, and impacts on soil system functioning elsewhere have also been found. Facilitation by Ungulates has been shown to be substantial in promoting invasive plant species. By contrast, little evidence exists for apparent competition. The largest impacts from introduced Ungulates are likely to be in cases where they perform novel functions in the new environment. However, to determine which types of impacts are likely to be most problematic, further evidence is required, ideally from well-designed field experiments.
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Taxonomic homogenization in Ungulates: patterns and mechanisms at local and global scales
Journal of Biogeography, 2008Co-Authors: Dian Spear, Steven L. ChownAbstract:Aim The aim of this paper is to examine taxonomic homogenization in Ungulates globally and at the local scale in South Africa. Specifically, we aim to examine the roles of distance, scale, time, extinctions vs. introductions, and extralimital vs. extraregional introductions in the homogenization of ungulate biotas, and to determine pathways of introduction of ungulate species globally and the proximate explanatory variables of ungulate introductions in South Africa. Location Forty-one countries globally and three spatial resolutions in South Africa. Methods Indigenous, extirpated and established introduced ungulate species data were obtained for countries globally, and at a quarter-degree grid-cell resolution in South Africa. Homogenization was calculated using Jaccard’s index of similarity (JI) for countries globally and for three spatial resolutions in South Africa. Zoo holdings and transfer data from the International Species Information System database were used to investigate the relationship between non-indigenous ungulate species introductions and the number of non-indigenous ungulate species in zoos. Relationships between JI and species richness, and between numbers of introductions and several environmental and social factors were examined using generalized linear models. Results Homogenization in Ungulates was 2% for countries globally and 8% at the coarsest resolution in South Africa. Homogenization increased with increasing resolution and with time, but it decreased with increasing percentage change in species richness. Globally, introductions contributed more to homogenization than did extinctions. Within South Africa, extralimital introductions contributed more to the homogenization of ungulate assemblages than did extraregional ones, and Ungulates were typically introduced to high-income areas with high human population and livestock densities. The same was not true in the past, when Ungulates were introduced to ungulate species-poor areas. The number of non-indigenous ungulate species established in a country is significantly related to the number of non-indigenous ungulate species in zoos in the country, possibly owing to sales of surplus animals from zoos. Main conclusions Ungulate faunas are homogenized at both the global scale and in South Africa, with extralimital introductions being of considerable significance regionally. In consequence, increasing attention will have to be given to the conservation consequences of ungulate translocations, both within particular geopolitical regions and across the globe.
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Taxonomic homogenization in Ungulates : patterns and mechanisms at local and global scales. Commentary
Journal of Biogeography, 2008Co-Authors: Michael L. Mckinney, Dian Spear, Steven L. ChownAbstract:Aim The aim of this paper is to examine taxonomic homogenization in Ungulates globally and at the local scale in South Africa. Specifically, we aim to examine the roles of distance, scale, time, extinctions vs. introductions, and extralimital vs. extraregional introductions in the homogenization of ungulate biotas, and to determine pathways of introduction of ungulate species globally and the proximate explanatory variables of ungulate introductions in South Africa. Location Forty-one countries globally and three spatial resolutions in South Africa. Methods Indigenous, extirpated and established introduced ungulate species data were obtained for countries globally, and at a quarter-degree grid-cell resolution in South Africa. Homogenization was calculated using Jaccard's index of similarity (JI) for countries globally and for three spatial resolutions in South Africa. Zoo holdings and transfer data from the International Species Information System database were used to investigate the relationship between non-indigenous ungulate species introductions and the number of non-indigenous ungulate species in zoos. Relationships between JI and species richness, and between numbers of introductions and several environmental and social factors were examined using generalized linear models. Results Homogenization in Ungulates was 2% for countries globally and 8% at the coarsest resolution in South Africa. Homogenization increased with increasing resolution and with time, but it decreased with increasing percentage change in species richness. Globally, introductions contributed more to homogenization than did extinctions. Within South Africa, extralimital introductions contributed more to the homogenization of ungulate assemblages than did extraregional ones, and Ungulates were typically introduced to high-income areas with high human population and livestock densities. The same was not true in the past, when Ungulates were introduced to ungulate species-poor areas. The number of non-indigenous ungulate species established in a country is significantly related to the number of non-indigenous ungulate species in zoos in the country, possibly owing to sales of surplus animals from zoos. Main conclusions Ungulate faunas are homogenized at both the global scale and in South Africa, with extralimital introductions being of considerable significance regionally. In consequence, increasing attention will have to be given to the conservation consequences of ungulate translocations, both within particular geopolitical regions and across the globe.
Anders Marell - One of the best experts on this subject based on the ideXlab platform.
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Ungulates increase forest plant species richness to the benefit of non forest specialists
Global Change Biology, 2018Co-Authors: Vincent Boulanger, Frédéric Archaux, Christophe Baltzinger, Jean-luc Dupouey, Vincent Badeau, Richard Chevalier, Emmanuel Corcket, Yann Dumas, Françoise Forgeard, Anders MarellAbstract: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 ten 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 analysed 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 a 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 forest-specialist species, and contributes to a landscape-level biotic homogenisation. Even at population density levels considered to be harmless for overall plant species richness, Ungulates remain a conservation issue for plant community composition.
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Ungulates increase forest plant species richness to the benefit of non-forest specialists
Global Change Biology, 2018Co-Authors: Vincent Boulanger, Frédéric Archaux, Christophe Baltzinger, Jean-luc Dupouey, Vincent Badeau, Richard Chevalier, Emmanuel Corcket, Yann Dumas, Françoise Forgeard, Anders MarellAbstract: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.
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The role of Ungulates in nowadays temperate forests. A response to Fløjgaard et al. (DOI:10.1111/gcb.14029)
Global Change Biology, 2018Co-Authors: V. Boulanger, Frédéric Archaux, Christophe Baltzinger, Vincent Badeau, Emmanuel Corcket, J.l. Dupouey, R. Chevalier, Y. Dumas, F. Forgeard, Anders MarellAbstract:In Boulanger et al. (2018), we investigated the effects of Ungulates on forest plant diversity. By suggesting a revisit of our conclusions regarding ecosystem dynamics since the late Pleistocene, Fløjgaard et al. (2018) came to the conclusion that moderate grazing in forest should be a conservation target. Since major points of our paper were mis‐ or over‐ interpreted, we put the record straight on our study system and on the scope of our conclusions. Finally, we advocate for an assessment of the conservation issues of Ungulates in forests not only regarding hypothetical and still debated states of past ecosystems but also considering timely challenges for forest ecosystems. In the study by Boulanger et al. (2018), we assessed the role of Ungulates' presence on short‐term understory plant dynamics, using a nationwide network composed of paired exclosure‐control plots. We demonstrated that Ungulates are key drivers of understory vegetation in managed forests since they alter the richness and abundance of the shrub layer, increase the richness of the herb layer, and favor open habitat plant species. Our results show that local scale mechanisms, here involving indirect facilitation, lead to global dynamics in forest‐ungulate systems. Our conclusions underline that an increase in species richness, often simplistically viewed as a positive change in ecosystems, can alter the community composition and thus require a more subtle interpretation regarding conservation issues. Fløjgaard et al. (2018) questioned them from a macroecological and evolutionary perspective with respect to general nature conservation issues. They argued that an "evolutionary informed baseline" would change our conclusions based on short‐term and experimental features. We need to specify three over‐ or misinterpretations. 1. Although Ungulates affect many groups of organisms, depending or not on the vegetation layer, our results were strictly limited to plant species. 2. Our investigations were not restricted to "ungulate grazing" (Fløjgaard et al., 2018), since the ungulate species generally co‐occurring at our study sites are not only obligate grazers (Gordon, 2003): roe deer is a browser, red deer an intermediate grazer-browser, and wild boar a frugivore-omnivore. Moreover, our interpretations included combined effects of different ecological processes in which sympatric forest Ungulates are involved, notably herbivory, zoochory, and physical engineering (Persson, Danell, & Bergström, 2000; Wilby, Shachak, & Boeken, 2001). 3. Fløjgaard et al. (2018) argued that our results were conditional on "mainly plantation" forests, in "highly managed landscapes." Our sampling design does not include intensively managed forest plantations isolated in an agricultural landscape matrix, but even‐aged stands mainly issued from natural regeneration, located in forest‐dominated landscapes, and mostly with a long history of forest continuity (Table 1). While Fløjgaard et al. (2018) consider that the landscape context may bias our results, recent independent (Jaroszewicz, Pirożnikow, & Sondej, 2013; Picard, Chevalier, Barrier, Boscardin, & Baltzinger, 2016), but also older studies (von Oheimb, Schmidt, Kriebitzsch, & Ellenberg, 2005; Schmidt, Sommer, Kriebitzsch, Ellenberg, & von Oheimb, 2004) on seed dispersal by wild Ungulates suggest that there is no overall effect of the landscape matrix on the traits of the plants dispersed by our three model Ungulates; these animals disperse preferentially plants typical of open habitats even in forest‐dominated landscape matrices. These exchanges of views revive the unsolved and current debate on the role of Ungulates as drivers of Anthropocene forest dynamics, as potential contributors to forest biodiversity in primary or secondary forests and more globally as dynamic actors of ecosystem functioning through direct, indirect, trophic, and nontrophic cascading effects. More specifically, the openness of Pleistocene forest stands and the primary habitat of light‐demanding species in ancient landscapes remain a matter of discussion (Mitchell, 2005). Consequently, from a conservation point of view, it seems unwise to recommend a uniform "moderate grazing" baseline without stronger scientific evidence and without considering current and future socioeconomic issues (Webster et al., in press).
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Overabundant Ungulates in French Sologne? Increasing red deer and wild boar pressure may not threaten woodland birds in mature forest stands
Basic and Applied Ecology, 2016Co-Authors: Marie Baltzinger, Anders Marell, Frédéric Archaux, Thomas Pérot, Franck Leterme, Marc DeconchatAbstract:Increasing ungulate populations have been considered to drive changes in woodland bird communities in temperate and boreal forests. Ungulates may negatively affect understory-dependent woodland birds either directly or indirectly. For instance Ungulates may prey on nests, or they may reduce the availability of nesting sites, foraging resources or cover for understory-dependent bird species. We conducted ungulate pressure, vegetation and bird surveys on 95 plots, in nineteen mature forest stands (9 fenced and 10 unfenced properties) located in the Sologne region (France). In such private forests, ungulate population densities are highly variable; we were therefore able to explore the effects of varying red deer (Cervus elaphus) browsing and wild boar (Sus scrofa) rooting intensity on bird communities. Bayesian Binomial mixture models indicated that ground-nesting birds were more abundant in forests with high observed wild boar rooting intensity. Generally, increasing deer browsing pressure did not have any negative effect on woodland birds in mature forest stands with a developed canopy, and did not result in lower shrub cover. Most previous studies documenting a negative effect of browsing on birds focused on young forest stands where overstory vegetation was scarce. Our results suggest that the impact of ungulate pressure on forest birds may decrease with forest stand age.
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Using basic plant traits to predict ungulate seed dispersal potential
Ecography, 2015Co-Authors: A. Albert, Anders Marell, M. Picard, Christophe BaltzingerAbstract:Habitat fragmentation contributes to the decline of plant species by decreasing gene flow among populations. Restoring connectivity among habitat patches is therefore a major issue for plant conservation. However, deciding where to focus restoration efforts requires identifying suitable dispersers for each target plant species. We collected data from the literature on wild and domesticated Ungulates, known to be effective seed dispersers, and on the plants they dispersed in Europe via epi- and/or endozoochory. We performed a systematic literature review to identify plant and animal traits relevant for seed dispersal. We first modeled the relationships between epi- or endozoochory and a priori selected plant traits (diaspore releasing height, length, shape and morphology, and habitat openness). The differences we underlined between the two dispersal mechanisms justified splitting our analyses accordingly. Then, for each dispersal mechanism, we asked whether basic plant traits could be used to predict specific traits of Ungulates as endozoochorous or epizoochorous seed dispersers. We modeled the relationships between a priori selected ungulate traits for epizoochory (habitat openness, shoulder height, hair curliness, and hair length) and for endozoochory (habitat openness, body mass, feeding type and digestive system) and plant traits. Plant habitat openness and diaspore morphology were the predictors that most often explained differences among Ungulates for epizoochory, whereas plant habitat openness and diaspore releasing height most often explained differences for endozoochory. Our trait-based predictive models can help improve our ability to propose more precise management decisions for the conservation of plant populations worldwide by taking into account ungulate dispersers.
Dian Spear - One of the best experts on this subject based on the ideXlab platform.
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The extent and impacts of ungulate translocations : South Africa in a global context
Biological Conservation, 2009Co-Authors: Dian Spear, Steven L. ChownAbstract:Despite the apparent risks of the introduction of non-indigenous Ungulates to biodiversity, relatively little is known globally about the pathways of introduction, propagule pressure and realized impacts of ungulate introductions. These issues were examined here by investigating ungulate introductions to South Africa within a global context. Across countries globally, introduced ungulate richness is not related to indigenous ungulate richness, and several countries are clear outliers. South Africa is second only to the USA in the number of ungulate species introduced to date. Zoos have traded more ungulate species and individuals to non-zoo recipients than to other zoos, highlighting the tensions that exist between in situ and ex situ conservation goals. Introductions to, and extralimital introductions within South Africa have increased through time, with propagule pressure being highest in areas with high human population density. The long distances Ungulates have been translocated raise concerns for genetic homogenization. Translocations of indigenous ungulate species extralimitally have significantly altered range sizes, typically to a greater extent than is expected from range shifts associated with global climate change. Although ungulate introductions and translocations are likely to have impacts on biodiversity, evidence for such impacts in South Africa, and elsewhere, is limited. Whilst arguments may be made for a precautionary approach to ungulate introductions, an evidence-based one is much more likely to deliver efficient and convincing conservation decision-making.
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Non-indigenous Ungulates as a threat to biodiversity
Journal of Zoology, 2009Co-Authors: Dian Spear, Steven L. ChownAbstract:Non-indigenous ungulate species pose a problem for conservation. They can be socially and economically valuable, but are also potentially harmful to biodiversity. Therefore, their introduction requires an explicit assessment of risk relative to benefit. To conduct such risk assessments, information regarding the impacts of non-indigenous Ungulates on biodiversity is required. Here, we review the available evidence for the biodiversity impacts of non-indigenous Ungulates. Hybridization, exploitation and apparent competition, vegetation impacts, predation, facilitation, trophic cascades and soil system functioning were assessed using a hierarchical set of criteria for the strength of the evidence. Strong evidence was lacking for risks posed by competition. Numerous reports exist of hybridization in captivity between ungulate species that normally do not co-occur, but conclusive evidence for introgression in the wild was restricted to one case. Strong evidence (using exclosure experiments) for the impacts of introduced Ungulates on vegetation structure and composition was found and in some cases introduced Ungulates caused the extirpation of plant species. Predation by Sus scrofa is a substantial threat to island faunas and systems, and impacts on soil system functioning elsewhere have also been found. Facilitation by Ungulates has been shown to be substantial in promoting invasive plant species. By contrast, little evidence exists for apparent competition. The largest impacts from introduced Ungulates are likely to be in cases where they perform novel functions in the new environment. However, to determine which types of impacts are likely to be most problematic, further evidence is required, ideally from well-designed field experiments.
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Taxonomic homogenization in Ungulates: patterns and mechanisms at local and global scales
Journal of Biogeography, 2008Co-Authors: Dian Spear, Steven L. ChownAbstract:Aim The aim of this paper is to examine taxonomic homogenization in Ungulates globally and at the local scale in South Africa. Specifically, we aim to examine the roles of distance, scale, time, extinctions vs. introductions, and extralimital vs. extraregional introductions in the homogenization of ungulate biotas, and to determine pathways of introduction of ungulate species globally and the proximate explanatory variables of ungulate introductions in South Africa. Location Forty-one countries globally and three spatial resolutions in South Africa. Methods Indigenous, extirpated and established introduced ungulate species data were obtained for countries globally, and at a quarter-degree grid-cell resolution in South Africa. Homogenization was calculated using Jaccard’s index of similarity (JI) for countries globally and for three spatial resolutions in South Africa. Zoo holdings and transfer data from the International Species Information System database were used to investigate the relationship between non-indigenous ungulate species introductions and the number of non-indigenous ungulate species in zoos. Relationships between JI and species richness, and between numbers of introductions and several environmental and social factors were examined using generalized linear models. Results Homogenization in Ungulates was 2% for countries globally and 8% at the coarsest resolution in South Africa. Homogenization increased with increasing resolution and with time, but it decreased with increasing percentage change in species richness. Globally, introductions contributed more to homogenization than did extinctions. Within South Africa, extralimital introductions contributed more to the homogenization of ungulate assemblages than did extraregional ones, and Ungulates were typically introduced to high-income areas with high human population and livestock densities. The same was not true in the past, when Ungulates were introduced to ungulate species-poor areas. The number of non-indigenous ungulate species established in a country is significantly related to the number of non-indigenous ungulate species in zoos in the country, possibly owing to sales of surplus animals from zoos. Main conclusions Ungulate faunas are homogenized at both the global scale and in South Africa, with extralimital introductions being of considerable significance regionally. In consequence, increasing attention will have to be given to the conservation consequences of ungulate translocations, both within particular geopolitical regions and across the globe.
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Taxonomic homogenization in Ungulates : patterns and mechanisms at local and global scales. Commentary
Journal of Biogeography, 2008Co-Authors: Michael L. Mckinney, Dian Spear, Steven L. ChownAbstract:Aim The aim of this paper is to examine taxonomic homogenization in Ungulates globally and at the local scale in South Africa. Specifically, we aim to examine the roles of distance, scale, time, extinctions vs. introductions, and extralimital vs. extraregional introductions in the homogenization of ungulate biotas, and to determine pathways of introduction of ungulate species globally and the proximate explanatory variables of ungulate introductions in South Africa. Location Forty-one countries globally and three spatial resolutions in South Africa. Methods Indigenous, extirpated and established introduced ungulate species data were obtained for countries globally, and at a quarter-degree grid-cell resolution in South Africa. Homogenization was calculated using Jaccard's index of similarity (JI) for countries globally and for three spatial resolutions in South Africa. Zoo holdings and transfer data from the International Species Information System database were used to investigate the relationship between non-indigenous ungulate species introductions and the number of non-indigenous ungulate species in zoos. Relationships between JI and species richness, and between numbers of introductions and several environmental and social factors were examined using generalized linear models. Results Homogenization in Ungulates was 2% for countries globally and 8% at the coarsest resolution in South Africa. Homogenization increased with increasing resolution and with time, but it decreased with increasing percentage change in species richness. Globally, introductions contributed more to homogenization than did extinctions. Within South Africa, extralimital introductions contributed more to the homogenization of ungulate assemblages than did extraregional ones, and Ungulates were typically introduced to high-income areas with high human population and livestock densities. The same was not true in the past, when Ungulates were introduced to ungulate species-poor areas. The number of non-indigenous ungulate species established in a country is significantly related to the number of non-indigenous ungulate species in zoos in the country, possibly owing to sales of surplus animals from zoos. Main conclusions Ungulate faunas are homogenized at both the global scale and in South Africa, with extralimital introductions being of considerable significance regionally. In consequence, increasing attention will have to be given to the conservation consequences of ungulate translocations, both within particular geopolitical regions and across the globe.
Isabel Barja - One of the best experts on this subject based on the ideXlab platform.
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does ungulate disturbance mediate behavioural and physiological stress responses in algerian mice mus spretus a wild exclosure experiment
Hystrix-italian Journal of Mammalogy, 2017Co-Authors: Alvaro Navarrocastilla, Mario Díaz, Isabel BarjaAbstract:Ungulate densities increased recently in Mediterranean oak ecosystem where acorn-dispersing small rodents, like the Algerian mouse ( Mus spretus ), are keystone species. Recent work showed important effects of Ungulates on the environment (vegetation and soil characteristics) influencing small mammal behaviour and population dynamics, but little is known on the physiological stress responses of small mammals to Ungulates. We studied wild ungulate effects on habitat characteristics and whether ungulate pressure influenced both behavioural and physiological stress responses in wild populations of Algerian mice. We manipulated Ungulates' presence by large exclosures in Holm oak Quercus ilex open woodland with paired controls, where live trapping of Algerian mice was combined with a detailed evaluation of relevant habitat features for this rodent species such as vegetation height, cover and soil compaction. Further we analysed faecal corticosterone metabolites (FCM) in captured Algerian mice to test whether ungulate presence led to increased glucocorticoids. Fresh faecal samples from 92 different individuals captured with Sherman live traps were collected and analyzed by an enzyme immunoassay. Mouse abundance was higher inside ungulate exclosures due to positive exclosure effects on understory vegetation cover and soil compaction. Mice selected smaller trees with more area covered by resprouts, and this selection was stronger outside than inside exclosures. FCM levels were higher in females than in males. FCM levels were positively correlated with soil compaction and inversely with tree canopy size; however, individuals showed higher FCM levels inside than outside exclosures probably due to the higher local mouse abundance inside exclosures. Mouse behaviour varied in relation to direct effects of wild Ungulates on key habitat traits whereas physiological stress responses seemed to be mediated by the increased intraspecific competition, an indirect effect of wild Ungulates.
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Does ungulate disturbance mediate behavioural and physiological stress responses in Algerian mice ( Mus spretus )? A wild exclosure experiment
Hystrix-italian Journal of Mammalogy, 2017Co-Authors: Álvaro Navarro-castilla, Mario Díaz, Isabel BarjaAbstract:Ungulate densities increased recently in Mediterranean oak ecosystem where acorn-dispersing small rodents, like the Algerian mouse ( Mus spretus ), are keystone species. Recent work showed important effects of Ungulates on the environment (vegetation and soil characteristics) influencing small mammal behaviour and population dynamics, but little is known on the physiological stress responses of small mammals to Ungulates. We studied wild ungulate effects on habitat characteristics and whether ungulate pressure influenced both behavioural and physiological stress responses in wild populations of Algerian mice. We manipulated Ungulates' presence by large exclosures in Holm oak Quercus ilex open woodland with paired controls, where live trapping of Algerian mice was combined with a detailed evaluation of relevant habitat features for this rodent species such as vegetation height, cover and soil compaction. Further we analysed faecal corticosterone metabolites (FCM) in captured Algerian mice to test whether ungulate presence led to increased glucocorticoids. Fresh faecal samples from 92 different individuals captured with Sherman live traps were collected and analyzed by an enzyme immunoassay. Mouse abundance was higher inside ungulate exclosures due to positive exclosure effects on understory vegetation cover and soil compaction. Mice selected smaller trees with more area covered by resprouts, and this selection was stronger outside than inside exclosures. FCM levels were higher in females than in males. FCM levels were positively correlated with soil compaction and inversely with tree canopy size; however, individuals showed higher FCM levels inside than outside exclosures probably due to the higher local mouse abundance inside exclosures. Mouse behaviour varied in relation to direct effects of wild Ungulates on key habitat traits whereas physiological stress responses seemed to be mediated by the increased intraspecific competition, an indirect effect of wild Ungulates.
Christophe Baltzinger - One of the best experts on this subject based on the ideXlab platform.
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Ungulates as dispersal vectors of non-native plants.
Plant invasions: the role of biotic interactions, 2020Co-Authors: Christophe Baltzinger, Ushma Shukla, Lindelwa S. Msweli, Colleen T. DownsAbstract:Abstract Ungulates are present worldwide with 257 recorded species, including livestock. They cover different functional gradients, be it feeding regime, digestive strategy, body size, body mass, fur characteristics or sociality. All these specificities may intervene at different stages of animal-mediated plant dispersal. Ungulates move diaspores from both native and non-native plants, through endo- and epizoochory. Initially introduced by humans, non-native plants bearing specific traits can be carried over long distances and to new environments by Ungulates. These vectors can further free local resources necessary for the germination and the subsequent growth of the released diaspores. We first looked at trait-based plant community changes at different timescales in the presence of different native Ungulates. We then reviewed the literature on endozoochory, regurgitation and fur-epizoochory assisted by Ungulates, focusing on the dispersal of non-native plants. We made an overall assessment of ungulate-mediated non-native plant dispersal by biogeographical zone and dispersal mode, and then provided additional information on plant growth form and taxonomy, vectors and associated modes of dispersal. Results are presented for four main ungulate families: Cervidae, Bovidae, Suidae and Equidae. For each family, we highlight our findings either by ungulate if sufficiently represented (e.g. Odocoileus virginianus, Bison bison, Bos taurus) or by group of species. According to their feeding regime, grazers dispersed solely forbs and graminoids whereas omnivores also dispersed plants from other growth forms (i.e. cactus, vine, shrub and tree). Numerous non-native plants are dispersed by Ungulates around the world, but this is probably the visible part of the iceberg, as only 32 Ungulates (i.e. 12%) have been studied as vectors so far, suggesting their overall contribution is certainly underrated.
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Plants on the Move: Hitch-Hiking With Ungulates Distributes Diaspores Across Landscapes
Frontiers in Ecology and Evolution, 2019Co-Authors: Christophe Baltzinger, Sorour Karimi, Ushma ShuklaAbstract: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.
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Ungulates increase forest plant species richness to the benefit of non-forest specialists
Global Change Biology, 2018Co-Authors: Vincent Boulanger, Frédéric Archaux, Christophe Baltzinger, Jean-luc Dupouey, Vincent Badeau, Richard Chevalier, Emmanuel Corcket, Yann Dumas, Françoise Forgeard, Anders MarellAbstract: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.
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Ungulates increase forest plant species richness to the benefit of non forest specialists
Global Change Biology, 2018Co-Authors: Vincent Boulanger, Frédéric Archaux, Christophe Baltzinger, Jean-luc Dupouey, Vincent Badeau, Richard Chevalier, Emmanuel Corcket, Yann Dumas, Françoise Forgeard, Anders MarellAbstract: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 ten 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 analysed 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 a 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 forest-specialist species, and contributes to a landscape-level biotic homogenisation. Even at population density levels considered to be harmless for overall plant species richness, Ungulates remain a conservation issue for plant community composition.
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The role of Ungulates in nowadays temperate forests. A response to Fløjgaard et al. (DOI:10.1111/gcb.14029)
Global Change Biology, 2018Co-Authors: V. Boulanger, Frédéric Archaux, Christophe Baltzinger, Vincent Badeau, Emmanuel Corcket, J.l. Dupouey, R. Chevalier, Y. Dumas, F. Forgeard, Anders MarellAbstract:In Boulanger et al. (2018), we investigated the effects of Ungulates on forest plant diversity. By suggesting a revisit of our conclusions regarding ecosystem dynamics since the late Pleistocene, Fløjgaard et al. (2018) came to the conclusion that moderate grazing in forest should be a conservation target. Since major points of our paper were mis‐ or over‐ interpreted, we put the record straight on our study system and on the scope of our conclusions. Finally, we advocate for an assessment of the conservation issues of Ungulates in forests not only regarding hypothetical and still debated states of past ecosystems but also considering timely challenges for forest ecosystems. In the study by Boulanger et al. (2018), we assessed the role of Ungulates' presence on short‐term understory plant dynamics, using a nationwide network composed of paired exclosure‐control plots. We demonstrated that Ungulates are key drivers of understory vegetation in managed forests since they alter the richness and abundance of the shrub layer, increase the richness of the herb layer, and favor open habitat plant species. Our results show that local scale mechanisms, here involving indirect facilitation, lead to global dynamics in forest‐ungulate systems. Our conclusions underline that an increase in species richness, often simplistically viewed as a positive change in ecosystems, can alter the community composition and thus require a more subtle interpretation regarding conservation issues. Fløjgaard et al. (2018) questioned them from a macroecological and evolutionary perspective with respect to general nature conservation issues. They argued that an "evolutionary informed baseline" would change our conclusions based on short‐term and experimental features. We need to specify three over‐ or misinterpretations. 1. Although Ungulates affect many groups of organisms, depending or not on the vegetation layer, our results were strictly limited to plant species. 2. Our investigations were not restricted to "ungulate grazing" (Fløjgaard et al., 2018), since the ungulate species generally co‐occurring at our study sites are not only obligate grazers (Gordon, 2003): roe deer is a browser, red deer an intermediate grazer-browser, and wild boar a frugivore-omnivore. Moreover, our interpretations included combined effects of different ecological processes in which sympatric forest Ungulates are involved, notably herbivory, zoochory, and physical engineering (Persson, Danell, & Bergström, 2000; Wilby, Shachak, & Boeken, 2001). 3. Fløjgaard et al. (2018) argued that our results were conditional on "mainly plantation" forests, in "highly managed landscapes." Our sampling design does not include intensively managed forest plantations isolated in an agricultural landscape matrix, but even‐aged stands mainly issued from natural regeneration, located in forest‐dominated landscapes, and mostly with a long history of forest continuity (Table 1). While Fløjgaard et al. (2018) consider that the landscape context may bias our results, recent independent (Jaroszewicz, Pirożnikow, & Sondej, 2013; Picard, Chevalier, Barrier, Boscardin, & Baltzinger, 2016), but also older studies (von Oheimb, Schmidt, Kriebitzsch, & Ellenberg, 2005; Schmidt, Sommer, Kriebitzsch, Ellenberg, & von Oheimb, 2004) on seed dispersal by wild Ungulates suggest that there is no overall effect of the landscape matrix on the traits of the plants dispersed by our three model Ungulates; these animals disperse preferentially plants typical of open habitats even in forest‐dominated landscape matrices. These exchanges of views revive the unsolved and current debate on the role of Ungulates as drivers of Anthropocene forest dynamics, as potential contributors to forest biodiversity in primary or secondary forests and more globally as dynamic actors of ecosystem functioning through direct, indirect, trophic, and nontrophic cascading effects. More specifically, the openness of Pleistocene forest stands and the primary habitat of light‐demanding species in ancient landscapes remain a matter of discussion (Mitchell, 2005). Consequently, from a conservation point of view, it seems unwise to recommend a uniform "moderate grazing" baseline without stronger scientific evidence and without considering current and future socioeconomic issues (Webster et al., in press).
