The Rise of the Anthroposphere since 50,000 Years: An Ecological Replacement of Megaherbivores by Humans in Terrestrial Ecosystems?

Bocherens, Hervé

doi:10.3389/fevo.2018.00003

Cited by 33 publications

(28 citation statements)

References 104 publications

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“…The effect of the absence of large predators may have been compensated by humans' over-exploitation on large herbivores (Darimont et al 2015), thereby substituting the role of large carnivores in the ecosystem -although often this effect has been, and still is, far beyond, leading to strong population reductions or losses of the herbivore species (Ripple et al 2015, Doughty et al 2016a, Malhi et al 2016. At the same time, humans may to some extent have replaced the ecological functioning of megaherbivores through agricultural practices (Bocherens 2018), albeit again the effect of humans has overcompensated these processes with detrimental effects (Ellis et al 2013, Ellis 2015.…”

Section: Discussionmentioning

confidence: 99%

Mechanistic insights into the role of large carnivores for ecosystem structure and functioning

et al. 2020

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Large carnivores can exert top–down effects in ecosystems, but the size of these effects are largely unknown. Empirical investigation on the importance of large carnivores for ecosystem structure and functioning presents a number of challenges due to the large spatio‐temporal scale and the complexity of such dynamics. Here, we applied a mechanistic global ecosystem model to investigate the influence of large‐carnivore removal from undisturbed ecosystems. First, we simulated large‐carnivore removal on the global scale to inspect the geographic pattern of top–down control and to disentangle the functional role of large carnivores in top–down control in different environmental contexts. Second, we conducted four small‐scale ecosystem simulation experiments to understand direct and indirect changes in food‐web structure under different environmental conditions. We found that the removal of top–down control exerted by large carnivores (> 21 kg) can trigger large trophic cascades, leading to an overall decrease in autotroph biomass globally. Furthermore, the loss of large carnivores resulted in an increase of mesopredators. The magnitude of these changes was positively related to primary productivity (NPP), in line with the ‘exploitation ecosystem hypothesis’. In addition, we found that seasonality in NPP dampened the magnitude of change following the removal of large carnivores. Our results reinforce the idea that large carnivores play a fundamental role in shaping ecosystems, and further declines and extinctions can trigger substantial ecosystem responses. Our findings also support previous studies suggesting that natural ecosystem dynamics have been severely modified and are still changing as a result of the widespread decline and extinction of large carnivores.

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Section: Discussionmentioning

confidence: 99%

Mechanistic insights into the role of large carnivores for ecosystem structure and functioning

et al. 2020

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“…Alternatively, one could use active anthropogenic management, in some cases (Owen‐Smith, 1989). Conservationists already apply various manual conservation interventions and these techniques (e.g., coppicing) may emulate some effects of extinct megafauna (Bocherens, 2018).…”

Section: Discussionmentioning

confidence: 99%

Reintroducing extirpated herbivores could partially reverse the late Quaternary decline of large and grazing species

Schowanek

Davis

Lundgren

et al. 2021

Global Ecol. Biogeogr.

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Aim Reinstating large, native herbivores is an essential component of ecological restoration efforts, as these taxa can be important drivers of ecological processes. However, many herbivore species have gone globally or regionally extinct during the last 50,000 years, leaving simplified herbivore assemblages and trophically downgraded ecosystems. Here, we discuss to what extent trophic rewilding can undo these changes by reinstating native herbivores. Location Global. Time period We report functional trait changes from the Late Pleistocene to the present, and estimated trait changes under future scenarios. Major taxa studied Wild, large (≥ 10 kg), terrestrial, mammalian herbivores. Methods We use a functional trait dataset containing all late Quaternary large herbivores ≥ 10 kg to look at changes in the body mass and diet composition of herbivore assemblages, a proxy for species’ ecological effects. First, we assess how these traits have changed from the Late Pleistocene to the present. Next, we quantify how the current body mass and diet composition would change if all extant, wild herbivores were restored to their native ranges (and if no functional replacements were used), exploring scenarios with different baselines. Results Defaunation has primarily removed large and grazing herbivores. Reinstating extant herbivores across their native ranges would reverse these changes, especially when reinstating them to their prehistoric distributions. It would partially restore herbivore body mass and diet composition to pre‐anthropogenic conditions. However, in the absence of complementary interventions (e.g., introducing functional replacements), many herbivore assemblages would remain down‐sized and browser dominated, relative to pre‐anthropogenic conditions. Main conclusions Many terrestrial herbivore assemblages—and hence ecosystems—would remain trophically downgraded, even after bringing back all extant, native herbivores. Therefore, complementary interventions would be required to achieve complete functional restoration. Nevertheless, our findings suggest that reintroducing the remaining native herbivores would diversify the herbivory and disturbances of herbivore assemblages.

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“…Another circumstance, seen as positive by conservationists, is when introduced animals replace lost native seed dispersers (Vizentin‐Bugoni et al , 2019). It has even been suggested that humans partly replaced the role of extinct megaherbivores in dispersing certain species (Bocherens, 2018).…”

Section: Hmd Effects On Vegetation Dynamicsmentioning

confidence: 99%

Human‐mediated dispersal as a driver of vegetation dynamics: A conceptual synthesis

Bullock

Pufal

2020

J Vegetation Science

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Question Human‐mediated dispersal (HMD) comprises human‐vectored dispersal (HVD; direct movement of organisms by people) and human‐altered dispersal (HAD; indirect change in dispersal patterns through human alteration of ecosystems). In the vegetation dynamics literature, human influence has primarily been studied in terms of perturbations to natural communities. Except for non‐native invasions, the role of HMD in vegetation dynamics has rarely been considered. Given the increasing human population and its pervasive impacts across the world, it is necessary to understand the different ways in which HMD drives changes in vegetation dynamics. Importantly how large are these influences and how do they disrupt natural processes? Method We reviewed studies examining aspects of HMD in relation to vegetation dynamics and used the broader literature to inform a conceptual synthesis of the impacts of HMD on vegetation dynamics. Results & Conclusions The propensity to be affected by HMD varies among species, and this is related to seed and plant traits. Together, these effects combine to determine whether HMD disrupts or enhances seed dispersal into a community. The ultimate consequences of changed arrival of seeds into a community are determined by the strength of the environmental and biotic filters, which govern the establishment and persistence of species. The effect of accidental HVD depends whether it follows the same rules as for natural dispersal; indeed humans might replace lost natural dispersers and thus enhance community resilience. Intentional HVD through sowing or planting will generally be highly disruptive especially as it often involves associated management. Traditionally, HAD has been considered to disrupt vegetation dynamics through, e.g., fragmentation or loss of natural dispersers. However, an HMD perspective can inform actions related to HAD that increase resilience, e.g., green infrastructure or vegetation management. Our framework encourages researchers to consider HMD holistically, to understand how the increasing human footprint might affect vegetation dynamics and resilience under future change.

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The Rise of the Anthroposphere since 50,000 Years: An Ecological Replacement of Megaherbivores by Humans in Terrestrial Ecosystems?

Cited by 33 publications

References 104 publications

Mechanistic insights into the role of large carnivores for ecosystem structure and functioning

Mechanistic insights into the role of large carnivores for ecosystem structure and functioning

Reintroducing extirpated herbivores could partially reverse the late Quaternary decline of large and grazing species

Human‐mediated dispersal as a driver of vegetation dynamics: A conceptual synthesis

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