Assessing the role of megafauna in tropical forest ecosystems and biogeochemical cycles – the potential of vegetation models

Berzaghi, Fabio; Verbeeck, Hans; Nielsen, Martin Reinhardt; Doughty, Christopher E.; Bretagnolle, François; Marchetti, Marco; Scarascia‐Mugnozza, Giuseppe

doi:10.1111/ecog.03309

Cited by 43 publications

(47 citation statements)

References 159 publications

(209 reference statements)

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“…The next generation of Earth system models may also benefit from integration of open trait data for (at least) two types of organisms: (1) terrestrial vertebrates; and (2) microbes. Terrestrial vertebrates provide key ecological functions (for example, dispersal and disturbance 108 ) and their loss may result in significant changes to ecosystem function 109 . However, capturing the influence of terrestrial megafauna on forest structure, function and biogeochemical cycles will be improved by access to data on traits (for example, size and diet) to parameterize processbased models.…”

Section: Box 1 | Research Programs Dependent On Comprehensive Trait Dmentioning

confidence: 99%

Open Science principles for accelerating trait-based science across the Tree of Life

et al. 2020

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raits, broadly speaking, are measurable attributes or characteristics of organisms. Traits related to function (for example, leaf size, body mass, tooth size or growth form) are often used to understand how organisms interact with their environment and other species via key vital rates such as survival, development and reproduction 1-5. Trait-based approaches have long been used in systematics and macroevolution to delineate taxa and reconstruct ancestral morphology and function 6-8 and to link candidate genes to phentoypes 9-11. The broad appeal of the trait concept is its ability to facilitate quantitative comparisons of biological form and function. Traits also allow us to mechanistically link organismal responses to abiotic and biotic factors with measurements that are, in principle, relatively easy to capture across large numbers of individuals. For example, appropriately chosen and defined traits can help identify lineages that share similar life-history strategies for a given environmental regime 12,13. Documenting and understanding the diversity and composition of traits in ecosystems directly contributes to our understanding of organismal and ecosystem processes, functionality, productivity and resilience in the face of environmental change 14-19. In light of the multiple applications of trait data to address challenges of global significance (Box 1), a central question remains: How can we most effectively advance the synthesis of trait data within and across disciplines? In recent decades, the collection, compilation and availability of trait data for a variety of organisms has accelerated rapidly. Substantial trait databases now exist for plants 20-23 , reptiles 24,25 , invertebrates 23,26-29 , fish 30,31 , corals 32 , birds 23,33,34 , amphibians 35 , mammals 23,36-38 and fungi 23,39 , and parallel efforts are no doubt underway for other taxa. Though considerable effort has been made to quantify traits for some groups (for example, Fig. 1), substantial work remains. To develop and test theory in biodiversity science, much greater effort is needed to fill in trait data across the Tree of Life by combining and integrating data and trait collection efforts.

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Section: Box 1 | Research Programs Dependent On Comprehensive Trait Dmentioning

confidence: 99%

Open Science principles for accelerating trait-based science across the Tree of Life

et al. 2020

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“…Defaunation may change plant community composition, forest structure, and productivity to the extent that the long-term viability and service delivery of ecosystems is affected [60,63]. However, our ability to predict the consequences of defaunation is constrained by the complexity of ecosystem interactions and the long-time horizons over which these changes materialize [67,68].…”

Section: Consequences Of Defaunationmentioning

confidence: 99%

“…Few studies have so far examined the effect of defaunation on carbon storage due to the inherent complexity [67]. However, simulating the local extinction of trees depending on large frugivores for seed dispersal in 31 Atlantic forest communities in Brazil using a dataset on tree species composition and abundance, seed, fruit and carbon-related traits, and plant-animal interactions, Bello et al [73] found that the extinction of even a small proportion of the large-seeded trees significantly eroded forest carbon storage capacity.…”

Section: Consequences Of Defaunationmentioning

confidence: 99%

“…A pan-tropical study of the potential effects of defaunation on above-ground carbon storage simulating extinctions of large-seeded animal-dispersed species found that carbon stocks in African, Indian, and American tree communities declined by 1-5% and 2-12% in 50% and 100% seed disperser removal scenarios, respectively [75]. Hence, there is sufficient support for the hypothesis postulating a long-term effect of hunting on forest carbon storage capacity and that defaunation will undermine REDD+ climate change mitigation efforts although researchers have only recently begun to examine this link using vegetation modelling [67]. Furthermore, an application using bioeconomic modelling reveals that total potential revenue was maximized at low hunting effort by increasing sellable carbon credits [34].…”

Section: Consequences Of Defaunationmentioning

confidence: 99%

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Not Seeing the Forest for the Trees: The Oversight of Defaunation in REDD+ and Global Forest Governance

Krause

Nielsen

2019

Forests

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Over the past decade, countries have strived to develop a global governance structure to halt deforestation and forest degradation, by achieving the readiness requirements for Reducing Emissions from Deforestation and forest Degradation (REDD+). Nonetheless, deforestation continues, and seemingly intact forest areas are being degraded. Furthermore, REDD+ may fail to consider the crucial ecosystem functions of forest fauna including seed dispersal and pollination. Throughout the tropics, forest animal populations are depleted by unsustainable hunting to the extent that many forests are increasingly devoid of larger mammals—a condition referred to as empty forests. Large mammals and birds, who often disperse seeds of larger more carbon-rich tree species, are preferentially targeted by hunters and the first to be depleted. Such defaunation has cascading ecosystem effects, changing forest structure and composition with implications for carbon storage capacity. Failure to address defaunation would therefore be a major oversight in REDD+, compromising its long-term viability. We carried out a desktop study reviewing REDD+ documents and national implementation efforts in Colombia, Ecuador, Nigeria, Tanzania, and Indonesia to assess the extent to which they address hunting and acknowledged the ecosystem functions of fauna. We also assessed sub-national REDD+ projects to determine whether they recognized hunting and if and how they incorporated hunting management and wildlife monitoring at the project level. Moreover, we assessed to what extent sub-national REDD+ projects addressed the long-term impacts of the sustainability of hunting on forest ecosystem function including carbon storage. We found that hunting, the risk of defaunation, and its effects have been ignored in the REDD+ policy process at both the international and national levels. At the project level, we found some reference to hunting and the risks posed by the loss of forest fauna, albeit only addressed superficially. Our results underline the fact that forest ecosystems are being reduced to their carbon content and that, despite the rhetoric of biodiversity co-benefits, fauna is not treated as a functional component of forests. This neglect threatens to undermine forest ecosystem function and service delivery as well as long-term forest carbon assimilation capacity and hence, ultimately, to compromise REDD+ objectives.

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“…By contrast, forest degradation and conversion drive changes in animal communities by altering resource availability for different dietary guilds (Gray et al, 2007), or by constraining dispersal across degraded or modified landscapes (Şekercioḡlu et al, 2002). Understanding variation in the nature of trait-mediated animal community change is useful not only for assessing conservation threats posed by different defaunation drivers, but can also improve our ability to predict knock-on impacts on forest vegetation dynamics and ecosystem functions such as carbon sequestration (Osuri et al, 2016;Berzaghi et al, 2018). However, even as previous studies have examined faunal responses to individual drivers such as hunting (Benítez-López et al, 2017) or selective logging (Burivalova et al, 2014), or responses of particular species groups such as frugivores to multiple drivers (McConkey et al, 2012), variation in the responses of tropical forest faunal communities to different defaunation drivers has not been systematically assessed.…”

Section: Introductionmentioning

confidence: 99%

Hunting and Forest Modification Have Distinct Defaunation Impacts on Tropical Mammals and Birds

Osuri

Mendiratta

Naniwadekar

et al. 2020

Front. For. Glob. Change

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The mammalian and avian assemblages of intact tropical forests are among the most diverse vertebrate communities on Earth and influence the structure, composition, and functioning of these forests in myriad ways. Over recent centuries, however, increasing human domination of the tropics has led to widespread defaunation, or the decline, local-, or global extinction of tropical animal species. Defaunation is one of the defining features of the Anthropocene and is best documented for vertebrate species, especially mammals and birds. Defaunation is driven by several direct (e.g., hunting) and indirect (e.g., habitat alteration) anthropogenic threats, but how these threats differ in the nature and magnitude of their impacts on tropical mammal and bird species remains unclear. Using a meta-analysis of 82 studies on 254 mammal and 1,640 bird species from across the tropics, we assess the effects of three major regionalscale drivers of tropical defaunation, namely hunting, forest degradation and forest conversion, on measures of abundance for tropical mammal and bird species belonging to different dietary guilds and IUCN conservation status groups. Mammal species across dietary guilds either declined or did not change, on average, in response to the three drivers, with hunting having the most consistent negative impacts on abundances of carnivores, frugivores, herbivores/granivores, large-bodied species, and species of high conservation importance. By contrast, bird species declined most strongly in response to forest conversion, with responses varying widely across different dietary and conservation importance groups, and not consistently related to body size. Our results reveal that hunting, forest degradation and conversion are associated with distinct types of defaunation of mammal and bird species, and are therefore likely to have distinct implications for animal-mediated interactions and processes, ecosystem functions, and conservation of tropical forests. Addressing major gaps in our empirical understanding of defaunation effects-e.g., hunting impacts on smaller-bodied mammals and birds, and responses of species in southeast Asian forests-is key to better understanding, predicting, and mitigating the impacts of this pervasive global threat.

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Assessing the role of megafauna in tropical forest ecosystems and biogeochemical cycles – the potential of vegetation models

Cited by 43 publications

References 159 publications

Open Science principles for accelerating trait-based science across the Tree of Life

Open Science principles for accelerating trait-based science across the Tree of Life

Not Seeing the Forest for the Trees: The Oversight of Defaunation in REDD+ and Global Forest Governance

Hunting and Forest Modification Have Distinct Defaunation Impacts on Tropical Mammals and Birds

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