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The role of megafauna in biogeochemical cycles and greenhouse gas fluxes: implications for climate and ecosystems throughout history

Periodic Reporting for period 1 - MegaBiCycle (The role of megafauna in biogeochemical cycles and greenhouse gas fluxes: implications for climate and ecosystems throughout history)

Reporting period: 2019-10-01 to 2021-09-30

The importance of Megafauna, terrestrial herbivores with body mass > 45kg, for ecosystems and their influence on biogeochemical cycles and climate is not well understood. Many megafauna species became extinct around 10,000 years ago due to a combination of overhunting and climatic changes. These past extinctions likely had important consequences on ecosystems and climate but are difficult to study. The still-existing megafauna populations are rapidly declining globally and the consequences of their extinction are unknown.

We need to better understand the multiple ecological roles of megafauna as they likely perform critical functions that maintain ecosystem healthy and contribute to carbon and nutrient cycling which influence plant productivity and climate. This is critical for society as megafauna could contribute to mitigate climate change and increase the resilience of nature and its services from which humanity depends for its long-term survival.

The MegaBiCycle objectives are to develop tools and methodologies to better study the global role of megafauna in biogeochemical cycles and their direct and indirect influence on climate. The knowledge, data, and advancements produced by the project will provide the building blocks for future research as well as will contribute to shape conservation and climate change policy.
The main results of the project are the creation of a global classification of terrestrial mammalian herbivores, which includes all existing herbivores; another classification was created to include extinct herbivores. These classifications were implemented in a model of herbivore populations which was also developed during the project. These two classifications and the herbivore model allowed to estimate at the global scale the density of different types of herbivores, their total population and biomass through different historical periods from the late Pleistocene through today. These population estimates allowed to quantify the contribution of megafauna to carbon cycling and plant productivity. In addition, the project quantified the magnitude of past and present population decline of megafauna in terms density and total biomass for different herbivore groups. Another important result is the discovery of the mechanisms, in particular seed dispersal and food preferences, through which megafauna has a significant influence on carbon cycling. Additional results included the first global estimates of past and present methane emissions from both small and large herbivores. Finally, the project also produced a new framework that allows to evaluate the carbon services produced by wild animals.

Dissemination activities:


- Poster presentation at the Ecological Society of America conference, 08/2021.
- Oral presentation at the Association for Tropical Biology and Conservation conference, 07/2021.
- Formal and informal meetings with a wide range of stakeholders: researchers, NGOs (including WWF, The Nature Conservancy, and WILD), private companies, civil society, and government representatives at the:
- 26th UN Climate Change Conference of the Parties (COP26); 11/2021.
- IUCN World Conservation Congress, Marseilles, 09/2021.

Results disseminated at prominent research labs in the field including: Northern Arizona University, Aarhus University, Yale University, and Würzburg University.

Two scientific articles are currently under review and have been uploaded on the bioRxiv preprint server. Three more publications will be submitted for review within the next two months.
Various outreach activities at public events and institutions including: world Elephant Day organized by China Biodiversity Conservation and Green Development Foundation, The World Bank, conference at EU commission TAO-AFI, The Future of the Asian Elephants conference, Lao Elephant Initiative, Science is Wonderful! Exhibition open to the public organized by the EU for MSCA projects.

Dissemination outside scientific publications
- At COP26, co-signed press release on the role of wild animals in the carbon cycle as a means to reach the 1.5° target
- Personal website has a section dedicated to the project which will continually be updated.
- Project Twitter account used to disseminate results
- Results from my collaboration with The International Monetary Fund were published in the IMF journal Finance and Development and were featured on the IMF podcast
The project greatly advances the knowledge of the global role of herbivorous megafauna, but also of mammalian herbivores in general. There was significant progress beyond the state-of-the-art including: the first and most comprehensive classifications of extinct and present herbivores, the first global model of mammalian herbivore populations, the first global methane budget for small and large herbivores, and a new framework to evaluate the carbon services produced by wild animals. Overall, these advancements will result in increased interdisciplinary science between ecology, Earth and climate science and the inclusion of animal processes in global vegetation and climate models that can contribute to policy making.

The Fellowship creates new opportunities related to the carbon market and addresses issues related to natural resource management, rewilding, and climate change. In particular, the results show the importance of wild herbivores in carbon cycling and thus their connection to climate change and importance for maintaining healthy and sustainable ecosystem. The project also opened a completely new research field by valuing the carbon services produced by wild animals. This has important implications for global economies and society dealing with two of the largest issues of our time: climate change and global biodiversity loss. Thus, results of the project will provide a critical contribution to implement and finance nature-based solutions for mitigating climate change for the benefit of nature and society. This methodology creates new market opportunities around the carbon offset market through the carbon sequestration services provided by wild animals. In addition, the increased understanding of the global role of wild herbivores in carbon cycling and methane emissions will contribute to improving projections of future climate scenarios, and helping in the conservation and management of natural resources.

The project results will be useful also to the EU policy objectives and strategies as the EU is a leader in climate change mitigation and nature preservation. The work carried out might also contribute to shaping the EU carbon offset market to include the services of wild animals.

The methodology and tools developed during the fellowship will be applied to different regional or local case studies. Some of these applications include rewilding projects in Denmark through Aarhus University researchers, contributions to the SECO Project ( which is studying the carbon dynamics of the dry tropics, NGOs working in Africa (Kenya and South Africa) to study the role of wild herbivores in savannas, and requests from PhD students and postdocs for collaborations.
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