The Amazon Fertilisation Experiment (AFEX)

Lead Research Organisation: University of Exeter
Department Name: Geography

Abstract

Terrestrial ecosystems currently absorb one quarter of the carbon dioxide that Humankind releases into the atmosphere, thus reducing the rate of climate change. In this context, Amazon rainforest is extremely important, absorbing more than half a billion tonnes of carbon per year. This represents more than the combined emissions from the USA and China. However, we have limited understanding of how the productivity of Amazon forests is controlled, and this reduces our ability to predict what will happen in the future as atmospheric CO2 concentrations continue to rise and the climate changes.

One of the main paradigms in ecology is that the productivity of tropical ecosystems, which occur on old, highly-weathered soils, is limited by the availability of phosphorus. This contrasts with more temperate ecosystems whose productivity has been shown to be limited by nitrogen availability. However, the phosphorus paradigm has not been tested in detail as there have been very few nutrient manipulation studies in tropical forests, and no large-scale study has been carried out in Amazon forest. This is a major issue because soil nutrient availability in most of Amazonia is substantially lower than in Panama, the location of the only ongoing fertilisation experiment in tropical lowland rainforest. Thus, the Panama findings may not be representative of large areas of Amazonia, and, therefore, our understanding of the role soil fertility plays in controlling tropical forest productivity is incomplete.

Testing the phosphorus paradigm in Amazonia is critical for two reasons. Firstly, eastern and central Amazonia, the area which contains the lowest fertility soils, is considered to be at risk from the adverse effects of climate change, with widespread dieback predicted by some scientists. The resilience of these forests is considered to be highly dependent on whether trees are able to increase their growth in response to rising atmospheric CO2 concentrations, and this ability is likely to depend on the extent to which their growth is currently limited by soil nutrient availability. Secondly, there is growing evidence that the response of ecosystems to global change may differ depending on which nutrient limits their productivity. Therefore, establishing the first large-scale nutrient manipulation study in Amazonia should represent one of greatest priorities for ecosystem and climate change research.

We will do just that, manipulating nitrogen, phosphorus and cation availability in central Amazon forest, at a site representative of the most common soil type in the Basin, and will quantify the response of key forest processes. We will determine the impacts on photosynthesis, plant respiration, biomass production and turnover, and decomposition, ultimately allowing us to take a full-ecosystem approach to establish how carbon storage has been affected. The new knowledge and understanding which we generate will be used to improve Amazon process representation in the Joint UK Land Environment Simulator (JULES). This will be the first time that multi-nutrient control of tropical forest function has been included in a dynamic global vegetation model, allowing for more realistic simulation of the response of the Amazon carbon cycle to environmental change. This will improve our ability to predict how the Amazon rainforest will change during the 21st century and what the implications will be for rates of regional and global climate change.

In summary, our project will address a fundamental ecological question and will improve greatly our understanding of an issue that contributes substantially to uncertainty in predictions of rates of 21st century climate change; namely, how the productivity of one of the most important natural carbon sinks on the planet, the Amazon rainforest, is controlled.

Planned Impact

Our ultimate aim is to improve understanding of how Amazon forest productivity is controlled, and thus how it may be affected by global change. Given the globally significant role the forest plays in the carbon cycle, as well as the ecosystem services it provides to the people living in Amazonian states and beyond, this work is likely to be of great interest to the IPCC and the Brazilian Panel on Climate Change (PBMC). Our work also has implications for local Environmental Protection Agencies (including those involved in climate change mitigation and the regional implementation of the UN REDD programme), and local communities in Manaus, the nearest major city. Finally, the experimental manipulation of nutrient availability in Amazon rainforest is likely to be of great interest to the general public.

The IPCC is placing a greater emphasis on earth system modelling and in particular climate-carbon cycle feedbacks. Given that Amazonia represents a globally significant carbon sink, the aims of our project are highly relevant to IPCC Working Group 1. In addition, our work will also provide valuable information on ecosystem resilience to global change in one of the IPCC focal regions, Latin America. This is therefore within the scope of IPCC Working Group II. The modelling in our project uses the Joint UK Land Environment Simulator (JULES) which is the land component of the Met Office Hadley Centre's flagship family of Earth System Models, HadGEM2 & 3, and thus developments in this project will directly lead to improvements relevant to IPCC-facing, coupled climate-C-cycle modelling. We enjoy excellent links with Met Office scientists; PI Hartley runs a joint Exeter University-Met Office carbon cycle research group, and CoI Mercado is the theme leader in plant physiology for JULES. We will also make our results available to our collaborators on the board of directors of the PBMC, including Prof. Jose Marengo and Prof. Carlos Nobre.

Our links with key Brazilian Project Partners, and CoI Aragao's proven track record in communicating his science to local government and environmental protection agencies, ensures that the key local beneficiaries of the science will be informed of the implications of our science. We will give public lectures in Portuguese at Partner Institutions to reach a broader audience including local people and governmental organisations. Furthermore, we will run a workshop at INPA, with a 3-day visit to the field station, for environmental studies students, and local environmental agency and local government agency representatives. Our project partners will help identify the key individuals to invite and will actively advertise the workshop.

We expect the project to be of great interest to the general public, and to be an excellent opportunity to promote NERC science and to outline the impacts that environmental change will have on the tropical forests. The investigators are committed to, and have strong track records in, communicating science to the general public through various media outlets. We will join three successful initiatives that promote dissemination of tropical science: (1) the NERC-funded Global Ecosystems Monitoring Web Portal (see Letter for Support from Prof. Malhi) (2) the RAINFOR network, and (3) the prize-winning public science web site 'Climate Kaleidoscope'. Finally, we will set up a website actively promoting the project.

In summary, together with our plans for academic dissemination, our impact plan will ensure our results have the maximum possible impact in terms improving the representation of the Amazon in IPCC-facing modelling, and we will give lectures and run a workshop to outline our findings to the local community and local government and environmental protection agencies. Furthermore, we will use various media, to ensure that our research reaches the wider society.
 
Description The nutrient manipulations have now been running for 4 years, and have generated new understanding into the to which soil fertility controls Amazon forest function. It appears that Amazon forests are more responsive to changes in soil fertility than other tropical forests that have been studied previously, perhaps reflecting the lower availability of element such as phosphorus, calcium and potassium compared with central America regions. The first post-fertilisation manuscript from the project has now been published in New Phytologist, identifying major changes in below-ground processes and root dynamics in response to phosphorus and cation additions. Above-ground responses have also been observed and these are currently being written-up for submission to a general science journal. The project has been very successful and developed findings that advance our understanding of how the productivity of Amazonian forests is controlled.
Exploitation Route The findings have been presented to Amazon forest scientists, including the AmazonFACE team which is investigating the impacts of elevated CO2 concentrations of forest processes. It is essential to know the level of nutrient limitation if we are to understand the results from this major study.
Sectors Environment

 
Description Working with the Eden Project we have been designing a teaching resource for educating A-level pupils about the role nutrient cycling plays in controlling rainforest productivity. This will involve measuring rates of litter decomposition in the contrasting environments in Eden, and linking the results back to AFEX, including showing videos of the fertiliser treatments. This exercise will be run for the first time with schools group in 2019.
First Year Of Impact 2018
Sector Education
Impact Types Cultural

 
Description Brazilian Science Without Borders programme
Amount £60,000 (GBP)
Organisation National Council for Scientific and Technological Development (CNPq) 
Sector Public
Country Brazil
Start 06/2015 
End 05/2018
 
Title Litterfall ant genus and abundance in a fertiliser experiment area in Central Amazon, 2018-2019 
Description Data are presented showing litterfall ant species and abundance from a plot based fertilisation experiment. The experiment was carried out at the Biological Dynamics of Forest Fragments Project (BDFFP) approximately 100 km north of Manaus. Data were collected in October 2018 and September 2019 by Santos-Neto. Sampling was carried out using a Wrinkler extractor. The data were collected to investigate the possible effects of different fertiliser applications on litterfall ant species and abundance. The work was carried out as part of the Amazon Fertilization Experiment (AFEX), funded by the Natural Environment Research Council (NERC), Award reference NE/L007223/1, by the Brazilian government (Researcher scholarship) and the Biological Dynamics of Forest Fragments Project (BDFFP - logistical support and camps maintenance). 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
URL https://catalogue.ceh.ac.uk/id/60e77fd4-7a24-4545-8d90-08e9dfcbd16a
 
Title Seedlings growth in a fertilized forest in Central Amazonia (2019 - 2020) 
Description Data are presented showing seedling height, diameter at ground height (DGH), total number of leaves, number of leaves with herbivory damage and leaf mortality, from a plot based fertilisation experiment. The experiment was carried out at the Biological Dynamics of Forest Fragments Project (BDFFP) approximately 100 km north of Manaus. Data were collected bimonthlyfrom February 2019 to January 2020, by the dataset first author. Height measurements were made with a tape measure and DRH measurements were made with digital calipers. Leaf numbers, damage and mortality were made from visual observations. The data were collected to investigate the possible effects of different fertiliser applications on seedling height, totalnumber of leaves, number of leaves with herbivory damage and leaf mortality.The work was carried out as part of the Amazon Fertilization Experiment (AFEX), funded by the Natural Environment Research Council (NERC), Award reference NE/L007223/1, by the Brazilian government (Researcher scholarship) and the Biological Dynamics of Forest Fragments Project (BDFFP - logistical support and camps maintanance). 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
URL https://catalogue.ceh.ac.uk/id/2da56eb1-ff01-48de-ba2a-d3afceefc85f
 
Title Seedlings leaf loss by herbivory in a fertilized forest in Central Amazonia (2019 - 2020) 
Description Data are presented showing for individual seedling, herbivory damage at the leaf level; galls, pathogens, trail herbivory presence/absence qualitative data; and leaf mortality. Data were collected in each leaf from a plot based fertilisation experiment. The experiment was carried out at the Biological Dynamics of Forest Fragments Project (BDFFP) approximately 100 km north of Manaus. Data were collected bimonthly from February 2019 to January 2020, by the dataset first author. Leaf loss in percentage was made using the choice for direct visual estimate. We also followed the recommendations proposed by the authors, sectoring the leaves with a millimetre grid, improving measurement accuracy. The presence of Galls, pathogens and trail herbivory presence/absence qualitative data were also collected in each leaf. The work was carried out as part of the Amazon Fertilization Experiment (AFEX), funded by the Natural Environment Research Council (NERC), Award reference NE/L007223/1, the Brazilian government (Researcher scholarship) and the Biological Dynamics of Forest Fragments Project (BDFFP - logistical support and camps maintanance). 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
URL https://catalogue.ceh.ac.uk/id/2b8029ff-ddf5-47b2-9231-5fa0cbb6cd41
 
Description Collaboration with Ben Turner 
Organisation Smithsonian Institution
Department Smithsonian Tropical Research Institute
Country Panama 
Sector Academic/University 
PI Contribution We are collaborating with Ben Turner on ensuring that the experiment we set up in Brazil is comparable to ongoing research in Panama
Collaborator Contribution Ben Turner has advised us on good practice based on long-term experimence of running a similar experiment in Panama
Impact Ben Turner will be a coauthor on many of the publications from AFEX.
Start Year 2014
 
Description Collaboration with Carlos Alberto Quesada 
Organisation National Institute of Amazonian Research
Country Brazil 
Sector Public 
PI Contribution We are collaborating closely with Dr Carlos Alberto Quesada in all aspects of AFEX. The project is also registered with INPA.
Collaborator Contribution Carlos Alberto Quesada providing field and logistical coordination for the duration of the project. Dr Quesada has put in a lot of time to ensuring the success of the project.
Impact Dr Quesada will eb a coauthor on all AFEX publications.
Start Year 2014
 
Description Eden Project A-level exercise 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact We have designed a new exercise for A-level school groups visiting the Eden Project for their 'field' days. This will demonstrate the role of decomposition and nutrient cycling in maintaining teh productivity of Amazon forests growing on ancient, weathered soils, and include video showing the fertilisation campaigns taking place in AFEX. The intended learning outcomes are to deomnstrate that it is only through highly-efficient nutrient recycling that forest productivity can be maintained and that this explains why low-input agriculture often fails within a few years as soil fertility declines. This understanding is essential for investigating how the rainforest biome will respond to direct and indirect human impacts.
Year(s) Of Engagement Activity 2018