An international project will take a closer look at the functioning of the Cerrado in Brazil

Cristina G. Pedraz/DICYT The Cerrado is the largest neotropical savanna in the world and is located almost completely in Brazil. it covers 24% of the country (approximately 2 million square kilometres or almost four times the surface area of the Iberian Peninsula) and has the greatest biodiversity of all the savannas. Owing to its considerable surface area and its biodiversity, the Cerrado is of vital importance in the maintaining of important ecosystem services related to energy, carbon sequestration, and the cycling of nutrients at both a regional and global level.

Despite its great ecological importance, we know very little as yet about its functioning. With the aim of taking a closer look at this biome and finding out the factors that control this functioning, researchers from four countries (Brazil, Spain, Portugal, and France) will implement the CONCERN (Present and future functioning of CarbOn- and Nitrogen-related proCesses and dispErsal processes in the BRasilian savaNna) project as from the middle of this year.

Jorge Durán, a researcher at the Functional Ecological Centre of the University of Coimbra in Portugal, one of the partner entities of the project, explains that the Cerrado of Brazil “has been surprisingly ignored by both the local authorities and the international community”. Only 2 per cent of its surface area enjoys any form of protection despite the fact that it is one of the most threatened biomes in the world, with over 50 per cent of its original surface area having been modified according to the scientific literature.

“Fire and the intensification of agriculture and stockbreeding are the traditional enemies of the Cerrado, but in recent years a new potential threat has emerged above all others, climatic change. In addition to the well known increase in temperature, climate models predict drastic changes in the rainfall distribution in the Cerrado. To be precise we expect a reduction in the number of rainy days, an extended dry season, and an increase in torrential rain”, the researcher notes.

These climatic changes may also affect the functioning of the Cerrado and in particular the cycles of carbon and nitrogen, two essential nutrients for the operating of any ecosystem. Some studies expect plant health to be affected and others predict extinction rates of between 39 and 48 per cent of the species depending on the climatic scenarios.

Effects on the carbon cycle

The effects of climatic change on the carbon cycle are also highly relevant as this influences whether the ecosystems operate as sources or sinks of the CO2 in the atmosphere, the main trigger of the greenhouse effect. A longer dry season together with increased torrential rainfall “could mean that these ecosystems change from being a carbon sink to a net source, which would leed back to climatic change”.

A similar effect might arise with other greenhouse gases such as methane and nitrous oxide, the emissions of which from the soil to the atmosphere could increase owing to the expected changes in the climate. “What is really relevant is that owing to the extent of the Cerrado any change affecting this ecosystem will also affect global biogeochemical cycles and the planet's climate”, Durán points out.

For all these reasons, the objects of the CONCERN project also include predicting how the Cerrado will respond to realistic scenarios of changes in the precipitation pattern, and in particular the future effects of various ecosystem processes related to the storage and the cycling of nitrogen and carbon. Finally, the researchers will attempt to find out whether the plant diversity and that of the soil (invertebrates and microorganisms) will confer any type of resistance to climatic change.

Work methodology

The study will be carried out in the National Paraopeba Reserve in the Braziian state of Minas Gerais. The scientific team will install plots of 20 square metres throughout the reserve and will divide them into two parts. Half the plot will be a control subplot and the other half will be subjected to precipitation modification treatment that will attempt to simulate the predictions of the climatic models for the forthcoming decades, in other words a dry season a month longer and an increase in torrential rain during the wet season.

In order to do so, at the end of the dry season and with the help of local workers, on the corresponding subplots rain exclusion structures will be erected. These will be made of wood and transparent plastic channelling suspended one metre from the ground. The plastic strips will prevent a large proportion of the rain from hitting the ground of the plots treated during the first month of the wet season, and will channel the water towards tanks. After this month has passed the structures will be removed and various episodes of intense rainfall will be prompted to simulate typical amounts of average local storms.

For two years starting in July 2015, soil samples will be taken on these plots at regular intervals to calculate a series of variables and processes related to the cycling of nitrogen and carbon in the soil. The taxonomic and functional diversity of plants will also be estimated, together with that of soil invertebrates and microorganisms, and the emission of greenhouse gases from the soil will be calculated.

Duties of each member

The Plant Ecology and Evolution Laboratory of the Universidad Federal de Viçosa in Brazil will be responsible for the administrative management of the project, the selection of plots, the coordination of the construction of the installations, and the consideration of the diversity of the plant taxonomy. For its part, the Ecology and Global Change Laboratory of the Spanish National Research Council (CSIC) will take charge of estimating the reserves and processes related to the nitrogen and carbon cycle in the soil, and of calculating greenhouse gas emissions and the taxonomic and functional plant diversity. Likewise, the Functional Ecology Centre of the University of Coimbra will work to assess the reserves and processes related to the nitrogen and carbon cycle in the soil, and to calculate greenhouse gas emissions and the taxonomic and functional diversity of soil microorganisms and invertebrates. Finally, the Université Paris Sud of France will also be in charge of calculating the taxonomic and functional plant diversity.

The idea is that all European members spend a short period in Brazil at the beginning of the project to train the Brazilian members of the team in the techniques necessary for carrying out the project. After this instruction it will be the local scientists who will be in charge of these tasks under the supervision of the associated European groups. To date the team has obtained two postdoctoral contracts associated with the project, which means that after the candidate selection process two more doctors will join the work group.

The data:

Title: Present and future functioning of CarbOn- and Nitrogen-related proCesses and dispErsal processes in the BRasilian savaNna (CONCERN) Call: MCTI/CNPQ/Universal (Faixa C) Project code: 446698/2014-8 Duration: two years, extendable Financing: CNPq brasileira Consortium: Laboratorio de Ecologia e Evolução de Plantas de la Universidade Federal de Viçosa in Brazil (João Meira Neto, Luiz Magnago, and Markus Gastauer) Laboratorio de Ecología y Cambio Global del Museo Nacional de Ciencias Naturales - CSIC of Spain (Alexandra Rodríguez, Fernando Valladares, Ana Rey, and Jorge Curiel). Centro de Ecologia Funcional de la Universidade de Coimbra in Portugal (Jorge Durán, Helena Freitas, Susana Rodríguez, and José Paulo Sosa) Université Paris Sud of France (Elena Granda)