Science updates carbon stock data on forest farms

The indicator faithfully represents the peculiarities of the country and shows greater potential for mitigating greenhouse gases through forest plantations

Studies by Embrapa Florestas (PR) show that carbon loss in soils converted to forest plantations is only 5% and not 33%, as previously thought. The update of this data is the result of the development of Brazilian science, which began to use the Soil Carbon Change Index (BAI) based on information from national research. In this way, the indicator faithfully represents the peculiarities of the country and shows greater potential for mitigating greenhouse gases through forest plantations.

The work was based on studies conducted in Brazil and published between 2002 and 2019, in areas converted into planted forests of eucalyptus, pine and black cattle. The data included information obtained in nine states: RS, SC, PR, SP, ES, MG, BA, PA and MS, covering more than 8.6 million hectares of forest plantations. “In the case of this indicator, the arithmetic value was not compatible with the reality of forest farms. However, as studies progress, each country can adjust and refine these indicators for the reality of their crops, which we did with the forest crops analyzed”, says the researcher at Embrapa, Joselia Zanata, who coordinated the study.

The type of plant grown interferes with the vegetation cover, and thus can affect soil carbon stocks, altering the balance between carbon uptake and rates of carbon loss. “The fact that an agricultural indicator was used ended up punishing forest plantations, as it indicated that about 33% of the carbon stored in the soil was lost after removal of native vegetation, pasture or cultivation, followed by the conversion to forest plantations,” analyzes Embrapa researcher Marcos Raschual, who shared In the study. “We have established that this indicator, in fact, is 0.95, that is, it is considered a loss of only 5%, which is a huge difference,” he adds.

“When we think of switching pastures to eucalyptus plantations, we see a 10% greater gain in soil carbon stocks. Historically, processes of switching from pastures to forest plantations predominate in Brazilian biomes, ignoring the Amazon, and this illustrates the participation of the forest-based sector in confront climate change,” says Zanata.

High carbon stocks in the soil

Another outcome of these studies is the higher performance of soil as a carbon store. The volume stored is equivalent to, and sometimes greater, the carbon accumulated in forest biomass. In addition, the soils of forest farms can act as sinks for methane, through microorganisms present in the soil, and methanotrophic bacteria, which consume methane and contribute to reducing the concentration of this gas in the atmosphere. “All well-ventilated soils that do not contain excessive moisture, under planted or native forests, have this ability,” Rachwal explains.

Data support document provided in COP26

The studies by Embrapa Florestas also made it possible for the “Reforestation” category in the Fourth National Inventory of Greenhouse Gas Emissions and Removals, an integral part of Brazil’s Fourth National Communication to the Climate Convention (4CN-4CN), submitted and published in December 2020, to provide data more consistent with Brazilian reality.

National Communications (CN) is held every four years, on average, by the Ministry of Science, Technology and Innovation (MCTI) to report on all national efforts to implement the United Nations Framework Convention on Climate Change (UNFCCC). This report updates information on greenhouse gas emissions and removals in Brazil and contributes significantly to improving public policies within the scope of the national and international climate agenda.

“It is about ensuring that the most diverse decision makers have the best available scientific knowledge as input. In this scenario, the involvement of Embrapa, especially in the case of Embrapa Florestas, with studies on carbon stocks in forest plantations, is essential to the success of the initiative”, says the General Coordinator for Climate Science and Sustainability at MCTI. , Marcio Rojas, who is also the National Director of the Fourth National Communication Project from Brazil to the United Nations Framework Convention on Climate Change.

Studies Development

Embrapa Florestas has been in the field of forestry and climate change research since 2000. Forests have the potential to mitigate greenhouse gas emissions (GHGs), by sequestering carbon and removing gases such as methane from the atmosphere. Carbon accumulates in its biomass and soil, as well as in wood products.

As of 2012, with the start of the Saltus Project, the unit began a set of actions to investigate how Brazilian forests contribute to the fight against climate change. The first phase of this project, from 2012 to 2017, carried out a comprehensive diagnosis of carbon balances in forest systems (in eucalyptus, pine and black cattle plantations), assessment of their compartments, and their capacity to store carbon or remove carbon gases. The greenhouse effect in the atmosphere. This work allowed for standardization of diagnostic protocols, facilitating the acquisition of carbon credits in future works, and is also another contribution built into 4CN.

In 2017, a new phase of the Saltus project began, with the goal of defining mitigation practices in planted forests, and maintaining focus on eucalyptus and pine plantations. At this point, we sought to extend knowledge of carbon compartments in Atlantic forest forest patterns, including urban forests. According to researcher Josileia Zanatta, a stronger focus on the Atlantic Forest is necessary because this biome still does not have indicators capable of estimating the reference level, associated with the Reducing Emissions from Avoided Deforestation (REDD) policy. “The research focused on the Atlantic Forest, one of the highly fragmented biomes and primarily on pine and eucalyptus, with the aim of identifying and qualifying silviculture practices that may have some potential to mitigate greenhouse gas emissions or increase carbon stocks,” he explains.

Check the benefits of carbon stocks in the soil

Forest plantations are a viable alternative for reducing total greenhouse gas emissions due to reduced pressure to extract timber from native forests, which also avoids emissions from deforestation.

Carbon accumulates on products from planted forests over a long period of time, and when properly produced, they are very effective at sequestering carbon and emit fewer greenhouse gases, which means they have a smaller carbon footprint than petroleum products or synthetics of various origins.

Planted forests have a high capacity to remove carbon dioxide from the atmosphere, incorporating carbon (C) into plant biomass and thus into soil, allowing for a very positive carbon balance.

Forest soils maintain the ability to consume atmospheric methane, being an additional mechanism for reducing this gas in the atmosphere.

These advantages allow the carbon balance of planted forest systems to be very positive, even making it possible to generate income from the adoption of low-emission forest products as well as the marketing of carbon credits. It is imperative that forestry enterprises are prepared to access these “green” economy opportunities.

Source: Embrapa Forests