The importance of the Amazon rainforest is expressed through numerous ecosystem functions and processes. First of all, its ability to operate as a “carbon sink”, absorbing a great amount of CO2 from the Earth’s atmosphere, greater than the amount it normally emits, contributing, in other words, to the storage of a part of the enormous quantity of carbon dioxide produced annually and released into the atmosphere by anthropogenic activities (33.3 Gt in 2019).
Although it is very hard to calculate, it is estimated that the entire Amazon is able to absorb and store 1 billion tons of CO 2 a year. According to a recent study, the amount of net ecosystem productivity (NEP) was estimated to be 0.56 Gt per year (about 617 million tons per year).
However, another study published on Nature states that the amount of CO2 stored appears to have decreased by a third during the last decade. It is well known that the Amazon rainforest represents a “resource” of considerable importance in the fight against climate change. Unfortunately, the greatest threat it is facing is the very high rate of deforestation: to date, about 17% of the entire Amazon basin has been deforested and converted into crops and pastures.
Forest cover, which largely determines the albedo rate, the water cycle and CO2 storage, has a strong influence on the climate. In order to maintain the current rainfall regime (which is already significantly reduced compared to the past), the Amazonian forest area must not fall below 70%. Beyond this limit, the increasingly marked aridity due to an increasingly low forest cover and, therefore, to a lower rate of evapotranspiration, will start a process of irreversible fragmentation of 60% of the Amazon, which will transition into a vegetation characterizing a biome of African savannah.
In 2018, Carlos Nobre, a climatologist and researcher at the University of São Paulo (Brazil), and Thomas Lovejoy an ecologist at George Mason University, Virginia, announced that the Amazonian “tipping point” (“point of no return”) coincided with a deforestation equal to 20-25% of the entire forest area. If this were to happen, it would not only affect the biodiversity of the Amazonian biome, but would cause, as a result of fires or illegal cuts, the release into the atmosphere of billions of tons of carbon dioxide previously absorbed by plants, less and less rainfall which would result in a longer dry season and an increasingly high probability of natural fires; this repeating cycle would lead to the progressive transformation of the Amazonian biome and to very serious repercussions on the global climate, influencing the atmospheric circulation.
A study following the admonition of Nobre and Lovejoy, in collaboration with international researchers, evaluated data collected from 106 plots of one hectare each over a period of 30 years. The analysis showed that species adapted to live in mesophilic conditions are giving way to more xerophilous species. The project only considered areas with low or no anthropogenic impact, showing how even remote and uncontaminated areas exhibit strong indirect degradation.
setting the Amazon rainforest on fire
In 2010, the very strong aridity that hit the Amazon region on more than 3 million km2 also had serious consequences on the flow of CO2 between the forest and the atmosphere, converting part of the ecosystem into a “carbon source” throughout the year. The same research claims that about 20% of the entire Amazon has become a source of carbon dioxide today. The loss of forest topsoil, and the related impoverishment of the soil, which will be discussed in detail below, was catastrophic in 2019, the year in which more than 80.000 fires were registered in the region by the Brazilian National Institute of Space Research (INPE), and hundreds of thousands of hectares of forest were lost especially in Brazil, with a very large part destroyed between July and September of the same year.
The fires started in Brazil during the three summer months also spread to Bolivia; in Peru, the number of fires started during the same period was not a direct consequence of the Brazilian and Bolivian ones, however the amount of CO2 and carbon monoxide released by these was undoubtedly felt by the population, mainly in the Madre de Dios Region. Although some fires, more and more frequent, are natural and caused by lightning, most are intentionally set in the dry period (July - October) following clear cuts on some portions of forest during the wet season (“slash-and-burn”). Most often, arsonists are not experts, and the fire also rages on surrounding forest territories, spreading.
Converting the rainforest into pasture land
The ultimate aim of the shocking deforestation that the Amazon is facing is above all to create new territories to be converted to pasture or crops. It is estimated that about 15% of the entire Amazon rainforest has been deforested and converted into pasture (900.000 km2 ).
Since 1960, when grazing in the Amazon began to develop, the number of cattle has increased from 5 million to 70-80 million in 2002 and to 200 million in 2019. The cattle are brought into the deforested and burnt areas already 3 to 18 months later. Due to an increasingly higher demand for meat in America and Asia, the Amazon deforestation continues and grows each minute. From 2010 to 2017, the export of meat produced in Brazil rose by 25% to reach 1.5 million tons, according to the Brazilian Beef Exporters Association. Hong Kong dominates the ranking with 1.5 billion dollars of Brazilian meat required.
Arial view of rainforest converted into pasture land in Peru. Photo by Elena Chaboteaux
Among the several companies that run the beef export market, Brazilian multi billion dollars company JBS holds about 35% of the international trade. The Washington Post reports that, although it has signed more than one agreement against the Amazon deforestation, to date it is involved in numerous scandals and corruption following evidence of procurement of beef from farms resulting from illegal clear cuts.
The territories converted into pasture, clearly, not only no longer represent a resource in carbon sink but it is estimated that deforestation from grazing is responsible for a quantity of emissions between 499 and 750 million tons of CO2 equivalent per year. Based on studies corroborated by numerous data conducted by the IBGE (Instituto Brasileiro de Geografia e Estatistica), in 2006 it was estimated that there were three head of cattle per inhabitant in the Region of Mato Grosso, Brazil.
In addition to the problems related to the change in use of forest land, grazing threatens the ecosystem by increasing the risk of fire, degrading riparian and aquatic ecosystems (due to the enormous quantities of agrochemicals released into the environment) and causing soil erosion. It often happens that soybean crops are substituted for pasture, not allowing previously deforested areas to start a slow natural evolution and pushing farmers to continue deforestation to make way for farms. Soybean production actually contributes to encouraging the cutting of trees and hides behind a formal and apparent eco-sustainability.
In recent times, there has been an important awareness on the part of small and medium-sized livestock farms, which thanks to government incentives, have planted trees of economic and/or conservation value in the areas used for grazing, in order to increase soil productivity and decrease, even if minimally, the negative impacts listed above. Other landowners have also integrated fruit and wood arboriculture to existing perennial crops.
Written by Elena Chaboteaux
Read the continued pieces by Elena describing other continued threats to the Amazon rainforest in our blog section.
Old growth tree in Peruvian Amazon. Photo by Charlotte Laursen
Sources:
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