Earth’s lungs, the Amazonian forest plays an essential role for terrestrial life. In addition to sheltering an exceptional biodiversity, it participates in the regulation of the climate. From the sky, satellites monitor its health. Combining satellite images with human initiatives on the ground allows us to fight against massive Amazon deforestation. Thinking globally and acting locally are the solutions to this environmental challenge.
The Amazon rainforest is one of the green lungs of our planet, due to its unique natural characteristics and size. With its surface of 6.5 million km2, it enriches nine South American countries with its incredible biodiversity. Among them, Brazil which it covers 63%. But it is because it is a fabulous natural reservoir that it is overexploited. Since 1970, its forest, soil, rivers, its whole ecosystem is damaged by human activities. Gold mining and deforestation by plundering the Amazonian forest contribute to global warming. Amazon deforestation causes almost 20% of the world’s carbon dioxide emissions.
Protecting the Amazon rainforest is therefore a global but also a local issue. Without its vegetation cover, the ecosystem services it provides no longer exist. And many indigenous peoples depend on its services. Actions to defend this green lung are flourishing throughout the world. Throughout our article, we will see how satellite data can assess anthropogenic pressures. And finally, we will take the example of French Guiana, which is committed to fighting Amazon deforestation.
The notion of a green lung implies breathing. In its human version, respiration consists of inhaling oxygen and exhaling carbon dioxide. The exact opposite of the plant world where carbon dioxide is captured by the leaves during photosynthesis. ( During this process, the sun’s rays are used to oxidize water, reduce carbon dioxide and thus produce carbohydrates, the energy necessary for plant growth. )
The Amazon rainforest is responsible for about 5 to 6% of the oxygen production on earth (compared to 50% for the oceans). In a state of equilibrium, a forest rejects as much carbon dioxide as it absorbs. But the imbalance, which can be caused by man through deforestation, means that a forest can generate more carbon dioxide than it captures. To reach a positive balance implies a protection and a preservation of the forest for a sufficiently long duration to arrive at this stage of “generator” of oxygen. This state is essential for the climatic balance and the sustainable development of the underlying ecosystem.
On the temporal scale, and like any act of destruction in everyday life, the degradation of an ecosystem takes a few months. In contrast, it takes years to restore it. Hence the importance of preservation actions, which are essential for maintaining the balance of ecosystems.
On both sides of the Atlantic Ocean, we find two very extensive areas that have reached this stage of “generators”, the Amazonian and African forests. These lungs of the terrestrial ecosystems and their biodiversity are true world heritage of humanity. Together they support life, its maintenance and its quality.
Tropical forests are carbon sinks storing a considerable amount of carbon. For example, it is estimated that the primary rainforest of French Guiana stores about 1 billion tons of carbon. It thus compensates our human activities equivalent to a country like Germany (per year). The monitoring and continuous observation of these sinks is therefore essential to ensure their preservation.
The satellite tool is particularly interesting and relevant for large-scale monitoring. Moreover, when it comes to vegetation, the sensors available on satellites are very rich. They allow us to observe, measure and quantify the evolution of the vegetation and its health.
After having observed the seasonal evolution at the continental scale by underlining this breathing effect, we focus on the French Guiana region. By using a simple indicator, the NDVI (Normalized Difference Vegetation Index), we are able to visualize the change in vegetation. This indicator measures the difference between the light reflected in the visible and the near infrared spectrums. It indicates the density of the green color on a land surface. A satellite flying over the earth from hundreds of kilometers away can regularly map all areas of vegetation. It quantifies their state of health at resolutions ranging from a few dozen centimeters to a few hundred meters.
Yearly average NDVI comparison between Guyane Francaise and South America between 2000 and 2020:
Monthly average NDVI comparison between Guyane Francaise and South America between 2000 and 2020:
We can observe a good seasonality in the NDVI trend over each years. To find out more about the seasonality, we can look at the overall month-wise average NDVI between 2000 and 2020.
Used alone, the vegetation index presented above has its limits. Indeed, often the Amazon deforestation gives way to various mono-cultures. The latter continue to appear as vegetated areas using this index. We will then have to combine the NDVI with another measure more representative of the structure of the trees or artificial intelligence methods where abrupt changes in vegetation (remember that we can have several measurements per day) are detected, recorded and tracked. These methods allow us to understand the dynamics of change. We can then alert in case of detection of anomalies.
Applying this type of methods on the Amazonian forest allows us to note a quasi stability of the extent of the forest in French Guiana (decrease of 0.5% during the last 20 years). Elsewhere in the Amazon, it decreases considerably. For example, 10% decrease in the adjacent region of Para in northern Brazil over the same period.
This scientific study of the evolution of the vegetation cover and the apparent growing discrepancies exposes a deeply weakened region. Reforestation campaigns are often identified as the only solution to the deforestation phenomenon. The latter has already destroyed 17.3% of tropical rainforests since 1990. However, silvicultural growth is relatively slow. Initiatives to prevent the destruction of ecosystems should also be taken into account.
Rich in biodiversity but also very fragile, French Guiana does not escape the local South American anthropic pressures. This region proposes several initiatives to support sustainable development of environmental resilience. Covered by 92% of primary forests and a complex river network, it combines many challenges in terms of sustainable development. Its development has been thought to respect its populations, its patrimonial and environmental wealth.
Created in 2007, the Amazon Park covers an area of 20,300 km2. Its Brazilian extension, located in the heart of Guiana, is an example of this wealth. It connects the park of the Tumucumaque Mountains. It is considered the largest tropical area under regional protection in the world. Officially created by the Law of July 22, 1960, and thus officially recognized by the government, its status gives an important place to sustainable development in these territories.
Sustainable development has a particular significance in these areas. Indeed, although they present an extraordinary biodiversity, anthropic externalities destabilize the whole. Among the most threatening are gold prospection, exponential urban development and poorly developed water resource management operations. One project in particular has been highly controversial in recent years because of its ecological impact: the Montagne d’Or project. This open-pit gold mine project, nearly 3 km long, planned to deforest more than 1500 hectares. This project was finally cancelled because of its contradiction with the locals and sustainable development of French Guiana and its impact on global warming.
In addition to resilience actions through reforestation, campaigns against the destruction of ecosystems exist. The following initiatives can be highlighted in Guiana.
Forests are important carbon sinks but they can also release it when they are destroyed. Created with the support of WWF in 2014, this educational trail allows you to discover the processes of production and storage of carbon in ecosystems. The focus on the carbon cycle helps to understand the link it has with global warming. In the heart of the forest itself, over 1.5 km, it is an awareness initiative that is directly integrated into its environment.
Rich in mineral resources, French Guiana is regularly impacted by illegal gold panning. The mining projects use explosives and sulfur which disturb the ecosystems. One of the solutions being considered is to extend the protection of these areas through the recognition of parks, reserves, indigenous land protection zones and sustainable management. It is also pursuing its efforts through its integration in REDD+ mechanisms by being part of the Regional Technical Platform for the Development of REDD+ on the Guiana Shield with the ONF International.
Other initiatives are already planned to continue prevention efforts. In 2021, the roadmap put forward by the “Regional Agenda of Guiana for 2021” are the following
In conclusion, the Amazon rainforest is a fragile space where it is possible to perceive an acceleration of deforestation, destabilizing all ecosystems. Indeed, the use of satellite data highlights the consequences of the anthropic footprint, especially concerning the renewal of the vegetation cover. Reforestation being a method of long-term resilience, we have highlighted various preservation initiatives at the source. The example of French Guiana reflects a local will to pursue its development while preserving its natural heritage. Many challenges are related to the profound changes that can be observed. The heart massage to keep the green lung of the Earth alive must be relentlessly undertaken in the light of tomorrow’s challenges.