What are secondary forests?
Secondary or regenerated forests are areas where new tree seedlings
- natural regeneration, which occurs when new seedlings or sprouts appear on trees left on or near the site (for example, aspen).
- artificial restoration, better known as tree planting
Parts of the Amazon, Panama and many other placeswhat we consider to be a place of untouched virgin forests are in fact the result of centuries of natural reforestation. Much of this renewed growth in the Americas occurred when American Indians, around the time of European colonization, abandoned their fields and drastically reduced their agricultural activities, while the need for forest conversion by early colonists was negligible.
After a series of devastating firesand barbaric tree felling, restoration of the Amazon forests seems unlikely. In addition, scientists are asking the question: will restored forests also work well as the lungs of the Earth? Will biodiversity be restored? How quickly do forests generally recover?
Unfortunately, today forest restoration is notcan happen as easily as before. Particularly where deforestation and forest degradation continue unabated and soil erosion is a serious problem, such as the Brazilian Amazon. And many of the countries that pledged to restore 350 million hectares of degraded land as part of the Bonn Challenge by 2030 are only seeing the situation worsen. Especially in Brazil, and here's why.
What's wrong with the Brazilian government?
Several events that took place in 2020 clearly show that the Amazon forests in Brazil are only waiting for degradation and complete disappearance.
For starters, it was in 2020 that vast areas of South America were devastated by unprecedented drought and fires. Thousands of living species died, forests turned into steppes and deserts.
Experts say that forest fires in the region,which covers Brazil, Argentina, Bolivia and Paraguay have reached critical levels in 2020. In early August, Brazilian authorities reported that forest fires in the Amazon increased by 28%. The scale of fires may reach the same levels as in 2019. However, the situation got out of control, and experts admitted that the situation in 2020 is much worse.
Fires are fueled by ideal conditions, includingstrong winds, temperatures above 40°C and a dry season when farmers use slash-and-burn farming methods to try to regenerate the soil.
However, the main problem is not farmers. The country's President Jair Bolsonaro encourages agricultural and mining activities in the Amazon - this is the main reason for the blazing fires.
According to images of the Brazilian National Space Agency, the area of fires in August increased by 28% compared to the same month last year.
These figures raise concerns among activists - theyare worried that the fires could reach the levels they recorded in August and September 2019. “This is a terrible sign,” said Ane Alencar, director of the Brazilian Institute of Environmental Research in the Amazon. “We expect the number of fires to only increase in August, and September will be even worse.” The activists' fears were justified.
And what is the government doing in response to save the forests? Canceling all measures to protect mangrove forests!
At the end of September the presidential governmentIn Brazil, Bolsonaro has repealed regulations protecting mangroves and other fragile coastal ecosystems. Of course, this threatens the "permanent protection zones" created in 2002 to preserve Brazil's tropical mangroves and scrub sand dunes along its Atlantic coast.
Environmentalists warned that the abolition of the rules would open up such land for development, with catastrophic consequences for their ecosystems.
“These areas are already under intensepressure from real estate tycoons, ”explains Mario Mantovani, head of SOS environmental group Mata Atlantica. "The 2002 rules at least protected them from further destruction," he said in an interview with AFP, calling their abolition "a crime against society."
The new ruling is part of a series of controversialenvironmental decisions by the far-right president, who has overseen the deforestation of the Amazon rainforest and the Pantanal wetlands since taking office in January 2019.
In other decisions, the government also canceleda measure requiring environmental permits for irrigation projects, and the president has allowed cement companies to burn empty pesticide containers to be converted into concrete, which environmentalists say is highly polluting.
It should be noted that the problem with fires, according toessentially, is not solved in any way. In addition, “in Brazil, 'the number of volunteer contracts' has dropped by 58%,” said Alika Tuo of the Centro de Vida, referring to people who had previously mobilized to put out fires. She firmly places the blame on Brazilian President Jair Bolsonaro, a notorious climate change skeptic.
If there is no hope for the government, can naturally regenerated forests somehow save the day?
The potential of reforested forests - is there salvation?
So how can reforestation support biodiversity in the 21st century?
Naturally or "passively" restored forests,certainly do better at restoring biodiversity than monoculture plantations. But this is slow. It may take centuries of revival before the original population of species returns to their original marks. Climate change, habitat fragmentation and fires can work together to slow down biodiversity recovery. However, this should not prevent us from naturally regenerating forests to protect biodiversity.
Recent research shows that passivereforestation may be cheaper and more socially acceptable than tree planting schemes. However, for sound decision making and cost effectiveness, it is essential to be able to predict where passive reforestation is more likely and where it is more likely to persist over time after farmland is abandoned. Another important element is knowing how much biodiversity both humans and nature need in reforestation to provide basic services such as insect pollination, hydrological regulation, erosion and pest management.
Reforestation planning andBiodiversity restoration also requires consideration of impacts on local livelihoods that may be affected far beyond actual restoration projects. For example, given the importance of Amazon moisture to Brazilian agriculture, it has been argued that much of Brazil's national goal of rehabilitating 12 million hectares of degraded land by 2030 should be met in the southern and eastern Amazon.
Forest biodiversity has gradually recovered inseveral locations across Latin America through passive recovery over the past decade, covering at least 2 million hectares, including parts of the tropical Andes. And natural reforestation in mountainous areas has important implications for watersheds affected by deforestation.
With limited funding and sometimesIn a short-term approach to restoration projects, the world needs both natural and active reforestation to accelerate the recovery of forest biodiversity, or, in some cases, a combination of both. Local conditions vary, and restoration efforts require approaches tailored to those conditions, notes CIFOR Forests News. These include changing stakeholder aspirations and goals, legal and regulatory changes, and natural cycles such as fires and droughts. There may also be failures due to lack of technical knowledge or access to it, especially in developing countries.
Will regenerated forests cope with carbon sequestration?
"The ability of secondary forests to absorb carbonknown from studies that include monitoring areas in the field. Their average net carbon sequestration rate in neotropical regions is 11 times higher than that of old-growth forests. However, the long-term dynamics of secondary forests in Brazil and around the world are poorly understood, ”said Cruz de Aragao, one of the authors of the INPE study.
In other words, regenerated forests are excellentcope with carbon absorption. Much better than old growth forests. But no one is in a hurry to restore them, the process itself takes a very long time, and the size and average age of these often abandoned areas where vegetation is growing again were still unknown
This knowledge is fundamental toso that Brazil can meet its commitments under the 2015 Paris Agreement. By 2030, the country is obliged to restore 12 million hectares of forest.
Age and size of secondary forests in each biome
The study calculated the increase in secondaryforests with anthropic cover (plantations, pastures, urban infrastructure or mining) and their age, biome by biome. According to scientists, the secondary growth of a forest is not linear and correlates with age, so it is important to establish the age of the forest in order to estimate its carbon uptake.
The data showed that between 1986 and 2018in Brazil, a total of 262,791 km² of secondary forest has been restored. This corresponds to 59% of the old growth forest area cleared in the Brazilian Amazon between 1988 and 2019.
Восстановленные леса были расположены по всей Brazil, and the smallest share was in the Pantanal [wetlands in the central-west region], accounting for 0.43% [1,120 km²] of the total mapped area. The largest share was in the Amazon - 56.61% [148,764 km²]. The Caatinga [semi-arid biome in the northeast] made up 2.32% [6,106 km²] of the total area and had the youngest secondary forests - more than 50% were between one and six years old. The Atlantic Rainforest is the second largest the size of the restored areas, with 70,218 km² (or 26.72% of the total area), and has the oldest.
Cruz de Aragao
Four steps of research
The researchers used the method implemented inGoogle Earth Engine (GEE), and time series data from the Brazilian Annual Land Use and Land Cover Mapping Project (MapBiomas) since 1986. They created 131 reference maps over 33 years between 1986 and 2018, covering secondary forests divided by biome. Source material is available here and here.
By eliminating the wetlands, they performedmethodology in four steps. First, 34 maps from MapBiomas were reclassified into binary maps in which pixels representing forest areas were assigned a value of "1" and pixels representing other land uses and coverage types were assigned a value of "0". Mangroves and forest plantations were excluded. Each pixel corresponded to an area of 30 meters by 30 meters.
The scientists then measured the growth of secondary forestareas, using the maps created in the previous stage, pixel by pixel. In the third stage, the researchers created 33 more maps showing the size of secondary forests from year to year.
Finally, it remained to calculate the age of the mapped secondary forests. To do this, scientists added up maps of the annual growth of secondary forest obtained at the previous stage.
Emissions and potential of forests
Potential net carbon uptakesecondary forests in each Brazilian biome from 1986 to 2018 were calculated pixel by pixel, assuming an average linear net carbon uptake rate of 3.05 Mg C ha −1 year −1 (megagrams per hectare per year) during the first 20 years. years of secondary forest succession regardless of age. It was assumed that net consumption would be zero in 20 years.
The Pantanal made the least contribution to its shareaccounted for 0.42% of forest carbon sequestration between 1986 and 2018. The Amazon biome contributed the most, at 52.21%. The study concluded that the estimated carbon sequestration of all secondary forests in Brazil offset 12% of carbon emissions from deforestation in the Brazilian Amazon alone between 1988 and 2018. But in reality, this is not very much.
What's the bottom line?
Considering how important the Amazon is, restorationthe forests must continue to go on. The total area of secondary forests, as can be seen, has not increased much compared to the area of deforested forests, scientists note. It is related to land use, especially in the Amazon. Deforestation means the loss of other benefits of natural forests, which play an irreplaceable role in the hydrological cycle and in maintaining biodiversity - much more than secondary forest. They are also more resilient to climate change.
New data could help Brazilian politiciansdecide on how to protect biodiversity and plan the use and protection of secondary forests. “They are not protected and provide important services. In fact, they usually suffer the most from land-use cycle conversions in the Amazon. Now we can understand why they are so urgently deserving of protection, ”the scientists conclude.
Will the authorities hear scientists?
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