Deforestation is a problem that affects many regions of the planet directly, but that generates indirect impacts throughout the globe. We are used to hearing news about the alarming rate of forest mass loss but, from time to time, data emerges that give rise to hope.
The last of these has been given to us by satellite measurements.
215 million hectares. A study based on these satellite measurements has estimated that some 215 million hectares of land in tropical areas of the world could recover their vegetation naturally. This represents an area larger than the size of Mexico or half the area of the European Union.
This possibility has enormous potential to slow down the rate at which the concentration of greenhouse gases grows: this hypothetical forest mass could store up to 23.4 gigatonnes of carbon, according to the calculations of the team responsible for the study. This reforestation would not only affect the climate, it would also increase biodiversity and help solve other problems, for example by improving water quality, the team explains.
“Planting trees in degraded landscapes can be expensive. By taking advantage of natural regeneration techniques, nations can meet their restoration goals in a cost-efficient way,” Brooke Williams, co-author of the study, explained in a press release.
Mapping reforestation. The study resulted in a map of the tropics in which the capacity for reforestation is evaluated with a definition of 30 kilometers. This shows us that there are five countries where more than half (52%) of the regions with “strong potential” for this reforestation are concentrated. These are Brazil, Mexico, Indonesia, China, and Colombia.
From orbit. To create this map, the team turned to satellite images of small areas where vegetation had grown. They studied images captured between the years 2000 and 2012, which they combined with observations from 2015 with which to validate whether this growth had been fleeting or had been maintained over time.
They turned to a machine learning tool (machine learning) to locate and discard those areas that had been replanted by people, in order to focus the study on natural growth. They combined these observations with measurements of various types: soil quality, terrain slope, population and road density, among other environmental and socioeconomic factors.
Main determinants. Knowing what conditions existed in the reforested environments in that period helped the team estimate the potential of deforested land to regenerate naturally. They observed that the factors that most helped determine whether an area would end up reforested were proximity to a forest, its density, and the carbon content of the soil.
Details of the study were published in an article in the journal Nature.
From the possible to the done. The results of the study give some room for hope, but whether this recovery materializes, or whether it is not spoiled by the advances of deforestation, will depend on the human factor. It is not only about allowing growth in net terms: if one of the factors for natural regeneration is the proximity of forests, protecting these is of vital importance.
The study also refers to natural reforestation. Knowing the areas prone to these can help us focus efforts on areas where human intervention may be more important, whether planting new trees or protecting vulnerable areas.
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Image | David Riaño Cortés
