By Madeleine Gregory
The Amazon is in trouble. From the satellite’s vantage, there’s sections of the rainforest that still resemble its storied past: mottle mats of deep green traversed only by the great brown snake of the Amazon River. More and more, though, the view is interrupted by bare soil spreading across the landscape like termite damage, a flare of wildfire smoke, or the perfect circles of carefully tended crops.
For nearly forty years, The Brazilian Amazon Satellite Monitoring Program (PRODES Amazonia) has been tracking losses in the Amazon rainforest. But in the process, they’ve left out big chunk of land—nearly 280,000 km2, or roughly the size of Ecuador. This land, classified as “non-forest vegetation,” is made up of open ecosystems like savannas, grasslands, seasonally flooded areas, and ecotones (transitions zones between biological communities). While they get less airtime than the rainforest, these non-forest regions are vital biodiversity hotspots, home to many endemic species.
In a study published in Communications Earth and Environment in August, researchers turned their attention to these understudied ecosystems. They found that, between 2000 and 2022, the Brazilian Amazon lost about 30,000 km2, or 10%, of natural non-forest vegetation.
“These ecosystems are among the least protected in the Amazon biome,” lead author Cassiano Messias said. “The continued loss of these ecosystems, many of which occur as isolated islands within the Amazon rainforest, represents a significant loss for both scientific knowledge and the biodiversity of the biome.”
Researchers used images from Landsat satellites to build a basemap for the year 2000 and then track changes up to 2014. From 2016 to 2022, the team used images from Sentinel satellites. To detect vegetation loss, the researchers did a visual assessment of changes in color, shade, texture, and shape of land. While the contrast between forested and deforested regions is pronounced in satellite imagery, non-forest ecosystems are much more heterogenous, and so their losses can be harder to track. Grasslands, for example, can be confused with cultivated pastures. To tackle this challenge, researchers used false-color images in a band combination commonly used for vegetation analysis, combining shortwave infrared, near infrared, and red bands to create images in which vegetation appears green and bare soil appears magenta. The researchers then worked with regional experts and on-the-ground data to validate their findings.
The hotspots of non-forest vegetation loss were the states of Mato Grosso, Roraima, and Amapá. The rate of loss was highest between 2001 and 2002, then declined until 2008. Losses were stable until 2014, when non-forest loss trended upward again. These trends track closely with trends in deforestation, suggesting that common factors are driving destruction across ecosystems. The researchers note that the decline in vegetation loss after 2004 could be a response to environmental protections put in place by the Brazilian government, while the increase in vegetation loss after 2013 could be influenced by the rising price of soybeans or an increased demand for cattle. Clearing land for soybean cultivation and cattle ranches is a main driver of vegetation loss in the Amazon.
To continue their work, the team built PRODES NF, a system designed to serve as a complement to PRODES. The Brazilian government can use PRODES NF annually to monitor changes in non-forest vegetation, the results of which are available on the TerraBrasilis portal. Alongside PRODES NF, a complementary research effort developed a monitoring tool called DETER NF, which provides daily alerts for vegetation suppression and fires in non-forest regions. While they keep track of the losses, the researchers also advocate for more research on these critical, understudied ecosystems to better understand the role they play in protecting the region’s biodiversity.
References
Messias, C. G.; de Almeida, C. A.; Silva, D. E.; Soler, L. S.; Maurano, L. E.; Camilotti, V. L.; Alves, F. C.; da Silva, L. J.; Reis, M. S.; de Lima, T. C.; Renó, V.; Lima, D. L. C.; Belluzzo, A. P.; Quadros, C. B.; Barradas, D. C. M.; de Moraes, D. R. V.; Bastos, E. F. M.; Cunha, I. P.; de Souza, J. J.; de Barros, L. S. Unaccounted for Nonforest Vegetation Loss in the Brazilian Amazon. Communications Earth & Environment 2024, 5, 1. https://doi.org/10.1038/s43247-024-01542-0
National Geographic. “The Amazon Rainforest.” Education.nationalgeographic.org, 2023, education.nationalgeographic.org/resource/amazon-rainforest/.
