Secondary forests in the Amazon are limited by human activities

The regrowth of deforested areas in the Amazon is greatly limited by climate and human disturbances, according to a new study from the University of Bristol. Secondary forests regrow naturally on land that was previously cleared for agriculture and is now abandoned. 

The secondary forests, which help absorb CO2 from the atmosphere, develop at different rates. The researchers have identified a link between slower tree-growth and land previously scorched by fire. 

The findings suggest that there is a need for a better protection of these forests if they are to help mitigate the effects of climate change.

“Our results show the strong effects of key climate and human factors on regrowth, stressing the need to safeguard and expand secondary forest areas if they are to have any significant role in the fight against climate change,” said study lead author 

Viola Heinrich.

Tropical secondary forests can absorb carbon up to 11 times faster than old-growth forests At the same time, however, many factors can influence the spatial patterns of regrowth.

The investigation was focused on a combination of satellite-derived images that can be used to detect changes in forest cover over time. This allowed the experts to identify secondary forest areas and their ages. 

The team also analyzed satellite data that can monitor important factors that influence regrowth, including aboveground carbon levels, environmental conditions, and human activities.

The study revealed that the impact of human disturbances in the past, such as fire and repeated deforestations, reduced the regrowth rate by 20 to 55 percent across different areas of the Amazon.

“Across the tropics several areas could be used to regrow forests to remove CO2 from the atmosphere,” said study co-author Dr. Luiz Aragão.

“Brazil is likely to be the tropical country with the largest potential for this kind of nature-based solution, which can generate income to landowners, re-establish ecosystems services, and place the country again as a global leader in the fight against climate change.”

The researchers will now focus on applying their methods to estimate the regrowth of secondary forest across the tropics.

“The findings in our study highlight the carbon benefits of forest regrowth and the negative impact of human action if these forests are not protected,” concluded study co-author Dr. Jo House.

“In the run up to the 26th Conference of the Parties, this is a time when countries should be raising their climate ambitions for protecting and restoring forest ecosystems, not lowering them as Brazil seems to have done.”

The study is published in the journal Nature Communications.

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By Chrissy Sexton, Earth.com Staff Writer