Measuring peat degradation in the Peruvian Amazon. Photo by Kristell Hergoualc’h/CIFOR-ICRAF

Deep in the palm swamps in Peru’s flooded Amazonian forest, thick layers of peat lock away large amounts of carbon. Scientists know that cutting the trees and exposing the soil releases greenhouse gases. Now, however, a new study by CIFOR-ICRAF researchers shows that degradation of the palm swamps in recent decades — by cutting some trees, but not clearing the entire swamp — has actually caused more greenhouse gas emissions than deforestation.

The findings underscore the importance of including peatland degradation, not just deforestation, in Peru’s calculations of its greenhouse gas emissions, as well as the need for policies to help keep the country’s large expanses of Mauritia flexuosa palm swamps intact.

“Many countries don’t have data about forest degradation,” said Kristell Hergoualc’h, a senior scientist in ecosystem functions with CIFOR-ICRAF’s Climate Change, Energy and Low-Carbon Development Team and a co-author on the paper. “In Peru, that information has been lacking for Amazonian peatlands.”

Peru recently developed a nationally determined contribution (NDC), its greenhouse gas emission reduction commitment under the Paris Agreement on climate change, for deforestation on peatlands. But the study, which mapped deforestation and forest degradation on peatlands, found that while both deforestation and degradation rose between 1990 and 2018, the greatest harm came from degradation.

Emissions higher from degradation

The researchers used satellite data to map deforestation and degradation in palm swamps over 28 million hectares in Peru’s Ucayali and Loreto regions from 1990 to 2007 and 2007 to 2018. The study, which used decreased density of tree cover to determine degradation, marks the first time degradation has been mapped in those regions.

Using measurements from earlier field studies in different types of swampland, they calculated the amount of carbon stored in peat and the emissions resulting from deforestation and degradation. 

About 5.1 million hectares of the study area were peatlands, storing an estimated 3.88 petagrams (4.3 billion tons) of carbon. The study found that about half a million hectares of that area had been deforested or degraded between 1990 and 2018. Although deforestation increased the most, more than doubling from 1,900 hectares annually between 1990-2007 to 4,200 hectares a year between 2007-2018, it was degradation that accounted for most of the change — about 85% of the change in tree cover.

As a result, carbon emissions from degradation were more than twice the amount from deforestation. Between 1990-2018, emissions from deforestation totaled around 12.9 teragrams (14 million tons), compared to 26.3 teragrams (29 million tons) of emissions from degradation during the same period. While emissions from deforestation result from a combination of felling trees and carbon loss from peat, virtually all the emissions from degradation come from peat, Hergoualc’h said.

The findings underscore the importance of including degradation of peatland in Peru’s carbon accounting, the researchers said. 

Sustainable harvesting is key

A key factor in degradation of palm swamps is the technique used for harvesting the fruit of the Mauritia flexuosa palm, called aguaje in Peru. Aguaje fruits are sold by street vendors and in markets in cities like Iquitos and Yurimaguas, and the pulp is used to make juice, ice cream and frozen fruit treats. As urban areas have expanded in the last few decades, so has market demand for the fruit.

Aguaje traditionally has been harvested by cutting down the entire tree to slice off the large bunches of fruit. That results in degradation of the palm swamp, as trees are felled and not replaced, the researchers said. Because only the female, fruit-bearing trees are cut down, the traditional harvesting method eventually reduces reproduction.

The researchers found greater degradation along the Marañón River near Iquitos, Peru’s largest Amazonian city, as well as near Yurimaguas, also a large market for the fruit.

Some government programmes and non-profit organizations encourage rural residents to climb the palms and cut down the huge bunches of aguaje, rather than felling the palms to gather the fruit. Around one community in the Pacaya Samiria National Reserve, a protected area, the forest showed recovery after the community began using sustainable harvesting methods.

“Some communities are dedicated to climbing the aguaje palms and not chopping them down,” said Matthew S. Marcus, the study’s lead author and an assistant professor at the University of Arizona. “The health of the palm swamp in those areas is clearly better.”

Policies that provide incentives for sustainable harvesting of aguaje can help reduce degradation, Hergoualc’h said. Monitoring of the harvest and traceability of fruit to ensure that it was harvested sustainably remain a challenge, however.

Local and regional-level policy makers also need more information about palm swamps and their importance for meeting the country’s climate goals, she added. 

While the new study revealed the extent of carbon emissions from palm swamp degradation, the researchers say more field work or “ground truthing” is needed to confirm the correlation between canopy density and peatland degradation. Marcus is also studying a group of communities to understand how they harvest and why they use sustainable techniques or opt to cut trees.

“To draw conclusions about peatlands, you have to go to the field,” Hergoualc’h said. “We’ve done various field studies of carbon storage and emissions in areas of low, medium and high tree density, but we need to continue those studies and do them consistently across the entire Amazon.” 

For more information, please contact: Kristell Hergoualc’h, k.hergoualch@cifor-icraf.org

Acknowledgments

CIFOR-ICRAF’s research on Peru’s palm swamp peatlands has been done in partnership with the Peruvian Amazon Research Institute (IIAP) through the Global Comparative Study on REDD+ (GCS), funded by NORAD, and the Sustainable Wetland Adaptation and Mitigation Program (SWAMP), a USAID-funded effort by the Center for International Forestry Research (CIFOR) and USDA Forest Service.