Selectively logged Amazon forests recover carbon stock rapidly

Published on
September 22, 2015

With careful management, selectively logged tropical Amazonian forest can recover their carbon stocks within a cutting cycle of 20 to 30 years. An international group of researchers, with Marielos Peña-Claros of Wageningen University amongst them, shows that sustainably logged tropical forests continue to play a key role in global carbon sequestration, with important implications for global climate. The findings are published today in the Cell Press journal Current Biology.

About 20% of the Amazonian forest has been cleared for pastures and agriculture. One fourth of the remaining forest is dedicated to wood production. Most of these production forests have been or will be selectively harvested for commercial timber. Yet little is known of how these forests respond to logging pressure at the regional level. “In our study we assessed the main drivers of time-to-recovery of post-logging tree carbon. This recovery time is of direct relevance to policies governing management practices, such as allowable volumes cut and cutting cycle lengths. Indirectly it is important to forest-based climate change mitigation interventions. Our study is the first comprehensive assessment of post-logging recovery of above-ground carbon stored in trees across the whole Amazon Basin.”

For this study the researchers used the Tropical Managed Forests Observatory, a pan-tropical network aimed to understand the long-term effects of logging on tropical forest ecosystems. They focused on 79 permanent sample plots representing 376 hectares of forested area at 10 sites across the Amazon Basin. Their goal was to determine the rate at which the recovering forest can recapture carbon emitted in logging. “We found that under the current timber harvesting intensities of 10 to 30 m3/ha, Amazon forests logged with reduced impact logging techniques shall recover their initial carbon stock in 7 to 21 years,” project leader Ervan Rutishauser of CIRAD says. “This is fast compared to the recovery time of commercial volumes that can take up to a century to go back to pre-logging stocks.”

The researchers also sought to identify the main drivers determining the time-to-recovery of post-logging tree carbon. Marielos Peña-Claros: “We found that the time to recover initial carbon stocks after selective logging depended almost exclusively on logging intensity, that is, on the amount of tree biomass removed or killed during timber harvesting. Interestingly, other abiotic and biotic factors did not play a role.”

These results also imply that the time to recover carbon stocks does not significantly vary across the entire Amazon Basin, despite a well-known Northeast-Southwest environmental gradient. The findings can serve as a useful decision-making tool for forest managers and policymakers. However, poor logging practices continue to degrade many forests, while others continue to be cleared and converted into more profitable pasture and plantations. “While carbon-oriented forestry might trigger a shift toward sustainable forest management, wood supply shall remain the principal objective of forest management,” Rutishauser said. “Our aim is to provide scientific evidence and practical guidance to define sustainable harvest intensities that ensure both long-term timber harvest and maintenance of carbon stocks.”

Read the article ‘Rapid tree carbon stock recovery in managed Amazonian forests’.