Carbon Losses Up as Logging Fragments Tropical Forests in Malaysia

(CN) — Though the destruction of tropical rainforests is known to negatively impact global carbon levels, new research revealed Monday shows that excessive logging also affects the growth and life of nearby trees left behind.

In a study published in the Proceedings of the National Academy of Sciences, scientists from Arizona State University and Harvard discovered that forest fragmentation caused by logging creates “edge effects” around the remaining forest that decrease the trees’ carbon storage.

The blue regions are oil palm plantation; the forest regions (yellows and greens) are colored by tree height, which is a proxy for carbon. (Global Airborne Observatory, ASU Center for Global Discovery and Conservation Science)

These effects include environmental alterations like decreased soil moisture and increased sunlight, which can result in increased mortality and decreased tree growth. Trees are an important part in combatting greenhouse gases, as they absorb harmful carbon dioxide.

To reach these findings, researchers used airborne mapping to examine changes in forest structure and canopy characteristics along the boundaries of forests and oil palm plantations in Malaysian Borneo.

The scientists discovered significant changes along forest edges, including canopy traits related to trees’ ability to absorb sunlight. They found an average 22% decline in aboveground carbon storage in forest edges that extend over 300 feet into interior forests.

“Our study suggests a need to mitigate edge-related declines in forest carbon stocks by creating buffer zones between intensively farmed areas and forest ecosystems,” said lead author Elsa Ordway, research fellow at Harvard University and ASU. “Although our results indicate that some forests are more vulnerable to edge effects than others, such a strategy could be implemented at scale to reduce the negative impacts of land-clearing on remaining forests.”

The research team also found that the negative effects worsened over time, extending deeper into remnant forests. Among forests set aside for conservation, the scientists found that they were also vulnerable if located next to a plantation.

“Not all forest-agriculture boundaries are created equal, and most remaining forests change for many years following the original land conversion that takes place nearby, said author Greg Asner of ASU. “The importance of this discovery trickles all the way down to how conservation managers work to mitigate biodiversity losses associated with agricultural expansion.”

The researchers said their findings have global implications as almost 20% of remnant tropical rainforests are located within 300 feet of a non-forest edge.

“We have 10 years to maintain our terrestrial carbon sinks if the world has any hope of staying below 1.5 degree Celsius global average temperature rise. The research presented here shows that a moratorium on forest conversion and emissions must occur even sooner than 2035,” said Eric Dinerstein, director of Biodiversity and Wildlife Solutions at Resolve.

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