Island logging must go beyond current ‘best practices’ to avoid erosion: New study


  • In a new study, a team of ecologists modeled what would happen if companies were allowed to log the forests of Kolombangara Island under several management scenarios, including those designed to minimize soil erosion and protect water quality.
  • As the model simulated higher proportions of land clearance, the most stringent methods couldn’t stop the soil erosion that would foul clean water and agricultural land for the island’s people, as well as the habitats of local aquatic plants and animals.
  • The Kolombangara Island Biodiversity Conservation Association is spearheading an effort to get intact forests at elevations higher than 400 meters (1,310 feet) designated as a national park on the island.

For logging on islands to be sustainable, it must adhere to clearly defined parameters that limit the impact on water quality and the erosion of topsoil, according to new research in the Solomon Islands of the southwestern Pacific Ocean.

“Saving tropical forests worldwide depends upon tighter regulation of national laws and policies, as well as local buy-in for forest management,” Stacy Jupiter, one of the study’s authors and the director of the Wildlife Conservation Society’s Melanesia program, said in a statement. “This study nicely illustrates why we need to take action now to protect the world’s remaining intact forest landscapes in order to preserve their biodiversity and important ecosystem services for people.”

Active logging area on slopes of Kolombangara Island in the Solomon Islands. Image by Joe McCarter/WCS.

It’s no secret that island ecosystems are especially delicate, as are the clean water, habitat and resources they provide. At the same time, some of those resources, such as the timber found in the Solomon Islands’ tropical forests, can help to bolster an economy struggling with high unemployment and few sources of revenue. Logging interests are increasingly targeting the forested slopes of the country’s volcanic islands.

The Solomon Islands has laws to protect the most sensitive areas of forest, including those 400 meters (1,310 feet) above sea level or with particularly steep slopes. But in spite of those laws, crews are still sometimes given access, write the authors of the paper in the journal Environmental Research Letters on April 17.

As part of their research, a team of scientists modeled what would happen if companies were allowed to log the forests on Kolombangara Island under several management scenarios. More than half of Kolombangara Island is forest, and no commercial logging has ever occurred there — part of the reason that it still teems with aquatic plants and animals, including several species of freshwater fish found nowhere else.

River plume draining into the sea full of sediment from upstream logging activity in Western Province, Solomon Islands. Image by Wade Fairley/WCS.

The highland trees on Kolombangara, where the elevation tops out at 1,750 meters (5,740 feet), also anchor ecosystems that provide fertile farmland and clean water to the people who live on the island. But as the team simulated higher and higher proportions of clearing for logging, they found that current “best practice” methods couldn’t stop the soil erosion enough to avoid fouling those vital linchpins of the local environment.

“When land-clearing extent reached 40 percent in our models, international standards for safe drinking water were exceeded nearly 40 percent of the time, even if best practices for logging were followed,” Amelia Wenger, an ecologist at the University of Queensland in Australia and the paper’s lead author, said in the statement. “Loss of the upland forest will compromise local access to clean water essential for drinking, bathing, and household washing.”

To protect this critical area, a group of indigenous landholders called the Kolombangara Island Biodiversity Conservation Association is working to get intact forests higher than 400 meters designated as a national park. Ferguson Vaghi coordinates the association, which aims to protect the natural resources on Kolombangara Island as well as to look out for the social and economic interests of local communities. It currently looks after a 194-square-kilometer (75-square-mile) reserve of the island’s high-elevation forests.

Community rangers inspecting recent clearing from logging activity in Western Province, Solomon Islands. Image by Joe McCarter/WCS.

Vaghi said that this research demonstrated that land managers must consider the ripple of effects that logging would trigger.

“Previously people in Solomon Islands made decisions about logging from a selfish economic perspective,” he said in the statement. “This study highlights that we also need to consider the impacts to the downstream environment.”

Banner image of a river plume by Wade Fairley/WCS.


Wenger, A., Atkinson, S., Santini, T., Falinski, K., Hutley, N., Albert, S., … & Jupiter, S. (2018). Predicting the impact of logging activities on soil erosion and water quality in steep, forested tropical islands. Environmental Research Letters.

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South Africa Today – Environment

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