Logging tropical forests jeopardizes fisheries important for food and livelihood

The study focused on Kolombangara, an island located in Western Province, Solomon Islands, and used cutting-edge methods for tracking soil erosion and sediment runoff from land to pinpoint areas where historically healthy reefs may have been negatively impacted by clear-cutting and deforestation. The maps that scientists generated also helped them identify currently healthy coral reefs that are at risk of impact should deforestation in sensitive areas continue on the island.

“Kolombangara has a long history of logging activities. We found that coral reef areas that had experienced more sediment runoff from this deforestation were more likely to have low coral cover and high amounts of turf algae, a type of algae that can indicate degraded conditions,” explains lead author Dr. Amelia Wenger, Research Fellow at UQ and Associate Conservation Scientist with WCS. “Moreover, the areas experiencing higher amounts of sediment runoff had fewer grazing fish. These fish are extremely important to local communities and make up more than a quarter of local catch, and up to 40 percent of what fishers bring to markets to sell.”

The authors also found that coral reef habitat and grazing fish populations were negatively influenced by proximity to logging ponds. Logging ponds are sites along the coast where felled timber is loaded on to barges, a process that creates chronically silty conditions which inhibit coral growth.

In Solomon Islands, where log exports having been rising every year and the industry is poorly regulated, the findings have severe implications for continuing to allow the extractive industry to operate unchecked. Proactive steps are needed now to ensure that landowners are armed with the knowledge they need to make an informed decision about leasing their land to logging companies. Disseminating this information is even more critical in a country where about 87% of land is owned by native people, many of whom rely on the health of their neighboring coral reefs and fisheries for food and livelihoods.

“Our first challenge is how we can translate the benefits of forest management into language that people understand,” said Ferguson Vaghi, Coordinator of the Kolombangara Island Biodiversity Conservation Association. “This research shows unequivocally that our health and livelihoods will be damaged if we do not stand together to manage our resources sustainably. We are not against logging, but it needs to be carefully planned to minimize negative impacts to our people. This means respecting national policy not to log above 400 meters and in sensitive areas.”

WCS Melanesia Regional Director Dr. Stacy Jupiter agrees. “Many governments are pro-logging because they only consider revenue and not the hidden costs. Our prior work identified how logging can affect drinking water safety. This new study shows additional impacts on downstream food resources. Taken together, our models help to provide information to decision-makers to avoid future scenarios where people will suffer from ill health because of poorly regulated commercial activity. The methods can be applied anywhere around the world where upstream human activity is threatening coral reefs, and the results provide justification for integrated watershed management that considers land and sea conservation measures simultaneously.”

The study was undertaken by a team from the University of Queensland, the Wildlife Conservation Society, Kolombangara Island Biodiversity Conservation Association, University of California-Irvine, and University of Hawai`i at Mānoa.

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Wenger, AS, Harris, D, Weber, S, et al. Best‐practice forestry management delivers diminishing returns for coral reefs with increased land‐clearing. J Appl Ecol. 2020; 00: 1– 12. https://doi.org/10.1111/1365-2664.13743