Globally, remaining tropical forests are being rapidly cleared, particularly in countries like the Solomon Islands where commercial logging accounts for about 18 percent of government revenue, and at least 60 percent of exports while providing the largest number of formal sector jobs. However, the loss of native forests has huge ecological and social consequences, many of which are poorly documented.
A team of researchers from The University of Queensland (UQ), Wildlife Conservation Society (WCS), and other groups have found that increasing land clearing for logging in Solomon Islands-even with best management strategies in place - will lead to unsustainable levels of soil erosion and significant impacts to downstream water quality.
Combined, these impacts will compromise the integrity of the land for future agricultural uses, interrupt access to clean drinking water and degrade important downstream ecosystems.
The researchers published the results of the study in the journal Environmental Research Letters.
The work focused on Kolombangara Island, where efforts are underway to create a national park to safeguard unlogged forests above 400 meters that have both cultural and ecological significance. This effort is being led by the Kolombangara Island Biodiversity Conservation Association (KIBCA), a community-based organisation focused on conserving the island's rich marine and terrestrial biodiversity. The declaration of a protected area would add significant levels of legal protection and explicit controls over land clearing.
UQ School of Earth and Environmental Sciences Postdoctoral Research Fellow Dr. Amelia Wenger, said the research can provide insight into the full range of impacts from logging activities, which are often not taken into consideration.
"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. Loss of the upland forest will compromise local access to clean water essential for drinking, bathing, and household washing," said Wenger.
Findings of this study are being used by KIBCA to communicate to island residents the potential impacts that could occur as a result of logging if the forest was not protected.
KIBCA coordinator Ferguson Vaghi said: "Previously people in Solomon Islands made decisions about logging from a selfish economic perspective. This study highlights that we also need to consider the impacts to the downstream environment."
More broadly, the findings demonstrate that national policies for logging practice must explicitly link soil erosion reduction strategies to natural and ecological thresholds, otherwise they will be ineffective at minimizing impacts.
WCS Melanesia Director Dr. Stacy Jupiter concurs: "Saving tropical forests worldwide depends upon tighter regulation of national laws and policies, as well as local buy-in for forest management. 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."
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Amelia S Wenger et al, Predicting the impact of logging activities on soil erosion and water quality in steep, forested tropical islands, Environmental Research Letters (2018). DOI: 10.1088/1748-9326/aab9eb