One of the biggest dangers to rainforests has been unnoticed until now. Researchers have uncovered a large network of illegally and unofficially built roads that are not included on official road maps. These so-called “ghost roads” are expanding in the biodiverse regions of the Asia Pacific, where they directly cut through the forest.
With the assistance of 210 trained volunteers, the researchers mapped over 850,000 miles (1.37 million kilometers) of roads in forested areas of New Guinea, Sumatra, and Borneo, three of the world’s six largest islands.
These regions are biodiversity hotspots, collectively hosting the largest stretch of tropical rainforest outside the Amazon and the Congo Basin.
“We found ghost roads in these regions to be 3 to 6.6 times longer than all mapped roads put together. What makes this situation uniquely dangerous for conservation is that the roads are growing fast while remaining hidden and outside government control,” Bill Laurance, one of the researchers and a professor at James Cook University, wrote in The Conversation.
Roads are “forest killers”
Roads enhance connectivity, facilitate transportation, promote the development of businesses, and make travel convenient, so aren’t roads good? Well, they are beneficial for cities and towns, but not for forests. This is because roads make it easier for hunters, timber smugglers, land hoarders, miners, and poachers to access natural habitats.
“Once they get access, they can destroy forests, harm native ecosystems and even drive out or kill indigenous peoples. This looting of the natural world robs cash-strapped nations of valuable natural resources. Indonesia, for instance, loses around A$1.5 billion each year solely to timber theft,” Laurance said.
To maximize profits from forests while avoiding authorities, poachers, smugglers, and miners often construct ghost roads that do not appear on official maps. Such roads exist worldwide, but their numbers are increasing rapidly in tropical forests of developing nations due to inadequate regulations and corruption.
“The toll of such ‘ghost roads’ on ecosystems is poorly understood,” the researchers note.
Ghost roads are even being constructed within protected areas and parks. For example, a US-based nonprofit has reported the degradation of 130 million hectares of protected land across the Asia Pacific due to new or illegal road construction.
Additionally, it is projected that the world will see a 15.5 million mile (25 million kilometer) expansion of its paved road network by 2050. Many of these new roads are likely to be built within jungles, parks, and protected areas, causing more destruction than ever.
“No matter how one assesses them, roads are forest killers,” Laurance added.
Ghost roads have penetrated deep into wooded areas
By utilizing high-resolution Google Earth images, 210 volunteers manually mapped roads in New Guinea, Sumatra, and Borneo. The mapping process took nearly 7,000 hours, and one of the study's authors cross-checked the data for quality and accuracy.
Upon further comparison with two official road databases, the researchers found that the total length of roads on these islands was actually three to six times greater than all officially mapped roads, indicating a vast network of ghost roads.
“Our map was explicitly designed to accurately detect forest loss while not misclassifying current land covers, such as oil-palm or wood-pulp plantations, as forested land, or open vegetation, such as wetlands, as deforested land. Our data revealed that 35–45% of all the unmapped roads were in oil palm or other plantations, 7–28% were in non-plantation agriculture, and 31–39% were in intact forests,” the researchers note.
Researchers also analyzed satellite imagery across the Asia Pacific from 1985 to 2020. This extensive observation allowed them to study the deforestation patterns linked to ghost road construction in the region.
“When ghost roads appear, local deforestation soars – usually immediately after the roads are built. We found the density of roads was by far the most important predictor of forest loss, outstripping 38 other variables,” Laurance said.
People and technology can combat ghost roads
You can’t eradicate a ghost road if you are unaware of its existence. Therefore, the initial step to prevent such roads from harming the environment is to create a map for them. However, the mapping procedure requires human resources and is time-consuming and labor-intensive. That's why many secret roads around the world remain undiscovered.
However, there are methods to tackle these difficulties. For example, a recently released research proposes that AI models trained using satellite maps and volunteer data can map unauthorized roads with more than 70 percent precision and automate this process to a large extent.
The current investigation, on the other hand, demonstrates the effectiveness of crowdsourcing. The researchers managed to recruit and train over 200 volunteers for their research. This approach enabled them to map numerous illegal roads with limited resources. Additionally, many participants who were previously unaware of the ghost road problem became informed through their involvement.
“The study demonstrates well how crowdsourcing can be used to solve scientific problems,” Carlos Souza Jr, an expert on forest mapping and monitoring, told Mongabay.
The research is published in the journal Nature.
