Roadless areas and the 30% protection target: contrasting national prospects in the Iberian Peninsula

Nature does not draw lines on a map, but humans do. When we build roads, we slice through the wild, breaking up habitats and forcing animals to navigate a landscape of noise, light, and danger. For decades, scientists have known that these lines of asphalt are among the most damaging forces on biodiversity. Yet, as the European Union set a goal to protect thirty percent of its land by 2030, a new question emerged: where is the land that is still wild enough to count, but has not yet been officially designated as a protected park? The answer lies in "roadless areas"—stretches of terrain so free from roads and heavy traffic that they remain largely untouched by human industry. These are not necessarily the remote, jagged peaks often associated with wilderness, but often the rolling hills and valleys where people live and farm, provided the roads have not yet reached them.

The challenge for conservationists is that the current network of protected areas is incomplete. While many nations have set aside land for nature, the protection is often uneven, favoring steep, difficult-to-reach mountains while leaving the flatter, more fertile lowlands exposed to development. To meet the ambitious new targets, countries need to find the remaining pockets of intact nature quickly. This is where the concept of roadless areas becomes a practical tool. If a piece of land has no roads running through it, it retains a level of ecological integrity that makes it a prime candidate for protection. The question is not just whether these areas exist, but whether they are in the right places to fill the gaps left by the current system, and whether they can help nations reach their legal obligations without waiting years to restore degraded land.

A team of researchers from the University of Córdoba and the University of Porto set out to answer these questions for the Iberian Peninsula, which includes Spain and Portugal. This region is a global hotspot for biodiversity, home to a vast array of unique plants and animals, yet it also possesses one of the densest road networks in Europe. The scientists began by mapping every square kilometer of the peninsula, identifying which areas were already protected by law and which areas were roadless. They then looked for the overlap, or lack thereof, between these two categories. Their findings revealed a striking separation: the land that is legally protected and the land that is roadless are largely different places. Only a small fraction of the territory is both protected and roadless. This means that the vast majority of roadless land sits outside the current safety net of protected areas, representing a massive, untapped reserve of ecological value.

When the researchers added these roadless areas to the existing network of protected lands, the picture changed dramatically. In Spain, the current protected areas cover about twenty-eight percent of the land. By including the roadless zones, this figure would jump to nearly forty-five percent. In Portugal, the increase would be even more significant relative to the starting point, pushing coverage from twenty-two percent to over thirty-four percent. This suggests that for Spain, simply recognizing and protecting the roadless land that already exists could be enough to meet the thirty percent target. Portugal, however, faces a steeper climb; while roadless areas would get them close, they would still fall slightly short, indicating a need for additional restoration efforts alongside protection.

The study also uncovered where these roadless areas are located and what kind of land they protect. The current system of protected areas is heavily biased toward high elevations. The researchers found that while only about sixteen percent of the lowlands below two hundred meters are protected, nearly eighty-seven percent of the land above two thousand meters is already under some form of protection. Roadless areas, by contrast, are most abundant in the middle elevations and the lowlands. They are particularly common in the agro-forestry systems of the southwest, known as dehesas in Spain and montados in Portugal. These are ancient landscapes of open oak woodlands used for grazing and farming, which are vital for biodiversity but have historically received little formal protection. The data showed that incorporating roadless areas would boost the protection of these specific agro-forestry systems by more than thirty percentage points, filling a critical gap in the conservation network.

To understand why these areas are different, the team analyzed the environmental factors that drive where protected areas are placed versus where roadless areas happen to exist. They found that the two are governed by different rules. Protected areas tend to be located in places with rugged, difficult terrain, likely because such land is less valuable for agriculture or development. Roadless areas, however, are defined more by the structure of the landscape and the presence of biodiversity than by steepness alone. They exist in valleys, on flat plains, and on ridges alike. This distinction is crucial because it means roadless areas are not just a duplicate of what is already protected; they are a complementary resource that covers the ecological ground that the current system has missed.

The researchers then used a prioritization system to identify which specific roadless patches would be most valuable to protect. They looked for areas that could connect existing protected sites, fill in missing habitat types, and bridge the gaps between isolated patches of nature. The result was a list of specific locations, primarily in the south-western part of the peninsula, that would deliver the biggest gains. For Spain, protecting just over thirteen thousand square kilometers of these prioritized roadless patches would be sufficient to reach the thirty percent goal. For Portugal, the same approach would not be enough on its own, highlighting that while roadless areas are a powerful tool, they are not a magic bullet for every country.

The study concludes that roadless areas offer a practical and immediate path to expanding conservation. They are not a replacement for traditional protected areas but a necessary addition that brings the network into balance. By protecting these roadless zones, nations can secure land that is already ecologically intact, maintain the connectivity that allows species to move across the landscape, and protect the lowland habitats that are currently under threat. The research suggests that for Spain, the path to meeting its 2030 biodiversity targets is clear and lies in recognizing the value of the land that has, so far, escaped the reach of the road. For Portugal, the roadless areas provide a significant step forward, but the journey will require a combination of protection and active restoration to reach the finish line.