Using environmental compensation to restore biodiversity and reconnect Santiago’s isolated hills as part of the city’s ecological infrastructure.

Chile is defined by its mountainous geography. While the Andes and the Coastal Range frame the country with peaks exceeding 3,200 and 2,000 meters above sea level respectively, this topographic character is also expressed within its valleys through cerros isla (island hills)—isolated landforms that rise from the plains and are visible from cities and towns across the country. These hills are a distinctive feature of the Chilean landscape and an important part of its territorial identity.

In Santiago, these landforms stand out within the urban fabric. Despite decades of urban expansion, the metropolitan area has retained 26 island hills, forming a network of natural remnants embedded within one of South America’s largest cities.

Historically, many of these hills have been subjected to timber extraction, quarrying, motocross, illegal dumping, and intentional fires. These activities have degraded their ecosystems and altered the Mediterranean sclerophyllous forest, part of one of the world’s 36 biodiversity hotspots. At the same time, hiking, recreation, sports, and wildlife observation continue to reveal the hills’ potential as accessible spaces for nature and public life.

Since 2013, Fundación Cerros Isla has worked to transform this potential into a long-term vision. The organization promotes the hills as both natural and social capital while developing mechanisms to convert them into Urban Natural Parks—a park typology that prioritizes ecological restoration, biodiversity conservation, ecosystem services, and public access through minimal and context-sensitive infrastructure.

One of the main challenges has been land ownership. Although most of the hills can be accessed by the public, approximately 80% of their surface is privately owned and fragmented among multiple landowners. This condition has made their transformation into public parks particularly difficult. The State cannot invest in private land, coordination between landowners is often complex, and aligning environmental, social, and economic interests can be challenging. In response, Fundación Cerros Isla began exploring environmental management instruments as a means of restoring these landscapes at a broader scale.

Within Chile’s Environmental Impact Assessment System, environmental compensation measures required from development projects can be implemented on private land, provided they satisfy the regulatory criteria associated with air quality, biodiversity, soil, or forest conservation. For instance, projects generating more than 2.5 tons of PM10 emissions per year must compensate for their impact through environmental improvement measures, creating opportunities to fund large-scale restoration initiatives. The island hills possess ecological conditions that make them suitable recipients for these compensatory actions, including restoration, conservation, and ecosystem enhancement projects.

Recognizing this opportunity, Fundación Cerros Isla, together with the Center for Innovation in Cities at Universidad del Desarrollo and the Regional Government of Santiago, created the Island Hills Compensation Platform, a mechanism that channels environmental compensation projects toward the hills through agreements between landowners—both public and private—and companies required to offset environmental impacts. Through this model, regulatory obligations are transformed into investments that directly contribute to the development of Urban Natural Parks.

These agreements are supported by landscape design proposals already in place. In collaboration with landowners, Fundación Cerros Isla has developed master plans for three island hills in Santiago.

The master plans are based on a landscape-led approach that recognizes each hill as both an ecological refuge and a public space. Rather than imposing intensive recreational programs, the proposals work with existing topography, native vegetation, hydrological processes, and cultural traces to guide future interventions. Ecological restoration areas, habitat protection zones, scenic viewpoints, trail networks, environmental education spaces, and low-impact recreational infrastructure are strategically organized to balance public access with biodiversity conservation. This approach allows each hill to retain its unique identity while contributing to a broader metropolitan network of urban nature.

As a result, compensation measures contribute not only to biodiversity recovery and air quality improvement but also to the implementation of landscape architecture projects grounded in ecological processes and long-term stewardship.

Within this model, environmental compensation becomes a tool for landscape transformation. Companies with compensation obligations support the development of trails, viewpoints, and public spaces, while also financing ecological restoration measures such as native vegetation recovery, soil restoration, and water and soil conservation works. The cumulative effect of multiple compensation projects over time helps ensure the long-term continuity, maintenance, and ecological enhancement of these interventions.

Today, the platform is consolidating nearly 60 hectares within Parque Metropolitano Cerros de Renca, a landscape-scale restoration project that will provide ecological, social, and climatic benefits to one of Santiago’s most underserved communities. The project already illustrates how environmental compensation can be translated into landscape transformation. Through the Island Hills Compensation Platform, the Portland Logistics Center, developed by Inmobiliaria La Montaña, has directed 18.6 tons of its total PM10 compensation requirement of 40.3 tons toward restoration actions in Cerros de Renca, supporting ecological improvements across approximately 40 hectares of the future park. These interventions contribute to habitat recovery, soil restoration, and the long-term ecological rehabilitation of one of Santiago’s most emblematic island hills.

Beyond the restoration of individual sites, the initiative seeks to reposition Santiago’s island hills as key components of the city’s ecological infrastructure. Distributed throughout the metropolitan basin, these hills function as stepping stones for biodiversity, helping reconnect fragmented habitats across an increasingly urbanized landscape. Their recovery therefore contributes not only to local environmental improvement but also to the creation of a more resilient and interconnected urban ecosystem.

At the same time, Fundación Cerros Isla is developing a complementary initiative that would extend compensation mechanisms to other forms of urban green infrastructure. The strategy aims to support the planning and implementation of ecological corridors and habitat networks that reconnect the island hills across the metropolitan landscape. Such an approach would also advance broader strategies promoted by regional authorities and the Ministry of the Environment, contributing to ecosystem protection, social well-being, and climate resilience. By linking environmental compensation with landscape planning, the initiative demonstrates how regulatory instruments can become catalysts for large-scale ecological restoration and the creation of a more biodiverse and resilient urban region.