Costa Rica paid landowners to restore forests and biodiversity: bioacoustic data confirm the success

Beyond Satellite Images: The Verdict of Sound

Space-based observation allows us to assess the extent of forest cover, but satellite techniques have proven to be of limited use in quantifying the actual recovery of biodiversity. To overcome this technological limitation, a team of researchers decided to capture the sound signals emitted by living organisms at the heart of ecosystems.

Their acoustic approach, published in the scientific journal Global Change Biology, focuses on forest restoration efforts undertaken by Costa Rica. Analysis of animal frequencies confirms that the national policy of compensating landowners is effective in promoting both tree regrowth and the recovery of lost wildlife.

The Origins of a Pioneering Conservation Policy

Between the 1960s and 1980s, a large portion of Costa Rica’s rich forests was cleared to make way for agriculture and pastureland for livestock. In response to this loss, the country established the world’s very first Payment for Environmental Services (PES) program in 1996. This program directly compensates landowners for their participation in restoring forest cover.

The initiative aims to generate simultaneous benefits for nature and local communities. This system now protects more than 200,000 hectares of land and serves as a testing ground for assessing the environmental impacts of wealth redistribution directed toward local land managers.

“Today, the PSE program is widely regarded as a model program and an integral part of Costa Rica’s progress in protecting its natural heritage. Recognizing the link between ecological degradation and inequality, the program is based on the need to address the social challenges underlying large-scale environmental destruction,” write the authors of the new study.

A Unique Listening Experience on the Nicoya Peninsula

While previous research had already established a link between PES programs, reduced deforestation, and improved human well-being, the actual restoration of biodiversity remained uncertain. Giacomo Delgado, a researcher at the Institute for Integrative Biology in Zurich, and his team developed an innovative method to resolve this uncertainty.

The scientists installed audio recorders at 119 sites across the Nicoya Peninsula in Costa Rica. The listening network covered various land types: forests that had been regenerated under the PSE program for at least 10 years, monoculture plantations, degraded pastures, and mature forests serving as reference points.

The monoculture plantations studied were typically timber plantations consisting of trees aged 7 to 20 years. In total, the team’s scientific equipment captured 16,658 hours of audio recordings across these different landscapes during the experiment.

Decoding the Soundscapes from Dawn to Dusk

The Zurich team used soundscape analysis to compare biodiversity across different land-use types. The researchers focused on biologically relevant time periods and frequencies associated with various animal groups or with sounds related to human activity. Particular attention was paid to the “dawn chorus,” between 5:00 and 6:30 a.m., as well as to dusk.

The data collected show that forests regenerating naturally under the PSE program are acoustically much closer to mature reference forests than to degraded pastures. Naturally regenerating sites were, on average, 1.4 times more similar to the reference forests than the pastures were, and up to 4 times more similar at certain times and at certain sites. Monoculture plantations, on the other hand, showed a similarity of 1.24 times.

"Among the PSE sites, those undergoing natural regeneration shared significant acoustic characteristics with the reference forests. This was significantly greater than the similarities between the reference forests and pastures or between the reference forests and plantations. The similarities peaked in the early afternoon and particularly during the twilight chorus, when average similarity values consistently exceeded 0.90, indicating an almost complete acoustic overlap,” explain the study’s authors.

The dynamics observed during the dawn chorus proved to be less pronounced. During this time period, natural regeneration sites and plantations showed significantly greater similarities with pastures than with reference forests. The team notes that a comparison of soundscapes based solely on dawn recordings might underestimate the actual level of ecological recovery, although regenerated forests remain the environment most similar to natural forests.

Social Equity as a Driver of Ecological Recovery

This fieldwork provides strong evidence that large-scale redistributive restoration leads to genuine ecological recovery. The study validates sound’s ability to serve as an accurate measurement tool for assessing biological diversity at the heart of a changing ecosystem.

The results demonstrate that a policy combining social considerations and environmental goals works in practice. Compensating local landowners for ecosystem services has restored biodiversity across a vast geographic area.

"Weaknesses remain in the PSE program, and improvements are needed to achieve a truly equitable redistribution of wealth, but studies suggest that many program participants are experiencing significant socioeconomic benefits. Costa Rica’s attempt to distribute wealth directly to those who live in harmony with nature—through taxes on environmentally destructive behaviors and rewards for ecological management—represents a model that could be replicated and scaled up globally. “Learning from Costa Rica’s efforts to improve the PSE is particularly relevant given the increase in environmental degradation and economic inequality in the 21st century,” the researchers conclude.

Source: phys.org

Costa Rica paid landowners to restore forests and biodiversity: bioacoustic data confirm the success