Tree planting has emerged as one of the most popular responses to environmental degradation. Governments announce billion-tree targets, corporations promise carbon-neutral forests, and philanthropies fund vast restoration drives. Forests are widely seen as natural solutions absorbing carbon, protecting wildlife, and sustaining livelihoods. But scientists warn that when restoration is poorly planned, it can undermine the very goals it claims to serve.
As global restoration pledges have expanded, so have concerns about their ecological validity. Studies over the past decade suggest that many high-profile commitments prioritise numbers over nature, replacing complex ecosystems with simplified plantations that offer limited benefits for biodiversity or climate resilience.
Big pledges, weak ecological foundations
The scale of the problem became evident as international commitments multiplied. A 2019 commentary published in Nature found that nearly half of the land pledged under the Bonn Challenge a global effort to restore degraded landscapes consisted of monoculture plantations. These tree farms often store less carbon over time and support far fewer species than natural forests.
More recently, a 2024 study in Science showed that large portions of land earmarked for reforestation in Africa were actually savannas ecosystems that evolved without dense tree cover. Introducing trees into such landscapes can disrupt native biodiversity, alter water cycles, and increase fire risk.
Experts say the issue is not lack of ambition, but lack of ecological precision. Restoration efforts have often raced ahead of scientific understanding, treating all landscapes as suitable for forests.
New standard to measure real biodiversity gains
Concern over these trends led to the creation of the Global Biodiversity Standard (TGBS), officially launched in 2024. Developed by Botanic Gardens Conservation International (BGCI), the standard is designed to distinguish genuine biodiversity restoration from projects that simply look good on paper.
Unlike existing certification schemes that focus largely on carbon or tree counts, TGBS prioritises measurable ecological outcomes. It evaluates whether restoration efforts actually improve native ecosystems, protect species, and involve local communities. Importantly, it is structured to be accessible to smaller, community-led projects that often lack resources for expensive certification.
How certification works on the ground
Projects seeking TGBS certification must provide evidence through satellite imagery and field-based surveys. These assessments examine plant and animal diversity, ecosystem integrity, protection measures, and governance structures. Each site is scored against eight criteria and reviewed by the TGBS secretariat, hosted by BGCI, with independent third-party audits ensuring credibility.
Based on performance, projects receive one of three levels of certification standard, advanced, or premium allowing for progress rather than a pass-or-fail outcome.
A key feature of the system is its reliance on regional hubs, often botanic gardens or local conservation organisations. These hubs carry out field assessments and mentor projects, avoiding a top-down, consultant-driven model. Supporters say this keeps costs low and ensures that restoration is grounded in local ecological and social realities.
Uganda project shows what success looks like
The approach was first tested in western Uganda, where the Jane Goodall Institute has been restoring a wildlife corridor between the Budongo and Bugoma forests. Supported by the search engine Ecosia, the project became the first to receive advanced TGBS certification.
Field surveys documented increasing numbers of native plant species and forest-dependent birds, while also highlighting the role of local communities in restoration. Many of the same people who had once depended on forest clearing were now employed in restoring it, linking conservation with livelihoods.
Researchers involved in the assessment noted that ecological recovery and social engagement reinforced each other, strengthening long-term outcomes.
For funders, the value of TGBS lies not only in certification but in guidance. Projects that fall short are not rejected outright; instead, they receive mentoring to improve ecological performance. Supporters argue this approach encourages learning rather than box-ticking.
As restoration gains momentum worldwide, advocates of the new standard say its core message is simple but often overlooked: forests should not be judged by how many trees they contain, but by whether they function as living ecosystems that support biodiversity and people alike.