European forests have long been celebrated for their expansion and resilience, growing by more than 30 percent since 1900—an area equivalent to the size of Portugal. Yet, a groundbreaking study from leading economists at the Toulouse School of Economics and the University of Pennsylvania challenges the narrative that the European Union's extensive land protection efforts are the driving force behind this greening. Published as a National Bureau of Economic Research working paper and forthcoming in The Review of Economic Studies, the research reveals that four decades of policies safeguarding over a quarter of EU land have delivered little measurable impact on forest health or vegetation cover.
This analysis, led by researchers Tristan Earle Grupp, Prakash Mishra, Mathias Reynaert, and Arthur A. van Benthem, draws on satellite data spanning 1985 to 2020 to compare protected sites against similar unprotected controls. The findings underscore a critical disconnect between the scale of protection—118,000 sites across Europe—and tangible ecological outcomes, prompting urgent questions for policymakers, academics, and conservationists alike.
The Evolution of EU Forest Protection Policies
The foundation of modern EU forest safeguards traces back to the Birds Directive of 1979 and the Habitats Directive of 1992, which together birthed Natura 2000—the world's largest coordinated network of protected areas. Covering about 18 percent of EU land and encompassing nearly 25 percent of its forests, Natura 2000 aims to halt biodiversity loss by designating sites critical for over 2,000 species and 230 habitat types. By 2023, protected areas spanned 26 percent of EU territory, positioning the bloc close to the Kunming-Montreal Global Biodiversity Framework's '30x30' goal of conserving 30 percent of land and seas by 2030.
Over four decades, these policies have evolved amid growing pressures from climate change, urbanization, and agriculture. The EU Biodiversity Strategy for 2030 intensified efforts, mandating stricter protections for primary and old-growth forests while promoting restoration. Forests, vital for carbon sequestration (absorbing 10 percent of EU emissions annually), biodiversity (home to 60 percent of terrestrial species), and recreation, became focal points. However, implementation varies by member state, with national parks and reserves (IUCN categories Ia/Ib, less than 8 percent of protected land) imposing the strictest rules, while many sites permit ongoing farming and forestry.
European universities have played pivotal roles in shaping these policies. Institutions like Wageningen University in the Netherlands and the European Forest Institute have supplied data on forest health, while Toulouse School of Economics' rigorous economic evaluations now test their real-world efficacy.
Unpacking the Toulouse School of Economics Study
At the heart of this discourse is the Toulouse School of Economics (TSE) study, a sophisticated causal analysis leveraging the staggered rollout of protections across Europe. Researchers constructed novel datasets from Landsat satellites for Normalized Difference Vegetation Index (NDVI)—a 0-100 scale proxy for greenness correlated with tree height, leaf area, and bird diversity—and nighttime lights as economic activity indicators.
Using a difference-in-differences framework with inverse probability matching, the team compared over 100 million 300m x 300m grid cells in protected areas to matched controls, accounting for soil quality, climate, slope, and pre-protection conditions. This 'doubly robust' approach mitigates biases from non-random site selection, providing gold-standard evidence over 35 years.
Affiliated with TSE's Energy & Climate Center, the study's interdisciplinary team bridges economics and environmental science, highlighting academia's role in policy scrutiny. TSE, part of the University of Toulouse, exemplifies how French higher education institutions contribute to EU-wide research, collaborating with U.S. peers at Penn's Wharton School.
Key Findings: Minimal Gains in Forest Vegetation
The headline result? No statistically or economically significant boost in vegetation from protection. EU-wide average treatment effects on NDVI hover at 0.08 points (standard error 0.01), indistinguishable from zero even 20-30 years post-designation. Event-study graphs reveal parallel trends pre- and post-protection, with no divergence.
For forests specifically, protected sites—often already lush—mirror natural regreening trends seen continent-wide. Europe's forests expanded 10 percent since 1990, but this stems from agricultural abandonment and rural depopulation, not policy. Country variations exist: slight positives in Denmark (+1.66) offset by negatives in Poland (-0.95), but all cluster near zero.
Historical land-use data from the Human-Induced Land Dynamics Assessment (HILDA) corroborates: forest transitions (e.g., cropland to woodland) occur similarly in protected and unprotected zones from 1900-2010. Heterogeneity tests via random forests confirm uniform null effects across soil fertility, elevation, and threat levels—no 'low-hanging fruit' regeneration in sparser areas.
Economic Activity Unaffected in Protected Zones
Equally telling, nighttime lights—a robust proxy for GDP and human presence—show no sustained decline post-protection. Effects remain below 0.5 units on a 0-68 scale, suggesting policies fail to curb development. This holds across cohorts (1991-2019) and event times, implying protections allow economic continuity, diluting ecological 'bite'.
In high-pressure regions near cities or fertile soils, lax rules (e.g., IUCN IV sites permitting grazing) prevail, while strict national parks cluster in remote, low-value uplands. This decentralized siting, influenced by local stakeholders bearing costs, prioritizes politically feasible over ecologically vital land.
Photo by Michael Michelovski on Unsplash
| Metric | EU-Wide Effect | Time Horizon | Proxy Interpretation |
|---|---|---|---|
| NDVI (Vegetation) | 0.08 (s.e. 0.01) | Up to 30 years | Forest greenness/biodiversity |
| Nightlights | <0.5 (s.e. <0.1) | Up to 28 years | Economic activity/human impact |
| Protected Land Share | 26% | 2023 | Natura 2000 + national sites |
Why the Disconnect? Site Selection and Enforcement Gaps
The study's null results stem from 'infra-marginal' selection: protections target already-green, low-threat land unlikely to develop anyway. Strict rules (<8% of sites) avoid economic hubs, while vast Natura 2000 areas (47% IUCN IV) accommodate farming. Local veto power exacerbates this, as communities resist high-cost designations.
Enforcement varies: Finland and Sweden log old-growth despite protections, per recent critiques. Climate stressors—droughts, bark beetles—exacerbate vulnerabilities, with 2025 EFI reports forecasting doubled damage by 2100 absent adaptive management.
Universities like Sweden's SLU highlight monitoring shortfalls, especially private lands, urging remote sensing integration.
Broader Context: Natura 2000 and Past Assessments
Natura 2000, integral to protections, safeguards 25% of EU forests but faces mixed reviews. EFI's 2017 assessment noted implementation gaps, while 2020 EEA reports praised management plans yet flagged effectiveness metrics. Earlier studies (e.g., 2019 Kubacka) found modest landscape benefits, but TSE's causal design surpasses them, using satellite causal inference over correlations.
Global contrasts: Tropical protections yield 5-10% deforestation reductions where threats loom; Europe's low baseline pressure mutes effects. The full NBER paper details these benchmarks.
Stakeholder Perspectives: Enviros, Foresters, and Policymakers
Environmental NGOs like WWF decry 'paper parks,' advocating stricter enforcement and high-risk targeting. Foresters from EUSTAFOR emphasize sustainable management over blanket bans, citing €6.5 billion annual Natura costs yielding unclear returns.
Policymakers grapple with trade-offs: The 2023 Nature Restoration Law pushes outcomes over areas, but farmer protests loom. MEPs reference TSE findings in debates, questioning 30x30 efficacy without 'additionality.'
Academics at Oxford and Wageningen propose hybrid models: incentives for restoration plus zoning reforms.
Implications for Europe's 30x30 Ambition
As EU nears 30% protection, the study warns of symbolic wins without substance. Current trajectories risk repeating errors: low-cost sites inflate coverage but bypass threats like urban sprawl (converting 1,000 km² yearly). Cost-benefit analyses, rare hitherto, could guide via biodiversity valuations (€1,000-10,000/ha for forests).
The EU Nature Restoration Law (2024) mandates 20% land restoration by 2030, a promising shift. Yet, derogations for agriculture threaten bite. EFI's Natura forest review echoes calls for outcome monitoring.
The Role of Higher Education in Forest Research
European universities drive scrutiny: TSE's econometrics complements ecology from Freiburg and Helsinki. Interdisciplinary hubs like Penn's Weitzman School model policy impacts, training PhDs in environmental economics.
Funding via Horizon Europe (€95 billion) bolsters such work, with calls for vegetation metrics. Careers in forest policy abound at research positions across EU campuses.
Pathways Forward: Actionable Solutions
To amplify impact:
- Target High-Risk Zones: Prioritize urban fringes, fertile plains via centralized siting.
- Outcome Metrics: Track NDVI, species via satellites/BioTIME.
- Adaptive Management: Permit resilient forestry amid climate shifts.
- Incentives: Payments for ecosystem services (€20/ha/year pilots succeed).
- Enforcement Tech: AI-monitored drones, as trialed in Spain.
Collaborations between universities, EEA, and states could recalibrate, ensuring protections deliver for forests and society.
Looking ahead, 2026 State of Europe's Forests reports will gauge progress. With researchers like Reynaert advocating evidence-based tweaks, EU forests may yet thrive beyond designations.
