Tropical forests underpin biodiversity, stabilise climate, and lock away vast stores of carbon—yet they are still being converted to other land uses at a rapid pace. In response, many global firms have pledged “zero-deforestation and zero-conversion” commitments, commonly called ZDCs, aiming to stop commodity-driven forest loss.
A new study evaluates whether these corporate pledges actually add extra protection beyond existing government actions. Led by Matthieu Stigler at the University of Geneva, the research team—including UC Santa Barbara’s Robert Heilmayr and Jason Jon Benedict—focuses on Indonesia’s palm oil sector, a major driver of agricultural expansion.
The central challenge is attribution: individual plantations sell to multiple mills, and mills can supply many companies, some covered by ZDC rules and others not. Using public company data, the authors mapped supply chains spanning more than 2,600 plantations, 1,200 mills, and 190 firms, then grouped plantations according to whether their linked companies had adopted ZDCs.
To measure land-use change over time, the team used satellite imagery to track deforestation trends across the study period. They then compared how forest loss evolved in supply chains tied to ZDC firms versus those tied to non-ZDC firms.
The results show compliance with ZDCs is high and deforestation declines in both categories. However, the decline is essentially the same in the two groups, implying that ZDCs do not produce a measurable additional effect when deforestation pressure is already weakening.
Quantitatively, deforestation fell by 6.63% in ZDC-linked plantations. In plantations connected to companies without ZDCs, deforestation fell by 6.50%, leaving only a 0.12% additional reduction attributable to ZDCs.
Lead author Stigler interprets the pattern as consistent with broader economic and policy forces. Unfavourable conditions for expanding agriculture and Indonesian government moratoriums may already have been suppressing deforestation during the study window.
The researchers caution that this does not mean ZDCs are useless. Instead, the findings suggest ZDCs may only become truly additive under worsening conditions—when forest pressure rises again due to economic shocks or policy rollbacks.
Finally, the team argues that the most effective forest-saving strategies may require looking beyond isolated corporate pledges, studying how ZDCs interact with national enforcement and market dynamics. Their next step is to pursue a more holistic view of policy “stacking” that could sustain long-term reductions across tropical regions.
Subject of Research: Tropical forests; deforestation; corporate zero-deforestation commitments; Indonesia’s palm oil sector
Article Title: Zero-deforestation commitments in Indonesia’s palm oil sector achieve high compliance but no additionality
News Publication Date: 13-Jul-2026
Web References: https://www.pnas.org/doi/10.1073/pnas.2511503123
References: DOI: 10.1073/pnas.2511503123
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Keywords: zero-deforestation commitments, palm oil, Indonesia, satellite monitoring, deforestation rates, supply-chain compliance, forest governance, carbon storage, biodiversity
