What policies improve forest cover? A systematic review of research from Mesoamerica

- We conduct a meta-analysis of case studies linking policies to forest cover change in Mesoamerica.
- Public policy effects on forest cover in Mesoamerica are poorly understood, yet few forest cover change studies address the effects of policies.
- Payments for ecosystem services and community-based management are most commonly associated with positive forest impacts, but have been studied in few contexts.
- Protected areas have more mixed results, with two-thirds of cases reporting positive outcomes.
- Our results associating agricultural subsidies with forest loss show the relevance of studying diverse policy types for reducing deforestation and forest degradation.

Despite many studies of the drivers of deforestation, few syntheses have been conducted of the effect of public policies on forest cover. This is problematic because policy is the primary tool that society can use to change outcomes, yet we lack information on the conditions which lead to successful policies. To address this deficiency, we conduct a meta-analysis of case studies of the impact of public policy on deforestation and reforestation in Central America and Mexico, drawing on a set of 159 studies. This region has recently experienced high rates of forest cover change and is well studied, providing a strong sampling frame. For each study, we record the reported change in forest cover, along with the scale and location of the study, the types of policy evaluated, and other relevant information. Some policy types are strongly associated with positive or negative forest impacts, though important gaps remain in our understanding. Nearly all studies of payment for ecosystem services indicate an association between payments and improvements in forest cover (88% of cases), however this evidence derives from only two countries (Mexico and Costa Rica), both of which have more clearly defined property rights and stronger governmental institutions than other countries in the region, raising questions about generalizability. Community-based management is associated with positive impacts on forest cover in 81% of cases, whereas protected areas are associated with positive impacts in 66% of cases. Studies of social and agricultural policies were rarer and more likely to be associated with negative outcomes. Agricultural subsidies were associated with negative forest outcomes in 86% of cases, raising the possibility that reducing agricultural subsidies could be an effective strategy for improving forest cover. Most studies do not adequately identify either causal effects or the mechanisms associated with policy change, and few studies examine interactions between policy types. The results of this review imply that, while some policies are more likely to make positive contributions than others, policymakers should remain cautious about the body of evidence supporting the effectiveness of policies for reducing deforestation.