The world’s forests provide valuable contributions to people but continue to be threatened by agricultural expansion and other land uses.Counterfactual-based methods are increasingly used to evaluate forest conservation initiatives. This review synthesizes recent studies quantifying the impacts of such policies and programs.Extending past reviews focused on instrument choice, design, and implementation, our theory of change explicitly acknowledges context. Screening over 60,000 abstracts yielded 136 comparable normalized effect sizes (Cohen’s d). Comparing across instrument categories, evaluation methods, and contexts suggests not only a lack of “silver bullets” in the conservation toolbox, but that effectiveness is also low on average. Yet context is critical. Many interventions in our sample were implemented in “bulletproof” contexts of low pressure on natural resources. This greatly limits their potential impacts and suggests the need to invest further not only in understanding but also in better aligning conservation with local and global development goals.
Diarrheal disease (DD) due to contaminated water is a major cause of child mortality globally. Forests and wetlands can provide ecosystem services that help maintain water quality. To understand the connections between land cover and childhood DD, we compiled a database of 293,362 children in 35 countries with information on health, socioeconomic factors, climate, and watershed condition. Using hierarchical models, here we find that higher upstream tree cover is associated with lower probability of DD downstream. This effect is significant for rural households but not for urban households, suggesting differing dependence on watershed conditions. In rural areas, the effect of a 30% increase in upstream tree cover is similar to the effect of improved sanitation, but smaller than the effect of improved water source, wealth or education. We conclude that maintaining natural capital within watersheds can be an important public health investment, especially for populations with low levels of built capital.
A growing set of policies involve transfers conditioned upon socially desired actions, such as attending school or conserving forest. However, given a desire to maximize the impact of limited funds by avoiding transfers that do not change behavior, typically some potential recipients are excluded on the basis of their characteristics, their actions or at random. This paper uses a laboratory experiment to study the behavior of individuals excluded on different bases from a new incentive that encourages real monetary donations to a public environmental conservation program. We show that the donations from the individuals who were excluded based on prior high contributions fell significantly. Yet the rationale used for exclusion mattered, in that none of the other selection criteria used as the basis for exclusion resulted in negative effects on contributions.
When designing schemes such as conditional cash transfers or payments for ecosystem services, the choice of whom to select and whom to exclude is critical. We incentivize and measure actual contributions to an environmental public good to ascertain whether being excluded from a rebate can affect contributions and, if so, whether the rationale for exclusion inﬂuences such effects. Treatments, i.e., three rules that determine who is selected and excluded, are randomly assigned. Two of the rules base exclusion on subjects’ initial contributions. The third is based upon location and the rationales are always explained. The rule that targets the rebate to low initial contributors, who have more potential to raise contributions, is the only rule that raised contributions by those selected. Yet by design, that same rule excludes the subjects who contributed the most initially. They respond by reducing their contributions even though their income and prices are unchanged.
Using case studies and concepts we suggest that constraints upon aggregate or global forest transition are significantly more severe than those upon local forest reversals. The basic reason is that one region’s reversal can be facilitated by other regions that supply resources and goods, reducing the demands upon the region where forests rise. Many past forest reversals involve such interdependence. For ‘facilitating regions’ also to rise in forest requires other changes, since they will not be receiving such help. We start by discussing forest-transitions analysis within the context of Environmental Kuznets Curves (EKCs), for a useful typology of possible shifts underlying transitions. We then consider the historical Northeast US where a regional reversal was dramatic and impressive. Yet this depended upon agricultural price shocks, due to the Midwest US supplying food, and also upon the availability of timber from other US regions. Next we consider deforestation in Amazônia, whose history (like the Northeast US) suggests a potential local role for urbanization, i.e. spatial concentration of population. Yet inter-regional issues again are crucial. For cattle and soy, expansion of global demands may give to Amazonia a role more like the Midwest than the Northeast US. In addition, across-region interdependencies will help determine where reversal and facilitation occur. Finally we discuss the constraints upon very broad forest transition.