Samii, C, Lisiecki, M, Kulkarni, P, Paler, L and Chavis, L, 2015. Payment for environmental services for reducing deforestation and poverty in low- and middle-income countries: a systematic review, 3ie Systematic Review 17. London: International Initiative for Impact Evaluation (3ie).Link to Source
Headline Findings: a summary statement
The evidence suggests PES has a very small effect on deforestation, reducing the annual deforestation rate by 0.21 percentage points on average. Only two studies assess effects on household incomes, and they suggest a modest improvement in incomes.
The authors included eleven studies evaluating the effects of six different PES programmes in four different countries – Costa Rica, China, Mexico and Mozambique. All of the studies use quasi-experimental methods and the authors conclude the evidence base is limited in both quantity and quality.
Implications for policy and practice
Effects on deforestation outcomes
Nine studies of four PES programmes in Costa Rica and Mexico assessed the effect on forest cover. The results suggest that PES programs reduce the annual deforestation rate by 0.21 per cent on average (95% CI: [0.03, 0.39]). The effect is slightly larger for forest cover change, which included measures of both forest loss and forest gain.
Effects on human welfare outcomes
Two studies assessed the effect of PES on human welfare outcomes. The authors found that PES improves participating households’ incomes by four per cent in Mozambique (95% CI: [0.96, 7.04]) and 14 per cent in China (95% CI: [7.3, 20.7]). The study in Mozambique finds effects substantially lower for poor households.
The role of institutional and social conditions
The authors extracted qualitative data from included quantitative studies as well as qualitative studies related to the included PES programmes to identify any findings on contextual factors that may influence effects. A study on the Mexican PSAH PES programme found that forest conservation effects were worse in poorer areas. Qualitative data from Costa Rica coroborated this finding. Several of the studies also addressed the issue of institutional capacity, describing situations where PES programmes did not have the ability to carry out their mandates. Corruption and possible misappropriation of project resources were also factors raised in a qualitative study of PES in Mexico. The study found that programme resources were applied to address inadequacies in other government programmes.
Implications for further research
The authors note there is limited high quality evidence to assess the effects of PES programmes on deforestation and poverty. The review team was unable to identify any completed randomised controlled studies, and many of the included quasi-experimental studies suffer from methodological weaknesses. They suggest randomised designs are feasible and should be prioritised in future studies. The authors also recommend researchers utilise tools such as Google Earth Engine’s high resolution forest cover mapping (Hansen et al. 2013) to conduct high quality quasi-experimental studies.
Future studies should assess both the environmental and human welfare outcomes of PES to allow an assessment of potential synergies or trade-offs between different program objectives. Quantitative studies should also collect data on context, implementation and costs. Future research should focus on assessing the effects of PES across a diversity of contexts, in particular contexts with high de-forestation rates.
Finally, the authors suggest priority topics for further research include mechanisms for more efficient contracting and strategies for boosting conservation performance in poor areas, such as allowing sustainable use (as opposed to only non-use) of forest lands to qualify for payments.
It is estimated that deforestation is responsible for 10 to 17 per cent of global carbon emissions. Natural forest preservation in the tropics is therefore important in helping to mitigate climate change. There has been an increased focus on conservation efforts in the last decade, particularly through the Reducing Emissions through Deforestation and Forest Degradation (REDD+) initiative which is designed to reduce the amount of forested land converted to other uses. A number of interventions are implemented to reduce deforestation, including Payment for Environmental Services (PES). PES programmes provide financial incentives to people or businesses to maintain or rehabilitate natural forests on their land. There is an ongoing debate as to whether or not PES programs in low- and middle-income countries (L&MICs) should also include goals of povery reduction.
The authors aimed to assess the evidence on the effects of PES interventions on deforestation and poverty outcomes in L&MICs. In addition, they aimed to assess whether there was a relationship between effects on poverty and whether or not conservation benefits are realised. Finally, the authors aimed to identify how institutional and social conditions may moderate the effects of PES programmes.
The authors included studies that assess the impact of PES programmes on deforestation or poverty outcomes in L&MICs. Studies were included where there was a clear start date for payments or incentives made for maintaining or rehabilitating natural forests. Rewards/incentives could be made by either public or private actors and the payments had to be conditional on the fulfilment of the prescribed action. The authors included both experimental studies and quasi-experimental studies.
The authors searched both published and grey literature with no restriction on publication date. They searched academic databases such as AgEcon and Greenfile (EBSCO), Google, specialist websites (iied, DFID and so on) as well as relevant journals. They then conducted a second targeted search for other relevant and methodologically adequate qualitative studies that the initial search did not identify. The authors assessed included quantitative studies for risk of bias using the IDCG Risk of Bias Tool and collected data on study characteristics, findings and moderators. Qualitative information was extracted from quantitative and qualitative studies which looked at the types of programmes and contexts covered in the quantitative studies. The authors standardised effects on forest cover into annual forest cover change rates and calculated effects on material welfare and poverty outcomes as percentage change over the estimated average counterfactual outcome. When feasible, they used meta-analysis to synthesis results.
This is a high quality systematic review with well-defined inclusion criteria, search and appropriate analysis of the available evidence. There is extensive reporting of methodology, especially with regard to the search parameters and effect size calculation.