Isabelle Tritsch

Gwenolé Le Velly

Benoit Mertens

Patrick Meyfroidt

Christophe Sannier

Jean-Sylvestre Makak

Kenneth Houngbedji

Gwenolé Le Velly

Gwenole Le Velly

Julien Calas

Christophe Du Castel

Pascale Combes

Georges Lemaitre

Do forest-management plans and FSC certification reduce deforestation in the Congo basin?

Keywords: Forest management plan, FSC certification, deforestation, quasi-experimental matching, causal mechanisms, Congo Basin JEL Classification: C21, Q23, Q56, Q58

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

About 400 million hectares of natural tropical forest are devoted to timber production [START_REF] Blaser | Status of tropical forest management 2011[END_REF]. Ensuring the sustainable exploitation of these forests is a crucial challenge, as they are a key factor for biodiversity, carbon sequestration and the global climate. In the Congo Basin, the second-largest tropical forest after the Amazon, with an area of about 178 million ha of dense humid forests [START_REF] Mayaux | State and evolution of the African rainforests between 1990 and 2010[END_REF], almost one third of forests are productive in terms of logging exploitation. National forestry regulations have made Forest Management Plans (FMPs) mandatory in logging concessions to ensure their sustainable exploitation, but in practice, compliance with these laws is incomplete. The FMP must ensure sustainable forest management, that is timber production that limits deforestation and guarantees the preservation of forest resources, biodiversity and ecosystem services, while contributing to local socio-economic development [START_REF] Nasi | Managing for timber and biodiversity in the Congo Basin[END_REF].

For this reason, and because of the extent of forest areas covered, FMPs are often considered as a major contribution to tropical forest conservation worldwide, and have been supported by international organizations and NGOs [START_REF] Clark | Logging Concessions Can Extend the Conservation Estate for Central African Tropical Forests[END_REF][START_REF] Lambin | Effectiveness and synergies of policy instruments for land use governance in tropical regions[END_REF]. However, there is relatively scant empirical work on their effect on deforestation in logging concessions. [START_REF] Cerutti | The impact of forest management plans on trees and carbon: Modeling a decade of harvesting data in Cameroon[END_REF] showed that FMPs in Cameroon between 1998 and 2009 effectively reduced carbon emissions from logging operations due to the reduced volumes of timber harvested, as imposed by the FMP, while presenting logging companies with acceptable financial trade-offs. On the contrary, [START_REF] Brandt | Deforestation and timber production in Congo after implementation of sustainable management policy: A response to[END_REF] found that FMP concessions in the Congo, compared to otherwise similar concessions without, were associated with greater deforestation. Further analyses suggested that, greater timber production driven by increased foreign capital and international demand contributed to greater deforestation in the six concessions with FMPs in the Congo [START_REF] Brandt | Deforestation and timber production in Congo after implementation of sustainable management policy: A response to[END_REF](Brandt et al., , 2014)). This led to a controversy between Karsenty et al. (2017) and [START_REF] Brandt | Deforestation and timber production in Congo after implementation of sustainable management policy: A response to[END_REF], emphasizing the need for more empirical work to understand whether and under which conditions FMPs affect deforestation.

While there is a paucity of work on the effects of FMPs, relatively more attention has been given to Forest Steward Council (FSC) certification: this is a voluntary marketbased approach to enhance sustainable forest management. As halting tropical deforestation remains a central FSC objective, within a wide range of issues covered by FSC standards, a number of empirical contributions have looked at the impact of FSC certification on deforestation. The results here are also mixed and context-dependent. Some work on Cameroon [START_REF] Panlasigui | Impacts of certification, uncertified concessions, and protected areas on forest loss in Cameroon, 2000 to 2013[END_REF], Mexico (Blackman et al., 2018), and Brazil, Gabon and Indonesia [START_REF] Rana | Does Certification Change the Trajectory of Tree Cover in Working Forests in The Tropics? An Application of the Synthetic Control Method of Impact Evaluation[END_REF] has shown that FSC certification reduced deforestation in most certified logging concessions, but that the estimated effects were rarely statistically different from zero and varied over time, thus providing inconclusive evidence of the deforestation impact of FSC. [START_REF] Miteva | Social and Environmental Impacts of Forest Management Certification in Indonesia[END_REF] showed that FSC certification in Indonesia reduced deforestation and improved household welfare. In Chile, [START_REF] Heilmayr | Impacts of nonstate, market-driven governance on Chilean forests[END_REF] compared the deforestation impacts of three different non-State market-driven governance regimes, among which FSC certification: they showed that FSC certification effectively reduced deforestation, and was more effective than the other measures tested, which were more industry-friendly.

Overall, the impact of the adoption of sustainable forest-management practices on deforestation in the Congo Basin remains an active research area. The results from similar policy interventions in Asia and South America suggest that the results are contextdependent and can therefore not be directly transposed. As reducing deforestation in low-income countries is arguably one of the most cost-effective ways of reducing global CO2 emissions [START_REF] Barker | Technical Summary. In Climate change 2007: Mitigation[END_REF][START_REF] Stern | The Economics of Climate Change: The Stern Review[END_REF], this paper aims to evaluate the change in forest cover following the implementation of an FMP or FSC certification in the Congo Basin, and to establish the underlying mechanisms explaining whether and how these work [START_REF] Baylis | Mainstreaming Impact Evaluation in Nature Conservation[END_REF][START_REF] Miteva | Social and Environmental Impacts of Forest Management Certification in Indonesia[END_REF].

To provide an empirical estimate of the impact of FMPs in the Congo Basin, we use original high-resolution maps of changes in forest cover in Cameroon, Congo, Gabon and the Central African Republic (CAR) over the 1990-2000 and 2000-2010 periods. The geographic area does not include forest-cover changes in the Democratic Republic of Congo, where FMPs were initiated later. The deforestation maps are complemented with relevant detailed information on the location and extent of logging concessions, including the timing of the official approval of their FMP and FSC certification. As the selection into FMP adoption is not random, we use quasi-experimental methods whereby the logging concessions that adopted FMP are compared to logging concessions that did not adopt an FMP but had otherwise similar observable characteristics that are known to affect deforestation. This approach will likely produce unbiased estimates of the effect of FMPs in the study areas for at least two reasons. First, since the 1990's, Cameroon, Congo, CAR and Gabon have all implemented reforms aimed at encouraging logging companies to adopt FMPs [START_REF] Karsenty | Comparaisons des législations et des réglementations dans les six pays forestiers d'Afrique Centrale[END_REF]. FMP were then gradually implemented in the 2000s, and by 2010 almost one-third of the concessions in the study area had an accepted FMP.

FSC certification is more recent in the region, starting only in 2005. Given the staggered rollout of reforms promoting FMP adoption in the region, it is likely that we will find otherwise-similar concessions with and without FMPs, which is a key requirement for unbiased quasi-experimental analysis. Second, even though national policies aiming to increase FMP adoption have been discussed since the 1990s, the first logging concessions with FMPs appeared in the early 2000s in the Congo Basin. Since we can also measure deforestation between 1990 and 2000, we fine-tune our estimates of the FMP impact on logging concessions by correcting for pre-existing differences in deforestation rates between early and late FMP adopters in the Congo Basin. Last, we test the robustness of the results and replicate our analysis in data from the widely-used Global Forest Change (GFC) dataset [START_REF] Hansen | High-Resolution Global Maps of 21st-Century Forest Cover Change[END_REF] over the 2000-2010 period. By doing so, we add to existing empirical work by considering the Congo Basin. As we cover a larger sample of logging concessions, we avoid the limitations of analyses based on smaller samples.

The remainder of the paper is organized as follows. In Section 2 we present background information on forest-management plans and the theoretical framework behind their potential deforestation effects in the Congo Basin. Section 3 then describes the main datasets used, and Section 4 outlines the empirical strategy used to explore the causal impact of FMPs on deforestation. Section 5 presents the main results and their robustness and limitations, and explores the channels underlying the link between FMPs and deforestation. Last, Section 6 discusses the implications of our work and offers some concluding observations.

Background and theoretical framework

In the Congo Basin, most forested areas are State-owned, and exploitation permits are granted to private logging companies for long periods (up to 100 years) under concession regimes, providing long-term resource-extraction rights in exchange for a stream of revenues [START_REF] Agrawal | Changing Governance of the World's Forests[END_REF]. In this context FMPs are a tool for sustainable forest management, combining timber production, local development and conservation values in the Congo Basin.

Forest-Management Plans in the Congo Basin

FMPs in a concession involve a range of environmental and social issues. They are based on forest inventories describing the distribution of trees species and their characteristics. Based on ecological and social studies (e.g., on fauna and the forest uses of local communities), these inventories allow us to divide each concession into "management series" areas according to the use of forest resources. Among these, the "production", "conservation" and "community management" series respectively refer to: wood exploitation; the preservation of biodiversity, seed trees and the most vulnerable areas (with buffer zones on steep slopes, riversides etc.); and last local-community development. These community-management series are located around settlements and agricultural areas, and aim to ensure the coexistence of different forest uses in order to guarantee the land rights of local populations and encourage local communities to carry out sustainable natural-resource management, in particular regarding hunting and agriculture [START_REF] Atibt | Study of a Practical Forest Management Plan for Natural Tropical Production Forests in Africa As applied to the case of Central Africa -Volume 1 'Forest Production[END_REF][START_REF] Nkeoua | Les defis d'une gestion durable dans le bassin du Congo[END_REF]. The production series are divided into "annual cutting areas" (ACA), for which the FMP presents a detailed plan for selec-tive logging over a specific time period. This plan aims to optimize the exploitation of timber, while ensuring the regeneration of forest species in order to guarantee the viability of the next logging cycle (the usual, rotation time is between 25 and 30 years).

In addition, FMPs recommend reduced-impact logging (RIL) practices and facilitate checks on operating activities by regulators [START_REF] Cerutti | Sustainable forest management in Cameroon needs more than approved forest management plans[END_REF][START_REF] De Blas | Prospects for Reduced Impact Logging in Central African logging concessions[END_REF]Karsenty et al., 2008;Putz et al., 2008b).

For local development, FMPs require that concessions adhere to "social contracts", redistributing part of the benefits to the local population, either through specific forest taxation or the direct funding of local infrastructure (for example, companies often build wood-processing facilities, such as sawmills, that employ local workers; [START_REF] Atibt | Study of a Practical Forest Management Plan for Natural Tropical Production Forests in Africa As applied to the case of Central Africa -Volume 1 'Forest Production[END_REF].

In all of the Congo Basin countries except the CAR, 1 the FMP is established by the logging company on the basis of national standards and under the control of forest administrations. After the attribution of forest concessions, logging companies can start logging immediately but have to prepare their FMP within a maximum of three years. The FMP is then reviewed by the forest administration, which evaluates the quality of the plan and either approves it or sends it back to the company with a request for review. In practice, this three-year period is poorly-respected. Moreover, FMPs may not deliver the expected outcomes. First, logging concessions are responsible for the drafting of the FMP, which will thus best fit their strategy: the FMP proposed by the owner of the logging concession will reflect the relative weight they put on conservation and economic outcomes [START_REF] Cerutti | The impact of forest management plans on trees and carbon: Modeling a decade of harvesting data in Cameroon[END_REF]. Second, the fact that an officially-approved FMP exists is neither a quality guarantee nor an indication of its implementation on the ground (Karsenty et al., 2017).

1 CAR is the only country in the Congo Basin where a public structure carries out the FMP for logging companies, mainly because the CAR has since 2000 benefited from a support project for the implementation of FMPs (the PARPAF project financed by the AFD).

FSC certification: an additional guarantee of sustainable forest management

To show their commitment toward sustainable forest management, logging companies with an accepted FMP can apply to be certified by the Forest Stewardship Council (FSC). This is a voluntary, market-based approach to enhancing sustainable forest management. Concessions with FSC certification commit to comply to FSC standards, which aim to promote "environmentally appropriate, socially beneficial and economically viable management of the world's forests" [START_REF] Fsc | Mission and Vision Protecting forests for future generations[END_REF]. In return, the FSC label on the forest's products is expected to be beneficial in terms of market access and share, and higher prices [START_REF] Romero | Evaluation of the impacts of Forest Stewardship Council (FSC) certification of natural forest management in the tropics: a rigorous approach to assessment of a complex conservation intervention[END_REF]. For certification, concessions commit to adhere to the ten international FSC principles and twelve criteria, covering social aspects such as workers' rights and employment conditions, and environmental aspects, including diverse measures of forest-management planning and monitoring similar to those that are supposed to appear in their FMP. Independent certifying bodies audit concessions prior to certification to determine their conformity to the FSC criteria: they then provide certification for five years, during which they carry out annual concession inspections to ensure their continued compliance (FSC, 2019).

In the context of weak developing-country institutions in, where regulators have limited resources to enforce compliance to Forestry Law and FMP, this third-party verification should provide additional guarantees that logging concessions have effectively adopted sustainable forest-management practices (Blackman et al., 2018). For this reason, regarding the environmental aspects of forest management, the added value of the FSC is to avoid FMPs that only reflect economic criteria and apply only on paper, with few, or no, measures implemented in practice. in logging concessions. FMP and FSC can have a variety of impacts, including social and economic benefits and reduced forest degradation, which are likely correlated with deforestation. However, the exact measurement of them mis beyond the scope of our work here, which will focus only on deforestation. Our theoretical framework is then articulated around five main causal pathways relating forest management to deforestation: (i) concession planning; (ii) monitoring of the concession for settlement expansion, agriculture expansion and illegal activities; (iii) planning of the loggingtrack network, log landings and skid trails; (iv) improvements in forestry-management practices and logging techniques; and (v) improved livelihoods for local communities [START_REF] Cerutti | The impact of forest management plans on trees and carbon: Modeling a decade of harvesting data in Cameroon[END_REF][START_REF] De Blas | Prospects for Reduced Impact Logging in Central African logging concessions[END_REF][START_REF] Madron | Estimation de l'impact de différents modes d'exploitation forestière sur les stocks de carbone en Afrique Centrale[END_REF][START_REF] Pearson | Carbon emissions from tropical forest degradation caused by logging[END_REF]Putz et al., 2008a,b).

Theory of change

The FMP first allows logging firms to plan their activity over time, by dividing the concession into different management series and through the production of forest inventories. Moreover, participatory mapping activities with local communities help identify the areas of the concession devoted to community development and smallscale agriculture. These activities could help reduce deforestation in different ways. In production series, rotation planning and the definition of annual cut areas should reduce the expansion, dispersion and sprawl of logging activities, while ensuring that the forest remains undisturbed between exploitation cycles, thereby reducing the repeated exploitation of the same areas. In addition, the definition of conservation series and buffer zones in more vulnerable areas should increase the area that is not logged and thus is without new logging roads. Last, the definition of community-development series should limit forest clearing for agricultural activities and settlement expansion in predefined areas.

Second, FMPs involve concession monitoring in order to control the expansion of settlements and agricultural areas, as well as illegal activities. This includes controlling concession access: the temporary or permanent closure of logging tracks, the dismantling of bridges and post-exploitation access control. This monitoring is expected to reduce illegal activities such as slash and burn agriculture, hunting and the illegal har-vesting of timber or fuelwood, which could produce deforestation through forest clearing, repeated forest exploitation or even fire spread.

Third, FMPs involve the planning of logging tracks, log landings and skid trails. The main technical intervention here is the planning and optimization of the track network according to the topography, forest inventories and the location of annual cut areas in order to preserve soil and valuable forest species for biodiversity and future exploitation. The objectives are to reduce the areas occupied by logging tracks, log landings and skid trails. This is expected to reduce deforestation and the damage to forest cover linked to logging.

Fourth, FMPs involve the adoption of a set of improved forestry-management practices and logging techniques, mainly (i) the application of a minimum log diameter (over the legal minimum) that should reduce the volume and increase the variety of logged species, reducing the pressure on the individual most-valuable species and (ii) the improvement of tree-felling techniques (controlled or directional tree felling) which should limit the damage to the remaining stand linked to tree fall and skidding manoeuvres. These practices are mostly expected to affect forest degradation, but should also reduce deforestation by preventing large canopy gaps and tree-felling in sensitive areas that may require long recovery times.

Finally, through the associated social measures, FMPs could enhance the livelihoods of those who live and work in and around logging concessions. Improved livelihoods in turn may reduce the incentives for both illegal and unsustainable logging, and could also reduce clearings by reducing the dependence on fuelwood and slash and burn agriculture. However, the relationship between livelihoods and deforestation is complex and, in some cases, improved livelihoods may spur forest-cover change or attract more people [START_REF] Chomitz | At Loggerheads?: Agricultural Expansion, Poverty Reduction, and Environment in the Tropical Forests World Bank e-Library[END_REF][START_REF] Rist | The impacts of selective logging on nontimber forest products of livelihood importance[END_REF], potentially increasing deforestation (Blackman et al., 2018).

FSC certification is hypothesized to affect deforestation through the same causal mechanisms as noted above. In addition, FSC certification should also enhance monitor-ing by external actors, including independent certifying bodies, NGOs and the media (Blackman et al., 2018). In the context of weak governance, this should result in better compliance with and performance of each of these mechanisms. To the extent that the enforcement of sustainable forest-management practices by regulators in the study area is weak, we may expect to find a greater fall in deforestation in concessions that are FSC-certified.

By their nature, these mechanisms are likely to produce effects over different time frames and in distinct areas inside concessions. At first, the planning and monitoring of concessions, as well as improved livelihoods, would likely produce effects that are visible in the short to medium term in areas close to settlements, the main transport networks and previously-opened logging roads. In the same timeframe, the planning of logging tracks and log landings is expected to affect the forest in production series through the enforcement of annual cut areas. In the second, more distant, period the adoption of improved forestry-management practices and logging techniques is also expected to affect the forest in production series by allowing valuable trees to regenerate. For these reasons, the impact of sustainable forest-management practices on deforestation should vary over both time and space within concessions with FMPs or FSC certificates.

Data

We here use two types of information to evaluate the effect of sustainable forest-management practices promoted via FMP and FSC.

We initially collected detailed information on logging concessions in the study area using the official land-tenure data released by the OFAC and World Resources Institute (WRI) in the "Congo Basin Forest Atlases". The datasets used in this study cover 397 concessions across the four countries under consideration (see Figure 1). The resulting database was updated using the gray literature and information collected on the ground from local actors, especially in the case of concession reallocation to another company during the study period. To establish when a logging concession

Forest cover in 2000

No forest Forest started implementing its FMP, we rely on the FMP-acceptance date, despite there being potentially long delays between FMP preparation, submission and acceptance by the competent authorities. We likewise used the issuance date of the FSC certificate to identify logging concessions whose practices have been verified and certified by an FSC-accredited external agent. As logging concessions may introduce sustainable forest-management practices ahead of FMP validation, we will underestimate the FMP effect as some no-FMP concessions in 2010 will already have a FMP in action. We explore some of these implications in Section 5 when considering the limits of our work.

Other information collected on logging concessions include the physical attributes of their environment (altitude, steepness and biomass) and their proximity to road infrastructures and settlements, which can affect both the likelihood of adopting sustainable forest-management practices and competition over forest resources and deforestation (see Table S1 for detailed characteristics of active logging companies included in the study).

The second type of information comes from high-resolution maps of forest cover and forest-cover changes across the Congo Basin. These come from two sources. We first re- accuracy than global data [START_REF] Sannier | Suitability of Global Forest Change data to report forest cover estimates at national level in Gabon[END_REF]. Combining these data, we produced homogeneous regional-level maps of forest cover at three points in time (1990, 2000 and 2010) and calculated gross deforestation between these dates (see Table 1 andFig

- ure S1).
Second, for comparison purposes, we use measures of tree-cover loss produced from the Global Forest Change (GFC) dataset (1.0) [START_REF] Hansen | High-Resolution Global Maps of 21st-Century Forest Cover Change[END_REF]. We calculated treecover loss between 2000 and 2010 for two tree-cover thresholds, 30% and 70%. The 30% tree-cover threshold is that used in most forest definitions, but in the case of the countries of the Congo Basin, the 70% tree-cover threshold seems to be more realistic given the forest conditions on the ground [START_REF] Sannier | Suitability of Global Forest Change data to report forest cover estimates at national level in Gabon[END_REF].

Combining the map giving the location and geographical coverage of each logging concession and its sustainable forest-management practice status to the high-resolution deforestation maps informs us about the deforested area over 1990-2000 and 2000-2010 in each concession. However, the raw comparison of the area deforested to time of FMP-acceptance or FSC certificate-issuance is unsatisfactory for at least two reasons.

First, logging concessions had their FMP accepted and received their FSC certificates at different points in time. Hence, in line with the theory of change, we need to take the appropriate definition according to the treatments in which we are interested. Second, the decision to adopt sustainable forest-management practices and submit an FMP is initiated by the logging companies, and is thus to some extent endogenous. The concessions that chose to adopt sustainable forest-management practices likely differ from those that did not, and these differences can affect deforestation. There is thus selection bias in the raw comparisons of logging concessions with and without an FMP, so that we risk attributing the effect of other observable or unobservable concession characteristics to sustainable forest-management practices. The next section describes the empirical framework used to address this problem and select concessions based on the likelihood that the effects of their activities contribute to the deforestation measured over the observation periods. We then present the potential-outcomes framework of [START_REF] Rubin | Estimating causal effects of treatments in randomized and nonrandomized studies[END_REF] that we use to deal with potential confounders and estimate the deforestation effect of sustainable forest-management practices.

Empirical framework

Following the theory of change outlined above, we wish to evaluate how deforestation in a concession changes with the adoption of sustainable forest-management practices, measured either by FMP-acceptance or FSC certificate-issuance. We would furthermore like to differentiate the short-and medium-to long-term impacts of sustainable forest-management practices. Finally, we will look for spatial heterogeneity in the average treatment effects.

Treatment groups

The first logging concession in the study area had its FMP accepted in 1999. We hence focus on the impact of (i Measuring the effect of the early adoption of sustainable forest-management practices (treatment FMP 2000(treatment FMP -2005) ) reflects the potential FMP impact on deforestation over the medium to long run. We expect the concessions with an accepted FMP before 2005 to adopt selective logging practices over at least five years, so that deforestation between 2000 and 2010 will be lower than in concessions without an FMP over this period.

)
However, as very few concessions had an accepted FMP in 1999, our data do not allow us to measure the impact of FMPs over longer time periods.

We next consider more treated concessions, defined as those that had an FMP accepted between [START_REF] Stern | The Economics of Climate Change: The Stern Review[END_REF]and 2010(treatment FMP 2006-2010)). As deforestation is measured in 2010, this treatment reflects the short term, and supposes that logging companies began improving their forest management before FMP acceptance, as otherwise the time period is too short for us to observe a reduction in deforestation. There may be a long delay between FMP preparation, submission and acceptance by the competent authorities, and concessions may begin to implement FMP activities before its acceptance.

The effects of the FMP may thus already be apparent in 2010.

In both of these two treatments, the control group is active concessions without an FMP. We define a concession as "active" if it was attributed to a logging company for Since the first FSC certificates were issued in 2005, we here evaluate the short-term impact of FSC certification (after one to five years of certification). It is however worth noting that all FSC-certified concessions already had a valid FMP. Furthermore, over half of the concessions with FSC certificates had an accepted FMP before 2005. As such, estimating the effect of FSC-certificate issuance is similar to measuring the impact of an FMP, but with these particular logging concessions in addition benefiting from thirdparty verification of sustainable forest-management practices. The treated group here is all active concessions that were certified before 2010. As in the previous treatments, the control group is all active concessions without an FMP in 2010. There are 25 FSC concessions and 194 no-FMP concessions in this treatment.

Econometrics and identification strategy

This subsection describes the strategy used to account for the endogenous selection of logging concessions into the adoption of sustainable forest-management practices described in Section 3. Our approach here is consistent with the previous empirical literature on the environmental impact of various policies (see for instance [START_REF] Blackman | Evaluating forest conservation policies in developing countries using remote sensing data: An introduction and practical guide[END_REF][START_REF] Börner | Emerging Evidence on the Effectiveness of Tropical Forest Conservation[END_REF][START_REF] Velly | Evaluating Payments for Environmental Services: Methodological Challenges[END_REF] and uses a propensity-score matching (PSM) approach to estimate the effect of FMP and FSC-certification in the Congo

Basin with the least possible bias.

Using the potential-outcome framework, we consider that each logging concession has two potential outcomes Y 1 and Y 0 , where Y 1 is the area deforested between 2000 and 2010 for logging concessions with an FMP (or with FSC certification) and Y 0 the analogous figure for concessions without an FMP (FSC certification). T is a dummy for the concession having either an FMP or FSC certification. We want to estimate the average effect of an FMP or FSC certification in the concessions that have them, i.e. the average treatment effect on the treated (ATET):

ATET = τ = E (Y 1 -Y 0 | T = 1) (1)
As Y 0 is never observed for a "treated" concession, the ATET cannot be directly estimated. Denote by X a set of characteristics that are known to affect both deforestation and the presence of an accepted FMP or FSC certificate (which we refer to as the treatment for brevity below). The propensity score is π (X) ≡ P T = 1 X . The following assumptions, often referred to as "strong ignorability" [START_REF] Rosenbaum | The Central Role of the Propensity Score in Observational Studies for Causal Effects[END_REF], imply that controlling for X suffices to account for the effects of the confounding factors:

(H1) (Y 1 , Y 0 ) ⊥ ⊥ T X and (H2) 0 < π (X) < 1
H1 is often referred to as "unconfoundedness", and states that, if all confounders are included in X, then controlling for X renders treatment exposure independent of the potential outcomes. Under H1, [START_REF] Rosenbaum | The Central Role of the Propensity Score in Observational Studies for Causal Effects[END_REF] show that (Y 1 , Y 0 ) ⊥ ⊥ T π (X). Consequently, logging concessions with similar propensity scores would have on average similar deforestation in the absence of an FMP or FSC Certification and

E Y 0 T = 1 , π (X) = E Y 0 T = 0 , π (X)
H2 implies that, for almost all values of X, both treated and untreated concessions have a probability of an accepted FMP or FSC certification at some point. If H1 and H2 hold, then [START_REF] Abadie | Matching on the Estimated Propensity Score[END_REF] suggest estimating the ATET τ as follows:

τ = 1 N 1 N i=1 T i   Y i - 1 M j∈J M (i) Y j   .
Here M is a fixed number of matches per logging concession i, J M (i) the set of matches for logging concession i, N the number of treated and untreated concessions, N 1 the number of concessions with the treatment and T i a dummy for the concession i being treated. The matching set J M (i) is defined as follows:

J M (i) = j = 1 . . . N : T j = 1 -T i , k:T k =1-T i 1 |π (X i ) -π (X k )| ≤ |π (X i ) -π (X j )| ≤ M .
where 1 is an indicator variable for the event inside the brackets holding. The set J M (i) hence consists of the logging concessions that are not treated and with a propensity score similar to that of logging concession i. Overall, τ is the average difference in the area deforested between each treated concession and the average deforestation in a set of untreated concessions with similar propensity scores. [START_REF] Abadie | Matching on the Estimated Propensity Score[END_REF] also show that τ produces an unbiased estimate of the ATET, while taking into account the fact that the propensity score is estimated.

Confounding factors and estimation

We consider ten key covariates that are known to be correlated with the likelihood of deforestation and the adoption of sustainable forest management to estimate the propensity scores [START_REF] Blackman | Evaluating forest conservation policies in developing countries using remote sensing data: An introduction and practical guide[END_REF]. The selected covariates include indicators of accessibility, population pressure, biomass productivity, average steepness and elevation. Four variables were used to proxy various dimensions of accessibility that are the most correlated with deforestation and the likelihood of adopting sustainable forestmanagement practices: the distance to the road network, the distance to the nearest settlement, distance to the capital of the country and main ports, and the travel distance to a market. Settlement density is the number of settlements in a 20-kilometre radius around each settlement, and picks up population pressure. We also include the distance to a deforested area in the 1990-2000 period. Above-ground forest biomass is based on [START_REF] Avitabile | An integrated pan-tropical biomass map using multiple reference datasets[END_REF] and measures the density of timber available (for example, forests from Southern Congo have less biomass than those in the Northern Congo, where most of the FMP concessions are located). Elevation and slope describe the topographic environment and so suitability for logging, as steep slopes can pose problems for logging machines. Last, we control for the concession area in hectares (see the supplementary information for more information on the covariates).

Robustness checks

To produce unbiased estimates of the treatment effects, quasi-experimental approaches based on matching techniques assume that all of the relevant variables that can affect both the likelihood of deforestation and the adoption of sustainable forest-management practices are observed and used as controls. However, this assumption is hard to test, as the real unknown variables are by definition unknown, while some known confounders (the quality of local governance) are hard to measure [START_REF] Panlasigui | Impacts of certification, uncertified concessions, and protected areas on forest loss in Cameroon, 2000 to 2013[END_REF].

If these unobservable confounders are spatially time-invariant, their effect should be seen in the difference in the area deforested in concessions with and without an FMP prior to FMP adoption, and hence between 1990 and 2000. Following this argument, we test for differences in 1990-2000 deforestation between concessions with and without FMP after matching. We furthermore consider an alternative identification approach that explicitly takes into account past deforestation by measuring the effect of FMP adoption on the change in deforestation over time. This change in deforestation (between 1990-2000 and 2000-2010) should in theory allow us to abstract from the effect of any unobservable factors that do not vary over time and hence should not affect the change in deforestation. This is akin to combining matching with a differencein-difference approach. This is however not our preferred strategy, given that we do not have a true panel of logging concessions. Some logging concessions observed in 2000-2010 were not active in 1990-2000. Moreover, the deforestation data are of poorer quality between 1990 and 2000 due to the lack of satellite imagery, and the GFC dataset only covers deforestation after 2000. Less deforestation close to previous deforestation due to rotation planning, avoiding the reexploitation of the areas previously logged.

Effectiveness of concession monitoring, especially control of access by closing former logging roads.

Less deforestation close to previous deforestation (due to the opening of logging roads) linked to the reduction of illegal activity along former logging roads Distance to main roads Effectiveness of concession monitoring with control of access.

Less deforestation close to main transport networks due to reduced access from public roads.

Distance to settlements

Effectiveness of concession planning, especially the definition of areas for community and agriculture development with the promotion of sustainable activities.

Less deforestation close to settlements due to the promotion of sustainable activities and better monitoring of settlement extension.

Effectiveness of concessions' "social contracts"

Impact heterogeneity

To explore the mechanisms of change, we assess impact heterogeneity via pixel-level analyses, which allows us to consider spatial heterogeneity in the average treatment effect inside concessions (see the SI for detailed information on the pixel-sampling strategy). This pixel-level data comes consists of a random sampling of 160 000 points within logging concessions from the high-resolution satellite imagery described in Section 3.

To test the most-plausible pathways of the theory of change outlined above, we explore heterogeneity by the proximity of pixels to past deforestation, road networks and settlements (see Table 2 for a summary of the main predictions of the different plausible mechanisms). More precisely, we compare how the difference in deforestation across pixels that are close (under median distance) and far (over median distance) differs by concession FMP status. In line with the theoretical framework, we focus the heterogeneity analysis on concessions that had their FMP accepted between 2000 and 2005,

where the expected impact of each mechanism is more likely to be seen.

Results

The impact of sustainable forest-management practices on deforestation

After matching, our estimates suggest that concessions with an accepted FMP between 2000 and 2005 have less deforestation compared to otherwise-similar concessions without an FMP (see Table S2 for more details). More precisely, FMP adoption between 2000 and 2005 is associated with average lower deforestation of 681 ha per concession (Fig-

ure 2). Since the area deforested between 2000 and 2010 is estimated at 921ha in control concessions, this represents a 74% fall in deforestation (Figure 2). We find similar results using estimates of the area deforested from the GFC dataset, with FMP adoption between 2000 and 2005 being associated with lower deforestation of 1,005 ha for tree

Note:

The capped vertical lines represent the 95% confidence intervals around the point estimates.

cover of 70% and 1,144 ha for tree cover of 30%, representing respectively drops of 74 and 75% (see Table S3).

For an accepted FMP between 2006 and 2010, after matching, we find no statisticallysignificant impact of the FMP 2006-2010 treatment on 2000-2010 deforestation. The same result applies when the area deforested is estimated using tree-cover loss from the GFC dataset for tree cover of 70% and 30%. As such, reduced deforestation is not seen in the short run, in line with the predictions from the theory of change.

Last, after matching, the FSC 2000-2010 treatment is also associated with a statisticallysignificant fall in deforestation between 2000 and 2010. Concessions with FSC certification, testifying that sustainable forest-management practices have indeed been implemented, have on average 514 ha less deforestation between 2000 and 2010. Compared to the average deforested area of 1,107 ha in the control concessions, this represents a drop of 48% (Figure 2 and3). This result can be replicated using deforestation from the GFC data, with avoided deforestation in FSC 2000-2010 concessions of 699 ha for

Note:

The capped vertical lines represent the 95% confidence intervals around the point estimates. tree cover of 70% (a 47% fall) and 789 ha for tree cover of 30% (a 50% fall).

Robustness checks

The validity of the above results rests on the assumption that the matching was successful in comparing treated and untreated concessions with similar propensity scores.

We moreover assume that no variables other than the 10 covariates used as controls predict FMP acceptance and/or FSC certification and deforestation in logging concession. In this subsection we discuss the sensitivity of our estimates to these two assumptions.

The matching was first successful in balancing treated and untreated households with similar propensity scores. Figures S2,S3 and S4 show that is was possible to associate each treated concession to a control concession with similar propensity score. Then, Tables S4 and Tables S5 show that the matching was successful at removing most difference in observable characteristics between treated and the untreated control conces-sions.

However, even after matching, control concessions cover larger tracts of land. The fact that concessions without an FMP cover larger areas than those with an FMP after matching may suggest that our estimate over-estimates the drop in deforestation from the FMP as larger concessions are more likely to have larger areas deforested, even with lower deforestation rates. However, this is not the case: further analyses show that the 2000-2010 deforestation rate is also lower in concessions with an accepted FMP between 2000 and 2005.

There is no statistically-significant difference in past deforestation (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000) for concessions with and without an FMP (although concessions with an accepted FMP between 2000 and 2005 exhibited qualitatively less 1990-2000 deforestation).

We introduce an alternative specification to account more directly for this 1990-2000 deforestation difference, which may reveal subtle but real differences in unobservable characteristics. This seeks to measure the effect of FMP adoption on the ability of logging concessions to reduce deforestation over time. Comparing the change in deforestation between 1990-2000 and 2000-2010 across logging concessions with and without an FMP, we find that deforestation fell more in treated concessions than in control concessions without an FMP, although this difference was not statistically significant for the FMP 2000-2005 treatment. We applied the same approach for our other treatment variables, and found similar statistically-significant results (see Table S6 for more details).

Impact heterogeneity

We first reproduce our analysis at the pixel rather than the previous concession level, and find that pixels located in treated concessions are less likely to be deforested than those in concessions without an FMP, as in the previous Sections.

Second, spatial-heterogeneity analysis using the pixel-level database revealed that 2000-2005 FMP is associated with significantly less deforestation in areas close to settle- ments, previously-deforested areas and main transport network, with the measured difference being stronger for observations below the median value of these three variables (see Table 3). The ATET for all concessions on the likelihood of deforestation was smaller by 0.27 percentage points, equivalent to 53% less deforestation; the analogous figures in areas close to settlements are 0.41 (57%), in areas close to previous deforestation 0.61 (69%) and in areas close to main transport network 0.24 (42%). Conversely, likelihood of deforestation was not statistically different across concessions with and without FMP in areas further from settlements, previously deforested areas and main transport road.

These results are in line with our expectations from our theory of change (Table 2 and Figure 1). They emphasize the effects of improvements in, first, the planning of the concessions, especially for rotation cycles and areas for community and agricultural development, second, the monitoring of concessions by closing former logging roads and monitoring the extension of settlements and agriculture areas, and, third, the monitoring of the incursion from public roads into concessions.

Discussion and concluding remarks

Curbing tropical deforestation is arguably a major environmental challenge. Addressing it requires the assessment of policy effectiveness and the understanding of the mechanisms underpinning their successes and failures. This paper contributes to this aim by showing that the area deforested is lower in logging concessions that adopt sustainable forest-management practices in the Congo Basin. Deforestation is lower in concessions that have had an FMP for at least five years. Like [START_REF] Panlasigui | Impacts of certification, uncertified concessions, and protected areas on forest loss in Cameroon, 2000 to 2013[END_REF], this highlights the importance of the time frame: interventions aimed at increasing

FMPs and FSC-adoption should be evaluated over long time periods.

Evidence from micro-level analyses suggests that FMP have allowed concessions to avoid the over-exploitation of previously-logged areas. Our results also suggest that FMP concessions are more likely to better control access into their perimeter and re-duce deforestation around communities located within or nearby the concession. This is in line with the theory of change underpinning the adoption of sustainable forestmanagement practices. These results confirm the utility of potential spatial heterogeneity in policy and management interventions [START_REF] Bruggeman | Impact of land-use zoning for forest protection and production on forest cover changes in Bhutan[END_REF].

While FMP acceptance is mandatory across countries in the Congo Basin, logging concessions chose when to draft and submit their FMP. It is then possible that concessions that had their FMP accepted earlier have unobserved characteristics that led them also to deforest less. Our efforts to account for this were limited by the fact that logging concessions change ownership over time, and that information about the former management was scarce. However, taking into account previous deforestation, we found that the area deforested fell more in concessions following the FMP adoption. Whether deforestation will also be lower in logging concessions that had their FMP accepted

later remains an open question. Will we continue to see lower 2005-2015 deforestation in concessions with an FMP accepted between 2005 and 2010? Will there continue to be lower deforestation in concessions that had their FMP accepted earlier?

Answering the above questions is a natural extension of our work here, and will help address the external validity of our results. This will also help inform us whether the adoption of sustainable forest-management practices works for all concessions, and how lower deforestation varies over longer time periods. Likewise, the adoption of sustainable forest-management practices is also expected to bring benefits other than reduced deforestation. These include, for example, conservation benefits such as reducing forest degradation and the preservation of biodiversity, and welfare improvements for the local population. Future work should therefore address other potential FMP impacts in the Congo Basin, and reveal whether lower deforestation has come at the expense of other dimensions of development and conservation.

Covariates used in Matching

A key assumption of PSM is the selection on observables. It requires that all confounding factors influencing both reception of the treatment and the outcome variable are included in the model [START_REF] Rosenbaum | The Central Role of the Propensity Score in Observational Studies for Causal Effects[END_REF]. We included ten key covariates in our estimations that are known to be correlated with the likelihood of deforestation and adoption of sustainable forest management. These include indicators of accessibility, population pressure, biomass productivity and slope and elevation [START_REF] Blackman | Evaluating forest conservation policies in developing countries using remote sensing data: An introduction and practical guide[END_REF]. We computed the average covariates values for each concession.

Covariates of Accessibility:

• Distance to the transport network: calculated as the Euclidean distance to the nearest transport axis (main road, railway, navigable river) in kilometres. Distance to the transport network accounts for accessibility in two ways: on the one hand, transport infrastructure break the isolation of the forest, and, on the other hand, the lack of transport infrastructure is a brake for agricultural and forestry development.

• Distance to the nearest settlement: calculated as the Euclidean distance to the nearest settlement in kilometres. Spatial locations of settlements was obtained from the Forest Atlas of Congo released by WRI and OFAC. Distance to the nearest settlement accounts for accessibility by foot and intensity of forest use from people living in the settlement.

• Distance to urban markets: calculated as the Euclidean distance to the nearest city in kilometres. In fact, the population of cities is large and the demand for agricultural products, wood and coal from the urban population is strong. Moreover, proximity to markets increases the profitability of timber extraction and agricultural land uses.

• Distance to the capital of the country and main ports: calculated as the lowest cumulative cost path to reach the nearest capital or port of export using the trans-port axes, which have been weighted according to their characteristics (main and secondary transport axes). This variable describes the transport constraints that weigh on some isolated regions, particularly Northern Congo, CAR or Eastern Cameroon. These logistical and financial constraints are strong for the export of timber from concessions located in these regions.

Population pressure:

• Settlements' density: computed using the number of settlements in a radius of twenty kilometres around each settlement. This variable describes the aggregates of settlements located close to each other, what therefore reflects a greater population pressure. In fact, the forest resources located near five settlements will, in most cases, be more intensively used than those located near a single settlement.

Several other global data on population distribution have been downloaded to analyse their consistency with local reality, such as the WorldPop and Gridded Population of the World data. However, we considered that they bring a lot of bias locally by creating artefacts in certain rural areas, in addition to have a rather low spatial resolution.

Environmental variables:

• Distance to previous deforestation: calculated as the Euclidean distance to the nearest deforested area in the previous period (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000) in kilometres based on the map of the national forest monitoring systems of each country. Indeed, areas close to previously deforested areas have a higher probability of being deforested whether related to the expansion of rural complexes or to the use of former logging tracks.

• Above-ground biomass in 2000: we used the map of [START_REF] Avitabile | An integrated pan-tropical biomass map using multiple reference datasets[END_REF] available at: http://lucid.wur.nl/datasets/high-carbon-ecosystems. This variable accounts for general differences in forest structure, forest type and forest productivity, which affect both logging and agriculture activities.

• Elevation and Slope: calculated using the Digital Elevation Model recorded by the Shuttle Radar Topography Mission (SRTM). These variables influence forest type, seasonal flooding, accessibility, and feasibility of logging forestry operations.

Finally, we controlled for the area of concession in hectare.

Analyse at the pixel level to study the heterogeneity of the impact inside concession

To study the heterogeneity of the impact inside concession, we worked at the pixellevel. We extracted a random sampling of 160.000 points in the concessions from the 2000 forest cover baseline. We did a stratified sampling with at least twice as many points in the control areas as in the treatment areas, in order to increase the probability of finding a good match for each point located in a concession that has adopted sustainable forest management practices. We imposed a minimum distance of 200 meters between each point to minimize spatial autocorrelation. We used each point as an observation, and extracted the value of the covariables and the outcome as a dummy variable equal to 1 if the point was deforested during the ten years period and 0 otherwise.

So, in contrast to our previous concession-level analyses where we measured avoided deforestation in hectares, at the pixel-level, we measured the likelihood that a given point appears deforested. . Note: The table reports estimates of average tree cover loss over the period 2000-2010 across treatment groups as described in Section 4. Mesures of tree cover loss is derived from the Global Forest Change (GFC) dataset (1.0) [START_REF] Hansen | High-Resolution Global Maps of 21st-Century Forest Cover Change[END_REF]. Standard errors are in parentheses. Significance levels are denoted as follows: * p<0.10, ** p<0.05, *** p<0.01.

Figure 1

 1 Figure1summarizes the theory of change through which the adoption of sustainable forest-management practices via FMP and FSC is supposed to reduce deforestation

Figure 1 :

 1 Figure 1: Theory of change

Figure 1 :

 1 Figure 1: Location of concessions in the countries analysed in the Congo Basin

  quested and obtained the original maps produced as part of the global effort to reduce emissions from deforestation and forest degradation in the Congo Basin. To quantitatively assess the spatial and temporal dynamics of forest change, the governments of Cameroon, CAR, Congo and Gabon developed national forest-monitoring systems (NFMS). As part of this programme, a number of remote-sensing projects were carried out in each of these countries in close collaboration with the administration in charge of forest monitoring. The resulting maps are based on high-resolution satellite imagery and ground-verification data, and should provide greater cartographic and thematic

  having an FMP accepted between 2000 and 2005, (ii) having an FMP accepted between 2006 and 2010 and (iii) obtaining an FSC certificate between 2000 and 2010 on deforestation between 2000 and 2010.

  at least two years for the FMP 2000-2010 treatment (i.e. since 2008) and at least five years for the FMP 2000-2005 treatment (i.e. since 2005, in order to be consistent with the treated concessions that, by definition, have all been active since 2005). The "no-FMP concessions" hence include all the active concessions that had no FMP in 2010 (in 2005, respectively, for the FMP 2000-2005 treatment), including concessions with accepted FMP after 2010 or that had an FMP in process in 2010. For the FMP 2000-2005 treatment, concessions that had an FMP accepted between 2005 and 2010 were excluded. Overall, there are 60 FMP concessions and 166 no-FMP concessions for the FMP 2000-2005 treatment and 121 FMP concessions and 194 no-FMP concessions for the FMP 2000-2010 treatment. Despite the certification of sustainable forest-management practices being recent in the Congo Basin, with the first certificates only issued in 2005, we can estimate the impact of FSC certification (the FSC 2000-2010 treatment) on 2000-2010 deforestation.

Figure 2 :

 2 Figure 2: Difference before and after matching across treatment groups

Figure 3 :

 3 Figure 3: The impact of treatment on 2000-2010 deforestation

Figure S2 :

 S2 Figure S2: Distribution of propensity scores for active concessions with and without an FMP accepted between 2000 and 2005.

  errors are in parentheses. Significance levels are reported for t-tests of the equality of the means across treatment groups. They are denoted as follows: * p<0.10, ** p<0.05, *** p<0.01.

  table reports differences between treated and control groups after matching. Standard errors are in parentheses. They do not account for the fact that the propensity scores are estimated and should be taken with caution. Significance levels are reported for t-tests of the equality of the means across treatment groups. They are denoted as follows: * p<0.10, ** p<0.05, *** p<0.01.

Table 1 :

 1 Forest cover and forest-cover change in the study area.

	Country	Period	Forest cover (km 2 ) area (km 2 ) Deforested Deforestation rate (%)
	Congo	1990-2000 2000-2010	223 554 233 595	1 375 1 911	0.62 0.82
	Gabon	1990-2000 2000-2010	237 242 236 634	1 025 512	0.43 0.22
	Cameroon	1990-2000 2000-2010	245 396 241 487	4 790 4 245	1.95 1.76
	CAR	1990-2000 2000-2010	98 759 96 364	3 140 2 632	3.18 2.73
	Total	1990-2000 2000-2010	804 951 808 080	10 330 9 300	1.28 1.15

Table 2 :

 2 Predictions of the main falsifiable pathways through which sustainable forest-management practices can affect deforestation in the short to medium run.

	Variables tested in the hetero-geneity analysis	Mechanism tested	Expected impact
		Effectiveness of concession
		planning, especially the map-
		ping of production series.
	Distance to past deforestation

Table 3 :

 3 Likelihood of deforestation across concessions with and without a 2000-2005 FMP: Geographic heterogeneity.

		Treated Control	Diff.	ATET
	Panel A: All pixels
	Coefficient	0.0024	0.0076 -0.0052*** -0.0027***
		(0.000)	(0.000) (0.001)	(0.001)
	Number of pixels	19,736	42,100 61,836	61,810
	Panel B.1: Pixels within median distance from settlements
	Coefficient	0.0031	0.0125 -0.0094*** -0.0041***
		(0.001)	(0.001) (0.001)	(0.001)
	Number of pixels	9,365	21,555 30,920	30,904
	Panel B.2: Pixels outside median distance from settlements
	Coefficient	0.0017	0.0024 -0.0007	0.0002
		(0.000)	(0.000) (0.001)	(0.001)
	Number of pixels	10,371	20,545 30,916	30,906
	Panel C.1:

Pixels within median distance from past deforestation

	Coefficient	0.0027	0.0129 -0.0102*** -0.0061***
		(0.001)	(0.001) (0.001)	(0.001)
	Number of pixels	10,665	20,254 30,919	30,903
	Panel C.2:

Pixels outside median distance from past deforestation

	Coefficient	0.0020	0.0027 -0.0007	0.0006
		(0.000)	(0.000) (0.001)	(0.001)
	Number of pixels	9,071	21,846 30,917	30,907

Panel D.1: Pixels within median distance of road network

	Coefficient	0.0033	0.0102 -0.0069*** -0.0024***
		(0.001)	(0.001) (0.001)	(0.001)
	Number of pixels	8,887	22,035 30,922	30,907
	Panel D.2: Pixels outside median distance of road network
	Coefficient	0.0017	0.0047 -0.0030*** -0.0010
		(0.000)	(0.000) (0.001)	(0.001)
	Number of pixels	10,849	20,065 30,914	30,903

Note: Standard errors are in parentheses. Significance levels are denoted as follows: * p<0.10, ** p<0.05, *** p<0.01.

  Distribution of propensity scores for active concessions with and without an FMP accepted between 2006 and 2010. Distribution of propensity scores for active concessions with and without an FSC certificate issued between 2000 and 2010.

	2 Figure S3: .2 Figure S4: .3
		.2
		.1 .1
		.1
	Density (%) Density (%) Density (%)	0 .1 0 .1 0 .1 .2
		.3
		.2 .2
		.4
		.3 .3 .5
		0 0 0	.2	.2	.2	.4	.4	.4	.6	.6	.6	.8	.8	1 .8
						Propensity Score Propensity Score Propensity Score
						Untreated Untreated Untreated		Treated Treated Treated
						(a) Before matching (a) Before matching (a) Before matching
		.2 .2 .3
		.2
		.1 .1
		.1
	Density (%) Density (%) Density (%)	0 0 0
		.1
		.1 .1
		.2
		.2 .2 .3
		0 0 0	.2	.2	.2	.4	.4	.4	.6	.6	.6	.8	.8	1 .8
						Propensity Score Propensity Score Propensity Score
						Untreated Untreated Untreated		Treated Treated Treated
						(b) After matching (b) After matching (b) After matching

Table S2 :

 S2 Deforestation in consessions and adoption of sustainable forest management practices.

		Deforestation in concessions	ATET
		Treated Control	Diff.	(in ha)
	Treatment: FMP validated between 2000 and 2005
	Coefficient	239.62	392.46 -152.84	-681.40**
		(91.7)	(82.9) (148.3)	(347.6)
	Number of concessions	60	165	225	225
	Treatment: FMP validated between 2006 and 2010
	Coefficient	1047.47	453.79 593.67*** 171.97
		(289.3)	(81.0) (216.9)	(273.5)
	Number of concessions	61	194	255	255
	Treatment:

FSC certificate issued between 2000 and 2010

	Coefficient	592.63	453.79 138.83	-514.11*
		(179.3)	(81.0) (234.9)	(292.5)
	Number of concessions	25	194	219	219
	Note: The table reports estimates of average deforestation over the period
	2000-2010 across treatment groups as described in Section 4. Standard er-
	rors are in parentheses. Significance levels are denoted as follows: * p<0.10,
	** p<0.05, *** p<0.01.

Table S3 :

 S3 Deforestation in consessions and adoption of sustainable forest management practices (Using data from GFC).

	Number of concessions 25 193 218 218	(259.7) (82.3) (247.0) (265.3)	Coefficient 785.28 522.23 263.05 -789.09***	Treatment: FSC certificate issued between 2000 and 2010	Number of concessions 61 193 254 254	(231.8) (82.3) (195.8) (204.8)	Coefficient 1034.87 522.23 512.65*** 126.86	Treatment: FMP validated between 2006 and 2010	Number of concessions 60 164 224 224	(91.7) (85.6) (152.1) (412.2)	Coefficient 377.89 450.79 -72.90 -1143.54***	Treatment: FMP validated between 2000 and 2005	Treated Control Diff. (in ha)	Deforestation in concessions ATET	Area with at least 30% tree cover
	25 193 218 218	(251.2) (73.3) (222.6) (237.6)	745.19 455.49 289.70 -698.68***		61 193 254 254	(205.3) (73.3) (173.9) (193.8)	913.32 455.49 457.83*** 67.29		60 164 224 224	(87.5) (76.5) (137.1) (374.7)	353.14 391.76 -38.62 -1004.96***		Treated Control Diff. (in ha)	Deforestation in concessions ATET	Area with at least 70% tree cover

Table S4 :

 S4 Characteristics of logging concessions across treatment groups before matching.

	FSC 2000-10	diff. Treated Control	453.79 138.83 592.63	(81.04) (234.89) (179.26)	522.23 263.05 785.28	(82.34) (247.02) (259.68)	455.49 289.70 745.19	(73.29) (222.60) (251.21)	327.56 540.51** 868.07	(68.65) (215.93) (281.73)	10.51*** 15.44 25.95	(2.99) (0.98) (3.33)	16.97** 82.78 99.74	(8.47) (2.88) (7.51)	113.82*** 443.70 557.53	(40.81) (13.76) (39.01)	-0.38 5.73 5.34	(0.85) (0.30) (0.51)	31.58** 102.17 133.75	(15.50) (5.36) (11.47)	-0.01** 0.01 0.01	(0.00) (0.00) (0.00)	65.15*** 356.34 421.49	(19.54) (6.92) (8.12)	92.74** 380.06 472.80	(44.82) (15.35) (37.12)	-0.25 1.82 1.57	(0.27) (0.09) (0.23)	118.37*** 77.61 195.98	(51.80)
	FMP 2006-10	Treated Control diff.	1047.47 453.79 593.67***	(289.33) (81.04) (216.88)	1034.87 522.23 512.65***	(231.82) (82.34) (195.83)	913.32 455.49 457.83***	(205.34) (73.29) (173.93)	1359.25 327.56 1031.69***	(372.68) (68.65) (241.50)	22.37 15.44 6.93***	(2.21) (0.98) (2.15)	115.35 82.78 32.57***	(7.46) (2.88) (6.62)	477.98 443.70 34.27	(27.40) (13.76) (28.95)	5.25 5.73 -0.47	(0.60) (0.30) (0.63)	123.55 102.17 21.38**	(7.99) (5.36) (10.56)	0.01 0.01 -0.00*	(0.00) (0.00) (0.00)	406.74 356.34 50.39***	(7.96) (6.92) (13.14)	491.06 380.06 111.01***	(22.08) (15.35) (30.06)	1.83 1.82 0.01	(0.13) (0.09) (0.18)	162.20 77.61 84.59***	(24.56) (9.38) (21.64)
	FMP 2000-05	Treated Control diff.	239.62 392.46 -152.84	(91.69) (82.88) (148.25)	377.89 450.79 -72.90	(91.69) (85.61) (152.13)	353.14 391.76 -38.62	(87.51) (76.46) (137.13)	425.57 251.48 174.08	(150.56) (55.85) (129.54)	26.94 15.63 11.31***	(2.01) (1.11) (2.21)	121.34 82.15 39.18***	(6.50) (3.20) (6.59)	525.30 438.41 86.89***	(26.80) (14.84) (29.43)	5.05 5.64 -0.59	(0.55) (0.32) (0.63)	131.60 100.50 31.11***	(8.26) (5.87) (10.94)	0.01 0.01 -0.00*	(0.00) (0.00) (0.00)	434.17 353.51 80.66***	(7.24) (7.65) (13.42)	545.29 361.58 183.71***	(22.62) (16.92) (31.22)	1.53 1.90 -0.37*	(0.11) (0.11) (0.19)	99.12 63.78 35.33**	(12.58) (9.60) (17.64)
	Variables	Forest loss over 2000-10 (ha)	-from national maps		-from GFC with 30% tree cover		-from GFC with 70% tree cover		Forest loss between 1990 and 2000 (ha)		Distance to nearest road (km)		Distance to market (km)		Distance to capital (km)		Distance to previous deforestation		Distance to nearest settlement (km)		Settlement density (nb villages within 20 km)		Above-ground forest biomass (Mg/ha)		Elevation (m)		Slope (%)		Area of concession (1000 ha)

Table S5 :

 S5 Characteristics of logging concessions across treatment groups after matching.

		Area of concession (1000 ha)		Slope (%)		Elevation (m)		Above-ground forest biomass (Mg/ha)		Settlement density (nb villages within 20 km)		Distance to nearest settlement (km)		Distance to previous deforestation		Distance to capital (km)		Distance to market (km)		Distance to nearest road (km)		Variables
	(20.56) (20.56) (29.08)	99.12 187.13 -88.02***	(0.11) (0.11) (0.16)	1.53 1.43 0.09	(20.94) (20.94) (29.62)	545.29 528.14 17.15	(7.20) (7.20) (10.18)	434.17 422.94 11.23	(0.00) (0.00) (0.00)	0.01 0.01 -0.00	(8.38) (8.38) (11.85)	131.60 117.48 14.12	(0.46) (0.46) (0.65)	5.05 4.69 0.36	(22.87) (22.87) (32.35)	525.30 451.12 74.18**	(6.20) (6.20) (8.77)	121.34 124.13 -2.80	(2.17) (2.17) (3.07)	26.94 23.97 2.97	Treated Control diff.	FMP 2000-05
	(23.42) (23.42) (33.12)	162.20 157.64 4.56	(0.16) (0.16) (0.23)	1.83 2.04 -0.22	(20.44) (20.44) (28.91)	491.06 492.48 -1.42	(6.91) (6.91) (9.78)	406.74 409.68 -2.94	(0.00) (0.00) (0.00)	0.01 0.01 0.00	(8.83) (8.83) (12.48)	123.55 135.36 -11.80	(0.47) (0.47) (0.67)	5.25 5.55 -0.29	(22.25) (22.25) (31.46)	477.98 448.42 29.56	(6.06) (6.06) (8.57)	115.35 105.20 10.15	(2.03) (2.03) (2.87)	22.37 22.17 0.21	Treated Control diff.	FMP 2006-10
	(40.47)	-14.32 210.30 195.98	(0.26) (0.18) (0.18)	0.02 1.55 1.57	(30.59) (43.26) (30.59)	468.55 4.25 472.80	(7.62) (10.78) (7.62)	421.09 0.40 421.49	(0.00) (0.00) (0.00)	0.01 -0.00 0.01	(10.09) (14.27) (10.09)	130.51 3.24 133.75	(0.46) (0.65) (0.46)	5.26 0.08 5.34	(29.68) (41.98) (29.68)	523.33 34.19 557.53	(6.64) (9.39) (6.64)	110.63 -10.89 99.74	(2.96) (4.18) (2.96)	23.98 1.98 25.95	diff. Treated Control	FSC 2000-10

Table S6 :

 S6 Deforestation across consessions and adoption of sustainable forest management practices (using past levels of deforestation).

		Deforestation over 1990-2000 (in ha)		ATET
		Treated	Control	Diff.	PSM	DID+PSM
	Treatment: FMP validated between 2000 and 2005
	Coefficient	425.57	251.48	174.08	-474.36	-207.04
		(150.6)	(55.9) (129.5)	(365.5)	(171.2)
	Number of concessions	60	165	225	225	225
	Treatment: FMP validated between 2006 and 2010
	Coefficient	1359.2472 327.5606 1031.69***	671.98** -500.00***
		(372.7)	(68.6) (241.5)	(309.5)	(171.0)
	Number of concessions	61	194	255	255	255
	Treatment:

FSC certificate issued between 2000 and 2010

  : The table reports the effect estimated using a difference-in-difference approach with a linear specification as described in Section 4. Standard errors are in parentheses. Significance levels are denoted as follows: * p<0.10, ** p<0.05, *** p<0.01.

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Note

1 CEE-M Working Papers Contact : laurent.garnier@inra.fr/ 04 99 61 31 21

* This work was supported by a grant of the Agence Française de Développement (AFD) and the Fonds Français pour l'Environnement Mondial, which, along with other donor agencies and banks, have funded several projects related to forest management in the Congo Basin. The authors gratefully acknowledge the national bodies of forest monitoring in Cameroon, Congo, Gabon and Central African Republic for giving us access to the data; to Jean Bakouma, Motel, Jean-Louis Doucet, Mathew Hatchwell and Benoit Jobbe-Duval for their invaluable advice, comments and insights throughout the study; to the participants of the CIFOR workshop at SupAgro in Montpellier, the Yaoundé-IUFRO conference in Yaoundé and CERDI Seminar in Clermont Ferrand for helpful discussions and suggestions.

Funding

This article was produced as part of a research project that sought to estimate and compare the relative effectiveness of the main forest management methods on deforestation in the Congo Basin. The research project was carried out by the French National Research Institute for Development (IRD) and was funded by a grant of the Agence Française de Développement (AFD) and the Fonds Français pour l'Environnement Mondial (FFEM).

Declaration of interest