A Critical Comparison of Conventional, Certified, and Community Management of Tropical Forests for Timber in Terms of Environmental, Economic, and Social Variables

Tropical forests are crucial in terms of biodiversity and ecosystem services, but at the same time, they are major sources of revenue and provide livelihoods for forest-dependent people. Hopes for the simultaneous achievement of conservation goals and poverty alleviation are therefore increasingly placed on forests used for timber extraction. Most timber exploitation is carried out unsustainably, which causes forest degradation. Two important mechanisms have emerged to promote sustainable forest management: certification and community-based forest management (CFM). We synthesize the published information about how forest certification and CFM perform in terms of environmental, social, and economic variables. With the caveat that very few published studies meet the standards for formal impact evaluation, we found that certification has substantial environmental benefits, typically achieved at a cost of reduced short-term financial profit, and accompanied by some improvement to the welfare of neighboring communities. We found that the economic and environmental benefits of CFM are understudied, but that the social impacts are controversial, with both positive and negative changes reported. We identify the trade-offs that likely caused these conflicting results and that, if addressed, would help both CFM and certification deliver the hoped-for benefits. (Resume d'auteur)

1 Supporting methods

Literature review
To carry out the qualitative literature review, we followed the search protocol recommended for systematic reviews (Pullin & Stewart 2006). The goal was to compare forest variables under two different management regimes, or before and after management implementation. To find relevant publications, we used the literature search engine Google Scholar (https://scholar.google.com/, search performed in April and May 2015) with the following search terms: community OR joint OR open access OR certification OR Forest stewardship council AND forest management AND tropical OR Africa OR Asia OR South America AND impact OR effect AND social OR economic OR environment.
This search returned 38,100 results that we first sorted by relevance, and then scanned the 1,000 most relevant titles, after which the relevance of search results became too low to justify further processing. Next, for the titles identified as potentially relevant, we read the abstracts and identified studies that measured one or more specific forest value under one of the following management regime combinations: i) FSC-certified industrial vs. conventional industrial; ii) community managed vs. open access (no specific management); iii) FSC-certified industrial vs. FSC-certified community managed; iv) FSC-certified community managed vs. community managed).
We excluded purely theoretical and modeling studies and studies based solely on Corrective Action Requests (CARs) by forest certification bodies, if they did not verify on the ground whether the CARs were fulfilled. We included meta-analyses and systematic reviews if they calculated overall effect size, and highlighted them as such, and did not further include the individual studies on which the reviews were based. We did not include reviews without an overall effect size, but we did use the individual case studies on which these reviews were based. We included only studies from natural tropical and subtropical forests, excluding Australia.
From each study, we extracted the following information: i) variable group (environmental, social, economic); ii) variable (e.g. animal biodiversity, health and safety of logging crews, or harvest costs; Table 1 in main text); iii) management regimes compared; iv) continent and country and; v) outcome of the comparison. We went through all selected studies three times: first time listing all potentially extractable variables, with short descriptions, and the outcomes of the comparisons. We then drew a final list of variables ( Table  1 in the main text), which grouped the existing variables into more general categories, and went through the studies again, to verify whether their results fitted to the new categories. During the writing process, and consultation workshop with representatives from the industry (Precious Woods, A.G.), the Forest Stewardship Council, and Non-Governmental Organizations, several new studies were incorporated into the study, which warranted a third, final check of all included studies. The extraction of information from studies was carried out by ZB and FH, and all studies were cross-checked by both ZB and FH.
We were only able to extract information on whether one management regime was better, same, or worse for a particular variable, but not by how much, as many studies did not quantify the outcomes. Therefore, our review is only qualitative, because we cannot tell whether an improvement reported by one study is equivalent to an improvement in the same variable in a different study. We also emphasize that not all the individual comparisons used are independent, as some studies contributed multiple comparisons. Also, the studies are geographically clustered and were carried out with different degrees of rigor and therefore do not deserve the same weight.

Variables and stakeholders
For forests leased by companies as concessions from the state or a community, the main stakeholder with respect to the economic variables is the logging company, which we presume aims to maximize profits. For forests managed directly by communities, the main stakeholder in terms of economic variables is usually a community enterprise (Humphries et al. 2012). For community enterprises, profit maximization may not be the principal goal -job creation or social capital building might be equally important. Community enterprises may therefore be judged successful even if no profits are generated (McDaniel 2003;Humphries et al. 2012).
Another issue that we do not consider is that some profits from private companies and community enterprises percolate upwards and contribute to national incomes through taxes, royalties, or increased investments (not quantified by any study). Similarly, some corporate profits may benefit local inhabitants through direct payments or general welfare subsidies such as schools, roads, or health services.
The core social value can be described as the welfare of local communities. No study captures all aspects of welfare: the definition and measurement of quality of life is considered a major challenge for scientists and policy makers alike. There are, however, several variables that are presumed to contribute to welfare (Table  1). In this study, we consider welfare to be the opposite of poverty (Hensbergen et al. 2011). The existing literature contains very few social variables that reach beyond local communities.
The environmental variables most often measured relate to carbon sequestration and biodiversity conservation (Table 1). These variables are interrelated and valued principally by the international community (Kuijk et al. 2009). Very few studies measure environmental variables valued specifically by local communities, and these indicators often fail to inform local decision making (Garcia and Lescuyer 2008) (Sheil et al. 2010).
2 Supporting data and reference 2.1 Full references of studies included in the analysis Numbering corresponds to Figure 1 in the main text. 2.2 Database of comparisons of environmental, economic, and social outcomes for different tropical forest management regimes