Adopt certification

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • One replicated, site comparison study in Ethiopia found that the risk of deforestation was lower in certified than uncertified forests. One controlled, before-and-after trial in Gabon found that when logging intensity was taken into account although tree damage did not differ, changes in above-ground biomass were smaller in certified than in uncertified forests.


About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A controlled, before-and-after study in 2010–2011 in two mixed lowland tropical forests in Ogooué-Ivindo, Gabon (Medjibe, Putz & Romero 2013) found that once logging intensity was taken into account a certified logged forest had similar tree damage but a smaller change in above-ground biomass than a more intensively logged uncertified forest. The amount of tree biomass damaged was lower in the certified forest than in the uncertified forest (certified: 18.7; uncertified: 33.7 Mg/ha). However, there was no difference in damage between the two forests when the higher logging intensity in the conventional forest was taken into account (certified: 3.3; uncertified: 2.9 Mg/m3). The change in above-ground biomass was smaller in the certified forest (certified: 7%; uncertified: 13%), even when corrected for logging intensity. The tree species composition after logging did not change in either forest (difference in Simpson’s Index before and after harvest: certified 0.96; uncertified 0.41). The logging intensity in the certified forest was 5.7 m3/ha and 11.4 m3/ha in the uncertified forest. Twenty plots in the certified forest and 12 in the uncertified forest were established (each 200 × 50 m). Measurements were taken within each plot 2-6 months before and 2-3 months after logging for all trees with a diameter breast height > 10 cm.

    Study and other actions tested
  2. A replicated, site comparison study in 2010 in highland rainforests in the Oromiya region, Ethiopia (Takahashi & Todo 2013) found that forests producing wild, shade-grown coffee Coffea arabica with a certification had a lower risk of deforestation than forests where coffee was grown without certification. Forests under a coffee certification program had a lower probability of deforestation (2.8%) than similar areas where no forest coffee was produced (4.5%). However, where coffee was grown without certification, the probability of deforestation (11.8%) did not differ from similar areas where no coffee was grown (12.4%). The study was conducted in two forests that were certified in 2007 and two forests that were considered uncertified during the study as they only received certification in 2009, just before the measurements of forest cover in 2010. Probability of deforestation was estimated using satellite images (Landsat, resolution 30 m) from 2005 and 2010.

    Study and other actions tested
Please cite as:

Agra, H., Schowanek, S., Carmel, Y., Smith, R.K. & Ne’eman, G. (2020) Forest Conservation. Pages 323-366 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.


Where has this evidence come from?

List of journals searched by synopsis

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Forest Conservation

This Action forms part of the Action Synopsis:

Forest Conservation
Forest Conservation

Forest Conservation - Published 2016

Forest synopsis

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What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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