Certified and uncertified logging concessions compared in Gabon: changes in stand structure, tree species, and biomass
This study is summarised as evidence for the following.
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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.