Treefall gaps of certified, conventionally managed and natural forests as regeneration sites for Neotropical timber trees in northern Honduras

Forest certification programmes promote sustainable management of the world's forests. Certification can be given to a forest management system that fulfils certain environmental, social and economic criteria. The ecological criteria for certified forestry include limiting harvest intensity and minimizing the mechanical damage of logging. Based on these requirements, we hypothesized that in comparison to conventionally managed forests, the logging gaps of certified forests would (1) host more established saplings of timber trees, due to a higher abundance of seed trees left in the forest, and (2) provide more favourable environments for the establishment and growth of timber seedlings, due to the control of negative logging impacts. We tested these hypotheses, using regeneration data on 10 shade-tolerant Neotropical timber species in a total of 46 treefall gaps in certified, conventionally managed and natural broad-leaved forests in northern Honduras. We analysed 12 environmental gap characteristics as determinants of sapling abundance, using a statistical approach that emphasizes their sensitivity to the forest management system as well as their ecological role. We found that gaps in certified forests were characterized by lower levels of logging-related disturbance than gaps in conventionally managed forests. The differences were however relatively small, since loggings are done at low intensity and without heavy machinery in the area. Despite the more favourable gap environment, regeneration success was poorer in certified forests than in conventionally logged forests. As expected, highest regeneration was found in natural forests. The good regeneration success in conventionally logged forests was largely due to the high abundance of a single species, Mortoniodendron vestitum. To explain the remaining differences in regeneration between management types, we suggest that loggings in certified forests have been more intensive in the past, leading to a scarcity of timber seed trees. We further propose two alternative explanations related to treefall gap frequency: (a) low logging intensity after certification may have led to low frequency of treefall gaps, limiting the recruitment of timber species; or (b) intensive loggings currently maintain an environment with too much disturbance for the success of timber regeneration. (C) 2008 Elsevier B.V. All rights reserved.