Redefining Secondary Forests in the Mexican Forest Code: Implications for Management, Restoration, and Conservation

The Mexican Forest Code establishes structural reference values to differentiate between secondary and old-growth forests and requires a management plan when secondary forests become old-growth and potentially harvestable forests. The implications of this regulation for forest management, restoration, and conservation were assessed in the context of the Calakmul Biosphere Reserve, which is located in the Yucatan Peninsula. The basal area and stem density thresholds currently used by the legislation to differentiate old-growth from secondary forests are 4 m(2)/ha and 15 trees/ha (trees with a diameter at breast height of >25 cm); however, our research indicates that these values should be increased to 20 m(2)/ha and 100 trees/ha, respectively. Given that a management plan is required when secondary forests become old-growth forests, many landowners avoid forest-stand development by engaging slash-and-burn agriculture or cattle grazing. We present evidence that deforestation and land degradation may prevent the natural regeneration of late-successional tree species of high ecological and economic importance. Moreover, we discuss the results of this study in the light of an ongoing debate in the Yucatan Peninsula between policy makers, non-governmental organizations (NGOs), landowners and researchers, regarding the modification of this regulation to redefine the concept of acahual (secondary forest) and to facilitate forest management and restoration with valuable timber tree species.