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 m²/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 m²/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.

The role of invasive species in ecosystem functioning represents one of the main challenges in ecology.Pteridium aquilinumis a successful cosmopolitan invasive species with negative effects on the ecological mechanisms that allow secondary succession. In this study, we evaluated the influence ofP. aquilinumon secondary succession under different disturbances in a seasonal dry forest of the Yucatán Peninsula. We determined species richness, composition and the relative importance value in four sampling units. Fabaceae followed by Asteraceae, Meliaceae, Rubiaceae, Sapindaceae and Verbenaceae were the most species rich families. A dissimilarity analysis determined significant differences in beta diversity between sampling units. With a generalized linear model we found that species richness was best explained by site conditions, followed by calcium and soil organic matter. Also, the generalized linear model showed that abundance resulted in a strong correlation with site conditions and soil characteristics. Specific soil conditions related to phosphoro and calcium were also detected as beneficiary to the successional processes. Our results suggest that applying fire restriction and periodic cutting of the bracken fern, this can increase a higher diversity of species.

Intensive production systems have damaged many natural ecosystems and have altered their capacity to provide ecosystem services such as climate regulation, soil fertility, and vector-borne disease control. Therefore, these agroecosystems are unsustainable and poorly resilient. However, traditional agroforestry systems (TAS) contribute to the conservation of biodiversity and to the provision of inputs for the maintenance of local populations. The objective of this study was to evaluate the contribution of the TAS in the food supply under the food sovereignty (FSv) approach in three different ethnic groups. The study was conducted in three communities of different origin in the State of Campeche, one Maya Tseltal-Chol, the other Mestizo, and the third Yucatec Mayan. The theoretical-methodological framework of this research was based on agroecology. Ethnographic methods and participatory research activities were carried out to describe and analyze the factors that strengthen FSv using five indicators. Our results present a description and analysis of resource access, current production models, patterns of consumption and food security, commercialization and participation in decision-making of these communities. Traditional agroecological management practices are still preserved and native species are still being cultivated. Farmers obtain about 55% of their food from TAS. The consumption of food is influenced by the culture, the purchasing power linked to economic activities and government support. TAS have played a strategic role for the survival of families but to ensure their contribution to FSv, it is necessary to articulate the actions of the sectors that share the same objective and encourage the active participation of communities in agricultural policies.