Can traditional selective logging secure tree regeneration in cloud forest?

Unplanned selective logging for charcoal and firewood is a common practice in tropical montane cloud forest (TMCF), a high priority ecosystem for biodiversity conservation at the global scale. However, limited information is available regarding the impact of such logging on forest regeneration. We evaluated the abundance and composition of tree regeneration in four TMCF sites subject to traditional selective logging in southern Mexico. At each site, we calculated a tree extraction index based on the number of stumps, logs and charcoal kilns and established six 200 m2 plots where the abundance of adult, sapling and seedling trees were recorded and canopy cover estimated. Based on the extraction index and estimated basal area values, two sites each were classified as being of low (L) and high (H) logging intensity; the extraction index was three times lower in L (7.5 and 9.2) than in H (35 and 35) sites, while basal area was significantly higher in L than in H sites (80.2 ± 10.2 vs. 41.9 ± 4.96 m2 ha-1, respectively). No significant differences were found among sites in terms of canopy cover, diameter and density of adult trees or in the density of saplings and seedlings (0.72 individuals m-2). In all sites, species of intermediate shade-tolerance dominated the regeneration (76%), followed by the shade-tolerant (23%) and pioneer (1%) species. Regeneration of Quercus spp. (four species) dominated at all sites (50.5%); this is a group of particular interest to the local communities because of its utility for firewood and charcoal. The similarity in composition between adult and regenerating tree species was relatively high in all of the sites (Morisita-Horn Index L1=0.86, L2=0.64, H1=0.69 and H2=0.71). These results indicate that, under the evaluated selective logging intensities, TMCF can sustain sufficient regeneration of Quercus spp. and thus presents an opportunity for sustainable management. The legacy effects of traditional selective logging on TMCF tree regeneration are discussed.