Copal is a resin of ritual uses in Mexico that is extracted from several species of trees of the genus Bursera. The effect of traditional management on phenotypical traits of copal trees has not been sufficiently studied. This research analyzed the traditional management and human selection on populations of Bursera bipinnata, and it also examined their influence on the quantity and quality of the resin produced by wild and managed trees. The management of copal was documented through semi-structured interviews and workshops. Samples of 60 trees from six wild and managed populations were selected to quantify the production of resin during two consecutive years. Fresh resin was collected to identify organic volatile compounds through gas chromatography and Principal Components Analysis (PCA); individuals were classified according to the amount and type of organic compounds produced. We identified management strategies from simple harvesting to seeds planting. The criteria of local people for selecting managed trees and seeds are based on the quantity and quality of the resin produced per tree, which were significantly higher in managed than in wild trees: 190.17 ± 329.04 g vs. 29.55 ± 25.50 g (p = 0.003), and 175.88 ± 179.29 g vs. 63.05 ± 53.25 g (p = 0.008) for the production seasons of 2017 and 2018, respectively. Twenty organic volatile compounds were identified, and the PCA showed that managed trees produce higher percentages of compounds associated with scent. The traditional management of Bursera bipinnata involves selective pressures, which generate the differentiation of wild and managed trees that may represent incipient domestication through silvicultural management.

Glyphosate, a systemic herbicide, is used against weeds in agricultural fields as well as against invasive plants in pastures, forest plantations, and urban environments. Its frequent and widespread use can negatively impact the surrounding natural non-target vegetation following the accidental drift of spray droplets, leaching, or persistence as residues in the soil. Because ferns possess a life cycle with independent sporophytic and gametophytic generations, herbicides may cause a different impact on each life stage. The objective of the present study was to evaluate the effect of four concentrations of glyphosate (0.33, 0.65, 2.72, and 10.89 g active ingredient L^-1) and water as control treatments on spores, gametophytes, and two sporophyte size classes of one native (Blechnum appendiculatum Willd.) and two introduced fern species in Mexico (Macrothelypteris torresiana (Gaudich.) Ching and Thelypteris dentata (Forssk.) E.P. St.John). Spore germination was evaluated 10 days after herbicide treatment and the percentage of remaining green tissue was measured at 7, 30, and 90 days after herbicide treatment. Plant survival was determined at the end of the experiment. Glyphosate suppressed spore germination nearly completely and increased tissue discoloration of all green life stages at higher concentrations and after longer time intervals. After 7 and 30 days, small sporophytes of all three species were significantly more discolored than gametophytes and large sporophytes at concentrations ≤ 0.65 g a.i. L^-1, although after 90 days differences among life stages were no longer significant, and no life stage survived at concentrations ≥ 2.72 g a.i. L^-1. At the lowest concentration (0.33 g a.i. L^-1), however, 50–69% of the plants of all three species and life stages survived after 90 days post-treatment. Macrothelypteris torresiana was significantly more tolerant to glyphosate than the other two species during the first 30 days after treatment, mainly because of its less damaged small sporophytes, perhaps due to a thicker waxy cuticle that may initially reduce herbicide absorption in this species. We conclude that even glyphosate concentrations of 0.33 g a.i. L^-1 may negatively impact natural spore banks of ferns and result in mortality of 31–50% of all green life stages. Such negative effects may also eliminate at least the most susceptible fern species in habitats that are frequently exposed to such glyphosate concentrations.

Neotropical bracken fern invades disturbed forests and burned and abandoned pastures in Latin America, inhibiting the growth of associated vegetation and altering community structure. Cutting of all aboveground vegetation every 6 to 12 mo has proven to be inefficient as a control method. We studied the impact of selective cutting of bracken every 2 mo, shading, and a combination of cutting + shading during 14 mo in a bracken-dominated, abandoned pasture in Veracruz, Mexico. At the end of the experiment, cutting with or without shading drastically reduced bracken cover from >90% to less than 1%, decreased leaf number from 18 to fewer than two leaves per m², and depleted bracken leaf biomass. The significant reduction of bracken was correlated with a significant 3.9- to 5.7-fold increase in richness of other plant species. Cutting without shading was the only treatment that significantly reduced rhizome biomass to less than 62% of control plots, whereas cutting + shading was the only treatment to promote a significant increase in both cover and shoot biomass of successional plant species. Selective cutting of P. arachnoideum repeated every 2 mo was more successful than nonselective cuttings repeated at longer intervals, because it removed newly emerging leaves before their complete expansion and supported the recovery and reestablishment of other plant species, which may help to control bracken. Although costs for the first year of selective cutting were twice as much as for nonselective cutting, it may prove less expensive and more efficient than nonselective cutting in the long term.

In this study, we carried out an inventory of butterfly diversity and an analysis of alpha and beta diversity considering the effects of phenology and degree of disturbance in tropical dry forest. The study included three localities: Cañadas de Ajuchitlán and El Limón, situated within the Sierra de Huautla Biosphere Reserve (REBIOSH) natural protected area, and San Miguel de los Elotes, which is outside of the REBIOSH. We systematically sampled each of the localities using two collection methods once per month for a full year (April 2013 to March 2014). A total of 4,017 specimens belonging to 119 species and 83 genera were collected. We recorded for the first time the presence of Perichares aurina Evans (Lepidoptera, Hesperiidae), in Mexico, 14 additional Hesperiidae species were new records for Morelos, Mexico, and 16% of the species recorded in this study are endemic to Mexico. Species richness was highest in August for the two localities (Cañadas de Ajuchitlán and El Limón), located within the REBIOSH. Species richness was highest in November for San Miguel de los Elotes, which is outside of the REBIOSH. In terms of the alpha diversity values (0D, observed diversity), Cañadas de Ajuchitlán had the highest species richness. In the analysis of similarity (Beta diversity), the two localities within the REBIOSH had the highest species similarity, despite being the most geographically distant.

Vascular epiphytes contribute significantly to tropical diversity. Research on the factors that determine vascular epiphytic diversity and composition in tropical areas is flourishing. However, these factors are entirely unknown in tropical-temperate transition zones, which represent the distribution limit of several epiphytic species. We assessed the degree to which climatic and structural variables determine the diversity of vascular epiphytic assemblages (VEAs) in a transition zone in Mexico: the El Cielo Biosphere Reserve. We found 12,103 epiphytic individuals belonging to 30 species and 15 genera along a climatic gradient from 300 to 2,000 m a.s.l. Bromeliaceae and Orchidaceae were the most species-rich families. Forests along the windward slope of the Sierra Madre Oriental (semideciduous forest and tropical montane cloud forest) had higher species richness than forests along the leeward slope (pine-oak forest and submontane scrub). Species richness was largely determined by seasonality and, to a lesser degree, by forest structure, whereas abundance was mainly determined by host tree size. Variation in VEAs composition was largely explained by climatic variables, whereas forest structure was not as important. VEAs differed among forest types and slopes in terms of taxonomic and functional composition. For example, certain bromeliad indicator species reflected differences between slopes. Although within-tree epiphytic species richness (alpha diversity) was low in this transition zone relative to other habitats, species turnover among forest types (beta diversity) was high. These findings suggest that each forest type makes a unique and important contribution to epiphytic diversity in this transition zone.