Consequences of Traditional Management in the Production and Quality of Copal Resin (Bursera bipinnata (Moc. & Sessé ex DC.) Engl.) in Mexico

Abstract

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.

Disentangling Domestication from Food Production Systems in the Neotropics

“…The Central Andes, a region that has the highest and longest segment of the Andes [185], has a vascular plant richness of 17,548, 19,147, and 14,431 species in Ecuador, Peru and Bolivia, respectively [166], with considerable overlap. Our focus will be restricted to the Andes above 500 m on the western slopes [186] and above the "eyebrow" of the Selva on the eastern slopes [187].…”

“…Although the dominant life form characteristic of high Andean ecosystems is herbaceous (567 species; Table 1), the number of perennials (mainly trees and shrubs, 587 species in total) is considerable. The perennials are characteristic of the Andean forests, such as the montane or yungas of the tropical Andes [185], which become premontane below 1000 m and gradually grade into the "eyebrow" of the Selva [192]. These forests contain great diversity, although this is little studied and vulnerable to degradation, and, together with other forests, such as the Peruvian relicts [193,194], equatorial and dry forests of the inter-Andean valleys, contribute to the list of perennial useful species.…”

How does urbanization affect perceptions and traditional knowledge of medicinal plants?

“…Notable examples are copal ( Bursera sp. [ 44 ];), jícaras ( Crescentia sp. [ 45 ],) and linaloe ( Bursera linanoe [ 46 ];).…”

Prediction of Resin Production in Copal Trees (Bursera spp.) Using a Random Forest Model

“…For the selection of Copal trees for resin extraction, the amount of resin produced is the primary criterion; however, there is no established method to estimate this quantity. According to Copal growers in this region and other regions [8,25], morphological characteristics affect resin production. Copal resin production was evaluated using the factors and indicators listed in Table 1.…”