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.

中文翻译：

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墨西哥传统树脂的生产和质量（Bursera bipinnata（Moc。＆Sesséex DC。）Engl。）的传统管理后果

Copal是墨西哥的一种仪式用树脂，是从Bursera属的几种树种中提取的。对表型性状传统管理的效果古柏树还没有得到充分研究。这项研究分析了传统的管理和人为选择对Bursera bipinnata种群的选择，并且还研究了它们对野生树和管理树生产的树脂的数量和质量的影响。合作伙伴的管理通过半结构化访谈和研讨会记录下来。选择了来自六个野生种群和受管理种群的60棵树的样本，以量化连续两年中树脂的产量。收集新鲜树脂，通过气相色谱和主成分分析（PCA）鉴定有机挥发性化合物；根据生产的有机化合物的数量和类型对个体进行分类。我们确定了从简单收获到种子种植的管理策略。当地人选择受管理的树木和种子的标准基于每棵树生产的树脂的数量和质量，受管理的树木和野生树的树脂质量和质量显着高于野生树：190.17±329.04 g与29.55±25.50 g（p = 0.003 ），以及175.88±179.29 g和63.05±53.25 g（p =0.008）分别用于2017年和2018年的生产季节。鉴定出了20种有机挥发性化合物，PCA表明，管理树木可产生与气味相关的化合物的百分比更高。传统双胞胎（Bursera bipinnata）的管理涉及选择性压力，这些压力会导致野生树和受管理树的分化，这可能表示通过造林管理开始驯化。