First typology of cacao (Theobroma cacao L.) systems in Colombian Amazonia, based on tree species richness, canopy structure and light availability

Aim and backgroundWe present a typology of cacao agroforest systems in Colombian Amazonia. These systems had yet to be described in the literature, especially their potential in terms of biodiversity conservation. The systems studied are located in a post-conflict area, and a deforestation front in Colombian Amazonia. Cacao cropping systems are of key importance in Colombia: cacao plays a prime role in post conflict resolution, as cacao is a legal crop to replace illegal crops; cacao agroforests are expected to be a sustainable practice, promoting forest-friendly land use.Material and methodsWe worked in 50 x 2000 m2 agroforest plots, in Colombian Amazonia. A cluster analysis was used to build a typology based on 28 variables characterised in each plot, and related to diversity, composition, spatial structure and light availability for the cacao trees. We included variables related to light availability to evaluate the amount of transmitted radiation to the cacao trees in each type, and its suitability for cacao ecophysiological development.Main resultsWe identified 4 types of cacao agroforests based on differences concerning tree species diversity and the impact of canopy spatial structure on light availability for the cacao trees in the understorey. We found 127 tree species in the dataset, with some exclusive species in each type. We also found that 3 out of the 4 types identified displayed an erosion of tree species diversity. This reduction in shade tree species may have been linked to the desire to reduce shade, but we also found that all the types described were compatible with good ecophysiological development of the cacao trees.Main conclusions and prospectsCacao agroforest systems may actually be achieving biodiversity conservation goals in Colombian Amazonia. One challenging prospect will be to monitor and encourage the conservation of tree species diversity in cacao agroforest systems during the development of these cropping systems, as a form of forest-friendly management enhancing sustainable peace building in Colombia.研究目的与背景 本研究提出哥伦比亚亚马逊地区可可农林业系统的分类体系。此前该类系统尚未在学术文献中得到系统描述，尤其是其在生物多样性保护方面的应用潜力。本次研究的样地位于哥伦比亚亚马逊地区的冲突后区域与森林砍伐前沿地带。可可种植系统在哥伦比亚具有关键地位：可可作为合法替代作物，在冲突后重建中发挥核心作用；可可农林业被视为可持续实践模式，可推广友好森林型土地利用方式。 材料与方法 本次研究在哥伦比亚亚马逊地区的50块面积为2000㎡的农林业样地开展。基于每块样地的28项特征变量，通过聚类分析构建分类体系，这些变量涵盖可可树的物种多样性、群落组成、空间结构以及光照可获得性。研究纳入光照可获得性相关变量，以评估各类型系统中传输至可可树的辐射量及其对可可树生态生理发育的适宜性。 主要研究结果 本研究基于乔木物种多样性、冠层空间结构对林下可可树光照可获得性的影响差异，识别出4类可可农林业系统。本次数据集中共记录到127种乔木物种，且每类系统均包含特有物种。同时发现4类系统中有3类出现乔木物种多样性退化的情况。遮荫乔木物种的减少或与降低遮荫强度的需求相关，但本研究同时发现，所有识别出的系统类型均适配可可树良好的生态生理发育。 主要结论与展望 哥伦比亚亚马逊地区的可可农林业系统实际上可达成生物多样性保护目标。未来一项具有挑战性的工作是，在该种植系统的发展过程中，监测并推动可可农林业系统中乔木物种多样性的保护，以此作为友好森林型管理手段，助力哥伦比亚可持续和平建设。