Cocoa is traditionally grown in agroforestry systems (AFS). It is essential to the household and regional economy and plays an important role in natural resource and environmental services conservation. In recent years, the vegetation structure and diversity of cocoa AFS throughout the world are being simplified as farmers consider that the removal of trees helps to increase yields and reduce disease incidence. However, debate exists on the relationship between tree shade and diversity and cocoa yields and the incidence of disease such as frosty pod rot, one of the most important fungal infections in cocoa cultivation. The objective of this study was to analyze changes in agroforestry structure, plant species diversity, uses, yields, the incidence of frosty pod rot disease in cocoa agroforestry systems, and discuss the consequences of the simplification of this particular AFS in the municipality of Acacoyagua, Chiapas, Mexico. Inventories were carried out in 27 plots. Interviews were applied to families to assess ecological, technical, and productive variables. Incidence of frosty pod rot disease and yields were estimated on-farm and through interviews over a period of 3 years. Multivariate cluster analysis, Pearson correlation analysis, the Levene test for equality of variances and a non-parametric U Mann–Whitney test were carried out. Three types of cocoa agroforests were identified as a result of a structure simplification: (1) traditional cocoa polyculture; (2) cocoa with Legumes Inga spp and Lonchocarpus spp.; and (3) cocoa with diverse, scattered, predominantly wild trees. Fifty species were recorded in shade vegetation, with a diversity index of 3.15. Simplification in tree structure did not have a significant effect on cocoa yield nor on the incidence of frosty pod rot disease. On the contrary, it resulted in a decrease in plant diversity and provisioning of food and other products. Farmers undertake few agricultural practices; some practices are eventually carried out, such as the pruning of cocoa trees and shade-trees, removal, and burial of diseased fruits, and weeding. Seven out of 27 plots sampled yielded more than 300 kg ha−1, and one plot attained a yield of 437.5 kg ha−1; however, yields averaged 155.8 kg ha−1 and incidence of frosty pot rot averaged 9.6%, regardless of AFS type. These results highlight the importance of improving AFS management which in this case appears to be the most critical factor for attaining an increase in yields. Low levels of production and the incidence of frosty pod rot subsequently reduces farmers’ motivation to continue cultivating cocoa, placing the crop at risk and increasing the possibility of a change in the land-use.

中文翻译：

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墨西哥恰帕斯州 El Soconusco 可可农林结构和多样性的简化不会增加产量，也不会影响霜冻荚腐病

可可传统上是在农林业系统 (AFS) 中种植的。它对家庭和区域经济至关重要，在自然资源和环境服务保护方面发挥着重要作用。近年来，世界各地的可可 AFS 的植被结构和多样性正在被简化，因为农民认为砍伐树木有助于提高产量和减少疾病发生率。然而，关于树荫和多样性与可可产量之间的关系以及霜荚腐病（可可种植中最重要的真菌感染之一）等疾病的发生率存在争议。本研究的目的是分析农林业结构、植物物种多样性、用途、产量的变化，可可农林业系统中霜冻荚腐病的发生率，并讨论在墨西哥恰帕斯州阿卡科亚瓜市简化此特定 AFS 的后果。在 27 个地块中进行了清查。对家庭进行访谈以评估生态、技术和生产变量。霜荚腐病的发生率和产量是在农场上和通过 3 年的访谈估算的。进行了多变量聚类分析、Pearson 相关分析、方差相等的 Levene 检验和非参数 U Mann-Whitney 检验。由于结构简化，确定了三种类型的可可农林：（1）传统的可可混养；(2) 可可豆与豆科 Inga spp 和 Lonchocarpus spp.；(3) 可可树种类繁多，分散，主要是野生树木。树荫植被中记录了 50 种，多样性指数为 3.15。树结构的简化对可可产量和霜荚腐病的发生率没有显着影响。相反，它导致植物多样性和食品和其他产品供应的减少。农民很少从事农业活动；一些做法最终得以实施，例如修剪可可树和遮荫树、移除和掩埋病果以及除草。抽样的 27 个地块中有 7 个地块的产量超过 300 kg ha-1，一个地块的产量为 437.5 kg ha-1；然而，无论 AFS 类型如何，产量平均为 155.8 kg ha-1，霜霉病发生率平均为 9.6%。这些结果突出了改进 AFS 管理的重要性，在这种情况下，这似乎是提高产量的最关键因素。