Shade trees in cacao agroforestry systems: influence on water resource use

可可农林复合系统中的遮荫树：对水资源利用的影响

• 批准号: 175292281
• 负责人: Professor Dr. Dirk Hölscher
• 金额: --
• 依托单位: Abteilung Waldbau und Waldökologie der Tropen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/175292281?language=en
• 关键词: Shade; trees; cacao; agroforestry; systems

In cacao agroforestry, competition between cacao and shade trees for limited resources may reduce yields. In particular water availability is regarded a main determinant of cacao yield. Results of our previous experimental study however suggest that (1) there was a strong vertical partitioning of soil water uptake among cacao and shade trees, (2) during low rainfall periods, mainly cacao trees took up the small volumes of water reaching the soil, and (3) an increased shade tree canopy cover led to an increased rather than a decreased water use of cacao trees. This study was conducted at one site and with a single type of shade tree admixture. I thus want to further test these contentions aiming at more general conclusions. The proposed project intends to study cacao cultivation at three different shade tree admixture types (no shade trees, Gliricidia shade trees, native shade trees) with replicated plots at two sites with contrasting rainfall. The methods emphasize the application of stable isotope techniques (deuterium and 18O), using natural abundances as well as tracer experiments, supplemented by tree sap flux studies. Cooperation is planned particularly with a project addressing the productivity and species-specific root distribution in these stands.

在可可农林业中，可可树和遮荫树对有限资源的竞争可能会降低产量。特别是水的供应被认为是可可产量的主要决定因素。然而，我们以前的实验研究结果表明，（1）可可树和遮荫树之间的土壤水分吸收有很强的垂直分配，（2）在低降雨量期间，主要是可可树吸收了到达土壤的少量水分，（3）增加遮荫树树冠覆盖导致可可树的水分利用增加而不是减少。本研究在一个地点进行，使用单一类型的遮荫树混合物。因此，我想进一步检验这些论点，以得出更一般的结论。拟议的项目打算研究可可种植在三个不同的遮荫树混合类型（无遮荫树，Gliricidia遮荫树，本地遮荫树）与复制地块在两个地点与对比降雨。该方法强调应用稳定同位素技术（氘和18 O），利用自然丰度以及示踪实验，补充树液通量的研究。计划特别与一个解决这些林分的生产力和物种特有的根系分布的项目进行合作。