Soil degradation in semi-arid West Africa can be reversed through an intensified application of organic matter, especially on coarse soils. Woody perennials have been promoted in the region to secure organic matter sources and improve soil productive capacity, yet the mechanisms by which perennials provide benefits to soils and crops remain poorly understood, and no effective, generalizable agronomic recommendations exist. Here, we reviewed the effects of trees and shrubs on soil properties and on crop yields in semi-arid West Africa (< 1000 mm year⁻¹). Specific objectives of this meta-analysis were to (i) describe and (ii) quantify the effects of the presence of woody perennials and of ramial wood amendments on crop productivity and soil characteristics, and (iii) identify general recommendations on the integration of perennials with crops. An iterative keyword search was conducted to gather relevant literature. The search string consisted of four parts: source, practice, responses, and countries of interest. In total, 26 references on agroforestry parklands and 21 on woody amendments were included in the meta-database (314 entries, 155 for parklands, and 159 for ramial wood). We show that (1) the presence of shrubs and trees on agricultural fields had an overall positive but variable effect on soil total C (i.e. + 20 to 75%); (2) millet and sorghum yields were often higher in the presence of shrubs (− 25 to + 120%); (3) more variability was observed in the presence of trees (− 100 to + 200%); and (4) the use of shrub- and tree-based ramial wood resulted in equal or higher cereal yields as compared to the control (− 30 to + 100%). Upscaling the use of biodiversity-driven processes in farming systems of West Africa may provide benefits to overall ecosystems, but species’ choice and trade-offs perceived at the farm level, including labour management and low ramial wood availability, should be addressed through future research.

中文翻译：

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在半干旱的西非，利用多年生木本植物提高农业生态系统的生产力。荟萃分析。

半干旱西非的土壤退化可以通过加强有机物质的施用来逆转，特别是在粗糙的土壤上。已在该地区推广了多年生木本植物，以确保有机质来源和提高土壤生产能力，但对多年生植物对土壤和农作物有益的机制仍知之甚少，没有有效的，可推广的农艺建议。在这里，我们回顾了树木和灌木对半干旱西非（<1000 mm年^-1的土壤性质和作物产量的影响））。这项荟萃分析的具体目标是（i）描述和（ii）量化多年生木本植物和木本修正物对作物生产力和土壤特性的影响，以及（iii）确定关于多年生植物整合的一般建议与庄稼。进行了迭代关键字搜索以收集相关文献。搜索字符串包括四个部分：来源，实践，响应和感兴趣的国家。在元数据库中，总共有26个关于农林业林地的参考文献和21个关于木本修正案的参考文献（314个条目，155个用于林地，159个用于粗木）。我们发现（1）灌木和树木在农田上的存在对土壤总C总体上具有积极影响，但变化不定（即+ 20％至75％）；（2）在有灌木的情况下，小米和高粱的产量通常较高（− 25至+ 120％）；（3）在有树木的情况下观察到更多的可变性（− 100至+ 200％）；（4）与对照相比，灌木和乔木的杂种木材的谷物收成相同或更高（− 30至+ 100％）。在西非的耕作系统中增加使用生物多样性驱动的过程可能会为整个生态系统带来好处，但应通过未来的研究来解决在农场一级对​​物种的选择和权衡取舍，包括劳动力管理和低木料利用率的问题。 。