Integrating effects of neighbor interactions for pollination and abiotic resources on coffee yield in a multi‐strata agroforest

• Published in: Biotropica 2022-09, Vol.54 (5), p.1226-1237
• Main Authors: Fitch, Gordon, Gonzalez, John, Oana, Anna M., Oliver, Maggie, Vandermeer, John
• Format: Article
• Language: English
• Subjects: Abiotic factors; Agricultural ecosystems; Agricultural production; agroecosystem multifunctionality; Agroforestry; Biodiversity; Biological fertilization; Canopies; Canopy; Chiapas; Coffea arabica; Coffee; Competition; Conspecifics; Crop yield; Evaluation; Farms; Fertilization; Fruit set; Fruits; Herbs; Mathematical models; Mexico; Multivariate statistical analysis; neighborhood effects; Plant cover; Plant reproduction; Planting density; Plants; Plants (botany); Pollen; Pollination; pollinator‐mediated plant interactions; Resources; Stigmas (botany); Structural equation modeling; Trees
• ISSN: 0006-3606; 1744-7429
• DOI: 10.1111/btp.13145

Animal‐pollinated plants interact with neighbors for both abiotic resources and pollination, with consequences for reproduction and yield. Yet few studies have compared the relative magnitude of these effects, particularly in agroecosystems. In vertically stratified communities, such as agroforests, neighbor effects may be stratum‐dependent. Understanding the net effects of neighbors on crop yield is important for managing multifunctional agroecosystems to simultaneously support production and biodiversity. This study evaluated the effects of neighboring plants on pollen deposition, fertilization, and yield in Coffea arabica in a shaded organic coffee farm with high non‐crop plant abundance and diversity in Chiapas, Mexico. We assessed the impact of (1) floral resources at three vertical strata (herbs, coffee bushes, and canopy trees) on stigma pollen load (a measure of interaction for pollination), and (2) floral density and canopy cover (proxies for competition for abiotic resources) on yield (final fruit set and per‐fruit weight), using structural equation modeling to evaluate the relative effect of each interaction type. Coffee competed for pollination with neighbors (conspecifics and heterospecifics) across strata. Pollen load influenced final fruit set, but the effect of neighbor competition for pollination was weaker than effects mediated by interactions for abiotic resources. Effects of interactions for abiotic resources were heterogeneous across strata, with negligible effects of herb‐layer or coffee flower density but net positive effects of canopy trees on final fruit set. Overall effects of neighbors on coffee yield were weak, suggesting that coffee agroecosystems can be managed to maintain high plant density and diversity without sacrificing yield. in Spanish is available with online material. Resumen Las plantas polinizadas por animales interactúan con las vecinas tanto por los recursos abióticos como por la polinización, con consecuencias para la reproducción y el rendimiento de cultivos. Sin embargo, pocos estudios comparan la magnitud relativa de estos efectos, particularmente en agroecosistemas. En comunidades estratificadas verticalmente, como los agrobosques, los efectos vecinos pueden depender del estrato. Comprender los efectos netos de los vecinos en el rendimiento de cultivos es importante para gestionar agroecosistemas multifuncionales y apoyar simultáneamente la producción y la biodiversidad. Este estudio evalua los efectos de las