Data from: Integrating effects of neighbor interactions for pollination

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 interaction 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.依赖动物传粉的植物会与邻近植株发生两类相互作用：争夺非生物资源与获取传粉服务，二者均会对植物的繁殖与产量产生影响。然而目前鲜有研究对这两类效应的相对强弱开展比较，在农业生态系统中这一研究短板尤为突出。在垂直分层的群落（如农林复合系统）中，邻近植株的效应可能会因所处层位不同而存在差异。明确邻近植株对作物产量的净效应，对于管理兼具生产与生物多样性保护功能的农业生态系统至关重要。本研究以墨西哥恰帕斯州一处非作物植物丰度高、多样性强的遮阴有机咖啡农场为研究对象，针对小粒咖啡（Coffea arabica）展开试验，评估邻近植株对其花粉沉积、受精过程及产量的影响。本研究通过结构方程模型（structural equation modeling）量化两类相互作用的相对效应：其一为三个垂直层位（草本层、咖啡灌丛层与冠层乔木层）的花部资源对柱头上花粉负载量（传粉相互作用的衡量指标）的影响；其二为花密度与冠层覆盖度（非生物资源竞争的替代指标）对产量（最终坐果率与单果重量）的影响。研究结果表明，咖啡植株在各个层位均会与邻近植株（包括同种与异种植株）竞争传粉服务。柱头上的花粉负载量会影响最终坐果率，但邻近植株间传粉竞争的效应弱于非生物资源相互作用所介导的效应。非生物资源相互作用的效应在不同层位间存在异质性：草本层或咖啡花密度的效应可忽略不计，而冠层乔木对最终坐果率具有净正向效应。总体而言，邻近植株对咖啡产量的效应较弱，这意味着可通过合理调控咖啡农业生态系统，在不牺牲产量的前提下维持较高的植物密度与多样性。