Deciphering the role of reproductive investment, pollination success and predispersal seed predation on reproductive output in <i>Juniperus thurifera</i>

<b>Background</b>: Plant reproductive output is determined by a complex set of factors including resource availability, pollination success and pre-dispersal predation. Disentangling the relative contribution of each factor is critical to underpin the factors determining plant fitness. <b>Aims</b>: To unravel the relative contributions of initial reproductive effort, pollination success and pre-dispersal seed predation to plant reproductive success in the fleshy-fruited, wind-pollinated <i>Juniperus thurifera</i>. <b>Methods</b>: We conducted an experiment including pollen addition and pesticide application on 40 female juniper trees for 20 months. Flower production was used as a proxy for resource levels. <b>Results</b>: Main fruit loss occurs in early stages of fruit development. Initial flower number affected fruit and seed set by (a) increasing the rate of fruit formation and the number of viable seeds within fruits and (b) modifying the incidence of low-mobile predators through a satiation effect. Pollination did not limit fruit set, although hand pollinated fruits had more viable seeds. Pre-dispersal seed predation by different arthropods was critical in defining final fruit set. <b>Conclusions</b>: Fruit set in <i>J. thurifera</i> was determined by the interaction of initial reproductive effort and pre-dispersal seed predation. Pollination was not a limiting factor in this relatively dense juniper forests during a year of high flower production.**背景**：植物繁殖产出受一系列复杂因素调控，涵盖资源可获得性、传粉成功率与扩散前捕食作用。厘清各因素的相对贡献，是阐明植物适合度决定机制的核心前提。 **研究目的**：本研究旨在明确初始繁殖投入、传粉成功率以及扩散前种子捕食作用，对肉质果、风媒传粉的欧洲刺柏（Juniperus thurifera）繁殖成效的相对贡献。 **研究方法**：我们针对40棵雌性刺柏开展了为期20个月的受控试验，设置花粉添加与农药喷施两个处理组。本研究以开花量作为资源水平的替代指标。 **研究结果**：果实的主要损耗发生在发育早期阶段。初始开花量通过两种途径影响坐果与结籽情况：其一，提升果实形成速率与果实内有活力种子的数量；其二，通过饱食效应降低低移动性捕食者的侵染概率。尽管人工授粉的果实所含有的有活力种子数量更多，但传粉并未对坐果率产生限制作用。不同节肢动物介导的扩散前种子捕食作用，是决定最终坐果率的关键因素。 **研究结论**：欧洲刺柏（Juniperus thurifera）的坐果率由初始繁殖投入与扩散前种子捕食作用的共同交互作用决定。在该相对密集的刺柏林中，开花量充沛的年份里，传粉并非限制坐果的关键因子。