Data from: Pre-dispersal seed predators and fungi differ in their effect on Luehea seemannii capsule development, seed germination and dormancy across two Panamanian forests

Pre-dispersal seed predation can greatly reduce crop size affecting recruitment success. Additionally, non-fatal damage by seed predators may allow infection by fungi responsible for post-dispersal seed losses. The objectives of this study were (1) to quantify pre-dispersal seed predation and fungal infection in a Neotropical tree species, Luehea seemannii, that produces dehiscent fruits and wind-dispersed seeds, and (2) to link pre-dispersal effects on seed quality to seed survival in the soil. To examine how seed predators and fungi influence seed losses, mesh exclosures, fungicide and the combination of both treatments were applied to separate branches in the canopy of trees in Gamboa and Parque Natural Metropolitano (PNM), Panama. To determine if treatments affect seed viability and survival in the soil, half of the seeds collected from each treatment were buried for four weeks in forest soils and subsequently allowed to germinate before and after the breaking of dormancy. Overall, 24 percent of developing fruit were lost to insect attack. In contrast, fungi infected only 3 percent of seeds at the pre-dispersal stage. For seeds germinated directly after collection, fungicide significantly increased germination in the wetter site (Gamboa) but decreased germination in the drier site (PNM). The pre-dispersal insect exclosure treatment increased the fraction of seeds that remained dormant after burial in the soil. This result suggests that exposure to insect predators may cause physical damage to seeds that results in the loss of physical dormancy but does not necessarily increase the susceptibility of seeds to pathogen attack in the soil.扩散前种子捕食（pre-dispersal seed predation）可显著降低植物结实量，进而影响种群更新成功率。此外，种子捕食者造成的非致死性损伤，可能会使种子被引发扩散后种子损耗的真菌侵染。本研究的研究目标分为两点：其一，对一种结开裂果实、种子靠风力扩散的新热带树种Luehea seemannii的扩散前种子捕食情况与真菌侵染率进行定量分析；其二，明确扩散前的种子损伤对种子品质的影响，及其与土壤中种子存活情况的关联。 为探究种子捕食者与真菌对种子损耗的影响机制，研究人员在巴拿马甘博阿地区与大都会自然公园（Parque Natural Metropolitano，简称PNM）的林木树冠层中，对不同枝条分别施加了昆虫阻隔网罩（mesh exclosures）、杀菌剂（fungicide）喷施以及二者联合处理三种实验处理。为明确各处理是否会影响种子生活力（seed viability）与土壤中种子存活情况，研究人员将各处理组采集到的半数种子埋入森林土壤中培养4周，随后分别在休眠打破前后开展萌发实验。 总体而言，24%的发育中果实因昆虫为害而损失。与之相对，扩散前阶段仅有3%的种子被真菌侵染。对于采集后直接萌发的种子，杀菌剂喷施可显著提升湿润样地（甘博阿）的种子萌发率，但会降低干旱样地（PNM）的萌发率。昆虫阻隔处理可提升埋土后仍保持休眠的种子比例。该结果表明，暴露于种子捕食者环境会对种子造成物理损伤，进而导致其物理休眠丧失，但未必会提升土壤中种子对病原菌侵染的敏感性。