Seed depot data.

Information about seed dispersal effectiveness (SDE) for plant species of conservation concern is rarely available to inform management strategies and actions. For Lindera subcoriacea (bog spicebush, Lauraceae), a rare endemic dioecious shrub of the southeastern United States, we examined the influence of two intrinsic and five extrinsic drivers on the number and proportion of seeds either dispersed, or predated pre- and post-dispersal. The number of seeds dispersed characterizes the quantitative component of SDE, while pre- and post-dispersal seed predation can affect the qualitative component of SDE. Using fruit counts, seed traps, and seed removal depots over multiple years, we estimated that approximately 28% of L. subcoriacea seeds are lost to pre-dispersal predation, 69% of seeds are dispersed, 3% of seeds fail to disperse, and 65% of dispersed seeds are predated post-dispersal. We observed substantial variation in these three processes among individuals. We also found that both intrinsic (plant height, crop size) and extrinsic (understory cover, time since last fire, conspecific fruiting neighborhood, substrate) drivers differentially influenced the three processes. We identified four generalist, seasonally frugivorous, avian visitors at fruiting individuals that likely act as variably effective dispersers, while the Northern Cardinal (Cardinalis cardinalis L.) is a seed predator. Rodent granivores were important pre- and post-dispersal seed predators. The magnitude of our pre-dispersal and post-dispersal seed predation estimates suggest that, given the low fecundity of L. subcoriacea, conservation strategies should emphasize facilitating dispersal and reducing the effects of seed predation.

针对具有保护优先级的植物物种，其种子扩散有效性（seed dispersal effectiveness, SDE）的相关信息往往较为匮乏，无法为管理策略制定与实践行动提供有效支撑。针对美国东南部的稀有特有雌雄异株灌木沼钓樟（Lindera subcoriacea，俗称bog spicebush，樟科Lauraceae），本研究探究了2种内在驱动因子与5种外在驱动因子，对种子被扩散、以及扩散前与扩散后种子被捕食的数量与比例的影响。被扩散的种子数量对应种子扩散有效性的量化维度，而扩散前与扩散后的种子捕食行为则会影响其质性维度。本研究依托多年间的果实计数、种子陷阱与种子移除试验站数据，估算得到：沼钓樟约28%的种子因扩散前捕食而损失，69%的种子成功扩散，3%的种子未能完成扩散，且65%的已扩散种子会在扩散后被捕食。我们观测到，不同个体间的这三类过程存在显著差异。同时我们发现，内在驱动因子（植株高度、结果量）与外在驱动因子（林下盖度、末次火烧后的时间、同种邻体结实情况、基质类型）均会对上述三类过程产生差异化影响。我们在结实植株上观测到4种广食性、季节性食果的鸟类访客，它们可能是有效性存在差异的扩散者；而主红雀（Cardinalis cardinalis L.）则属于种子捕食者。啮齿类食籽动物则是重要的扩散前与扩散后种子捕食者。结合本研究得到的扩散前与扩散后种子捕食估算结果，考虑到沼钓樟的繁殖力较低，相关保护策略应重点促进种子扩散，并降低种子捕食带来的负面影响。