Benefit versus cost trade‐offs of masting across seed‐to‐seedling transition for a dominant subtropical forest species. (29th June 2021)

• Record Type: Journal Article
• Authors: Huang, Li; Jin, Cheng; Zhou, Lihua; Song, Kun; Qian, Shenhua; Lin, Dunmei; Zhao, Liang; Chen, Bo; Yan, Enrong; Michalet, Richard; Yang, Yongchuan
• Is Part Of: Journal of ecology. Volume 109:Number 8(2021)
• Page Start: 3087
• Page End: 3098
• Publication Date: 2021-06-29
• Subjects: benefits -- Castanopsis fargesi -- costs -- evergreen broad‐leaved forest -- masting -- seed‐to‐seedling transition; Plant ecology -- Periodicals; 577.05
• DOI: 10.1111/1365-2745.13722
• Languages: English
• ISSNs: 0022-0477

Abstract

Abstract: Masting is a common reproductive strategy regulating seedling regeneration in many perennial plant species. The evolutionary origins and functional benefits of masting have been explained by well‐supported hypotheses relating to economies of scale of seed production. Nevertheless, our understanding of the potential costs of masting for the plant seed‐to‐seedling transitions remains limited. We tracked the seed fate and documented changes in the seed spatial distribution patterns during the seed‐to‐seedling transition process of Castanopsis fargesii, a dominant species of subtropical evergreen broad‐leaved forests in China under natural conditions for more than 6 years. Masting resulted in a high proportion of seeds escaping predation by vertebrates and rodents, supporting the predator satiation hypothesis. However, it increased the pre‐dispersal seed predation by insects, and decreased the seed germination rate due to a negative effect on seed mass. This resulted in seed‐to‐seedling transition rates during mast years to be roughly half as much as during non‐mast years. In addition, masting negatively affected the spatial rearrangement of seeds, resulting in a spatial aggregative distribution pattern of newly germinated seedlings. The combined negative effects of smaller seeds and spatially aggregated seedlings reduced the survival rate of newly germinated seedlings at seedling establishment stage. Synthesis . Considering the whole seed‐to‐established seedling transition process, the benefits of masting on seedling recruitment due to the effective seed predator situation by vertebrates and rodents were decreased by the additional costs on seed mass, seed germination, seed spatial arrangement and seedling establishment. Our results highlight the importance of considering both the positive and negative effects of masting at each stage of the seed‐to‐seedling transition. Inferences based on seed predation and recruitment of newly germinated seedlings alone would lead to an overly optimistic conclusion about the benefits of masting. Abstract : Considering the whole seed‐to‐established seedling transition process, the benefits of masting on seedling recruitment due to the effective seed predator situation by vertebrates and rodents were decreased by the additional costs on seed mass, seed germination, seed spatial arrangement and seedling establishment. Our results highlight the importance of considering both the positive and negative effects of masting at each stage of the seed‐to‐seedling transition. Inferences based on seed predation and recruitment of newly germinated seedlings alone would lead to an overly optimistic conclusion about the benefits of masting. 中文摘要: 大年结实是许多多年生植物调节幼苗增补的繁殖策略, 大年结实的进化起源和收益被与种子生产规模经济效应相关的假说所支持。然而, 目前我们对大年结实在植物种子幼苗转化过程中潜在成本的了解仍然十分有限。 我们在自然条件下对亚热带常绿阔叶林的优势种栲 ( Castanopsis fargesii ) 的大年结实格局和种子幼苗转化过程中的种子命运与种子空间分布格局的变化进行了长达6年的监测。 大年结实降低了种子扩散前被啮齿动物取食和扩散后被鼠类取食的概率, 支持了捕食者饱和假说。然而, 大年结实增加了种子在散布前被昆虫取食的强度, 并且通过降低种子重量间接对种子萌发产生负面效应, 这些额外的种子成本导致结实大年的种子幼苗转化率只有结实小年的约一半。此外, 大年减弱了种子在扩散后的空间变化, 导致新生幼苗聚集的空间分布格局。种子重量的降低和幼苗的聚集分布导致结实大年的新生幼苗在建成阶段具有更低的存活率。 从种子到建成幼苗的转化看, 大年结实在种子逃避啮齿动物和鼠类取食上获取的收益在很大程度上被在种子重量、种子萌发、种子空间变化和幼苗建成上的成本所降低。我们的研究结果凸显了全面评估大年结实在植物种子幼苗转化过程中各个阶段的积极影响和负面影响的重要性, 仅基于种子捕食或新萌发幼苗数据评估大年结实在植物幼苗更新中的收益很可能得出过于乐观的结论。