RUI: The Contribution of Secondary Seed Dispersal to the Reproductive Success of "Wind-Dispersed" Pines

Vander Wall 9708155本研究的目的是确定初级(风)和次级(动物分散囤积)扩散对种子质量不同的四种带翅种子的松种繁殖成功的相对贡献：短叶松(7毫克/粒)、黄皮松(55毫克)、杰弗里松(146毫克)和糖松(288毫克)。分散囤积的动物为种子提供了几个重要的好处，包括经常将种子从源植物带走的散布，将种子埋藏在土壤中，以及将种子储存在通常有利于幼苗形成的微生境中。种子大小的变化预计会影响种子的空气动力学行为以及种子对脊椎动物觅食动物的吸引力(即初级和次级扩散)。随着种子大小的增加，风传播的相对有效性应该降低，而动物媒介传播的相对有效性应该增加。这项研究将为我们理解种子在植物中的传播和繁殖成功做出基础性贡献，特别是关于二次传播的作用，这方面的研究很少。此外，这项研究还将提供信息，帮助林农更有效地管理这些具有经济价值的树木。对于这些松树来说，种子传播和幼苗建立的关键步骤知之甚少。根据种子形态和球果物候，目前的假设是这些松树是风散布的，动物几乎完全是种子捕食者。这项研究的结果将填补我们知识的这一空白，并为管理决策提供科学可靠的数据。

Vander Wall 9708155 The objective of this research is to determine the relative contributions of primary (wind) and secondary (animal scatter hoarding) dispersal to the reproductive success of four species of pines with winged seeds that vary in seed mass: lodgepole pine (Pinus contorta; 7 mg/seed), ponderosa pine (Pinus ponderosa; 55 mg), Jeffrey pine (Pinus jeffreyi; 146 mg), and sugar pine (Pinus lambertiana; 288 mg). Scatter-hoarding animals provide several important benefits to the seeds, including dispersal that often carries the seed away from the source plant, burial of the seeds in soil, and caching the seed in microhabitats that often favor seedling establishment. The variation in seed size is expected to influence the aerodynamic behavior of the seed and the attractiveness of the seed to vertebrate foragers (i.e., both primary and secondary dispersal). As seed size increases, the relative effectiveness of wind dispersal should decrease and the relative effectiveness of animal-mediated dispersal should increase. This research will make fundamental contributions to our understanding of seed dispersal and reproductive success in plants, especially with regard to the role of secondary dispersal, which has received little study. Further, this study will also provide information that will help foresters more effectively manage these economically valuable trees. The critical steps of seed dispersal and seedling establishment are poorly understood for these pines. The current assumption, based on seed morphology and cone phenology, is that these pines are wind dispersed and that animals act almost exclusively as seed predators. The results of this research will fill this gap in our knowledge and provide scientifically sound data on which to base management decisions.