Depto. Biología de Organismos y Sistemas, Universidad de Oviedo, and Instituto Cantábrico de Biodiversidad (CSIC-UO-PA), C/Rodrigo Uría s/n, Oviedo 33071, Asturias, Spain.
Conserv Biol. 2010 Aug;24(4):1070-9. doi: 10.1111/j.1523-1739.2009.01440.x. Epub 2010 Feb 4.
Seed dispersal by animals is considered a pivotal ecosystem function that drives plant-community dynamics in natural habitats and vegetation recovery in human-altered landscapes. Nevertheless, there is a lack of suitable ecological knowledge to develop basic conservation and management guidelines for this ecosystem service. Essential questions, such as how well the abundance of frugivorous animals predicts seeding function in different ecosystems and how anthropogenic landscape heterogeneity conditions the role of dispersers, remain poorly answered. In three temperate ecosystems, we studied seed dispersal by frugivorous birds in landscape mosaics shaped by human disturbance. By applying a standardized design across systems, we related the frequency of occurrence of bird-dispersed seeds throughout the landscape to the abundance of birds, the habitat features, and the abundance of fleshy fruits. Abundance of frugivorous birds in itself predicted the occurrence of dispersed seeds throughout the landscape in all ecosystems studied. Even those landscape patches impoverished due to anthropogenic disturbance received some dispersed seeds when visited intensively by birds. Nonetheless, human-caused landscape degradation largely affected seed-deposition patterns by decreasing cover of woody vegetation or availability of fruit resources that attracted birds and promoted seed dispersal. The relative role of woody cover and fruit availability in seed dispersal by birds differed among ecosystems. Our results suggest that to manage seed dispersal for temperate ecosystem preservation or restoration one should consider abundance of frugivorous birds as a surrogate of landscape-scale seed dispersal and an indicator of patch quality for the dispersal function; woody cover and fruit resource availability as key landscape features that drive seedfall patterns; and birds as mobile links that connect landscape patches of different degrees of degradation and habitat quality via seed deposition.
动物传播种子被认为是一种关键的生态系统功能，它驱动着自然生境中的植物群落动态和人类干扰景观中的植被恢复。然而，对于这种生态系统服务，缺乏合适的生态知识来制定基本的保护和管理准则。一些基本问题，如在不同的生态系统中，有多少食果动物的丰度可以预测种子传播功能，以及人类景观异质性如何影响传播者的作用，仍然没有得到很好的回答。在三个温带生态系统中，我们研究了受人类干扰影响形成的景观镶嵌体中食果鸟类的种子传播。通过在系统间应用标准化设计，我们将景观中鸟传播种子的出现频率与鸟类的丰度、栖息地特征和肉质果实的丰度联系起来。食果鸟类的丰度本身就可以预测在所有研究的生态系统中，种子在整个景观中的传播。即使是那些由于人类干扰而变得贫瘠的景观斑块，当鸟类密集光顾时，也会收到一些传播的种子。然而，人类造成的景观退化在很大程度上影响了种子沉积模式，减少了树木植被的覆盖或吸引鸟类并促进种子传播的果实资源的可用性。鸟类在传播种子过程中对树木覆盖和果实可用性的相对作用在不同的生态系统中有所不同。我们的研究结果表明，为了管理温带生态系统的种子传播以进行保护或恢复，应该将食果鸟类的丰度作为景观尺度种子传播的替代物，以及传播功能的斑块质量的指示物；将树木覆盖和果实资源的可用性作为驱动种子降落模式的关键景观特征；并将鸟类作为通过种子沉积连接不同退化程度和栖息地质量的景观斑块的移动纽带。
