Seed rain mediated by frugivores is influenced by (1) the seed-deposition distances following fruit ingestion, (2) the disperser activity, as determined by its behaviour and habitat preferences, and (3) the structure of the habitat within the landscape. Here, we evaluated such components using the fleshy-fruited shrub Ephedra fragilis and the frugivorous Balearic lizard Podarcis lilfordi. We estimated seed-deposition patterns based on the displacements and habitat preferences of lizards, derived from visual surveys and telemetry data. The influence of variables potentially determining lizard habitat preference (i.e., height, slope, four measures of habitat abundance and four measures of habitat fragmentation) was evaluated at three spatial scales: ‘home-range’ (c. 2.5–10*103 m2; telemetry data), ‘within home-range’ (c. 100 m2; telemetry data) and ‘microhabitat’ (<100 m2; visual survey). Cumulative lizard displacement (from each telemetric location to the initial capture point) saturated before the peak of seed defecation (seed-retention time), indicating that lizard home-range size and habitat preferences were the main determinants of the spread and shape of seed shadows. Shrub cover was positively correlated with habitat preference at the three scales of analysis, whereas slope was negatively correlated at the home-range scale. Model scenarios indicated that spatially-aggregated seed rain emerged when we incorporated the joint effect of habitat preference at the two largest (home-range and within home-range) scales. We conclude that, in order to predict seed rain in animal dispersed plants, it is important to consider the multi-scale effects of habitat preference by frugivores.
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机译:由节食动物介导的种子雨受到以下因素的影响:(1)水果摄入后的种子沉积距离;(2)由其行为和生境偏好决定的分散剂活性;(3)景观内生境的结构。在这里,我们使用果肉灌木脆弱的麻黄(Ephedra fragilis)和食肉的巴利阿里蜥蜴Podarcis lilfordi评估了这些成分。我们根据蜥蜴的位移和栖息地的偏好估计了种子的沉积模式,这些蜥蜴是从视觉调查和遥测数据中得出的。在三个空间尺度上评估了可能决定蜥蜴栖息地偏好的变量的影响(即高度,坡度,四个栖息地丰度度量和四个栖息地破碎度度量):“家庭范围”(c。2.5-10 * 10 3 sup> m 2 sup>;遥测数据),“在范围内”(约100 m 2 sup>;遥测数据)和“ microhabitat”(<100) m 2 sup>;视觉调查)。在种子排便高峰(种子保留时间)之前,累积的蜥蜴位移(从每个遥测位置到初始捕获点)已达到饱和,这表明蜥蜴的居家范围大小和栖息地偏好是种子阴影扩散和形状的主要决定因素。在三个分析尺度上,灌木覆盖度与生境偏好呈正相关,而在家庭尺度上,坡度呈负相关。模式情景表明,当我们在两个最大的(家庭范围和家庭范围内)尺度上纳入栖息地偏好的共同影响时,就会出现空间聚集的种子雨。我们得出的结论是,为了预测动物分散植物中的种子雨,重要的是要考虑到节食动物对栖息地偏好的多尺度影响。
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