The animal dispersal hypothesis predicts that mast seeding can increase dispersal rate of seeds by dispersers and enhance reproductive success of plants. However, in contrast to pollination efficiency and predator satiation hypothesis, the animal dispersal hypothesis has received mixed support.

Using 12-year data on fruit production and seedling recruitment of a fleshy-fruited tree rowan (Sorbus aucuparia, Rosaceae), we tested if an increase in the fruit production at the population level results in higher proportion of fruits recruiting into seedlings. Recruitment was recorded near (under rowans) and far (under heterospecifics) from conspecifics. Higher recruitment rates under rowans would support predator satiation hypothesis. Higher recruitment rates under heterospecific trees, where fruits can only arrive with animal assistance, would support animal dispersal hypothesis.

High population-level fruit production increased the proportion of fruits recruiting into seedlings both near and far from rowans. In contrast, high individual-level fruit production did not have a positive effect on the proportion of fruits recruiting into seedlings.  

Synthesis. Population-level synchronization of fruit production is required to generate a more effective plant regeneration. Our findings show that masting enhances seedling recruitment through predator satiation and increased seed dispersal by frugivores. The results provide support for both animal dispersal and predator satiation hypotheses indicating that both mechanisms can operate simultaneously.

The study was conducted in a subalpine old-growth spruce forest on the north slope of the Babia Góra massif (1,725 m a.s.l.) in the Western Carpathians (Poland). We studied fruit production on a permanent rectangular site (27-ha; 564 × 480 m), at 1170–1310 m a.s.l. We searched all living rowan trees (n = 228-310 depending on the year) for fruits in September between 2008 and 2019. We measured fruit production by counting the number of infructescences of each individual tree with the use of binoculars. We randomly sampled five infructescences from each tree and counted all fruits in them. On the same site, we haphazardly selected and permanently marked 33 rowan individuals. For each selected rowan, we established permanent plots to assess seedling establishment (1 m 2 , N = 33) that were located under the crown of the nearest spruce. A similar set of plots was established directly under the rowan trees (N = 33). In 2010-2019, we counted and individually marked all new rowan seedlings recruiting in these plots.

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