Frequency-dependent predation and seedling fate: Effect of forest litter on regeneration of the Quercus wutaishanica seedling

Abstract

Rodents attack oak (Quercus wutaishanica) seeds based on their sizes and frequencies before germination. However, the predation of oak seeds post-germination (seedling cotyledons) is not well studied. Here, we not only tested the preference of rodents for oak seedlings from different-sized seeds, but also traced the seedling fate under different litter treatments. We transplanted seedlings with frequency of large and small seed (FLSD) ratios as 1:9, 3:7, 5:5, 7:3, and 9:1, respectively, with each set treated with the litter cleared and covered. Our results showed that small-seeded seedlings were more preferred when the FLSD was 1:9 and 3:7, whereas large-seeded seedlings had a higher preference when the FLSD was 9:1 and 7:3. Moreover, the predation and survival rates of the seedlings decreased when covered with litter, thus indicating that, although forest litter prevented the seedling predation by rodents, it was unfavorable for seedling survival. Furthermore, we found that cotyledon predation by rodents had no significant effect on seedling performance, but their growth was severely inhibited when the apical bud was bitten off, thus suggesting that the apical bud loss was the main cause of seedling recruitment failure. Our study indicates that positive frequency-dependent predation helps maintain the polymorphism of germination type of Q. wutaishanica seedlings. Additionally, in the forest, the presence of litter may change the predation behavior of rodents, which consequently affects the growth and survival of the seedlings. Moreover, future studies should focus on how the forest species’ specific predatory habits and the litter of different thicknesses affect the growth and survival of the oak seedlings, to better understand the renewal mechanism of the oak trees.