关键词: 人工种壳, 种壳厚度, 种子命运, 鼠类, 栓皮栎

Abstract: Seed dispersal is an important strategy for seed regeneration and distribution expansion of plants. Rodents adopt different seed dispersal and hoarding strategies in response to food shortages, which also promote seed dispersal. Seeds have evolved a series of traits, such as physical and chemical defenses in response to overfeeding by rodents. Seed coat thickness, as a physical defense strategy, is a key factor affecting the hoarding behavior of rodents and seed fates. However, there is still a lack of effective methods to artificially simulate seed coat thickness. In this study, by removing the coat of natural Quercus variabilis seeds, and then wrapping the seed kernels with different layers of polyethylene plastic, we aimed to accurately control the artificial seed coat thickness of the seed coats. The effects of seed coat thickness on seed dispersal and seed fate of artificially simulated seeds were investigated in the forests of the Dujiangyan region, Sichuan Province of China, from October 2020 to January 2021. We found that:(1) rodents preferred to disperse artificial seeds with the thinner coat (covered with 1 layer of polyethylene film); with the increase of seed coat thickness, the seed removal rate gradually decreased; the seeds with the thickest coat (covered with 6 layers of polyethylene film) had the slowest removal rate (P < 0. 001); (2) Rodents preferred to scatter-hoard seeds with 1 and 2 layers of polyethylene film. When the coat thickness increases to 4 and 6 layers of polyethylene film, the proportion of scatter-hoarded was significantly reduced (P < 0. 05); (3) Rodents preferred to larder-hoard seeds with 4 layers of film, compared to seeds covered with the other layers of polyethylene film (P < 0. 05); (4) There was no significant difference in seed dispersal distance among seeds with different seed coat thickness (P > 0. 05); (5) Seeds with thinner coat thickness (1 layer of film) had a higher proportion of scatter-hoarding within 3 m. The use of polyethylene film wrapping is a feasible method for simulating the seed coat, and could be used to evaluate the impact of the thickness of the seed coat on the hoarded behavior of rodent seeds and the fate of seeds.

Key words: Artificial seed coat, Seed coat thickness, Seed fate, Rodents, Quercus variabilis