Abstract:

Aim: Pinus dabeshanensis, an endemic species in the Dabieshan Mountains, has significant scientific values for studying the taxonomy, phylogenetic relationships, and distribution of the Pinus genus. Currently, the wild population of P. dabeshanensis is severely limited in natural regeneration and is critically endangered. Here, we explored the potential effects of seed predation and dispersal by animals on the regeneration of P. dabeshanensis.

Methods: First, we investigated the seed production of P. dabeshanensis by focusing all the adult trees in two 1-ha plots (n = 88). Second, by tracking the fate of 2,000 seeds, we compared the seed predation and dispersal by animals between P. dabeshanensis and three sympatric tree species. These included two dominant native species, Castanea seguinii and Quercus serrata, and an introduced species Pinus armandii that is a sister species of P. dabeshanensis, which all mainly depend on scatter-hoarding animals for seed dispersal. Third, we compared the visitation frequency of potential seed predators and dispersers between P. dabeshanensis and its sympatric species by using camera-trap surveys.

Results: The results showed that: (1) The seed production of P. dabeshanensis was low, with only 312 cones produced by 21 of the 88 adult trees surveyed, and the seed abortion rate reaching 51.89% ± 0.07% (mean ± SE). (2) A total of 146 cones were collected to assess the seed predation by birds, and 90 of them were pecked by birds which was significantly more than un-pecked cones (n = 56), with an average pecking intensity of 8.94% ± 0.55%. (3) Small rodents and ground-dwelling birds (e.g., Garrulus glandarius) were the main visitors to the seeds in the forest ground, and visitation frequency varied significantly among different tree species. Specifically, for P. dabeshanensis, birds visited the seeds more frequently (n = 77) than rodents (n = 46). (4) Seeds of C. seguinii were harvested the fastest, followed by Q. serrata and P. dabeshanensis, while P. armandii were harvested the slowest. (5) Of the 2,000 seeds released in the forest, 157 seeds were successfully dispersed, including 96 P. armandii seeds and 57 P. dabeshanensis seeds, which were significantly more than C. seguinii (3 seeds) and Q. serrata (1 seed). (6) The seed dispersal distance of C. seguinii was 13.9 ± 4.0 m (mean ± SE), followed by P. dabeshanensis (7.3 ± 0.8 m), P. armandii (3.8 ± 0.4 m) and Q. serrata (1.5 m, only one seed was successfully dispersed).

Key words: Pinus dabeshanensis, animal dispersers, seed dispersal, natural regeneration, plant animal interaction