Swida amomum seed germination

Premise: Effective seed dispersal is essential in population dynamics of
plant species. Swida amomum (Silky dogwood) exhibits a dispersal syndrome
characteristic of autumn-ripening shrubs with fleshy fruits, where
attached fruits are ingested and defecated by birds while fallen fruits
are consumed by ground-foraging birds and mammals.  Methods: We
documented that fallen fruits of this shrub were consumed by two aquatic
turtle species (Eastern painted turtle, Chrysemys picta and Red-eared
slider, Trachemys scripta) and that their seeds were defecated.
 We compared germination success (percentage of seeds germinated)
of defecated seeds, seeds collected from pond surface, and seeds removed
from shrubs. Results: While four seed taxa were identified in fecal
samples, seeds of S. amomum were the most frequent (93%) among samples and
the most numerous (106 seeds) in any sample.  Average proportion
of fecal seeds germinated (85.99%) exceeded that of seeds from pond
surface (82.76%) and from shrubs (60.24%), albeit the difference in
germination success was insignificant. When analyzed using fecal samples
from Painted turtles only, the difference in germination success between
fecal seeds and those collected from pond or shrub became significant.
Conclusions: Our findings represent the first report of S. amomum seeds
being dispersed by turtle gut passage and suggest aquatic turtles could be
an important part of a secondary seed dispersal process influencing woody
plant community composition in temperate wetland ecosystems.