Seed fates of Arctomecon californica.

摘要

Seed fates were investigated for Arctomecon californica a Critically Endangered plant in the State of Nevada. This species is a short-lived rare perennial plant endemic to the Mojave Desert. Conservation plans for the species would benefit by understanding the fate of A. californica seeds from seed production, dispersal, and granivory to incorporation within the seed bank. Each year, 18% of the capsules suffered predispersal loss. The average number of seeds per capsule ranged from 87 to 99 seeds. Seed viability ranged from 87.5% to 100% per plant. Seed production was highly dependent on the number of mature capsules per plant and was used to predict seed output per plant. Dispersal from the capsule mainly by the ejection of seeds triggered by wind tended to disperse seeds away from parent plants. Once seeds reached the soil surface, ants were the main agents responsible for seed removal. The role of rodents appeared to be minimal in A. californica seed removal experiments. Examination of the potential role of seed elaiosomes in dispersal elicited variable responses from ants. The seed bank of this species was spatially heterogeneous with most seeds found either close to the surface (34%) or deep within the soil column (26%). The proportion of viable seeds tended to be highest within the 6--15 cm depth increment, suggesting the presence of a long-lived seed bank. The distribution of seeds within the seed bank with respect to viability indicated 10.5% were viable seeds while 35.6% consisted of seed fragments or decayed seeds and the rest, 53.9% were filled but non-viable seeds.