The Effect of Some Mediterranean Scrubland Frugivores Upon Germination Patterns

Abstract

SUMMARY (1) The probabilty of germination, the length of seed dormancy, and the temporal pattern of germination of five bird-dispersed plant species of an eastern Mediterranean scrubland community varied depending on the plant species, on which of seven bird species they were experimentally fed to, on whether or not they remained covered by pulp, and on whether or not the pulp was experimentally removed before sowing. (2) It is proposed that, in order to withstand the passage through the gut, seeds are protected in a way that may delay their germination after defecation and alter the inherent dormancy, depending on the amount of wear the seeds go through while in the gut. The experimental results suggest that frugivory modifies the length of this dormancy so that the evenness of seedling emergence over time increases as more dispersers, each of which treats the seed in its gut differently, ingest the fruit. This may help to spread the risks encountered during germination, as an adaptation to a relatively mesic environment with an unpredictable rain pattern. (3) Rhamnus palaestinus seeds are encased in a sheath with unique features. It fully protects the seeds during passage through the gut of a disperser, and is shed immediately after defecation. Thus protection does not wear out in the gut, yet germination is not impaired and remains totally independent of gut characteristics of the various dispersers.