Invasion of Maritime Chaparral by the Introduced Succulent Carpobrotus-Edulis the Roles of Fire and Herbivory

TitleInvasion of Maritime Chaparral by the Introduced Succulent Carpobrotus-Edulis the Roles of Fire and Herbivory
Publication TypeJournal Article
Year of Publication1993
AuthorsD'Antonio, CM, Odion, DC, Tyler, CM
JournalOecologia (Berlin)
KeywordsAizoaceae Cervidae (Ecology Environmental Biology–Plant) (Ecology Environmental Biology–Animal) (Plant Physiology, Biochemistry and Biophysics–Temperature) Plants Vascular plants Spermatophytes Angiosperms Dicots Animals Chordates Vertebrates Nonhuman vertebrates Mammals Nonhuman mammals Artiodactyls Deer Scat Seeds Temperature Herbivory Fire Seedling Mortality

Invasion by the alien succulent, Carpobrotus edulis, has become a common occurrence after fire in maritime chaparral in coastal California, USA. We studied post-burn Carpobrotus establishment in chaparral that lacked Carpobrotus plants before the fire and compared seedbank and field populations in adjacent burned and unburned stands. Carpobrotus seeds were abundant in deer scat and in the soil before burning. Burning did not enhance germination: many seeds were apparently killed by fire and seed bank cores taken after fire revealed no germinable seeds. Laboratory tests showed that temperatures over for five minutes killed Carpobrotus seeds. In a field experiment involving use of herbivore exclosures, we found that herbivory was an important source of mortality for seedlings in both burned and unburned chaparral. All seedlings, however, died outside of the burn regardless of the presence of cages. Establishment there is apparently limited by factors affecting plant physiology. In the burned area, seedlings that escaped herbivory grew very rapidly. Overall, it appears that herbivory limited seedling establishment in both burned and unburned sites but that the post-burn soil environment supported Carpobrotus growth in excess of herbivore use, thus promoting establishment.