Variation in bradyspory and seedling recruitment without fire among populations ofBanksia serrata(Proteaceae)

Abstract

AbstractLong‐term canopy storage of seeds in fruits (bradyspory) varies among species and is thought to be related to the fire regime experienced by the plant community. This study sought to quantify intraspecific variation in bradyspory among nine populations ofBanksia serrata(Proteaceae) on the south coast of New South Wales. Marked differences were found between populations, ranging from more than 30% of follicles open at two coastal sites, to less than 5% of follicles open at two inland heath sites. Low levels of bradyspory occurred particularly in coastal sites which also hadBanksia integrifolia, a non‐bradysporous species, present. In addition to spontaneous follicle opening without fire, fall of infructes‐cences to the ground after breaking of branches was observed to be a major contributor to seed release. At three sites where fire had not occurred for many years, the amount of seedling establishment since the last fire corresponded well with levels of bradyspory; there were no inter‐fire recruits at the site with the strongest bradyspory, while at the site with the weakest bradyspory there were numerous inter‐fire plants, some with lignotubers large enough to be able to tolerate the next fire. It is argued that populations ofB. serrataexhibit variable patterns of recruitment, depending on the site characteristics, ranging from complete dependence on fire for population maintenance to bet‐hedging (spreading potential recruitment between fire events and inter‐fire periods). Variations in populations and reproductive characteristics among sites make the application of demographic models to management decisions habitat‐specific.