title: Disproportionate allocation of mineral nutrients and carbon between vegetative and reproductive structures in Banksia hookeriana.
abstract: We compared above-ground allocation patterns in mature shrubs of Banksia hookeriana from three 13-year-old populations, growing on nutrient-impoverished sands to determine whether C (dry mass) could be a substitute for mineral nutrients (N, P, K, Ca, Mg and NA). The percentage of reproductive structures to total above-ground growth (reproductive effort; RE) was integrated over nine successive reproductive cycles. Only 0.5% of above-ground dry mass was allocated to seeds compared with 31% to total RE. Allocations of N (24%) and P (48%) to seeds, and N (44%) and P (65%) to RE were much higher. Allocations of K, Ca, Mg and Na to seeds (<1-3%), and RE (21-35%) were closer to that of dry mass. Relative allocation (RA) is defined as the proportion of a nutrient element allocated to a structure relative to its dry mass. RA of P to seeds was 91 and N was 44, but for K, Ca, Mg and Na ranged from only 6 for K to<1 for Na. Thus P, and to a lesser extent N, provide a much more sensitive measure of the relative cost of reproduction than C in this nutrient-limited system.
authors.affiliation: Botany Department, University of the Witwatersrand, P.O. Wits, 2050, Johannesburg, South Africa. ed@gecko.biol.wits.ac.za.
authors.forename: E T F
authors.initials: ET
authors.lastname: Witkowski
authors.affiliation: School of Environmental Biology, Curtin University of Technology, GPO Box U1987, 6001, Perth, Australia.
authors.forename: Byron B
authors.initials: BB
authors.lastname: Lamont
keywords: Canopy seed storage; Limiting resources; Proteaceae; Reproductive effort; Seed production