Understorey shrub-legumes native to Western Australia have evolved numerous adaptations to prevail, although they experience fires at more or less frequent intervals. This study examines the differences in regenerative strategy between two species of Bossiaea, one classed as a seeder (succumbing to fire), the other as a resprouter (surviving fire). Rates of biomass accumulation in juveniles of the resprouter B. ornata were considerably less than in the congeneric seeder B. aquifolium, rising to an 18-fold difference by 6 years after germination. Equilibrium values for shoot: root dry weight ratio also showed great disparity between the species (100 for B. aquifolium, 0.8 for B. ornata). Cumulative seed production per plant in the first 6 years after establishment from seed was nearly 32 times greater in the seeder than in the resprouter, but was not noticeably different when compared with the seed output of plants of B. ornata which had survived several fires. Because of their great proportional biomass, roots of B. ornata were the principal organs for storage of nutrients (P, N, K, Ca, Mg), while B. aquifolium stored mainly in its shoots. Average values for seasonal reproductive effort and investment into seed were significantly higher in terms of both dry matter and specific nutrient elements for the obligate seeder than for either seedlings or survivors of a single fire in B. ornata. The latter species, however, exhibited increasing reproductive effort with the number of fires experienced. Assuming a continuum amongst species in emphasis on regeneration after fire from seed or through resprouting, B. aquifolium displayed features akin to short-lived seeder species, while B. ornata appeared to be positioned close to the sprouter-end of the continuum in terms of growth rate and resprouting ability, but in an intermediate position in terms of reproductive effort. © 1991 Annals of Botany Company.
