Estimating seed bank accumulation and dynamics in three obligate-seeder Proteaceae species

TL;DR

This study investigates seed bank accumulation and reproductive strategies of three obligate-seeder Proteaceae species in Sydney, revealing species-specific seed bank sizes, regeneration strategies, and minimum fire-free periods needed for persistence.

Contribution

It provides detailed data on seed bank dynamics and regeneration strategies of three co-occurring Proteaceae species, highlighting their differences and fire management implications.

Findings

B. marginata accumulates ~3000 seeds per plant after 20 years

B. ericifolia accumulates ~500 seeds per plant

Minimum fire-free periods of 8-10 years are needed for seed bank development

Abstract

The seed bank dynamics of the three co-occurring obligate-seeder (i.e. fire-sensitive) Proteaceae species, Banksia ericifolia, Banksia marginata and Petrophile pulchella, were examined at sites of varying time since the most recent fire (i.e. plant age) in the Sydney region. Significant variation among species was found in the number of cones produced, the position of the cones within the canopy, the percentage of barren cones produced (Banksia species only), the number of follicles/bracts produced per cone, and the number of seeds lost/released due to spontaneous fruit rupture. Thus, three different regeneration strategies were observed, highlighting the variation in reproductive strategies of co-occurring Proteaceae species. Ultimately, B. marginata potentially accumulated a seed bank of c. 3000 seeds per plant after 20 years, with c. 1500 seeds per plant for P. pulchella and c. 500 for B. ericifolia. Based on these data, B. marginata and B. ericifolia require a minimum fire-free period of 8-10 years, with 7-8 years for P. pulchella, to allow for an adequate seed bank to accumulate and thus ensure local persistence of these species in fire-prone habitats.