Persistence of resprouting species after fire in natural and post-mine restored shrublands in southwestern Australia

Abstract

Questions: Is post-fire persistence of resprouting spedes lower in restored sites, and is survival related to lignotuber size? Location: Southwestern Australia, Eneabba, 300 km north of Perth. Methods: Post-fire persistence of 10 lignotuberous shrub species was compared between three sites restored 8-24 years ago after mineral-sand mining and three surrounding natural shrubland sites (8-24 years since previous fire). Results: Overall persistence of species was 11-93% in restored sites (mean 52%) and 79-100% in natural sites (mean 96%). Persistence increased with time since rehabilitation for five species with <25% of individuals in three species surviving in the youngest stand. For equivalent crown size, average lignotuber drcumferences were 50% smaller at restored sites and this probably accounted for their higher post-fire mortality. Apart from differences in the age of plants, restored sites had lower soil penetrability than natural sites, which may have restricted rootstock development. A tradeoff favoring a higher crown volume to lignotuber size ratio was apparent in nine of the ten species with greater crown volumes (by 37%) and smaller lignotubers (by 36%) in restored sites. Two resprouting species for which crown seed store was quantified had much higher fecundity in restored, sites. Conclusions: Fires reduced resprouter persistence in restored sites owing to poor development/insufficient size of lignotubers. Further management after fires is required, including application of resprouter seeds/seedlings on restored topsoil, transplanting adult resprouters (where viable) from natural areas ahead of the mining front. Low intensity/patchy fires are recommended on long unburnt sites. Resprouter survival would have likely been much greater in the first place if a deeper sandy soil profile was rehabilitated, thereby providing a more suitable medium for lignotuber development. © 2009 International Association for Vegetation Science.