Landscape patterns of woody plant response to crown fire: Disturbance and productivity influence sprouting ability

Abstract

1. - The relationship between environment and the ability of plant species to resprout has been explored more in terms of disturbance frequency than of resource gradients, and has rarely been examined in non-Mediterranean landscapes. 2. - The fire response of 296 non-eucalypt woody taxa was recorded in five habitats in the New England Tablelands (NET) Bioregion of eastern Australia: grassy woodlands, dry sclerophyll forests, rocky outcrops, wet heaths and wet sclerophyll forests. We then tested whether there was a dichotomy of response to crown fire, whether the proportion of resprouters differed among habitats, and if disturbance frequency or resource-productivity models could account for landscape patterns of resprouting. 3. - There was a continuum of sprouting ability but most species could be classified as obligate seeders (killed by fire) or resprouters. Habitats differed in the proportion of resprouting species, with rocky outcrops having the lowest proportion and grassy forests and wet heaths the highest. This pattern was consistent at the congeneric and confamilar phylogenetic levels of comparison. 4. - Resource/productivity models better explained landscape patterns of resprouting than disturbance frequency models. There was a strong positive relationship between resprouting and increasing soil fertility and moisture gradients. Species richness and obligate seeder richness increased with climate variability and landscape heterogeneity. 5. - Landscape resprouting patterns were explained by a resource-competition model where resprouters are favoured because of their ability to persist in more competitive environments. Overall, we suggest that disturbance frequency has larger effects on species richness at the low end of the productivity gradient than at the high end.