High post-fire mortality of resprouting woody plants in Tasmanian Mediterranean-type vegetation

Abstract

Plant regeneration strategies are commonly dichotomised as ‘resprouter’ v. ‘non-resprouter’, but this fails to recognise that the extent and type of resprouting following fire disturbance vary within species. Here, we report a case of widespread mortality of resprouters following a fire that burnt 98% of an 80-km2 island in Bass Strait, Australia. A field survey, which assessed woody vegetation in 197 plots across the island, showed fire severity ranged from low to high, with crown defoliation occurring across 85% of the island. In total, 1826 of the 1831 woody stems in the burnt plots were top-killed. Only 7.5% resprouted, despite 89% of the stems belonging to species that have the capacity to resprout. Even in species with at least 5% resprouting, only 22% of top-killed stems resprouted. Resprouting rates were maximal (30%) at intermediate fire severity, and only 5 and 8% at the lowest and highest severity classes respectively. Our findings demonstrate the need to understand factors influencing resprouting, and to incorporate these when modelling vegetation recovery after wildfire.