Fire severity and nutrient availability do not constrain resprouting in forest shrubs

Abstract

Plants often survive disturbances such as fire by resprouting which involves having both protection traits and carbohydrate storage capacity. Protection traits not only act directly to insulate meristems but also prevent combustion of carbohydrate stores. Rapid stem growth also allows replenishment of carbohydrate stores ensuring persistence through another event. Resource availability may, however, constrain the ability to develop resilience to high-severity fires through either nutrient limitation or light limitation. We tested whether fire severity influenced resprouting ability of woody plants in two contrasting environments, low nutrient dry sclerophyll forest and more fertile wet sclerophyll forest. We tested which fire protection and growth traits were associated with resprouting ability (27 species) and resprouting vigour (16 species). Fire severity did not limit the ability of most species to resprout in either forest type. There was no generalized protection syndrome for surviving top kill, but combinations of bud protection and growth together with storage capacity appear to drive resprouting ability. In nutrient-limited forests, low specific leaf area (SLA) may reduce stem growth in resprouters, causing more reliance on bud protection through bark thickness. Conversely, in the more fertile forests, where light becomes limiting with time-since-fire, high SLA appears to increase the capacity for rapid stem growth with less emphasis on developing thicker bark. These different syndromes appear to be adaptive as fire severity did not influence survival in either forest type.