67. Sprouting Behaviour

Organised by Mike Lawes (Charles Darwin U), Lindsay Hutley (Charles Darwin U) and Peter Clarke (U New England). First meeting 18 August 2009, at the Queensland State Library, Brisbane Second meeting 5-8 July 2010 at University of New England, Armidale

PARTICIPANTS INCLUDE Mike Lawes - Charles Darwin U - ecology of sprouting and multistemming in forests and fire-prone savannas Lindsay Hutley - Charles Darwin U - carbon cycle and physiology of sprouting Peter Clarke - U New England - ecology of sprouting in fire-prone heathlands Hans Lambers - UWA - ecophysiology of sprouting and resource allocation Samantha Setterfield - Charles Darwin U - regeneration ecology of trees in fire-prone mesic savannas William Bond - U Cape Town (South Africa) - savanna dynamics, disturbance ecology Jeremy Midgley - U Cape Town (South Africa) Ross Bradstock - U Wollongong - plant response to fire Kirsten Knox - U New England Rod Fensham - Queensland Herbarium Neal Enright - Murdoch U - ecology and management of fire-prone ecosystems Participating in the second meeting Lawes, Clarke, Midgley, Knox, Fernando Ojeda, Geoff Burrows, Enright, Byron Lamont, Philip Groom, Michael Cramer

July 10>

GOAL

In this workshop we will explore fundamental issues about the nature of resprouting, where knowledge gaps occur and whether it is possible to develop functional models of community response to disturbance regimes under future climate change scenarios for mainly fire prone landscapes.

Background
Many Austral biomes are fire disturbance driven systems, such as tropical savannas, mallee and fire-prone heathlands. Their plant dynamics are dependent mainly on fire severity and frequency and individuals often persist through repeated disturbance by resprouting from vegetative tissue and so mostly survive fire. Resprouting after disturbance from vegetative tissue buffers the infrequent recruitment of seedlings and facilitates persistence and population maintenance in disturbance-prone environments. While resprouting confers persistence under disturbance, a lack of sexual reproduction limits gene flow and understanding this balance between asexual and sexual reproduction and the mechanisms of sprouting behaviour is important for understanding long-term vegetation dynamics, extinction risks, carbon balance and woody plant management.

Resprouting ability and the relative dominance of resprouters depends on both genetic and environmental factors. Environmental factors include, the severity of disturbance to aboveground biomass, and whether resources in below- and remaining aboveground structures can be mobilised to aid sprouting following disturbance. In systems where aboveground biomass may be destroyed, basal sprouting can be common. However, in savannas and open forests, eucalypts and other clades may also persist by sprouting from the surviving stem (epicormic sprouting), which allows faster recovery of photosynthesis and growth. Depending on the severity of disturbance, there is a trade-off in sprouting response between investment in the current generation through resprouting and investment in future generations by seeding. Under severe disturbance regimes basal sprouting ensures the longevity and persistence essential to maximize individual life-time fitness. In contrast, epicormic sprouting using stored carbohydrate resources is an effective ‘bet-hedging’ strategy when disturbances are spatio-temporally variable and of low to medium severity, and minimizes the effects of disturbance by speeding up recovery of vegetative tissue and seed production. Landscape patterns of resprouting in relation to disturbance frequency support the notion of disturbance severity being a major selective factor yet resource availability may also be critical.

Last Updated March 2010