Using heat and smoke treatments to simulate the effects of fire on soil seed banks in four Australian vegetation communities

Abstract

The aim of this project was to investigate the ability of artificially applied smoke and heat stimuli to simulate field responses of soil seed banks to fire. The ability to simulate field responses to fire would allow managers to better understand the effects that fire might have on a community before actually burning it. This knowledge is greatly lacking for many Australian ecosystems at present, such that fire is avoided as a management tool for fear of negative ecological impacts. The composition and density of seedlings was compared between soil samples subjected to fire in the field and soil samples treated with a range of heat and smoke stimuli in 4 different Australian ecosystems along a rainfall gradient from subtropical to arid. The treatments used were: no treatment; smoke for 1 hour; heat at 80°C; heat at 80°C and smoke for 1 hour; heat at 105°C; heat at 105°C and smoke for 1 hour. The results vary greatly between ecosystems with no one treatment closely simulating the effects of fire. In addition, there was no significant difference between the control and the fire treatment in terms of the number of species or the abundance of seedlings that emerged from the seed bank. Thus the role of fire and fire related cues in stimulating seed banks is discussed. The results also revealed a relationship between seed bank response and the likely "natural" fire frequency of an ecosystem which may be useful to identify optimal fire intervals when managing for biodiversity. However, this needs further investigation.