Persistence ability of soil seed banks in burnt landscapes

Abstract

Seed banks play a critical role in the persistence of plant populations in variable environments. In the context of fire, seed banks are a particularly important source of seed for species which are killed by fire and rely on seed stored in the soil to regenerate and persist in the landscape following such disturbance events. Fire severity can vary, depending on a number of factors including: intensity, duration of the fire, fuel loads, fuel and vegetation type, topography, climatic condition, soil texture and moisture, soil organic content, time since last fire and area burnt. Essentially fires that consume a large amount of fuel can result in greater heat penetration of the soil profile, greater soil temperatures and longer residence times during the passage of fire. This is particularly important for species with a soil-stored seed bank as heating of soil may promote or inhibit the germination of seeds in the soil and affect the regeneration of species following fires of different severities. I examined the soil seed banks of five different plant communities in the Gibraltar Range and Washpool National Parks, New South Wales, Australia. The five communities ranged from those dominated by mesic elements with low fire frequency (Wet Sclerophyll Forest and Rainforest), to those with a strong sclerophyll component and a relatively higher expected fire frequency (Dry Sclerophyll Forest, Rocky Outcrop and Wet Health). This thesis consists of five data chapters, each written in the style of a scientific paper.