Comparisons of vegetation recovery post-fire, logging and salvage logging in the Victorian Central Highlands

• Main Author: Blair, David
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Subjects: Antarc*; Antarctica
• Online Access: http://hdl.handle.net/1885/163768; https://doi.org/10.25911/5d51482378c9d; https://openresearch-repository.anu.edu.au/bitstream/1885/163768/3/BLAIRThesis_with_Examiners_corrections.pdf.jpg

ABSTRACT Disturbance is an important ecological driver of plant community composition and adaption. My research was in the Mountain Ash (Eucalyptus regnans) forests of the Central Highlands in Victoria where the primary forms of disturbance are wildfire and clearfell logging. Three large conflagrations in 1939, 1983 and 2009 resulted in uniformly aged stands of Eucalyptus regnans. My research, comprising four interrelated studies, uses these major fire events and recent logging, to compare the recovery attributes of the plants in Mountain Ash forest. Chapter one compares plant species richness and functional group responses to logging and fire of different intensities. I found species richness declined across a 'disturbance gradient' of low severity fire (30.1species/site), high severity fire (28.9spp/site), clearfell logging (25.1spp/site) and salvage logging (21.7spp/site). The greatest differences between the effects of fire and logging are on sprouting species including ferns and midstorey trees, with logging causing a simplification of the forest biota. Species losses are attributed to the mechanical disturbance of harvesting and the fire/logging disturbance sequence. Chapter two studies growth rates of tree ferns, Cyathea australis and Dicksonia antarctica. Five years after the 2009 fires, I measured the new growth of 335 tree ferns and found Cyathea australis averaged 73(+/- 22)mm/year of growth, while Dicksonia antarctica averaged 33(+/- 13)mm/year. An unexpected finding was higher growth rates in taller tree ferns, increasing with height by 5-6mm/yr/m in both species. The non-linear growth is explained by the taller ferns being exposed to greater amounts of sunlight as the dense regeneration progressively shaded the shorter ferns. In Chapter three, I use a chronosequence from the major fire events of 2009, 1983, 1939 and 1851 to determine how species richness and functional groups differ in forests of different ages. Species richness is highest in the youngest cohort (17.1species/plot) when many early ...