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

Abstract

Understanding the impacts of natural and human disturbances on forest biota is critical for improving forest management. Many studies have examined the separate impacts on fauna and flora of wildfire, conventional logging and salvage logging, but empirical comparisons across a broad gradient of simultaneous disturbances are lacking. We quantified species richness and frequency of occurrence of vascular plants, and functional group responses, across a gradient of disturbances that occurred concurrently in 2009 in the Mountain Ash forests of southeastern Australia. Our study encompassed replicated sites in undisturbed forest (~70 years post-fire), forest burned at low severity, forest burned at high severity, unburned forest that was clearcut logged, and forest burned at high severity that was clearcut salvage logged post-fire. All sites were sampled two and three years postfire. Mean species richness decreased across the disturbance gradient from 30.1 spp/site on low severity burned sites and 28.9 spp/site on high severity burned sites, to 25.1 spp/site on clearcut sites and 21.7 spp/site on salvage logged sites. Low severity burned sites were significantly more speciesrich than clearcut sites and salvage logged sites; high severity burned sites supported greater species richness than salvage logged sites. Specific traits influenced species’ sensitivity to disturbance. Resprouting species dominated undisturbed Mountain Ash forests, but declined significantly across the gradient. Fern and midstory trees decreased significantly in frequency of occurrence across the gradient. Ferns (excluding Bracken) decreased from 34% of plants in undisturbed forest to 3% on salvage logged sites. High severity burned sites supported a greater frequency of occurrence and species richness of midstory