The effects of fire and manual biomass removal on the vegetation of granite inselbergs

Abstract

The vegetation on granite inselbergs (island mountains) within the New England Bioregion of eastern Australia and the adjacent matrix were chosen as subjects in this study on the effects of aboveground biomass removal on community recovery. Undisturbed inselberg vegetation was treated by manual removal of biomass through clipping and also by burning. Inselbergs and the adjacent matrix that had been burned the previous year were also treated to an additional burn. The recovery of vegetation was measured over the following year across all experiments. The change in vegetation composition was analyzed using Detrended Correspondence Analysis (DCA), Generalized Linear Modeling (GLM), and variance partitioning of Canonical Correspondence Analysis (CCA) results, along with SIMPER and PERMANOVA analysis of composition difference and treatment interactions. Species turnover between start and end points of monitoring was also tested for significance between treatments. Comparison of floristic composition before experimentation and at the end point (12 months later) indicated that a single clipping of biomass had little statistical effect on inselberg floristic composition. In contrast, previously unburned inselbergs treated by fire did not recov er to starting conditions. The imposition of a second burn did not significantly change the composition on inselbergs or within the matrix. Subsequent fires on inselbergs increased species richness within plots. This increase in richness was associated with a loss of the previous endemic obligate seeding dominants and an increase in ubiquitous resprouting taxa, leading to the homogenization of inselberg floras and decreasing their distinctiveness from the matrix.