The floristic differences found in vegetation ranging from sedgeland-heath to rainforest were sampled by the placement of 80 quadrats in an area 2 km2 near Bathurst Harbour, Tasmania. A direct gradient analysis using the time since last fire as the major axis of variation suggests that the changing species composition of sites is both gradational and fire-related. This interpretation is supported by a point- centred quarter analysis of the forested communities and by Principal Coordinates and Detrended Correspondence Analyses of the entire vegetation sequence. Previous descriptive models based on correlations between he frequency and structural formations are confirmed by this study. A broad correlation between fire frequency and floristic associations within non-forested vegetation is also demonstrated. However, explanation of detailed patterns requires consideration of the total fire regime (including duration and intensity of fire) and its interaction with edaphic factors. For example, fires which burn in peat lead to hysteresis in the successional pathways.
Use of Direct Gradient Analysis to Uncover Biological Hypotheses in 16S Survey Data and Beyond