Temporal Changes in Tropical Forest Plant Habitats after a Severe Tropical Cyclone, With and Without the Effects of Fire

The forests of the tropical lowlands between Cairns and Ingham in North Queensland are among the most biodiverse and complex ecosystems in Australia. They consist of a myriad of regional ecosystems inter-mixed and positioned into a patchwork mosaic that ranges from open tropical woodlands, to flooded forest types to closed forest types known as “Vine Forests” (Cumming, 1993). These forests are continually in a state of change, regenerating from severe disturbances such as tropical cyclones, floods and fire events. This area was struck by severe tropical cyclone Yasi in early 2011. 31 plots estab-lished in the lowlands of the wet tropics after the cyclone, additional factors of influence to fire were added to the study, with approximately half the plots being treated with fire in the years that followed. All plots were then resurveyed in 2014. It was found that the fires promoted Acacia spp. stem density and this genus was significantly linked to higher fire frequency and scorch height. In terms of the effects of the cyclone, there were abundant woody plants in the ground layer following the cyclone, and this may also have been encouraged further by the fires, although that combined effect was not con-clusive. Across all forest types, numbers of ground plants were significantly more abundant with increasing distance from closed forest patches in the initial surveys. In the final survey greater ground plant species richness was significantly linked to increasing distance from closed forest. There was a significantly greater number of ground plants in the final survey. Most of the very large trees survived, while some trees throughout the tree layers died slowly over a year or more after the cyclone. The mean height and di-versity of all tree species combined increased significantly by the final data survey. Ul-timately the forest was changed but survived.