Open Access

Stephen D. Skull, Robert A. Congdon

• Tropical lowland plant communities in north-eastern Queensland remain under pressure from continuing clearing, fragmentation, exotic species invasion, inappropriate fire regimes, and altered hydrological patterns. Comparatively little scientific research has been conducted on the highly diverse and ecologically significant range of remnant vegetation types. Additionally, most plant communities remain very poorly represented in the existing conservation reserve system. Melaleuca viridiflora Sol. ex Gaertn. open woodlands were selected for investigation based on their relatively simple structure, compared to other lowland communities, and the large extent to which they have been affected by past clearing patterns. A detailed analysis of community structure and composition was conducted at 24 sites throughout the wet-tropics coastal region between Townsville and Cooktown. Surprisingly, a high diversity of structural and floristic types was recorded, with a total of 127 species documented across the 24 sites. Classification analyses of species composition data produced seven or eight main groups of sites (dependent on the statistical technique used), essentially related to a gradient of latitude and rainfall. These floristic groups were not well explained by either species richness, past fire frequencies or soil types. Structural classification analyses based upon DBH data identified six or seven main groups, the singularly most striking of which were sites with annual fire histories. Ordinations based on both the DBH and species composition data produced groupings that supported those detected by the classification techniques. On closer examination of sites with similar fire histories, soil moisture and soil type were both found to have significant effects on community structure and composition. Many of the woodland types recorded are not adequately included (some not at all) in the existing conservation reserve system.