North Queensland Naturalist 50: 25-37

Plant biodiversity differences between rainforest plots in different stages of recovery in the uplands of the Wet Tropics

Marley V. Mullin, Emmanuela F. Salecki, Cherry R. Li, Anna M. Avinger, Ethan W. Landen, Jade S. Thurnham, Catherine L. Pohlman and David Y. P. Tng


Rainforests are one of the most diverse ecosystems in the world. In Australia, the Wet Tropics Rainforests of North Queensland are especially speciose, containing a wide range of flora and fauna, including a high number of endemic species. Unfortunately, the region has also been threatened by human impact such as land clearing. Relatively few studies have conducted full plot-level floristics in this region. In our study in the Gadgarra region of the Atherton Tablelands, Queensland, we looked at full floristics in 500m2 plots that we established in four vegetation types: a relatively undisturbed Old growth rainforest, an Old secondary rainforest (recovering from clearance since 1947); a Young secondary rainforest (recovering from clearance since 1972), and an Abandoned Orchard area. Across all plots, we found a total of 214 species belonging to 162 genera and 74 families. We found that the Old growth forest had the highest number of species, genera and families. The diversity present in the Older secondary plot was comparable to that displayed by the Old growth forest plot. In general, our results indicate that previously cleared forests have a lower species richness, a decrease in endemism, and altered species composition due to the effects of clearing. However, over time secondary succession results in some recovery of both forest structural and species composition similar to that of an undisturbed forest. Our study is descriptive in nature due to the lack of replication in sampling plots within vegetation types. However, we present a plant biodiversity list for each plot that can serve as baseline data for further studies in the region.