Vulnerability of vegetation to mining dust at the Jack Hills, Western Australia

[Truncated] This thesis examines if dust produced by an iron-ore mine in the Jack Hills, Western Australia, has a negative impact on health and physiological function of the surrounding native flora. To this end, I characterised dust generated by the mine in terms of grain-size distribution and mineralogy and measured its spatial and temporal ‘footprint’. I then classified the dominant perennial species around the mine in terms of their structural and morphological ‘traits’ (e.g., plant height, leaf area, leaf surface characteristics) and quantified the dust trapped on the leaves of these species. I analysed the relationship between these plant ‘traits’ and dust on the leaves with Linear Mixed Effect Models (LMEM). Multivariate cluster analysis was used to group species based on similar traits to test if a group of species with similar traits increased dust loading. I then quantified the physiological performance of plants under different dust load conditions via stomatal conductance (gs), chlorophyll fluorescence (ΦPSII) and carbon isotope composition (δ13C). The correlation between the physiological measures, dust load and/or plant traits, was then examined with LMEM.
I found that the Jack Hills mine generated dust in excess of natural background levels at distances of up to 2000 m from the mining operations. It thus imposed elevated dust loads on the surrounding vegetation. Leaf morphological traits relating to surface roughness (e.g. the presence of hairs and unevenly textured surface) and leaf posture (revolute, involute, or flat) predicted dust load. Plant structural traits, including plant height and leaf orientation, did not significantly contribute to dust accumulation of plants in this study. The plant trait group analysis was not forthcoming, mainly because of restrictions in the spatial distribution of species across the study area.