Ecosystem development on a titanium dioxide residue pond after five years in Capel, Western Australia

ABSTRACT

Rehabilitation with native plant species of an experimental titanium dioxide residue containment pond on dune swales at Capel, Western Australia was undertaken in 1990. The treated residue comprised unreacted ilmenite, coking coal, metal hydroxides, gypsum and lime inerts, and titanium dioxide. It was an inert, insoluble, non-toxic, clay-like material. This paper describes the growth and establishment of terrestrial vegetation in the residue material after five years and its associated symbiotic root fungi and ant communities. The total number of plant species present after five years was comparable to a nearby Eucalyptus gomphocephala woodland and dune vegetation. Vegetation cover was similar to the dune site but less than the woodland. Litter cover was similar to the burnt dune site. Mycorrhizal infection rates were similar in the roots of plant examined in experimental and control sites. Ant species richness was approaching levels in control sites. Soil analysis showed that topsoil in the residue pond had similar attributes to reference soils in the area. Young leaf tissue did not accumulate trace heavy metals. These observations indicated adequate rehabilitation after 5 years which would likely lead to a self sustaining ecosystem.