Environmental Engineering Reference
In-Depth Information
A major target that is often considered for below-ground restoration success
is the return of the soil microbial biomass (the standing crop of microbes)
(Sawada
1999
; Harris
2003
). In some cases after bauxite mining, the soil micro-
bial biomass has remained consistently lower (by about one third) than the
equivalent standing crop of microbes found in natural sites (
Fig. 15.13
) (Spain
et al.
2006
). It is noteworthy that the same sites in Gove in the Northern
Territory had low microbial biomass and correspondingly large litter masses,
indicative of low rates of decomposition. It is possible that this accumulating
litter and reduced microbial biomass represents some form of soil microbio-
logical dysfunction; however, further study is required to unravel the processes
leading to these conditions in the restored forests.
Conclusions
Reconstruction of functional forest ecosystems are major operations for baux-
ite mining companies in Australia. Given the size and complexity of the task, it
is generally considered to be well executed and among the better restoration
schemes after mining (Koch & Hobbs
2007
). This is in part due to the intelligent
soil management methods employed, although issues still remain with artifi-
cial chemical fertilisation (George et al.
2006
; Standish et al.
2008
).
The above-ground parts of the ecosystem that are more easily observed show
the greatest parity with natural systems. Plant populations are on track to
match native systems fairly well, with discrepancies largely accounted for by
the restored forest age. The below-ground parts of the ecosystem are harder to
track and also show some similarities to natural systems, at least after decades
of growth. However, it is in aspects of soil fertility, particularly biological
fertility, that some differences are evident. The true long-term effect of these
differences may only become clear over much longer time scales or after a
major perturbation such as a cyclone or wildfire.
References
Abbott, I. (1989) The influence of fauna on soil
structure. In: Animals in Primary Succession:
The Role of Fauna in Reclaimed Lands
(ed. J. D. Majer), pp. 39 50. Cambridge
University Press. Cambridge, UK.
Bell, L. C. (2001) Establishment of
native ecosystems after mining Australian
experience across diverse biogeographic
zones. Ecological Engineering 17, 179 186.
Bradshaw, A. D. and Chadwick, M. J. (1980) The
Restoration of Land. Blackwell Scientific
Publications, Oxford, UK.
Connin, S. L., Feng, X. and Virginia, R. A. (2001)
Isotopic discrimination during
decomposition of organic matter: a
theoretical analysis. Soil Biology Biochemistry
33, 41 51.
Chen, Y., Worthington, T., George, S., Walker, E.,
Wallrabenstein, H. and Tibbett, M. (2008)
Characterisation of Materials Planned for Use
in the Closure of BRDA1 II. Nutrient Assessment
and Constraints to Plant Growth. Report
No. CLR 08 04 C. Centre for Land
Rehabilitation, University of Western
Australia.
