Wambo Coal AEMR 2011-2012 - Peabody Energy

Acacias such as these. Acacias are known as a “pioneer” species that germinate quickly
within disturbed areas and have a relatively short lifespan, which can improve conditions
(such as shade, wind protection, moister habitat) for other species to establish.
However, it is considered that many of the observed dead specimens of Acacia pendula
have succumbed to infestations of large numbers of Mistletoe.
Soil
The soil supporting the population of A. pendula is fine and clayey with a well
established crust that incorporates mosses and lichens. The initial inspection in June
2011 found that the crust was broken or absent in some small areas (usually less than
2m 2 ). These crustless areas are possibly due to past land management practises (such
as slashing) or disturbances from livestock or tree removal. No cracks larger than 5mm
wide and 20cm long were observed in the soil surface during the June 2011 (baseline)
inspection.
During the post-undermining inspection (December 2011) the soil surface was relatively
unchanged except for a small area (approximately 5m 2 ) which contained approximately
4 interconnected surface cracks that were a maximum of 1 cm wide and 150 cm long. It
is considered that these cracks may have been created by subsidence. As these cracks
are relatively small and located in a fine-grained crusted, clayey topsoil it is considered
that these cracks will most likely be self healing.
Drainage
The initial (June 2011) inspection took place on a day with significant rainfall. The
drainage throughout the A. pendula stand is via overland flow in the form of small
rivulets and pools. The slope of the area is approximately 1% with a northerly aspect.
The post undermining inspection in December 2011 was undertaken a few days after a
significant rainfall event. The drainage within the Acacia pendula area has not
significantly changed. There was evidence of the same types of small overland rivulets
and pools. No areas of retained surface water were observed during the post
undermining inspection. It is considered that the overland drainage within the Acacia
pendula conservation area is unchanged.
Conclusion
The stand of Acacia pendula (Weeping Myall) within the RWEA area is generally healthy
with respect to Age Classes, Recruitment, Health, Infestations and Senescence. The
stand shows the typical attributes of a dynamic population which is currently selfpropagating
and is likely to continue to do so provided no stochastic events impact upon
the area. There are large numbers of the parasitic mistletoe Amyema pendula present
on many of the Weeping Myall trees. In high numbers these mistletoes have a
detrimental effect on the Weeping Myall and have most likely caused the death of some
specimens.
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