The
Wangaloa coal mine closed in 1989, and an attempt to grow Pinus radiata
on quartz-rich overburden dumps was not successful. The site is currently
being rehabilitated with re-profiling and native plant establishment. Plants are
being established in a range of substrates that consist of variably
disaggregated Tertiary coal measure sediments derived from the mine sequence.
This material has low organic matter content (typically <10 %), originating>
from coal fines or carbonaceous sediment. Substrate samples were collected
during December 2003 from a range of sites varying in age, slope, and parent
material. Nutrient analysis includes nitrate, ammonia, total N, total P,
available P and readily exchangeable base cations. Total nitrogen and phosphorus
are low on areas of recently disturbed, quartz-rich overburden, with total N
1200 mg/kg, and
total P 200 mg/kg.
Background forested areas have total N ranging between 2800 - 3300 mg/kg and
total P of 420 - 500 mg/kg. Quartz-rich overburden sites contain available
nitrogen levels of less than 6 mg/kg, while background forested areas are
generally >20 mg/kg. The soils and water runoff are generally acid, with pH
down to three. Water samples have been collected from both ground and surface
resources on a monthly basis since December 2003. The main lake on the site had
pH of 4.6 in 1999, and this remained relatively unchanged when 850 tonnes of
lime were added in 2002. However, the lake pH changed to 6.4 within a one month
period in 2004, and has fluctuated since that time.