Recreating a Functioning Forest Soil in Reclaimed Oil Sands in Northern Alberta: An Approach for Measuring Success in Ecological Restoration
Rowland, S.M., Prescott, C.E., Grayston, S.J., Quideau, S.A. and Bradfield., G.E. 2009. Journal of Environmental Quality 38: 1580-1590
Abstract
During oil-sands mining all vegetation, soil, overburden,
and oil sand is removed, leaving pits several kilometers wide
and up to 100 m deep. Th ese pits are reclaimed through a
variety of treatments using subsoil or a mixed peat-mineral soil
cap. Using nonmetric multidimensional scaling and cluster
analysis of measurements of ecosystem function, reclamation
treatments of several age classes were compared with a range
of natural forest ecotypes to discover which treatments had
created ecosystems similar to natural forest ecotypes and at
what age this occurred. Ecosystem function was estimated
from bioavailable nutrients, plant community composition,
litter decomposition rate, and development of a surface organic
layer. On the reclamation treatments, availability of nitrate,
calcium, magnesium, and sulfur were generally higher than in
the natural forest ecotypes, while ammonium, P, K, and Mn
were generally lower. Reclamation treatments tended to have
more bare ground, grasses, and forbs but less moss, lichen,
shrubs, trees, or woody debris than natural forests. Rates of
litter decomposition were lower on all reclamation treatments.
Development of an organic layer appeared to be facilitated
by the presence of shrubs. With repeated applications of
fertilizers, measured variables for the peat-mineral amendments
fell within the range of natural variability at about 20 yr. An
intermediate subsoil layer reduced the need for fertilizer and
conditions resembling natural forests were reached about 15 yr
after a single fertilizer application. Treatments over tailings sand
receiving only one application of fertilizer appeared to be on a
different trajectory to a novel ecosystem.
