An investigation of potential weed management practices and multivariate assessment parameters for Alberta's oil sands reclamation efforts
deBortoli, L.A. 2018.
Abstract
Reclamation efforts that promote the re-establishment of native tree and plant
communities subsequent of large-scale oil sands mining land disturbances are crucial in restoring
natural ecosystems. It is important that reclamation procedures capable of facilitating the
establishment of native species be identified and put into practice. The objective of the first study
was to determine plant community development and aspen seedling establishment in response to
different combinations of coversoil types and experimental plant establishment treatments on an
oil sands overburden waste area. Eighteen field plots, established in 2014, were re-monitored
annually to compare plant community development and trembling aspen seedling density on 3
coversoil types (forest floor-mineral mix [FFMM], transitional, peat-mineral mix [PMM]) with 4
plant establishment treatments (seeding native species, weeding undesirable weeds, seeding &
weeding, control). Coversoil type was found to be a dominant plant community driver, with
FFMM and transitional soils showing higher species richness, diversity, and total vegetation
cover than PMM, while PMM supported greater aspen seedling densities. Minimal weed
establishment on PMM coversoils resulted in weeding treatments having a lesser effect on plant
community development; however, trembling aspen seedling densities were found to have
increased. Weeding on FFMM and Transitional did not result in the significant increase of native
forb presence. Instead, the decrease in introduced weed species prompted an increase in
graminoid cover, particularly Calamagrostis canadensis on FFMM.
In addition to the refinement of reclamation procedures, we must work towards
developing an effective evaluation framework in order to track ecosystem recovery progress. To
date, no official standards, nor suitable criteria and indicators have been established to
thoroughly assess and certify reclamation sites. As such, the objective of the second study was to explore the use of multivariate datasets as parameters within a rudimentary ecosystem function
assessment framework. Natural reference soil samples and reclamation coversoil samples
corresponding to the aforementioned field plots were collected in 2016 following vegetation
surveys and in-field bioavailable nutrient profiling. Following a two week laboratory incubation
period, soil samples were used to determine microbial function via community level
physiological profiling (CLPP). Through the use of non-metric multidimensional scaling
ordination analyses, similarities and dissimilarities were determine for bioavailable nutrient
profiles, microbial function, and plant community composition parameters between coversoils
and natural soils. Ordination analyses were also completed to determine similarities between
weeding and control plots on coversoils. As with the first study, coversoils/soils were the
dominant drivers of dissimilarities, while weeding treatments did not significantly change
bioavailable nutrient profiles or microbial function. Overall, the use of multivariate analyses was
able to provide additional insight into the aboveground and belowground recovery on
reclamation sites, suggesting that this method of assessment, with further research, holds
potential.
