Two persistent problems face land reclamation in the Athabasca oil sands region; how to build functioning soil profiles from materials salvaged during mining and how to measure that functionality meaningfully. There is a limited supply of suitable topsoil materials as well as clean subsoil materials for use in reclamation. Furthermore, some of the topsoil available is from drastically different ecosystems than the targets of reclamation. Much of the affected landscape is being converted to upland forest ecosystems; however, the soil is being salvaged from wetlands. The other problem is how to determine if reclamation soil prescriptions have restored an appropriate level of ecosystem function when there are no accepted thresholds. Attempts have been made to use criteria and indicator systems from forestry, but these breakdown when soils have been disturbed and whole communities need to be recovered. We propose to test a functional similarity index derived from soil and foliar nutrient pools and compared to an ecosystem recovering from wildfire.
Results/Conclusions
We evaluated the similarity of forest floor-mineral mix (FFM) and peat-mineral mix (PM) as topsoil, as well as the effect of different depths of salvaged B and C horizon subsoil with PM on top. All reclamation treatments were planted with jack pine (Pinus banksiana) and trembling aspen (Populus tremuloides) which were used to examine foliar nutrient concentrations. Individual macronutrient concentrations were different among treatments in the total soil nutrient pool, but differences decreased in the soil bioavailable pool and disappeared altogether in the foliar nutrient pool. The similarity index revealed that distinct differences existed between treatments, with FFM being the most similar to the wildfire site. It also revealed a potential deficiency in foliar and soil bioavailable Mn on PM, and that increased water content of deeper sub-soils had little to no effect. With use of this functional similarity index, reclamation practitioners might be able to determine if different soil prescriptions lead to higher levels of similarity more quickly.