Soil and plant response to wellsite rehabilitation on native prairie in southeastern Alberta, Canada

Rehabilitation of disturbed native prairie is a challenge facing many in the petroleum industry, with implications for prairie ecology and productivity. The purpose of this research was to examine the relative influence of four rehabilitation strategies on biogeochemical processes (i.e., nitrogen availability, plant uptake of nitrogen, biomass production, carbon allocation, and soil biological activity). Seven petroleum wellsites were selected on Chemozemic and Solonetzic soils in southeastern Alberta. Undisturbed native prairie was compared with four seeding treatments: not seeded, a low diversity seed mix commonly used by industry, a low diversity mix of species more typically dominant in native prairie, and a diverse seed mix. Flux of NO3- and NH4+ were measured in situ using ion exchange membranes. Soil total C and N were lower and available N higher as a result of disturbance. In the seeded treatments, biomass production was higher and soil nitrogen flux was lower due to higher plant uptake than in the unseeded treatment. Higher initial N availability favoured species with rapid growth and colonization rates, particularly Agropyron dasystachyum [(Hook.) Scribn.j and Agropyron trachycaulum [(Link) Malte]. Seed mix composition and species attributes were deemed to have greater influence on N cycling and biomass production than seed mix diversity.