Evaluating foliar nutrient concentration as an indicator of soil nutrients in reclaimed and natural forests in Alberta, Canada

Abstract

ABSTRACT Foliar nutrient concentrations are commonly recommended as indicator for soil nutrient status in managed and wildland ecosystems. Using data from an oil sands mine reclamation site in Alberta, Canada, we evaluated whether trembling aspen (Populus tremuloides Michx.) foliar concentrations of macronutrients accurately represent soil solution and soil nutrient pools in both reclaimed and wildfire-impacted natural reference boreal forest ecosystems. Reclamation soils were upland-based forest soil (forest floor-mineral mix; FFMM) and lowland-based peat soil (peat-mineral mix; PMM) with and without fertilisation. Individual macronutrient concentrations differed among treatments in the soil nutrient pool, but differences decreased in the soil solution pool and disappeared in the foliar pool. Few significant correlations between foliar and belowground pools were observed, but foliar phosphorus was correlated to soil phosphorus in natural reference sites. Multivariate analyses showed reclaimed sites were different from reference sites across all nutrient pools. Again, few significant multivariate correlations between foliar and belowground nutrient pools were observed, except for the unfertilised forest floor-mineral mix site, where foliar nutrients were positively correlated with soil solution. Based on our findings, we suggest that trembling aspen foliar nutrient concentrations are not a consistently reliable indicator of soil and soil solution nutrients in reclaimed or natural ecosystems.