Comparing Spatial Heterogeneity of Bioavailable Nutrients and Soil Respiration in Boreal Sites Recovering From Natural and Anthropogenic Disturbance
Dietrich, S. T. and M.D. MaKenzie. 2018.
Abstract
he mining of oil sands in Alberta, Canada is a large-scale disturbance that requires land
reclamation to equivalent land capability. Cover soils used for upland forest reclamation
are forest floor mineral-mix (FFM) sourced from upland forest ecosystems and peat
mineral-mix (PM) sourced from lowland ecosystems. Spatial heterogeneity and quantity
of soil resources, especially nutrient bioavailability, is important because it affects the
establishment of native vegetation in forest ecosystems and soil respiration is an indicator
for overall soil biologic activity. We studied spatial heterogeneity of soil nutrients as well
as seasonal and spatial patterns of soil respiration in two sites reclaimed either with
FFM or PM and two reference sites recovering either from harvest or fire. Contrary to our
initial hypothesis, we identified spatial heterogeneity in some bioavailable nutrients in FFM
and PM cover soil, indicating that standard placement processes can recreate spatial
heterogeneity. However, some nutrients such as P, K and S showed no heterogeneity
in PM at all. P and K availability was significantly lower and S was significantly higher in
PM than in FFM and reference sites. Seasonal pattern of respiration showed variability
on natural reference sites and on FFM, indicating that disturbance had not removed
belowground function completely. PM reclaimed sites showed no strong seasonal
respiration patterns indicating homogeneous belowground function. Surprisingly PM
treatments were not characterized by highest rates of soil respiration, while having highest
amounts of total organic carbon. We conclude that FFM reclaimed sites may be more
successfully reclaimed than PM sites because they are more similar to reference sites in
terms of nutrient status and seasonal respiration patterns.
Key Words
spatial heterogeneity, boreal, land reclamation, nutrient bioavailability, soil respiration
