Recovery of reclaimed soil structure and function in relation to plant community composition

Abstract

Recovery of belowground properties, such as soil aggregation and microbial community composition, in relation to aboveground plant community characteristics is important for determination of reclamation success. The objectives of our research were: (1) to track ecosystem recovery based on soil aggregation and microbial biomass in different reclaimed soils (sandy loam and clay loam) and under different plant communities (shrub and cool season grass) through time and (2) to find relationships among aboveground plant composition, soil aggregate size distribution and microbial biomass. We hypothesized that the belowground properties of soil aggregation and microbial communities will recover simultaneously through time and will be highly related to the aboveground plant community composition. Aggregate size distribution did not show any patterns in the sandy loam soils underlying shrub communities; however did show progress towards a native condition in the clay loam soils underlying the cool season grass communities. Soil microorganisms showed recovery after 5 years (29.6 × 10 3 area) in soil underlying shrub communities and after 14 years (22.0 × 10 3 area) in soils underlying cool season grass communities. Macroaggregates were related to bacteria (r = 0.40) and fungal (r = -0.31) biomass under cool season grasses. Microaggregates were correlated with bacteria biomass under both shrub (r = -0.26) and cool season grass (r = -0.40) communities and also to living fungal biomass (r = -0.39) in the shrub soils. Microaggregation, fungal and actinomycete biomass were correlated in native cool season grasses (r = -0.25, 0.66 and -0.47, respectively) and annual forbs (r = 0.52, -0.75 and 0.49, respectively) in shrub community soils. Macroaggregates, microaggregates and bacteria were related to native cool season grasses (r = -0.61, 0.56 and -0.39, respectively), annual grasses (r = 0.69, 0.71 and 0.37, respectively) and annual forbs (r = 0.69, -0.40 and 0.41, respectively). The ability to track aggregate and microbial changes through time as well as find relationships amongst ecosystem variables leads to better reclamation techniques and success.