Soils As an Integrator of Wetland Structure and Function Following Restoration.

Soil properties often are used to infer the development of plant, animal and microbial communities and processes following creation and restoration of wetlands.  As heterotrophic, detritus-based ecosystems, wetlands rely on inputs of organic matter that enrich the soil and sustain food webs and microbial processes. Using data from freshwater and estuarine wetlands, I demonstrate that soil organic matter (SOM) is key to the development of healthy foods webs and essential biogeochemical processes – decomposition, carbon sequestration and denitrification.  Healthy food webs require a threshold SOM concentration (2-4%), thickness of the SOM-enriched layer, (5-10 cm), and SOM stock (1-2 kg/m²) to sustain the faunal community. Microbial processes, decomposition – CO₂, CH₄ production - and denitrification, respond linearly to increasing SOM.  Wetlands with the highest SOM (8-10%) exhibit the greatest microbial activity.  Increasing SOM also leads to reduced bulk density and increasing porosity over time, improving air and water movement through soil.  While surface SOM pools, essential for vigorous wetland structure and function, achieve equivalence to reference wetlands within 10 to 20 years, subsurface SOM stocks, which are less important for wetland food webs but not necessarily for biogeochemical processes, require considerably longer to develop.