Belowground carbon and nitrogen dynamics following wet meadow restoration

Wet meadow systems in the Platte River valley consist of linear slough wetlands in a matrix of mesic prairie.  These systems have been degraded and diminished mostly by conversion to agricultural fields.  Restoration in this region typically involves ceasing cultivation followed by land contouring and seeding of natural vegetation.  Because belowground dynamics following restoration in these wetlands are virtually unknown, we measured recovery of root biomass, soil physical and chemical properties, and C and N pools in 6 restored slough wetlands (1-10 years old) and compared them with 3 proximal natural systems.  Root biomass increased linearly over the chronosequence by 135 g m^-2 yr^-1 (r² = 0.21, P = 0.055) and root storage of C and N also increased.  Root C:N ratios were similar across the chronosequence, indicating that root tissue quality did not change over the 10-year restoration interval.  Total soil C increased in the surface 10 cm by 160 g C m^-2 yr^-1 (r² = 0.48, P = 0.012), and slight increases in C mineralization rates were also evident.  Total soil N within the surface 10 cm also increased linearly with years restored by 8 g N m^-2 yr^-1 (r² = 0.25, P = 0.098).  Microbial biomass N increased in the surface 10 cm, although no clear patterns in recovery of net N mineralization rates were evident.  Although changes in belowground properties and processes were evident over time, restored wetlands remain structurally and functionally distinct from natural systems in the Platte River valley after 10 years of restoration.