|Title||Changes in ecosystem structure and function along a chronosequence of restored grasslands|
|Publication Type||Journal Article|
|Year of Publication||2002|
|Authors||Baer, SG, Kitchen, DJ, Blair, JM, Rice, CW|
|Keywords||ecosystem, function, grassland, structure|
Changes in aboveground vegetation, roots, and soil characteristics were examined from a 12-yr chronosequence of formerly cultivated fields restored to native C4 grasses through the Conservation Reserve Program (CRP). Following 6–8 yr in the CRP, the native grasses dominated vegetation composition, and the presence of forbs was negligible. Productivity of the restored grasslands did not exhibit any directional changes with the number of years in the CRP, and productivity was generally higher than native prairie in this region. Over time, the restored grasslands accumulated root biomass of decreasing quality as indicated by increasing root biomass and C:N ratio of roots along the 12-yr chronosequence. Root biomass, root C:N ratio, C storage in roots, and N storage in roots of restored grasslands approached that of native tallgrass prairie within the 12 yr of restoration. Establishment of the perennial vegetation also affected soil physical, chemical, and biological characteristics. Soil bulk density in the surface 10 cm decreased with time since restoration. Total C, microbial biomass C, and C mineralization rates increased as a function of time since restoration. The greatest change in total C occurred in the surface 5 cm, where total C was 26% greater in 12- vs. 2-yr restored grasslands. Extractable soil nitrate and soil N transformations (i.e., net N mineralization rates and net nitrification rates) declined over the restoration chronosequence, but these values were not representative of steady-state conditions due to the high variability in these measures among the native prairies. Although complete restoration of ecosystem structure and function was not the primary intention of the CRP, this study demonstrates that establishment of the matrix vegetation (i.e., native C4 grasses) drives ecosystem processes in the trajectory of the original system. Moreover, restoration may hasten the recovery of soil C pools relative to formerly cultivated systems undergoing natural succession.