Influence of restoration and succession on bottomland hardwood hydrology
The hydrologic pathways of four bottomland hardwood wetland sites were investigated with transects consisting of nests of shallow wells and piezometers. Sites included a disturbed but recently restored system, two disturbed systems that are recovering naturally and a relatively undisturbed reference site. Water table elevations in both uplands and bottomlands were significantly higher in the reference site than in disturbed sites. Hydrologic budgets were developed that included throughfall inputs, upland inputs, bottomland interflow, bottomland losses to the stream and evapotranspiration (ET) losses. The recently restored bottomland had significantly higher throughfall and lower ET than the naturally recovering sites. Higher throughfall and lower ET is attributed to canopy manipulations that occurred during restoration. Other hydrologic fluxes are relatively similar among the disturbed sites. Reference site flow pathways were significantly different than those of the disturbed sites. Higher ET in the reference site is attributed to differences in canopies between the reference and disturbed sites. Higher upland inputs, bottomland interflow, and bottomland losses to the stream are the result of higher water tables in the reference site. Lower water tables in disturbed sites may be caused by the geomorphic changes that occurred during elevated flow periods prior to recovery.