Ecosystem restoration - Water quality changes from riparian buffer restoration in Connecticut

One-half of a 35- by 250-m riparian buffer cropped in corn (Zea mays L.) was seeded with fine leaf fescue (Festuca spp.) and allowed to remain idle to determine water quality changes resulting from riparian buffer restoration. A corn control was also used in this paired watershed design located in Connecticut. Water, N, and P fluxes were determined for precipitation, overland now, and ground water. Also, an N mass balance was calculated. Total Kjeldahl nitrogen (TKN) and total phosphorus (TP) concentrations significantly (P < 0.05) increased as ground water flowed through the restored buffer. Nitrate N (NO3-N) concentrations declined significantly but most (52%) of the decrease occurred within a 2.5-m wetland adjacent to the stream. An N mass balance for the 2.5-m strip indicated that denitrification only accounted for 1% of the N losses and plant uptake was from 7 to 13% of the N losses annually. Ground water was the dominant source of N to the buffer and also the dominant loss. Restoration of the riparian buffer decreased (p < 0.05) overland flow concentrations of TKN by 70%, NO3-N by 83%, TP by 73%, and total suspended solids (TSS) by 92% as compared with the control. Restoration reduced (p < 0.05) NO3-N concentrations in ground water by 35% as compared with the control. Underestimated denitrification and dilution by upwelling ground water in the wetland area adjacent to the stream were believed to be primarily responsible for the decreasing NO3-N concentrations observed.