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Title: LONG-TERM PHYSICAL AND BIOLOGICAL CHANGES TO THEREE ALTERED ALABAMA BLACK BELT STREAMS AND surrounding RIPARIAN AREAS

Author
item McIntyre, Sherwood
item ANKUMAH, RAMBLE - TUSKEGEE UNIVERSITY
item HULUKA, GOBENA - AUBURN UNIVERSITY

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/10/2005
Publication Date: 10/1/2007
Citation: McIntyre, S.C., Ankumah, R.O., Huluka, G. 2007. Long-term physical and biological changes to three altered Alabama black belt streams and surrounding riparian areas. In: N.O. Tackie, R. Zabawa, N. Bharanyi, W. Hill, editors. Proceedings of the 63rd Annual Professional Agricultural Workers Conference, December 4-6, 2005, Tuskegee, Alabama. p.194-207.

Interpretive Summary: Riparian areas including the streams within them provide many important environmental functions including sediment trapping, nutrient cycling and water storage. Agricultural activities have often adversely affected the functioning of riparian areas so the long-term effect of agricultural alteration of three Alabama Black Belt riparian sites were investigated over a four-year period. Each riparian study site had an intermittent stream flowing through permanent pasture and an adjoining forested area. The stream channel in the pasture at each site had been straightened or relocated more than thirty years prior to the study. Physical effects of alteration were investigated by measuring stream features and the most important effect was more than a fifty percent reduction in the stream area occupied by riffles in altered stream reaches. Stream water quality was not found to vary appreciably between pasture and forested reaches with combined nitrate and nitrite nitrogen levels being low at all sites. Biological effects were investigated by collecting aquatic insects that are sensitive to environmental alterations. Study results did not indicate any real differences between insects present in forested and pasture stream reaches and the insects present were indicative of fair water quality. The study sites were evaluated using the Riparian Channel and Environmental Inventory for environmental condition and level of needed conservation management. Forested riparian areas were found to be in very good condition while the pasture riparian areas were either in good or fair condition. Agricultural alteration of riparian areas was found to cause long lasting adverse effects to study sites and conservation management that would increase wooded riparian areas along pasture stream reaches would provide the greatest benefit.

Technical Abstract: Riparian areas including the streams within them provide many vital environmental functions that have often been adversely affected by agricultural activities. Long-term effects of agricultural alteration of three Alabama Black Belt riparian sites were investigated over a four-year period. Each riparian study site had an intermittent stream flowing through permanent pasture and an adjoining forested area. The stream channel in the pasture at each site had been straightened or relocated more than thirty years prior to the study. Physical effects of alteration were investigated by stream morphology measurements that indicated a significant difference between stream riffles in pasture and unaltered stream reaches with riffles occupying zero, 6 and 23 percent of pasture stream reaches compared to 13, 20 and 48 percent of unaltered reaches. Water quality measurements indicated stream water temperature, dissolved oxygen, pH, conductivity and turbidity did not vary significantly between forested and pasture reaches and the combined nitrate and nitrite nitrogen levels were low (< 1 mg/L) in all stream and runoff water. Biological effects were investigated by collecting benthic macroinvertebrates to determine family-level biotic indexes which were 5.51, 6.26 and 6.75 for forested stream reaches and 5.59, 6.08 and 7.1 for pasture stream reaches. Biotic indexes indicated fair water quality for all stream reaches. The Riparian Channel and Environmental Inventory was used to determine condition of study sites and level of management needed for each study reach. Inventory scores of 236, 245 and 290 indicated the three forested riparian areas were in very good condition. One pasture riparian area had a score of 171 indicating good condition while the other two pasture riparian areas had scores of 87 and 113 indicating fair condition. Alteration of riparian areas has caused long lasting adverse effects to study sites and conservation management that would increase wooded riparian areas along pasture stream reaches would provide the greatest benefit.