Title: Effects of agriculture on wood breakdown and microbial biofilm respiration in southern Appalachian streams
Author: McTammany, M.E.; Benfield, E.F.; Webster, J.R.;
Source: Freshwater Biology, Vol. 53: 842-854
Publication Series: Miscellaneous Publication
Agriculture causes high sediment, nutrient and light input to streams, which may affect rates of ecosystem processes, such as organic matter decay. In the southern Appalachians, socioeconomic trends over the past 50 years have caused widespread abandonment of farmland with subsequent reforestation. Physical and chemical properties of streams in these reforested areas may be returning to pre-agriculture levels thereby creating the potential for recovery of ecosystem processes.
We examined wood breakdown and microbial activity on wood substrata in streams with different historical and current agricultural activity in their catchments. We analysed historical (1950) and recent (1998) forested land cover from large areas of the southern Appalachians and categorized streams based on percent forested land cover in these two time periods. Categories included a gradient of current agriculture from forested to heavily agricultural and reforestation from agriculture due to land abandonment. We compared microbial respiration on wood veneer substrata and breakdown of wood veneers among these land-use categories. We also compared temperature, sediment accumulation and nitrogen and phosphorus concentrations.
Streams with current agriculture had higher concentrations of dissolved inorganic nitrogen than forested streams. Despite reforestation from agriculture, nitrogen concentrations were also elevated in streams with agricultural histories relative to forested streams. Temperature was also higher in agricultural streams but appeared to recover from historical agriculture through reforestation and stream shading.
Keywords: agriculture, biofilm, decomposition, disturbance, organic matter
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McTammany, M.E.; Benfield, E.F.; Webster, J.R. 2008. Effects of agriculture on wood breakdown and microbial biofilm respiration in southern Appalachian streams. Freshwater Biology, Vol. 53: 842-854
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