Portal de Periódicos da CAPES

The Effect of Natural and Artificial Shade on the Macrophytes of Lowland Streams and the Use of Shade as a Management Technique

1979; Wiley; Volume: 64; Issue: 4 Linguagem: Inglês

10.1002/iroh.19790640402

0020-9309

F.H. Dawson, Ulrich Kern-Hansen,

Hydrology and Sediment Transport Processes

Abstract The reduction of the biomass of three main problem species of submerged aquatic macrophytes was proportional to the light at the stream surface both under artificially shaded sections of stream and in naturally shaded areas when compared to the biomass in adjacent open and unshaded sections of stream. The effect of marginal vegetation in varying the shading effect given to streams of differing width and orientation are described. It is recommended that light should be reduced to about half that presently available in the open, by shading from marginal vegetation but it is warned that too much shade is detrimental to the fish populations of the stream and leads to accentuated local accumulations of leaves. The long term effects are considered but it is expected that partial shading will increase the diversity of submerged plant species. It is suggested that the practice of stream realignment is discontinued and that the natural tendency of streams to create their own meandering channels is allowed but within some defined and generally acceptable framework.