Streamside management zones (SMZs) are special landscape units that include riparian areas and adjacent lands that mitigate the movement of sediment, nutrients, and other chemicals from upland forest and agricultural management areas into streams. The size, shape, and management of SMZs are governed by various combinations of economic, ecological, and regulatory factors. SMZs used around the world have a wide range of widths, but in many cases they are between 5 and 20 meters.
Streamside management zones are important barriers or buffer areas that protect water resources from non-point source pollution. Vegetation and the geomorphic characteristics of SMZs result in infiltration, filtering, and deposition from sediment- and nutrient-laden water flowing off intensively managed forestry, agriculture, and urban lands. Their effectiveness at trapping sediment depends upon the velocity of water flow, size of sediments, slope and length of slope above the SMZ, slope and length of the SMZ itself, depth of water flow into the SMZ, and vegetation characteristics such as type, density, and height. Nutrient removal is a function of SMZ width, runoff water residence time in the SMZ, the abundance and type of SMZ vegetation, and the amount of runoff water infiltrating into the soil.
Streamside management zones provide a number of important functions in ecosystems. These include water quality protection, streamflow maintenance, geomorphic stability, flora and fauna habitat, and social and economic benefits. While the protection of water quality is highly valued, SMZs in an agricultural and forestry landscape provide important socio-economic functions which are important for their incorporation as a best management practice.
The social and economic benefits of forested SMZs in agroforestry landscapes have also been recognized. Some of the key functions are:
Neary, D.G., P.J. Smethurst, B.R. Baillie, and K.C. Petrone. 2011. Water quality, biodiversity and codes of practice in relation to harvesting forest plantations in streamside management zones. Commonwealth Scientific and Industrial Research Organisation (CSIRO), National Research Flagships, Sustainable Agriculture, Clayton South, Victoria, Australia. 101 p.
Neary, D.G., P.J. Smethurst, B.R. Baillie, K.C. Petrone, W.E. Cotching, and C.C. Baillie. 2010. Does tree harvesting in streamside management zones adversely affect stream turbidity? —preliminary observations from an Australian case study. Journal of Soils and Sediments 10(4):652-670.
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