Structure and function of buffer strips from a water quality perspective in agricultural landscapes

Buffer strips can greatly improve the water quality of nearby agricultural streams by reducing nutrient leaching in groundwater and surface water runoff, even though they comprise little of the total catchment area. Hence, vegetated buffer zones located along streams and in the upland portions of the catchment can minimize erosion or trap sediments in surface runoff and thereby decrease phosphorus loading in surface water. For example, a buffer strip 10 m wide can reduce the phosphorus load, typically bound to sediment, by as much as 95%. Moreover, both natural and constructed riparian forests and wetlands may create conditions favorable for nitrogen transformation/removal by soil microbial processes such as denitrification, with as much as 100% of the nitrate being removed in these zones. In addition to nutrient removal, buffer strips will increase the diversity of flora and fauna in the otherwise monocultural landscape. The vegetation along the stream will also stabilize the stream banks and improve habitat for both fish and invertebrates within the stream.