Effectiveness of vegetation barriers for marly sediment trapping

Vegetation barriers cm be effective in trapping eroded sediment, but little knowledge exists on the characteristics of vegetation barriers efficient in trapping all sediments from an eroded zone upslope. The objective of this study is to quantify the effectiveness of vegetation barriers for marly sediment trapping. Relationships between eroded zones and vegetation barriers - composed of low vegetation, that is to say herbaceous and under-shrub layers - located downslope and sufficient to stop all the sediments eroded above, have been studied in the Brusquet experimental marly catchment in the French southern Alps. Forty plots with surface areas less than 500 m(2) were studied. The eroded zones and the vegetation barriers were characterized by their surface areas, between which an average linear relationship exists. Results also showed that, for a marly plot with a given surface area, a downslope vegetation barrier covering only 20 per cent of this plot can be sufficient to trap all the sediments eroded above it. Copyright (C) 2004 John Wiley Sons, Ltd.