Impacts of different vegetation in riparian buffer strips on runoff and
sediment loss
Abstract
Buffer strips continue to feature in the management of agricultural
runoff and water pollution in many countries. Existing research has
explored their efficacy for reducing environmental problems in different
geoclimatic settings but, the evidence on the efficacy of different
vegetation treatments is less abundant than that for other buffer strip
characteristics, including width, and is more contradictory in nature.
With policy targets for various environmental outcomes including water
or air quality and net zero pointing to the need for conversion of
agricultural land, the need for robust experimental evidence on the
relative benefits of different vegetation types in buffer strips is now
renewed. Our experiment used a replicated plot scale facility to compare
the efficacy of 12 m wide buffer strips for controlling runoff and
suspended sediment loss during 30 sampled storms spanning 2017-2020. The
buffer strips comprised three vegetation treatments; a deep rooting
grass ( Festulolium cv. Prior), a short rotation coppice willow
and native broadleaved woodland trees. Over the duration of the
monitoring period, reductions in total runoff, compared with the
experimental control, were in the order: willow buffer strips (49%);
deciduous woodland buffer strips (46%); grass buffer strips (33%). The
corresponding reductions in suspended sediment loss, relative to the
experimental control, were ordered: willow buffer strips (44%)
> deciduous woodland buffer strips (30%) >
grass buffer strips (29%). Given the three-year duration of our new
dataset, our results should be seen as providing evidence on the impacts
during the establishment phase of the of the treatments.