Optimizing agri-environment schemes to improve river health and conservation value

• Conservation value increased with the proportion of woodland within 100 m or 500 m.
• Pollution and sedimentation measures decreased with high proportions of woodland.
• AES will be optimized by preserving woodland within 100–500 m along the river.

Freshwater ecosystems deliver services that are crucial to human existence and well-being, yet, globally, their degradation has outpaced remedial management. Rivers can be subjected to a range of anthropogenic pressures and agricultural land use is one major cause of water pollution and habitat degradation in European rivers. The Water Framework Directive is a major legislative driver for good ecological status in Europe's rivers and in the UK; this has led to attempts to reduce the negative effects of agriculture on rivers through agri-environment schemes (AES). AES are funded from tax revenue and it is important that they are optimized to deliver measurable ecological improvements. The purpose of this paper is to assess the ecological effectiveness of AES in a lowland English river basin. We examined the effect of distance from river in optimizing AES for the biological heath and conservation value of rivers.We used aquatic macroinvertebrates as indicators of river health and conservation value, to assess the effects of AES likely to improve river health (hereafter “AES river options”). This catchment in lowland England had a very high (over 80%) level of uptake of entry level AES, and facilitated a comparison between schemes that do or do not contain AES river options. The conservation value of macroinvertebrate communities and the proportion of macroinvertebrates intolerant of water pollution and sedimentation increased with high proportions of woodland within 100 m or 500 m of the river throughout the entire upstream catchment. High proportions of AES river options within the same distance were correlated with higher proportions of sediment-sensitive macroinvertebrates. We conclude that for improving biological quality or promoting the conservation value of river communities, AES will be optimized by preserving woodland within a 100–500 m buffer zone along the upstream length of the river.