Accounting for Nature: Assessing habitats in the UK countryside
7.   Rivers, Streams and Standing Waters

Conclusions

7.38 For the Standing Waters Broad Habitat the results from CS2000 indicate a small, 6%, net increase in lowland ponds between 1990 and 1998 in England, Wales and Scotland. This reverses the losses observed in 1980s. Biological condition of standing waters was not assessed.

7.39 There have been significant improvements in the biological condition of Rivers and Streams and the habitat quality of their corridors in England and Wales, and in Scotland. These changes are consistent with some of the key BAP objectives for this Broad Habitat (Box 7.1), most notably, the goal of reducing nutrient enrichment.

7.40 A general improvement in the biological condition of Rivers and Streams as measured by macro-invertebrates has coincided with reduced inputs of pollutants into the waters following tighter regulation and more rigorous enforcement¹² . At the same time, in England and Wales, the Environment Agency’s strategy has been to encourage separate forms of management for river corridors, which are designed to be beneficial in several ways, including improvements in water quality¹³ . Thus it is possible that this policy has contributed to the general improvement of the biological condition of the CS2000 sites.

7.41 These gains within the freshwater environment must, however, be set against evidence for a decline in the ecological quality of streamside vegetation. During the 1990s, there has been an increase in tall growing, common grasses and herbs and an increase in woody species at the expense of lower growing stress-tolerating plants that are also declining elsewhere in the landscape.

7.42 The reduction in vegetation species richness and increase in woody plant species along the sides of streams probably results from less intensive or different forms of land management. This change in vegetation may be beneficial for birds and small mammals and for the biological condition of streams and rivers. At the same time the frequency of some plants typical of infertile grassland habitats that are found along streamsides may also be declining.

7.43 Thus, while the changes recorded in biological condition of Rivers and Streams are concordant with BAP objectives, the extent to which the changes in vegetation indicate the ‘appropriate management’ of adjacent land along streamsides must be considered carefully. The results of CS2000 suggest that further management strategies may need to be developed to ensure that the plant and animal diversity of streams, rivers and their banks is maintained.

12 Environment Agency (1997) The quality of rivers and canals in England and Wales 1995. Environment Agency, Bristol: 35pp.
13 Environment Agency (1996) Understanding buffer strips. An information booklet. Environment Agency, Bristol: 12pp.