Effects of ditch-blockage on adult Odonata at a coastal raised mire site in central West Wales, United Kingdom

In an attempt to halt the effects of drainage in peripheral areas of a coastal raised mire peatland system in central Wales, ditches were blocked with transverse dams. Dams created long linear pools, flooding the areas of most serious water-table draw-down and peat slumping resulting from the past drainage activity. As a consequence, the wildlife interest of the ditches has been considerable enhanced. The existence of high and stabilised water-tables in areas surrounding the ditching has eliminated non-peatland plant species established since water-table decline. The establishment of the long linear pools has led to increases in the numbers of adults of at least 6 odon. spp. and of breeding teal; overall numbers of insects were 2-43 times greater over blocked ditches than over undammed ditches.