Dynamics and management of plant communities in ditches bordering arable fenland in eastern England

• Published in: Agriculture, ecosystems & environment ecosystems & environment, 2004-06, Vol.103 (1), p.85-99
• Main Authors: Milsom, T.P., Sherwood, A.J., Rose, S.C., Town, S.J., Runham, S.R.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Aquatic plants; Biological and medical sciences; Conservation, protection and management of environment and wildlife; East Anglian Fens; Field margins; Fundamental and applied biological sciences. Psychology; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Riparian plants; Vegetation management
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2003.10.012

This study investigated plant communities in ditches bordering arable fields in the Fens of eastern England, and their response to bank mowing and dredging. The effects of mowing on species turnover were investigated by experiment. The first experiment compared the effects of four mowing frequencies (2×, 1× per year, 1 cut in alternate years, no cut). The number of emergent aquatic and riparian species decreased over 4 years but the magnitude of the decrease was negatively correlated with mowing frequency; it was greatest in the unmown plots. A second experiment compared two treatments (2× per year, 1 cut in alternate years) on a larger sample of ditches. Turnover of emergent aquatic and riparian species did not differ between the treatments but more floating and submerged species colonised ditches mown twice a year. The number of floating and submerged species per ditch tended to increase following dredging. The increase was greatest in ditches between 200 and 600 m from the main drain. Assemblages of floating and submerged plants in ditches 800 m from the main drain were species-poor and were not colonised after dredging. A dredging cycle of at least 3 years is necessary for the maintenance of diverse assemblages of floating and submerged aquatic species. The maintenance of diverse assemblages of emergent and riparian species on ditch banks relies on frequent mowing carried annually and no less than once every 2 years. Mowing regimes for floating and submerged species should incorporate an annual spring cut and be targeted at ditches within 600 m of main drains.