Control of Bracken and the Restoration of Heathland. I. Control of Bracken

Abstract

1. This paper examines the effectiveness of a range of bracken control and heathland restoration treatments on bracken performance and the redevelopment of heath vegetation over a 10-year period on a Callunaand a grass-heath in Breckland. Initial treatments were a combination of cutting and spraying with asulam, with and without sowing seeds of heathland species. After 6 years a further two treatments were added, with the bracken control treatments being either continued/reapplied or discontinued. 2. No treatment eradicated bracken completely, although all had some control. Asulam was the most effective treatment in the 2 years after treatment, but bracken recovered rapidly thereafter. Yearly cutting reduced bracken fronds by 70%, and cutting twice yearly by >90%. 3. After cutting was stopped, bracken recovered rapidly on plots cut yearly, but more slowly where it was cut twice-yearly. Reapplication of asulam produced a similar response to the initial application, with a rapid decrease followed by recovery. 4. Heathland at the Calluna site took 6 years to reach maximum biomass levels, and seeding had no effect on biomass. On the grass heath, vegetation developed much faster on the seeded plots where bracken was also controlled. At both sites cutting appeared to accelerate vegetation establishment probably because of litter disturbance. 5. At the grass heath, vegetation development suppressed bracken recovery 5-6 years after treatment started, when there was a maximum difference in grass biomass between unseeded and seeded plots. 6. The relevance of these results to both conservation management and the assessment of bracken distribution and encroachment are discussed.