Control of bracken and the restoration of heathland. IV. Effects of bracken control and heathland restoration treatments on nutrient distribution and soil chemistry.
Field trials were conducted on Calluna and grassland heaths in the UK (Cavenham and Weeting Heaths, resp.) to compare bracken [Pteridium aquilinum] control treatments (cutting annually in late July or twice/year in mid-June and late July, and the application of asulam), followed by seeding with Calluna at Cavenham and with Holcus lanatus, Festuca spp., Lotus corniculatus and Rumex acetosella at Weeting. The most successful treatment was cutting bracken twice yearly for at least 10 years, which reduced frond-bearing rhizomes to 2-4% and storage rhizomes to 8-11% of untreated levels. There were differences in the amounts of nutrients found in the bracken rhizomes and litter in the untreated plots at the 2 study sites. The max. potential flux of nutrients to the soil was lower for some elements in plots with max. heath development or bracken recovery, but for other elements no significant effects were found. There were a few significant differences in soil chemical properties between the different management treatments, but they were difficult to interpret. There was no evidence of any reduction in soil chemical properties in these plots where Calluna heath and grassland had re-established.