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Bracken management in the uplands |
Home > Our work > Farming > Advice for farmers > Managing farmland for wildlife > Managing farmland for wildlife > Bracken management in the uplands > Managing bracken
Managing brackenRemoving bracken encourages primary habitats to re-establish, which are of greater importance for wildlife. Bracken controlControlling bracken is a long-term and often expensive undertaking and specialist advice should be sought. The expense of large-scale management is often beyond most individuals and needs collaboration of individuals and organisations. Develop a long-term bracken control programme following expert advice Where a small-scale approach is adopted, annual ongoing management is required to prevent rapid recolonisation. Identify key target areas, and tackle these first. Targeting the leading edge of bracken stands may slow down colonisation into bracken free areas. These should be identified and mapped by surveying bracken distribution in July to October when bracken is most visible. The peak time to control bracken may coincide with other wildlife activity, especially nesting birds and their unfledged young, and deer fawns. When planning to manage an area, survey it first for evidence of any breeding activity by birds and other wildlife and avoid disrupting them. Where bracken cover encourages the growth of violet species, consider the potential occurrence of the high brown fritillary. This butterfly is a rare species in the UK and bracken control may be detrimental. Methods of bracken controlThough cutting and rolling both reduce bracken vigour and encourage recovery of vegetation, they do not provide full control. Alternative methods are needed to achieve this. Cutting regimesCutting is most effective when bracken is at, or near, full frond. This is even more efficient if bracken is cut twice in the same growing season. In many upland areas slow growth may mean two cuts is not possible. In this case a single cut, close to the ground, in mid late July can increase the potential for early frost damage to regenerating bracken and surface rhizomes. Annual cutting will need to be repeated until thebracken disappears, which can take in excess of 10 years in well established stands. Cutting once will produce an even stand with more active buds, which may increase the effectiveness of chemical treatment in the following year. Where ground-nesting birds are present, cutting should be avoided during May July. Leave those areas until last or avoid until after any nests have become inactive. The period to wait is likely to be only a matter of days or a couple of weeks. If in doubt seek specialist advice. The use of rollingIf cutting is not possible, consider rolling the bracken. The timing is the same as for cutting. There are a number of small machines on the market designed specifically for this type of work, which can be towed behind tractors or 4x4 vehicles. Rolling does not cut off the stems but leaves them attached to the root to bleed the sap, this reduces food energy for bud development in the following year. Each rolling operation can reduce shoots by about one third, reducing a dense stand of bracken into more scattered fronds. Rolling for three consecutive years has been shown to be more effective than carrying out a one-off operation. Even so, bracken control will need to continue for more than three years to avoid recolonisation. Grazing regimesTemporary mob stocking, particularly using cattle, horses or ponies in May and June, may crush emerging bracken fronds resulting in reduced bracken cover. Sufficient fodder will be required to prevent livestock eating the bracken. Mob stocking can damage vegetation beneath the bracken canopy. It can also lead to nutrient enrichment and damage bird nests. Where the management objective is to restore heather moorland, and other semi-natural vegetation communities, mob stocking is often inappropriate. Trampling also increases the rate of breakdown of dense bracken litter. Correct stocking levels can be critical to prevent bracken invasion. In the uplands overgrazing can reduce vegetation competition, which favours bracken spread. Herbicide treatmentHerbicide treatment is highly effective if a full programme of primary treatment and aftercare is undertaken. Asulam is a selective, systemic herbicide known to be effective against bracken, but thought to have only low toxicity. It can be applied either as a spot treatment to individual fronds, or by using a tractor or ATV mounted sprayer. In large scale bracken control programmes aerial spraying using helicopters is a valid and cost effective option. The systemic nature of Asulam means that for effective treatment it should only be applied to mature fronds ensuring maximum translocation to the underground rhizomes. Fronds are normally mature from mid July to the end of August. At this time most birds should have completed breeding and are not likely to be affected by herbicide application. Glyphosate can be used to spray dense areas of bracken with no understorey. Where stands are more open, and there is an issue of affecting non-target species of flora, consider the possibility of weedwiping or application with a hand lance. The statutory conditions of use on the product label must be adhered to when using any chemicals for bracken management. Other management considerationsAny bracken control programme must be completed, otherwise bracken will re-establish. The management of heather moorland often encourages the growth of bracken. Burning should not be undertaken in close proximity to existing stands of bracken. Bracken is carcinogenic to humans, and high numbers of sheep ticks associated with bracken can increase the likelihood of transmission of Lyme disease. |
Herd of cows, West Sedgemoor RSPB reserve - David Kjaer (rspb-images.com, Ref: D_2006_11413_0029)
Archie Carmichael (L, on tractor) & Gus Keys (R = site manager) in farm yard at Kinnabus. Mull of Oa RSPB reserve. Islay - Andy Hay (rspb-images.com, Ref: D_2005_9857_009)