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Providing evidence to improve practice

Action: Cut to control bracken Shrubland and Heathland Conservation

Key messages

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Supporting evidence from individual studies

1 

A randomized, controlled study in 1978–1990 in a heathland in Suffolk, UK (Lowday & Marrs 1992) found that annual cutting of bracken Pteridium aquilinum increased the biomass of heather Calluna vulgaris and reduced the biomass of bracken  after 12 years. In two of seven years heather biomass was higher in areas that had been cut than in areas that were not cut (data presented in log units), but heather biomass was not significantly higher in the remaining five years. In six of seven years bracken biomass was 14–99% lower in areas where bracken had been cut, than in areas that were not cut. In 1978 twelve 18 m2 plots were established. In four plots bracken was cut annually in 1978–1990, in four plots bracken was cut twice a year in 1978–1990, and in four plots bracken was not cut. Vegetation cover was assessed every year in three 1 m2 plots which were randomly located in each plot. Vegetation was cut in 20 cm x 20 cm areas in each quadrat and dried to calculate biomass.

2 

A randomized, replicated, controlled study in 1978–1996 in heathland invaded by bracken Pteridium aquilinum in Suffolk, UK (Marrs et al. 1998) found that repeatedly cutting bracken did not increase heather Calluna vulgaris cover, but did increase cover of wavy hair-grass Deschampsia flexuosa and sheep’s fescue Festuca ovina. After 10 years and in one of four cases, areas where bracken was cut had higher cover of heather (38%) than where bracken was not cut (0%), but after 18 years heather cover in cut plots was 0%. Cover of wavy-hair grass and sheep’s fescue was higher in two of four cases after 18 years where bracken was cut (wavy hair-grass: 30%; sheep’s fescue: 17%) than where it was not (wavy hair-grass: 0%; sheep’s fescue: 0%). In 1978 twelve 70 m2 plots were established. Between 1978 and 1996 bracken was cut once a year in four plots, twice a year in four plots, and four other plots were never cut. Vegetation cover in plots was surveyed annually using three quadrats in each plot in 1978–1996.

3 

A randomized, replicated, controlled, paired study in 1993-1995 at a heathland site in Suffolk, UK (Paterson et al. 2000) found that cutting to control bracken Pteridium aquilinum had mixed effects on bracken cover and wavy-hair grass Deschampsia flexuosa, but no significant effect on the cover of six other plant species. In three of four cases bracken cover in areas that were cut (16-47%) was lower than in areas that were not cut (89-93%), in one case there was no difference in bracken cover (cut:85%, uncut 89-93%). In one of four cases cover of wavy-hair grass was higher in areas that were cut (18%) than in areas that were not cut (0%), but in three of four cases there was no significant difference in wavy-hair grass cover (cut: 0-10%, uncut 0-4%). The cover of the following plants did not differ significantly in cut and uncut areas: common heather Calluna vulgaris (cut: 0%, uncut: 0%), sedge species Carex spp. (cut: 0%, uncut: 1-7%), sheep’s fescue Festuca ovina (cut:0-15% , uncut: 0-5%), Yorkshire fog Holcus lanatus (cut: 0%, uncut: 0%), sheep’s sorrel Rumex acetosella (cut: 0-7%, uncut:3-5%), and woodland ragwort Senecio sylvaticus (cut: 0%, uncut: 0%). In 1993-1995 three 8 x 8m plots were cut one a year, three plots were cut twice a year, and three plots were not cut. In July 1994 and 1995 plant cover was assessed in two 1 m2 quadrats placed in each plot.

4 

A randomized, replicated, controlled, before-and-after, paired study in 2005–2013 in a site dominated by bracken Pteridium aquilinum in the UK (Milligan et al. 2016) found that cutting decreased bracken cover, had no effect on the number of plant species, and increased plant diversity. In plots that were cut bracken cover declined over eight years (before: 26–27%, after: 2%) while in plots where bracken was not cut bracken cover increased (before: 24%, after 75%). There was no difference in the number of plant species found in plots that had been cut and those that were not cut. Over eight years in plots where bracken was cut plant diversity increased, while in uncut plots it declined (data presented as Shannon-Weiner index). In 2005–2012 three 20 x 20 m plots were cut twice a year, three plots were cut twice a year, and three plots were not cut. All plots were paired such that they were located next to the different treatments. In 2005–2013 plant cover was assessed by eye in five 1 m2 quadrats which were randomly located in each plot.

5 

A randomized, controlled, before-and-after trial in 1997-2001 in a heathland invaded by bracken Pteridium aquilinum in Norway (Maren et al. 2008) found that repeatedly cutting bracken increased the heather cover and reduced bracken cover. Cutting bracken increased heather cover from 3–5% before cutting to 14–26% four years after cutting started, while heather cover in uncut plots was approximately 1% for all four years of the experiment. Cutting reduced bracken cover from 75–76% before cutting to 2–17% four years after cutting started, while bracken cover in uncut plots remained above 75% during the four years of the experiment. Twelve 25 m2 plots were randomly allocated to be cut either once a year, twice a year or were left uncut. In plots which were cut bracken was cut to a length of 20–30 cm in July. Three 0.25 m2 quadrats were placed in each plot and used to monitor vegetation cover annually.

6 

A replicated, randomized, controlled study in 1993–2003 in four heathland sites in Cannock and the Peak District, UK (Alday et al. 2013) found that cutting of bracken Pteridium aquilinum increased heathland species richness and moved heathland species composition towards pre-invasion conditions. In both plots where bracken was cut once and twice per year, species richness was higher ten years after cutting (bracken cut once a year: 6.5–9.8; bracken cut twice a year: 6.8–10.1) than one year after cutting (bracken cut once a year: 4.3–6.2; bracken cut twice a year: 3.7–6.7). However, over the same period species richness decreased in uncut plots (one year after: 3.2–4.9; 10 years after: 2.6–3.9) (data presented as model results). Ten years after treatment, species composition in plots where bracken was cut was significantly different from uncut plots and closer to pre-invasion conditions (data presented as ordination results). Between four and twelve plots measuring 10 x 12 m, 10 x 5 m and 6 x 5 m were selected and bracken was cut once a year in June in three of four sites, and twice a year (June and August) in all four. Vegetation was monitored annually in June using 1 x 1 m quadrats.

7 

A controlled study in a heathland in 2002–2007 in the United Kingdom (Brook et al. 2007) found that using cutting to control bracken Pteridium aquilinum did not increase the abundance of gorse Ulex europaeus or of common cow-wheat Melampyrum pratense or decrease the abundance of bracken. After five years, gorse cover was not significantly different in areas where bracken had been cut (26%) compared to where it had not been cut (21%). The abundance of common cow-wheat and bracken in areas where bracken had been cut (cow-wheat: 3 plants/quadrat; bracken: 12 bracken stems/quadrat) was not significantly different to that where bracken had not been cut (cow-wheat: 0.4 plants/quadrat; bracken: 7 bracken stems/quadrat). In 2002–2005 bracken was cut in six 40 m x 20 m plots with a further six plots remaining uncut. Abundance and cover of plants was recorded every year in thirty 1 m2 quadrats randomly placed in each plot.

8 

A replicated, randomized, controlled, paired study in 1992-1995 in a former heathland invaded by bracken Pteridium aquilinum in the Wirral, UK (Snow & Marrs 1997) found that cutting to reduce the cover of bracken did not increase the number of common heather Calluna vulgaris seedlings relative to spraying with herbicide. In eight of eight cases plots that were cut did not have a significantly higher number of common heather seedlings than plots that were sprayed with herbicide (cut: 1-76 seedlings/m2, herbicide: 8-20 seedlings/m2). Three 15 x 5 m plots were cut once a year, three plots were cut twice a year, and three plots were sprayed with the herbicide asulam. Cover of plants was assessed in three 1m2 quadrats in each plot in September 1993 and June 1994.

Referenced papers

Please cite as:

Martin P.A., Rocha R., Smith R.K. & Sutherland W.J. (2018) Shrubland and Heathland Conservation. Pages 447-494 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2018. Open Book Publishers, Cambridge, UK.