The bracken problem in Great Britain: Its present extent and future changes

Diversity in the cork oak forests of the northern Straits of Gibraltar Region (Southern Spain)

“…4, mitigation of drought favours the extensive cover of Pteridium aquilinum, which is considered one of the most successful invasive plant species, common all over the world, except in very cold or dry conditions (Taylor 1990). It is mostly associated with human activities (Rymer 1976;Pakeman et al 1996). The presence of allelopathic substances (Gliessman 1976), the vegetative reproduction, the resistance of the rhizome to fire and adverse weather conditions, the high density of the frond canopy and the dense accumulations of litter, which may obstruct the establishment of other species (Fletcher and Kirkwood 1979;Page 1986;Lowday and Marrs 1992), make it highly competitive.…”

Competing conservation goals, biodiversity or ecosystem services: Element losses and species recruitment in a managed moorland–bracken model system

“…These predicted values are subject to considerable uncertainty, first the estimates for element stock have been derived from just the one site sampled here, and the UK estimates for dense bracken cover have very large standard errors (Pakeman et al, 1995). Moreover, the amount of dense bracken in subject to considerable flux over quite short time intervals (Pakeman et al, 1995), positively as a result of encroachment from linear features, change from sparse stands to dense bracken and deforestation, and negatively through bracken control measure and afforestation (Marrs and Watt, 2006).…”

“…If data for total element stocks for dense bracken in Table 2 were extrapolated to the countrywide scale using the estimate of 4800 km 2 of dense bracken in the open within the UK (Pakeman et al, 1995), this biotope could contribute 0.5 Gt C to the UK Kyoto account in either the ''agricultural'' or ''open'' category (http://unfccc.int/resource/docs/convkp/kpeng.pdf). This value assumes that the data presented here were typical, or at least close to, the value of the countrywide mean; this remains to be tested.…”

“…There are also good practical reasons for studying this system as bracken-dominated land currently occupies large areas of the UK. Bracken is present on approximately 17,100 km 2 of land (7.3% of the total land area), with 4800 km 2 directly referable to the model system referred to here (Pakeman et al, 1995). However, this situation could change markedly, in different directions, as a result of changing management policies.…”

Isolation and characterisation of 13 pterosins and pterosides from bracken (Pteridium aquilinum (L.) Kuhn) rhizome

“…In the UK, P. aquilinum subsp. aquilinum comprises the majority of bracken, with a dense coverage estimated at 4782 km 2 (dense) or 17000 km 2 (presence), representing 7% of the land area in the UK, including sparse bracken (Pakeman et al, 1996). This corresponds to 1.1 -5 Gigatonne (Gt) of plant material above ground and 5 -20 Gt of rhizome biomass (dry weight, calculated from data in (Marrs and Watt, 2006)).…”