Individual study: The effects on flora of alternative management methods of reed Phragmites australis beds in Norfolk and Suffolk, England
Cowie N.R., Sutherland W.J., Ditlhogo M.K.M. & James R. (1992) The effects of conservation management of reed beds. II. The flora and litter disappearance. Journal of Applied Ecology, 29, 277-284
Phragmites australis reed beds are valuable wildlife habitats and in the UK support some national rare fauna and flora. For conservation purposes reed beds may be managed by cutting, and in some areas reed is still harvested for thatching. Burning may also be used to arrest succession in reed beds, with periodic flooding also used as a management tool. Accumulation of reed litter and resultant raising and drying out of the ground surface is a problem in conservation management, cutting or burning, often in combination with periodic flooding, are management options. In this study, the effects of management type on flora was determined by comparing pairs of adjacent cut and uncut reed beds at 12 sites in East Anglia, eastern England.
Study sites: Twelve sites in the counties of Norfolk and Suffolk (eastern England) were selected which had reed cut regularly on a commercial basis for the last 20 years adjacent to a reed bed uncut for 3 years or longer. Sites in Norfolk were: How Hill (3), Hickling (4), Haddiscoe (1), Fritton (1) and Belton (1); sites in Suffolk were both at Walberswick (2). At an experimental site at Hickling burning was also undertaken as an additional treatment in some plots, mainly to compare the effect on invertebrate communities (Ditlhogo et al. 1992).
Vegetation monitoring: In July or August 1988, plant species were recorded in 20 random 0.25 m² quadrats. In each the number of reed stems was counted. At Hickling, live and flowering stems were counted, and height and diameter at 10 cm of 40 live stems was measured. Site salinity was also measured.
In total 99 plant species were recorded, with 25 significantly more abundant in cut reed but only three (common couch grass Elymus repens, goat willow Salix caprea and the non-native, orange balsam Impatiens capensis) more abundant in the unmanaged ones.
At Hickling, where burning management had been undertaken in some plots, eight species were more abundant in unmanaged plots , none in managed plots, seven more abundant in burnt than cut plots, and only rough meadow grass Poa trivialis more abundant in cut than burnt plots.
At Hickling, reeds were shorter and at higher densities where cut (148 cm, 720 stems/m²) or burnt (143 cm, 736 stems/m²) than where unmanaged (177 cm, 484 stems/m²). The proportion of reed flowering stems was highest in burnt plots (34%), intermediate in unmanged (26%) and lowest in cut (21%) plots. At the other sites, reed densities in cut beds were twice that of the unmanaged beds.
Neither species diversity or richness were correlated with salinity, but both were significantly higher in the cut than unmanaged reed beds.
Conclusions: Managed reed beds had a higher reed density and higher plant diversity than those unmanaged for 3 years or longer. Cutting and burning positively affected floristic diversity of most marsh plants. Lower light levels and litter build up probably suppressed the associated flora in unmanaged beds.
Ditlhogo M.K.M., James R., Laurence B.R. & Sutherland W.J. (1992) The effects of conservation management of reed beds. I. The invertebrates. Journal of Applied Ecology, 29, 265-276.
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