Study

Effects of cutting Phragmites australis along an inundation gradient, with implications for managing reed encroachment in a South African estuarine lake system

  • Published source details Russell I.A. & Kraaij T. (2008) Effects of cutting Phragmites australis along an inundation gradient, with implications for managing reed encroachment in a South African estuarine lake system. Wetlands Ecology and Management, 16, 383-393

Actions

This study is summarised as evidence for the following.

Action Category

Cut/mow herbaceous plants to maintain or restore disturbance: brackish/salt marshes

Action Link
Marsh and Swamp Conservation
  1. Cut/mow herbaceous plants to maintain or restore disturbance: brackish/salt marshes

    A replicated, randomized, controlled, before-and-after study in 2004–2006 in a brackish marsh in South Africa (Russell & Kraaij 2008) found that cutting common reed Phragmites australis had mixed effects on vegetation structure after 1–2 years, depending on water levels. For example in the driest zone, cut plots always contained more reeds than uncut plots (cut: 67–68; uncut: 17–28 shoots/1.5 m2), but there was no difference in overall reed volume (cut: 5,150–5,620; uncut: 3,280–6,880 cm3/1.5 m2). In cut plots, reeds were always shorter (cut: 21–23; uncut: 30–35 m/1.5 m2) and thinner (cut: 6; uncut: 8–9 mm diameter). Meanwhile in the wettest zone, cut plots always contained fewer reeds than uncut plots (cut: 3–6; uncut: 68–104 shoots/1.5 m2) with a smaller volume (cut: 180; uncut: 1,190–1,870 cm3/1.5 m2). The low density of reeds in wetter cut plots negates meaningful interpretation of length and diameter. Before intervention, vegetation structure did not significantly differ between plots (averaged over moisture zones; data not reported). Methods: In 2004, eight plots (each 200–400 m2) were established in a reed-invaded marsh on the edge of a brackish lake (5–8 ppt). Stabilized water levels, reduced disturbance from large herbivores and reduced fire frequency likely contributed to reed encroachment. In three random plots, reeds were clipped to ground level in late summer 2004 and 2005. Cuttings were removed. The other five plots were left uncut. All plots were perpendicular to the lake edge so were divided into three moisture zones: dry (flooded for roughly 30% of the study), moist (50%) and wet (100%). Reed structure was surveyed before (late summer 2004) and after 1–2 cuts (late summer 2005 and 2006), in six 0.25-m2 quadrats/zone/plot.

    (Summarised by: Nigel Taylor)

Output references

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