Phragmites or Common Reed (Phragmites australis) is a natural component of many wetlands but can be highly invasive. I recently worked on a project with Paul Rees from Melbourne Water at the Ramsar-listed Seaford Wetlands (Melbourne, Victoria), where Phragmites is encroaching into important mudflat habitat areas which are critical for migratory birds. We assessed the efficacy of slashing as a means of controlling Phragmites by establishing twelve 5 m x 5 m quadrats within mature Phragmites reed beds and slashing half of them. The response of Phragmites to slashing was highly variable and dependent on the elevation (i.e. subsequent flooding) of the slashed quadrats. Phragmites regrowth was minimal in lower-lying quadrats which were wholly inundated for several months each of the following two years (to a mean depth of ~22 cm). In contrast, in quadrats of higher elevation, which were mostly only partially or shallowly inundated, Phragmites recovered almost completely within 10 months. In quadrats that were not slashed there was no change in Phragmites cover (i.e. it remained ~100%) irrespective of flooding extent. We propose that prolonged flooding above the height of the remaining stubble is necessary to prevent Phragmites recovery. Thus, slashing may be a successful means of controlling Phragmites when low-lying areas are targeted and these are subsequently flooded to a sufficient depth (e.g. >20 cm) for at least several months.
This study was recently published in Ecological Restoration and Management.
Please don’t hesitate to contact me to discuss the project or for a copy of the manuscript.