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Threatened Habitats | Salt Marsh Monitoring | Phragmites

Pickman Park Phragmites Eradication Pilot Project

The project was sponsored by Salem Sound Coastwatch (SSCW) in conjunction with Salem State University (SSU) , under a City of Salem Conservation Commission Order of Conditions.

In this Pilot Project, SSCW partnered with SSU to experiment with three different methods to eradicate the invasive common reed, Phragmites australis, in a half-acre perched marsh in Pickman Park, Salem, MA. The marsh contains three distinct stands of Phragmites. Because of the distinct elevations and hydrological characteristics of the stands, SSCW and SSU tested a different control method in each stand. SSU students monitored the salt marsh vegetation and salinity.

 

Phragmites australis is a serious threat to wetlands. Also known as common reed, it is an invasive plant that can spread throughout a wetland, crowding out other more productive plants with its dense roots and vegetation.

GOALS:

  1. Document methods to remove small stands of Phragmites before wetlands become phragmites monocultures
  2. Involve college students in environmental research
  3. Share this phragmites control information with conservation agents/commissions and private landowners.

OBJECTIVES:

  1. Use three different control methods on the three discrete stands of Phragmites in the study marsh. See Methodology below.
  2. Provide college students direct field experience with wetland restoration.
  3. Share the study results and conclusions with the public.

Two SSU professors, Dr. Young, SSU Biology Department and Dr. Luna, SSU Geography Department used the study to expand their curriculas. SSCW has prepared a PowerPoint presentation (1.2MB PDF) for 5th – 10th grade students that covers salt marsh ecology and Phragmites.

 

METHODOLOGY
Baseline data were collected during the summer of 2006 for the marsh vegetation and salinity. SITE MAP

Method 1: cut and increase salinity through tidal flow.
In 2007, Area 1 Phragmites, those closest to the tidal river in the southwest corner, were cut weekly from early June through mid August, than bi-weekly until the end of the growing season. In December 2007, the concrete wall separating the river from the marsh was breached and a ditch dug into the marsh to increase tidal inundation. The ditch is approximately 20 feet in length and 2 feet wide by 1 foot deep. Cutting was biweekly in 2008 over the same time period.

Method 2: cut and apply BurnOut II
The higher elevation of Area 2 eliminated the possibility of increasing salinity from tidal flow. SSC students followed the same cutting schedule as with Method 1 and BurnOutII sprayed on the cut stalks at same time as cutting in 2007 and 2008. A single clearing of cut stalks took place in late summer.

Method 3: excavate wetland to increase tidal inundation
The largest stand of Phragmites was at the back of the wetland and the greatest distance from the river. Sandwiched between the toe of an upland slope and a tidal ditch, Area 3 required wetland alteration. A perimeter 2 feet by 2 feet ditch was dug around the back of the Phragmites stand. The Phragmites dominated area between the new ditch and old ditch was excavated to lower the elevation by 6 inches to increase tidal inundation. The old ditch was left undisturbed. After the excavated earth was dewatered it was removed offsite to an upland area.

Northeast Wetland Restoration (Geoff Wilson, Berwick ME) was contracted to dig the new ditch and excavate the phragmites stand. The excavation work took place from August to December in 2007. Timber matting was used to reduce the impact of the small excavator (TBO45) on the marsh to approximately 1 lb. per square inch of pressure.

Results/Lessons Learned

All activities of the grant to restore one-half acre of salt marsh by the removal of Phragmites have been completed. Post-restoration monitoring continues.

 

Complete removal of Phragmites is a difficult challenge. The greatest success in removing Phragmites came in Area 1 where the breach in the wall increased saltwater intrusion. In the elevated Area 2, Phragmites have been removed from the center of the area but plants still remain at the edges. In Area 3, the Phragmites in the excavated site experienced stunted growth during the 2008 summer (average maximum height of 143.4 cm (4.7 ft.) in 2008 compared to 246.1 cm (8.1 ft.) in 2006), despite frequent rains throughout the 2008 summer which provided ideal growing conditions for Phragmites.

 

View results in a powerpoint (4.16MB PDF) developed by Dr. Alan Young.