Controlling phragmites (Phragmites australis) can be difficult. But as a widespread and high impact species (Tier 4), it is important for LIISMA to control small populations, especially where it co-occurs with rare species and communities. For this reason, managing phragmites in coastal plain ponds has become a top priority for LIISMA; these ecosystems contain some of the highest biodiversity in New York State, and are home to numerous rare plant and animal species. Phragmites is a threat to the rare plants and communities in these ecosystems that rely on a particular pattern of water level rise and fall. Should phragmites fully invade a coastal plain pond, the hydrology can be severely altered, causing the water levels to skew lower, and overtime lead to losses of different plant species.
In 2021, the LIISMA team piloted the technique of underwater cutting of small stands of phragmites in a few coastal plain ponds: Big House Pond and Little House Pond in Sears Bellows County Park, and in Long Pond within the Long Pond Greenbelt. This cutting technique, described by the Great Lakes Phragmites Collaborative, involves using gardening shears, scissors, or raspberry cane cutters to cut phragmites at least 6 in. below the waterline and drown them – starving the plants of oxygen to eventually kill them.
This past month, the LIISMA team returned to these sites to conduct follow up cutting and monitoring – and were pleasantly surprised. In Big House Pond the team documented an 85% reduction of phragmites. In Little House Pond where less than 10 stems were detected in 2021, zero phragmites stems were found in 2022.
Upon returning to the larger patches of phragmites in the middle of Long Pond in the Long Pond Greenbelt, the team – with the help of Jacqueline Fenlon of the Town of Southampton – found a 91% reduction of phragmites, from 910 to only 85 very thin, short stems! Much of the area was completely free of phragmites. Following these preliminary results, the LIISMA team is eager to continue to monitor and manage these stands for several years in an effort to suppress, contain, or eradicate phragmites at these sites.
In 2022, LIISMA employed a spading technique for managing a small stand of phragmites along the shoreline of Bellows Pond in Sears Bellows County Park. As the name suggests, this involves using a spade or shovel to sever the phragmites rhizome at a 45º angle at the base of each stem. By simply inserting, cutting, and removing the spade, soil disturbance is minimized and native vegetation protected. The team is looking forward to assessing the results of this effort next year.
