Connecticut began clearing an invasive reed from Highstead Pond in 2012; 98% was killed, and by 2017 native plant richness around the pond had increased 39%

An invasive reed that had spread around a pond in southwestern Connecticut was brought under control through a multi-year removal project, allowing a more diverse mix of plants to return. The work at Highstead Preserve showed how long-term vegetation monitoring can help conservationists assess whether removing an invasive species benefits the wider ecosystem.

Removing an invasive reed from the pond

According to Highstead’s account of the project, the organisation began planning to control common reed (Phragmites australis) around its pond in 2012. The aim was to improve views across the pond and encourage a more diverse community of native wetland plants. Although common reed occurs naturally in many parts of the world, the invasive European lineage has spread widely across North America. It can form dense stands that occupy large areas and restrict the space available to other plants. Its vigorous growth can change the structure of wetlands, making it harder for a varied plant community to persist.


Phragmites was found to occupy nearly 39% of the shoreline around the pond at Highstead prior to starting the work. The site included several smaller clumps of Phragmites and one larger clump of about 1,300 square metres. Vegetation monitoring took place between 2012 and 2017, when researchers recorded plant species and counted living stems in sample plots. Herbicide treatments began in winter 2013 and continued each year thereafter. They used three application methods: hand wiping, a long-handled applicator, and a backpack sprayer.

Native plants return as the reed declines

The results showed a substantial decline in Phragmites. After four years of treatment, the number of stems had fallen by 98 per cent, according to Highstead. The team also recorded an increase in the diversity of woody and herbaceous plants around the pond. A study published in Rhodora, the journal of the New England Botanical Club, documented the project’s findings. It reported that native vegetation recovered from the initial damage caused by herbicide application and became more diverse than it had been before treatment.

Hand wiping proved to be the most effective of the three methods, controlling the invasive reed while causing the least damage to surrounding vegetation. By 2017, the pond’s plant community had changed markedly from the reed-dominated conditions recorded at the start of the project. However, the increase in plant diversity was not limited to native species. Both native and non-native plants increased after the reeds were removed.

Why monitoring matters after removal

The Highstead project highlights an important consideration in invasive plant management: removing the dominant species is only part of the process. Conservationists also need to establish what grows in its place. A review published in Invasive Plant Science and Management examined native plant recovery after three years of common reed control at five tidal wetland sites. When thick stands of invasive plants are removed, the newly opened space can be filled by other non-native species. The scientists emphasised that clearing Phragmites alone did not guarantee the return of native vegetation. The Highstead project shows how repeated treatments and monitoring can reveal changes that a one-time study might miss.

Wetland recovery can take time, and the results may vary from one site to another. Even after Phragmites has been reduced, other non-native plants may begin to grow in the space it leaves behind. Checking the vegetation over several years can help conservationists see how the plant community changes and whether further treatment is needed.