Volunteers brought in to remove Himalayan Balsam

As part of the CAISIE project, volunteers from Conservation Services joined IFI staff and Carlow County Council in removing the highly invasive plant Himalayan Balsam (Impatiens glandulifera) from the banks of the Barrow Navigation near Carlow town.  CAISIE is a Life+ EU funded project which aims to control and eradicate invasive species in Lough Corrib and throughout the Grand Canal and Barrow Navigation.  Impatiens glandulifera is native to the Himalayas and thrives along river banks and in damp woodlands. It has spread prolifically in the UK since its introduction in the 19th Century.  Each plant produces large numbers of seeds and the seed capsules explode when mature, ensuring its rapid spread in suitable habitats.  Himalayan Balsam can attain a height of 2.5 meters and, when it invades the riverbank, it forms monocultures that shade  and out-compete  native plants.  These dense vegetation stands can also restrict access to the river for anglers and other user groups.

Efforts to control Himalayan Balsam at trial locations on the River Barrow were undertaken through hand pulling. This method has proved to be successful in parts of England and  works effectively because of the small root ball of this species (see photo).  Approximately 38,000 m2 of riparian zone was cleared of Himalayan Balsam at one site, where both open clearings and dense wooded river banks were treated.  At a second site approximately 625 m2 of ground occupied by Himalayan Balsom was cleared.

Hand pulling enables the selective clearance of this invasive species while native and ecologically valuable  riparian species are left undisturbed.  It also permits treatment in areas where access is difficult. A further survey of the areas will be undertaken in mid to late summer to assess the re-growth of Himalayan Balsam and/or the level of recolonisation by native plants.

For more information see www.caisie.ie