Invasive non-native species harm the environment and wildlife, are costly to the economy, and can even pose a risk to our health and way of life.
During Invasive Species Week (13-17 May), organisations across the UK, Ireland, Jersey, Guernsey and the Isle of Man work together to raise awareness and ask everyone to help prevent their spread to protect the environment and recreational spaces for future generations to enjoy.
Our Rangers and volunteers were busy along the length of the valley on a number of projects throughout the week.
In Wellesley Woods and in the Wellesley Green corridors Laura and Stuart mounted a concerted attack on the False Acacia Robinia Pseudoacacia. Although it is generally uncommon in the wild, we have a significant amount of False Acaia at Wellesley. Its rapid spread, suckering nature, ability to re-grow when cut down and spiny, impenetrable habit when established means that it is a major cause for concern. The Rangers have trialled different methods of removing this plant, including felling and digging out of the ground – both of which has produced vigorous regrowth. Following further research the Rangers are now trialling use of herbicide in selected areas and will continue to monitor the response from the plant.
Chalk Farm at Wellesley Woodlands has been invaded by Variegated Yellow Archangel – Lamiastrum galeobdolon ssp argentatum. This innocent looking relative of the dead-nettles produces spreading stems (stolons) with beautifully variegated leaves and spikes of yellow flowers.
Once this species gets into the wild, it rapidly spreads and carpets the floor to the exclusion of other plants. The smallest stolon fragment with just one pair of leaves can grow into a new colony, and stolons break readily if the plant is pulled up. It’s usually found in shady habitats such as woodland edges, hedgerows, roadside banks and stream sides. This plant has been identified as such a critical risk that it is it is also an offence to plant or otherwise cause to grow these species in the wild.
Previous attempts to eradicate this plant with herbicide have failed, so Ranger Laura and the volunteers created a thick mulch of cardboard. This method has been successful in other parts of the UK – so we will continue to monitor the Variegated Yellow Archangel at Wellesley and share our findings.
Himalayan Balsam – Impatiens glandulifera, is the largest annual plant in Britain, growing up to 2.5m high from seed in a single season. This non-native plant spreads quickly and forms dense thickets, altering the ecological balance and character of wetland habitats. Many seeds drop into the water and contaminate land and riverbanks downstream, but the explosive nature of its seed release (seeds can be projected up to four meters away) means it can spread upstream too. It produces a lot of pollen over a prolonged season and is attractive to pollinating insects. There is concern that its presence may therefore result in decreased pollination for other native plants.
Stu, Jeremy and Bobbie mounted an attack on the Himalayan Balsam at Gerry’s Copse and Moor Green Lakes. With the help of our regular Moor Green Lakes volunteers Bobbie’s teams were able to pull-up a substantial amount of the plant before it had a chance to flower and spread its seeds. Regular removal throughout the summer months should prevent the spread of this plant.