Don't rock the boat

Pond with ice and Crassula by Ruthie Cooper

Invasive weeds and rowing boats...Ruthie discovers that it's all in a day's work...

Who knew you’d need rowing skills for a conservation traineeship? Not us, that’s for sure! Yet a boat plays a key role in helping to control and manage the spread of invasive aquatic weed species across many of Worcestershire Wildlife Trust's nature reserves.

One such invasive species is the New Zealand pygmyweed Crassula helmsii found in the pond at Trench Wood as well as at other sites. This weed creates an incredibly dense, carpet-like surface across the pond, displacing other aquatic species, compromising water quality and unbalancing the biodiversity of the pond overall. If left unmanaged, this weed would eventually take over and choke the entire pond.

Pond at Trench Wood - Crassula and ice are visible by Ruthie Cooper

Pond with ice and crassula by Ruthie Cooper

A boat is necessary to enable us to reach every inch of the 3m deep pond and carefully remove the Crassula using long handled rakes or by hand (all done, of course, whilst taking care to NOT rock the boat and capsize straight into the pond itself). As if this wasn’t a task enough, we were also dealing with a thick layer of frost, turning the pond surface to ice. Now that’s a challenge! 

It is important to be cautious of breaking the stems of the Crassula as they can easily take root and regrow, a common characteristic of invasive plant species. Once dragged out of the pond, the Crassula is bagged up and set aside to dry out over several days, before being taken away from the site entirely. Thoroughly cleaning any equipment used in the removal process as well as washing down shoes, coats and anything that Crassula leaves or stems can be carried on is also vital to prevent the spread of this highly invasive weed. 

Other invasive aquatic weed species found on some of the reserves include: floating pennywort, Himalyan balsam and azolla, though we have yet to tackle these during our traineeship workdays.

Snowberry growth taking over a hedge by Ruthie Cooper

Snowberry taking over a hedge by Ruthie Cooper

It isn’t only aquatic plants causing issues, there are numerous terrestrial invasive plant species also present on the reserves, disrupting native species and taking over patches of meadows or woodland. One such example is snowberry, a plant native to the US and Canada that outcompetes native British flora in hedgerows. Reportedly grazed by moose and grizzly bears over in the States, in England there are no such predators to keep snowberry growth under control. Hence, it takes root along many hedgerows, encroaching onto and shading meadows and crowding other hedgerow species such as blackthorn.

We dealt with small patches of snowberry using loopers and bowsaws, cutting the small stems as close to the ground as possible before piling up the trimmings and stashing them away to compost down. 

The main thing to remember when dealing with invasive plant species is to clean EVERYTHING that may have come into contact with the plant during the removal process. With one in seven wildlife species in the UK being at threat of extinction, it is crucial that even the smallest fragments of invasive plant species are cleaned away effectively.


Ruthie Cooper has grown up in rural Worcestershire and is at home in the outdoors whatever the weather. She's volunteered with a varieties of charities but couldn't pass up the opportunity of becoming a trainee with Worcestershire Wildlife Trust, gaining formal training and qualifications to help with a future career in practical conservation.
Check Clean Dry - 'sticker' to advertise the CCD message to stop the spread of invasive plants and animals