Norfolk Non Native Species Initiative and a visit to the Wensum Valley.

Continuing with my interest in Non-Native Species I contacted the NNNSI (Norfolk Non Native Species Initiative) and arranged to meet a member of the team and a contractor who were clearing a site which was situated on private land in the Wensum Valley close to Lenwade that had been overrun and was being cleared of Himalayan Balsam. As part of my research I spoke to Katy Owens who works for the NNNSI, about the work of the organisation including the projects, initiatives and species which are particularly problematic in Norfolk. Below is a copy of the interview which I documented:

A photograph of a contractor clearing Himalayan Balsam from the Wensum Valley close to Lenwade

R: Could you tell me a little bit about the NNNSI.

K: To keep an eye on non native species in Norfolk, only a few of which go on to be invasive. Generally the invasive species have no natural predators in the UK. Very often the Victorians introduced them in the 19^th century. It was not only plants that were a problem but also animals such as, Muntjac Deer and Chinese Water Deer.

R: Once introduced into the UK and taken out of their natural habitat do they spread like wildfire?

K: If they find a habitat that suits them they will spread to the detriment of the other species in that area. Often they form monocultures; they change the structure and function of the ecosystem. Himalayan Balsam can cause the soil to become very loose, once they die back in the winter then there may be a lot of erosion as their roots are no longer holding the soil together. Dense coverage can stop light getting to the species at the bottom, this in turn may block out all of the ground vegetation, which would normally exist close to the earth. They will also suck out all the nutrients from the earth meaning there are none left for the native species.

A photograph of a patch of Himalayan Balsam from the Wensum Valley Site.

  

R: Aren’t Himalayan Balsam flowers really popular for bees?

K: Yes, if another plant relies on bees for pollination then that can also be a problem. There is no way of eradicating the species however with areas like the Wensum Valley, which is an SSSI (Site Of Special Scientific Interest) there is money to try and control the issue. There is three years worth of funding, to deal with the problem, which hopefully will help to ease it by the third year.

R: Which is the worst of the invasive species in Norfolk in particular?

K: Himalayan Balsam is generally considered to be a big problem in Norfolk. Japanese Knotweed is a big problem on Brownfield Sites, abandoned sites or railway sidings. Once it becomes established on these areas where there is nobody in charge of keeping it in check it can spread very severely. Japanese Knotweed is particularly bad as there is no way to effectively treat it. The best way is to inject it with herbicide at the root and let it die off. If it is cut down it will re-grow, or if some root material is left in the ground it will re-grow. Once is has been cut down it is classified as practically hazardous waste. It has to be disposed of using an environmentally certified waste-site as it is so invasive.

R: I read that if it is found on your property it is so destructive that you may not be able to get a mortgage as it can grow through bricks and concrete!

K: Possibly a bit of an exaggeration. One of the problems is that less scrupulous developers have developed Brownfield sites without eradicating or clearing it and have built over the top meaning that knotweed may grow up through the foundations. Lots of money was spent on the Olympic Site in Stratford.

R: I think I read it was £70million?

K: Something like that, unexploded bombs were easy to deal with but Japanse Knotweed was a real problem. We do get issues with Knotweed but the problem is if we don’t have any funding for it on private land there is nothing we can do about it. Currently we are on private land but we have the landowners permission to deal with it plus private money to pull it out for free, as this is part of the Wensum valley and an SSSI.

R: You mentioned Muntjac Deer, are they part of the eradication scheme as well?

K: Yes, we had a group of Belgium stakeholders who came over as they started to have a Muntjac population appearing in Belgium. They are now in a position we were in 40 years ago so they came over to see what they could be doing differently to us to stop the deer from taking hold. Mainly they are found out towards Thetford Forest Way, particularly in ancient woodlands, which is where they cause most of the problems.

R: What do they do in particular?

K: In the same fashion as all invasive species they start to change the ecosystem in which they inhabit, this affects its structure and therefore its function. In the case of Muntjac Deer they nibble all of the new shoots so they clear the ground of cover, which the native species need in order to survive. They eat all the crops and breed prolifically being able to reproduce every 9 months. They are also very difficult to track down as they are very secretive and stay hidden.

R: How are they kept in check?

K: licensed gamekeepers employed by the forestry commission shoot them to keep them in check often. Farms with woods are generally a big problem as the Muntjac live in very small areas with dense cover. This is particularly an issue in Norfolk as there are a lot of these areas. Particularly areas where pheasants are kept are a problem as these condition suit the Muntjac really well as they are often wooded areas with dense cover.

Himalayan Balsam was originally introduced due to its ornamental qualities.

 R: There is a certain irony that these species were introduced as ornamental. Is that the case with a lot of them?

K: The Victorians introduced a lot of them and usually they have been introduced as an ornamental species or for fur farming, in the case of Mink, which are also a problem in Norfolk as they eat water voles, which are rare and also eat Crayfish.

R: isn’t there a problem with Crayfish as well?

K: Yes most of the native crayfish have been wiped out by the non-native crayfish. The non-native signal crayfish carry something called crayfish plague, which our native crayfish are susceptible to.

R: Is the problem of non-native species getting worse? Or was there a big boom in the last ten years or so?

K: It’s hard to say, a lot of this has been going on for a long time. It’s ongoing, different issues come in and out of fashion. Ecologically it has been a problem for sometime, the problem is usually addressed when it becomes an economic issue and therefore money is provided to deal with it.

R: Is that what is happening at the moment?

K: With some species yes, particularly the Muntjac Deer due to the crop devastation it had become a big problem for farmers and is now costing a huge amount of money. In order to control invasive species the government is starting to put new legislation in place to have a better management of species between countries. One of the big things at the moment is ballast water. Huge container ships travelling between continents have to take on ballast water in order to adjust their height in the water to load and offload cargo. For example a ship may take on water in Japan and release it in Harwich, Chinese Mitten crab are a particular species which have arrived here, possibly as a result of the movement of ballast water. They can live in salt and freshwater, making them particularly hardy. One of the problems is that they live in little holes in riverbanks and estuaries, which as a result can become destabilized and fall in. However it is very hard to prove, as it is particularly ephemeral and unless there is a particular release date of the ballast recorded it is really hard to prove anything. The scale of global movement these days is a big problem, there are so many people moving across the world. Things come in and go out of the country on a massive scale.

R: At this particular moment in time what are the worst non-native species that are a problem in Norfolk!

K: Muntjac Deer, Himalayan Balsam, Japanese Knotweed, Giant Hogweed and Killer shrimp in the broads are all a big problem. The Broads have a very unique ecology and are therefore especially easily affected. The Broads also have heritage status so it means the problem will get more attention. We have just finished writing a book for kids about killer shrimp. The non-native mink are also a problem, there is a way of observing whether they are present using a little tunnel with a pad in it which is made from moist clay able to soak up water. The mink will leave imprints in it if it runs through. It is therefore possible to distinguish between whether it was an otter or mink that ran through. If it is a mink it is possible to set a cage in order to catch it.

R: where could I go in order to see some good examples of these species?

K: Sheringham Park is a great place to go to see rhododendron Ponticum.  Here in the Wensum Valley is a good place to see a proliferation of Balsam. Knotweed can be found at Whittlingham Broad particularly where the railway goes by and also at Thorpe St Andrew on the island although it is impossible to go out without a boat. Muntjac are everywhere around Thetford forest, they often jump out in front of your car and they also make a barking noise like a dog. Giant Hogweed may be found on certain stretches of Marriott’s way in the vegetation along the sides. It can also be found at Lynford Hall where it is also a big problem. Killer shrimp can be found in the broads. Crayfish may be found in the river at Swanton Morley, they can be caught from the river using bacon attached to fishing line. The native ones have white claws and it is an offence to catch them.

R: Katy thanks so much for speaking to me and showing me this eradication site it has been a really big help for my research.

 

A path cleared through a proliferation of Himalayan Balsam as part of the eradication scheme in the Wensum Valley