Typical non-native species that cause a problem in Meirionnydd are: -
Rhododendron, Japanese Knotweed, Hymalayan Balsam, Non-native Trees.

Exotic Species Many of the species now planted in this country are not originally from this region, we call these 'exotic species'. Species from this country are known as 'native'. Invasive species are those that can actively take over a site by excluding all other species. Exotic species tend to be invasive too because there are little to no plants and animals associated with them in this country. This means that they tend to be less susceptible to disease and predation and so can survive where our native plants are attacked by our native animals. In forestry and agriculture, exotic species have been selected in the past for exactly these reasons. Because they can grow and provide a crop in places and circumstance where our native plants cannot. These species tend to be faster growing too, so from a commercial point of view produce a crop faster. In a natural environment exotics become a problem because many of them grow faster and cast dense shade which can stop native species from growing and spreading. Over time this can lead to the loss of natural sites as our native species die out. The problem is extended because the plants are food for insects and small mammals, which in turn are food for more of our native species, so losing one species tends to have a knock on effect causing greater and greater loss of native biodiversity. It is thought that invasive species have caused the second greatest loss of biodiversity world wide after mans influence. www.agf.gov www.introduced-species.co.uk/Plants

Rhododendron Rhododendron Rhododendron ponticum This species is extremely hardy, growing and spreading very quickly. It is originally from Northern Turkey where growing conditions are tough and there are animal species that eat rhododendron and diseases that infect it keeping the plants in check. In its natural conditions rhododendron is a tough plant but not a pest species. It produces 1 million seeds per plant, but that is to survive and produce the next generation. In Wales the conditions for growth are a lot better and there are no associated species to limit its growth. So those million seeds spread the plant at a phenomenal rate and the species has thrived to the point it is now a major pest. Rhododendron ponticum can physically exclude other species from around it by releasing chemicals into the soil that kill off other plants. This creates bare soil for its seedlings to exploit. The leaf cover is also very dense so very little light gets to the floor under the bushes - again excluding other species. Controlling rhododendron is a difficult process requiring a great deal of persistence. Rhododendron Clearing Spraying There are two main ways: The traditional method is to cut down all large bushes and burn or chip the cut material. The rhododendron will grow back the next year and at this point you need to spray them with a herbicide. If you leave the bushes to grow for too long their leaves develop a thick waxy layer, which stops herbicides from entering the plant, and put you back to square one. So it is vitally important to follow any cutting the next growing season with chemical treatment. Follow up treatments are considered to be most effective towards the end of the growing season (September) as the plants are beginning to draw their reserves down to their roots for storage through the winter. This means that the chemicals are taken right round the plant and have the chance to kill off every part of it. You may need to spray every season for up to 5 years. This will allow any seedlings that are dormant in the soil to grow once the bigger parent plants have been taken away and any re-growth from cut plant material to show up. All of the new growth must be sprayed in order to control this plant. Rhododendron Injection A new method has been invented which is intended to be more effective with less follow up treatments. It is called stem injection. Basically you drill a hole down into the stem with a normal cordless drill and fill it with herbicide. Again this gets the chemical right into the plant improving the chances of killing the whole bush. This leaves you with standing dead bushes, which should be left for at least a year to limit re-growth. The dead bushes can then be tidied up again by felling and burning or chipping. If the site is not highly visible you may just leave the bushes to rot down naturally. There will always be a few bushes that are too small to drill and these should be treated as re-growth and sprayed as soon as possible. Click here for more details on stem injection: www.forestry.gov.uk/newsrele.nsf/AllByUNID/196010F167115B7180256ED9004A090C Or for a comprehensive guide to using any chemicals in forestry try the Forestry Commission’s Field Book 8, The Use of Herbicides in the Forest Click here for more details www.forestry.gov.uk/website/Publications.nsf/DocsByUnid/943FE0B42DAB91BC80256F9B005ADCF3).

Japanese Knotweed Japanese Knotweed Fallopia japonica This is one of our worst offenders but you have to admire its ability to survive. Japanese Knotweed was introduced from Asia to Europe in the mid-nineteenth century as an ornamental and fodder plant. It can grow up to 2-3 meters tall. It's stems look a bit like orangey brown bamboo. The creamy white flowers are seen from mid to late summer and form in. The dead stems persist throughout the winter and new shoots grow up amongst these the following spring. The dead stems and leaf litter decompose very slowly forming a deep organic layer which stops light getting to the soil stopping native seeds from germinating or even reaching the soil. This means that the plants can quickly exclude all other plants, actively taking over a site as it spreads. The main spread is by vegetative reproduction from rhizomes (the underground part), and fresh stems that break off or fall over. Tiny fragments from any part of this plant can start growing in soil or water within 6 days! This is why much of the plant's spread has been along rivers and streams, roads and railways. As bits break off or are hit by cars and trains they are carried along to new areas where they can start growing again. Knotweed Flower The rhizomes of one plant can reach 7 metres across and 2 metres deep. It is now a world-wide offender. It has been so successful out of its natural range (again with no associated species to keep it in check) that the species occupies more than half of the 10 km squares used to map plant distribution in the British Isles and is only absent from the Orkney Islands. It is found across much of mainland Europe from southern France and Northern Italy to Norway, many States in the USA from California to Washington and throughout Canada and is increasingly being reported as a nuisance weed in New Zealand. Knotweed Shoots The biggest female in the world! The reason that the plants are spreading here by vegetative reproduction is due to the fact that to produce new plants through sexual reproduction it needs both a male and a female plant. But in the whole of Europe researchers have proved that we only have female plants and in Britain and parts of Europe and North America it is even the same female clone. Looking at its total mass on this scale gives it the title of the biggest female in the world! If you want to do your bit please remember that this plant is such a threat to our countryside that any cutting or chemical treatments must be carried out under license from the Environment Agency. Though for a more holistic approach there are people that eat the young plants (up to 6 inches) comparing them to rhubarb in taste and laxative properties! If you would like some recipes for Apple and Knotweed pie, Knotweed soup, sherbet and so on have a look at: www.wildmanstevebrill.com/Plants.Folder/Knotweed

Himalayan Balsam Himalayan Balsam Impatiens glandulifera Himalayan balsam is an introduced species that has escaped from gardens. It has also been spread from country to country by merchant ships emptying and filling their ballast tanks in port with water contaminated with seeds. It likes river banks and other damp environments. The plant stems look a bit like bamboo in that they are segmented along their length. The flowers are pink to purple and can be seen from June to August. They are best described as looking like a Policeman's helmet, which gives the plant its more common name. Seed Pods The flowers give rise to seed pods which explode when the seeds are mature. When the pods explode they can propel the seeds for up to 20 feet, usually into rivers and streams where they are carried to new seeding grounds. Each plant can produce up to 800 seeds per year so you can imagine how quickly it can spread. Shoots The problems Himalyan balsam are similar to Japanese knotweed in that it readily shades out and suppresses the growth of our native riverbank grasses and flowers. This leaves us with bare riverbanks during the winter increasing erosion. It differs from Japanese knotweed by being relatively easy to control. Where it is accessible cutting at soil level tends to suffice. It is also possible to pull these plants up as they have relatively shallow roots. Chemical control is also effective but using chemicals near to any watercourse can only be carried out under license from the Environment Agency. Timing of control is essential and any operations should be carried out before seeding.

Beech, Sycamore, Larch, Spruce species, Western hemlock and Fir species None of these species is originally from Wales. They have been brought in by man over the years to suit the needs of the time. For example beech is native to south-east England and was spread further afield by the Romans who used the oil from its mast (seed) in their lamps. It is also extremely hardy and can survive in exposed conditions and so has been used to create shelter-belts and mark boundaries (known as policy planting) across the country for centuries. There is some thought that with global warming the natural range of beech is spreading north and west towards Wales and so may be accepted as a native by the middle of the century.

Larch, spruce, fir and Western Hemlock were among some of the huge number of trees and plants brought to Britain in the middle of the nineteenth century by the great plant collectors of the time. Since then they have been used in forestry trials looking to discover species that grow quickly and produce quality timber in plantation conditions. These were the more successful species and are still used in commercial forestry today for their growth qualities. But this is what makes them a threat to native woodlands, out growing and out competing our native flora, the life support system of our native fauna. Dense Canopy Dense Stand Where there are mature trees of these species through the oak woodland sites, the project will aim to slowly remove them by felling. The gaps created by this process will allow young trees to become established, and we can then select native species. Any young trees of these species already established will be either pulled up by hand or cut down. Typically the conifer species listed above are planted in fairly large blocks. In some cases old oak woods have been felled and planted over with conifers. There are two ways of restoring these sites to oak woods. The first option is to remove them all at once and either plant the site with native species or wait for the seed to fall from neighbouring native trees. The second option is to thin the conifers out slowly over time, concentrating your efforts around areas that have existing native trees, creating gaps for new seedlings. Both options work, the first option may be cheaper and easier but may result in a less natural woodland. This type of woodland will be appropriate if you still want to use the woodland for timber growing. The second option is more suitable to sensitive sites especially those with Atlantic species, as maintaining the damp woodland conditions allows these plants to survive through the changes.

Clearfell at Coed y Garth Halo Thinning at Hafod Boeth