At a Cloneen Tidy Towns Committee meeting it was decided to appoint a member to monitor the changes to the flora and fauna in the vicinity of Cloneen Village, having regard to exotic species, which may try to establish themselves locally (or have already done so) and to monitor the impact they may have on native habitats. Some exotic’s have found Irish climate conditions to their liking and have rapidly expanded and have become invasive in certain habitats, to the exclusion of other species. Is this spread of alien species harmful to Biodiversity in our locality?
The effect (for good or bad) of alien species on Biodiversity
Biological diversity (Biodiversity) is a term given to life on earth. It covers all life on earth and the ecosystems that support it. Biodiversity provides humankind with the basics to sustain life. Ireland, being an island nation and inhabited for thousands of years, would have lost many native species of plants and animals in that period, but if we lost some we also gained many more and they have become part of our heritage. Our flora and fauna would be very sparse without them. Many of these alien species contributed greatly to our food sources. Potatoes has been the number one food for many years and kept our ancestors alive (apart from the famine). Over the centuries, potatoes are one of the main food crops grown in Ireland and originated in South America. Tomatoes are another food source which originated in the same area.
Corn, maize, and countless other food crops grown in the Ireland originated outside the country. Many of our grass species, which farmers use for pasture, is also from outside the country.The alien species which we can control, like crops and large trees, add to the diversity when kept under check. If Sycamore trees were allowed to regenerate as they like, then large tracts of woodland and the larger countryside would, in a few years, be overwhelmed by regenerating Sycamore.
At the height of the ice period, some fourteen thousand years ago, very few trees remained in Ireland, except a few in the Kerry area. These were Arbutus Yew, and Scots pine, and Willow. The melting ice raided sea levels and cut off any contact with mainland Europe. After the ice melt the climate got warmer and other trees began to appear, like Silver Birch, Hazel, Wych Elm, Alder, Sessile Oak, Rowan, Holly, Crab Apple. Later on other varieties were established. Most were introduced by man for food and shelter. Some of our native woodlands, like Killarney National Park, were overwhelmed by exotic species.
The worst and most persistent was Rhododendron. It was a serious inhibitor to the growth of understudy vegetation and took many years to control this very invasive shrub.
Rhododendron has several varities all with large colourful flowers and evergreen leaves, because they are colourful they were popular in some of the big estates (for their aesthetic value), from where they made their way to our native woodlands.
Rhododendrons are more at home on acidic soils and will multiply prolifically in the right conditions.They grow in tangled bunches (and are impassable), which excludes all other vegetation from regeneration. Rhododendron Ponticum is the most likely species of this shrub to be found in the Cloneen area, but because of the soil type locally it is rare.
Exotic species, as the name employs, are species which are non-native, whether they be flora or fauna. Some species, which many people might consider native because they are familiar with them for so long, are not indigenous and that includes all conifers, with the exception of the Yew (Taxus bacata) and Scots Pine (Pinus Sylvestris), which became extinct in the seventeenth century and was believed to have been reintroduced soon after by Cromwellian settlers but might not have died out completely anyway. The Irish Yew (Taxus bacata) is a familiar site throughout the country, especially in graveyards. The reason for this is uncertain but might be because of their toxicity, and were enclosed in graveyards and walled gardens to stop livestock from foraging on them. The Yew is deadly poisonous if eaten by man or beast and means an almost certain painful death if not treated immediately.
This ancient tree was thought to be extinct in Ireland until a pair were found in Fermanagh circa 1747 and from this pair all Yew trees in the country were regenerated.
Exotic species nowadays are appearing here on a regular basis. With easy access to the outside world, and the popularity of garden centres, it’s almost impossible to stop the spread. In the last few years alone many new plants and animals have been seen in areas around the country. With the huge trade with other countries and the import of timber and young trees for planting it’s no wonder that we have encountered plant and animal diseases. The Ash disease, which is currently sweeping Europe, has infected our Ash plantations. This was caused by imported young Ash for planting. We have just gotten over Dutch Elm disease, which destroyed our mature Elm trees, with not one large Elm left in the country.
Children of today have never had the pleasure of seeing a majestic mature elm tree. Other species of trees have also succumbed to diseases from outside the country. The latest threat to our Oak comes from a pest called the Procession Moth, so called because the caterpillars march in line eating the greenery from the trees as they travel, and as a result the trees will die. This moth is now well established in Britain, where remedial action is been taken ie the forests are being sprayed from the air to try and stop the destruction of their oak trees. It is also leading to an outcry from naturalists, as they claim that this insecticide is decimating native insects, including the Red Admiral Butterfly. It probably only remains a matter of time before we in Ireland have this problem.
Ireland is one of the best countries in the world for plant growth, with its temperate climate and plenty of water. Most alien species thrive here, some have added to the diversity of species and are of value to the overall natural web of nature, others seem to be of little use and could be detrimental to the development of biodiversity.
In the Cloneen area we have an array of such plants, which includes Japanese Knotweed. This particular plant is considered in the world’s one hundred most invasive plants, and is very difficult to contain it’s spread, it regenerates by means of its root system, not by seed dispersal. It grows in thick clumps. Excluding other species, Gryslenia is also widely used as hedging and grows fast in Irish conditions and cast’s a strong shade, which excludes other plants. Laurel, and other exotic species, are also extensively planted (but thankfully they are mostly confined to gardens) and are scarce in the wider countryside. These shrubs and trees, because of their usage as hedging, are clipped many times during the year and are not allowed to flower (and hence are of little value to insects) and because of the way they are encouraged to grow right down to the ground other vegetation cannot emerge, hence this type of monoculture discourages Biodiversity. As a result locals will be encouraged to plant native hedging in the future. Lawson Cypress is also widely planted for hedging, and it was a policy of the forestry service to plant this tree on the perimeter of large forestry areas as a shelterbelt. This practice has been discontinued for a number of years.
Holly, one of our native species, is abundant in the countryside around the Cloneen area and is also planted for hedging. Because of its berries it is an excellent source of food for wintering birds. Holly has built-in protection, which deters would be browsers on its leaves. On the lower leaves it has nasty thorns to deter animals from eating them but the leaves higher up are usually without thorns.
Ivy (Hedera helix), the most prolific plant of all, is native and a climber and is a fantastic food, shelter and nesting source for birds, but because of it’s habit of completely taking over and covering trees and walls etc it is often cut from these hosts.
Ivy is an incredible fast grower and it is abundant along the hedge rows and in some cases completely takes over trees and telephone poles. It is most prominent along the roadway hedgerows. A few years back it was not unusual to see cattle and horses and other animals grazing (what was known as “The Long Acre”) the road margins. Grass was plentiful and sweet and also the added bonus of ivy, which most animals love to forage, kept ivy in check. But animals are no longer allowed on roads because of the danger to traffic and the spread of tuberculosis and other diseases among herds.
Giant hogweed (Heracleum mantegazzianum) is now growing profusely on the Clashawley River and its’ only a matter of time before it reaches the waterways in the Cloneen area. This plant, which can reach heights of two metres, will cause severe burn if it comes in contact with the skin, children are especially vulnerable to this umbelifer, it needs to be closely watched and destroyed at the first sign of emergence locally, because it is nearly always found close to or on the embankments of waterway’s, the seedlings are ripe come late summer and they drop into the flowing water and are carried on until they are transported to an outlet on the river where they will propagate in soft mud etc.
Some plants whether they be native or escapees from gardens have a tendency to be very invasive and as stated above our temperate climate encourages this, in most cases also the fact that many plants (especially exotic’s) have an in built preservation system, whether it be they are stingy, thorny, or toxic, they are less likely to be predated upon by animals or insects.
Some alien species are more invasive than others and can cause financial headaches for local authorities and others in how best to deal with the threat they may cause.
Take, for example, Creeping Water Primrose (Ludwigia grandiflora). This water plant has recently been seen in a pond in Co. Kerry. It has spread panic amongst environmentalists because of it’s tendency to take over rivers and lakes.
To the eventual exclusion of native plants, fish, and other wildlife, it will eventually become so matted that boats are restricted when the stems become entangled in the motor propeller shaft. Exotic plant species that invade our waterways are more difficult to deal with than those on `terra firma.
Many wildflower plants,which we take for granted, are toxic or may cause burns to the skin. Some will give severe stings, especially to children. One plant, the Buttercup, which is abundant in semi-improved grassland during the summer will give what is called Buttercup burn to horses. Those with white mussels are more susceptible to this, as they can get severe blistering of the nose and face by coming in contact with the sap from this plant. Ragworth and Hemlock is also a danger to grazing animals and may cause the animal to die.
Though many of the plants that are found growing today in the countryside are alien, it is believed that many more are native and were just lying dormant during the big freeze and, when conditions were suitable, they began to emerge. This includes the ancient plant’s Horsetail (Equisetacea) wild Garlick (Allium ursinum) and many of the heath family (Ericaceae). In the case of Horsetail this plant will appear especially in waste ground and neglected corners of gardens. If the area is sprayed with Roundup etc it kills all other vegetation and, soon after, the Horsetail begin to spring up when it gets a clear site. Excluding other flora, Horsetail and Ferns has been found fossilised in ancient rocks which date back millions of years.
With the importation of cereals over hundreds of years i.e.Wheat, Oats, Barley etc wild flowers and what is considered weeds also gained a foothold in the country. Because the screening methods for imported grain, whether it be for food or seed, was not near as selective as it is today, many of these wild plant seeds were mixed up and planted with the corn. The same also applied to other imported crops like seed potatoes and other root crops. We have reversed this situation now and wild plants that were once reluctantly tolerated, and were aesthetically pleasing (to the non-grower) amongst crops are no longer allowed to grow. One reason for this is the selective spraying of cereals, the second reason is the process that seeds are put through to eliminate contaminants.
Whether we like it or not, plants which are considered alien species have made steady inroads into Ireland over thousands of years, and are well established here. New ones are being added to all the time they have found a niche and don’t seem to harm biodiversity, but in most cases enhances the diversity, which nature requires to sustain itself, the greatest threat to wildlife would be the domination of one species of flora to the detriment of others, for example, Rhododendron in native woodland, which almost excludes all other plants from the understudy.
Wild plants and trees, which are a feature of our countryside in spring and early Summer, are written about by poets and scribes over centuries. These include Primrose, Bluebells, Violets, Daffodils, Hawthorn, Cherry, Chestnut, etc. Wild plants which are most prominent in the Spring and Summer and can be seen growing profusely along the road margins are Lesser Celendine (Ranunculus ficaria) Cow Parsley (Anthriscus sylvestris) Wild Garlick (Allium ursinum) Bluebells (Hyacinthoides non scripta) and Alexanders ( Smyrnium olusatrum) along with other species grasses Brambles etc almost completely obscure the other dominant plant which is best seen in the winter this being Ivy (Hedera helix)
One of the most prolific and invasive of our natives is Gorse, of which we have two species in Ireland (Ulex europaeus) and (Ulex gallii). Both are in flower at different times of the year and are a beautiful site to behold when in bloom. Gorse will spread rapidly in an area, especially on higher ground. They have the capacity to obtain nitrogen from the soil as the tips of the roots are equipped with nitrogen fixing nodules. Gorse bushes provide excellent breeding habitats for many birds and insects, also some of our rarer flora can be found adjacent to Gorse.
The hedgerows around the village of Cloneen are a beautiful sight in springtime with colourful foliage and bloosoms in abundance to be seen, almost one hundred per cent are native shrubs and trees, or at least are claimed as native as they have been around so long. Hedgerows are very important to biological diversity, as they are safe passageways for wildlife. They host an incredible amount of plants and insect life, and some are adjoined by wet areas and streams, which makes them much more interesting.
FINALLY ON FLORA
Having taken note of the flora of Cloneen and its environs little has changed over the centuries except in the last fifty years. The exotic species mentioned below have made a gradual appearance here and there throughout the locality, mostly in gardens close to dwelling houses, and are dominated by Lawson cypress (Chamaecyparis lawsonina) Grysalenia, Box, laurel, Chilean pine, Poplar, Magnolia, Sycamore, Eucalyptus, Evergreen Oak, Cotoneaster, Snowberry, many gardens today are awash with colourful and exotic flowers, which adds to the biological diversity of the area, these colourful blooms attract Butterflies, Bees and other insects, the foothills of Slievenamon, which is approximately two kilometres from the village, has extensive Conifer plantations with a few broadleaf sections here and there. These woodlands are owned and managed by Coillte, with some smaller plantations in private hands. Overall the exotic species in the Cloneen area and its environs are just a small percentage of the plant species adjacent to the village and if the more invasive plants are kept in check biological diversity will thrive.
Article by: Paddy Clancy, Cloneen