Tag Archives: wetlands
National Heritage Week 2014 is coming up next week, running from 23rd to 31st August. Heritage Week is coordinated by the Heritage Council each year, and they put on a series of events throughout the country celebrating our natural, cultural and built heritage.
This year, I will be running two events at the Dún na Sí Heritage and Amenity Park in Moate, Co. Westmeath. The centrepiece of the park is Westmeath’s only known turlough, a special kind of wetland and natural wonder unique to Ireland.
On Sunday 24th August from 3-5PM, I’ll be hosting a nature walk around the Park. We’ll explore the wildlife of the park, especially the turlough, in a leisurely nature walk. There’ll be flowers, birds, bugs and more. All ages are welcome. We’ll be meeting at the main park entrance by Gráinne Óg.
If that gives you a taste for more, on Saturday 30th August from 2-4PM, we’ll be learning wetland wildflowers. I’ll get you acquainted with some of the wildflowers that grow in the turlough. No experience with wildflowers is necessary, and the event will be suitable for adults and older children. Wear your wellies and bring your enthusiasm!
There’s more information on the events on the National Heritage Week 2014 website. Just follow the links above. I hope to see you there.
An interesting review paper is in press at the journal Ecological Engineering, entitled “Ecological consequences and restoration potential of abandoned wet grassland” (http://dx.doi.org/10.1016/j.ecoleng.2013.05.008). The paper reviews the effects of agricultural abandonment on wet grasslands and assesses the potential for restoring species-rich wet grassland after abandonment. Seventy-one (71) papers on wet grassland abandonment and restoration in continental Europe were reviewed. No Irish (or British) research was reviewed because there apparently haven’t been any relevant studies done here. So what, if anything, can we learn from the situation on the continent and how can it be applied here in Ireland?
In Europe, abandonment of wet grasslands is a significant concern. Although there are no comprehensive data for Ireland, abandonment of Molinia meadows was found to be the most significant threat to the conservation of that special type (Habitats Directive Annex I) of wet grassland. Wet grasslands need regular, extensive rather than intensive management to maintain their conservation value. Grazing or hay-cutting prevents the more competitive grasses from dominating and keeps trees and shrubs from invading. In some situations, it may be a good thing to let a wet pasture revert to woodland. But there are a suite of species that rely on wet, open habitats, including orchids, breeding waders and invertebrates, such as the endangered marsh fritillary butterfly. Abandonment of marginally productive land in Europe is often the result of rural population declines, aging farmers, improved off-farm opportunities, and increased costs in farming marginal lands. The situation in Ireland is exactly the same. Intensification, or agricultural improvement in the form of drainage, fertilisation and weed control, is often the other side of the abandonment coin. Some fields may be abandoned as a result of intensification in other fields when less land is needed to maintain the same levels of productivity. The review found that in many cases, the effects of wet grassland abandonment on biodiversity are apparent in three years. Competitive grasses increase in height and cover and aboveground biomass and litter rapidly accumulate. Tree invasion can happen quickly, or can be delayed for years if dense litter prevents seedling establishment. Smaller species can be quickly eliminated as they lose the competition for light. According to the studies reviewed, the losers frequently include legumes, orchids and fen or meadow species. In general, small, stress-tolerant species decline during abandonment. Natural nutrient enrichment may play a part as biomass formerly removed from a site is instead retained as litter, which eventually breaks down and becomes incorporated into the soil. Although there aren’t any monitoring studies in Ireland that give us detailed data on the biodiversity effects of wet grassland abandonment, the same sorts of changes can be seen across the country.
The good news from the review is that abandoned wet grasslands seem like they can often be successfully restored to good conservation condition. Depending on how long the grassland has been abandoned, the first steps are measures to reverse ecological succession: cutting trees and shrubs and reducing the abundance of dominant grasses, rushes and sedges. Repeated mowing and removal of the cuttings is often the easiest and the most common method. Cattle grazing was also found to be beneficial in most cases. This would also have the benefit of exposing some bare soil by poaching to allow colonisation or regeneration from the seed bank of species that may have vanished from the site. Where dense stands of reeds have invaded, a few studies have attempted more intensive restoration work, such as herbicide use or removal of vegetated turves. In general, restoration can be successful in less than 10 years, where the site’s hydrology remains unchanged or is easily restored and where the soil fertility has not increased. The review concludes that there are four key factors on which success will hinge:
- Seed sources and
- Seed dispersal mechanisms: If a nearby source of colonist species isn’t available or if there are limited opportunities for dispersal via wind, flooding or animals, then introducing lost species through seed sowing or hay-strewing may be required.
- Soil fertility: Grasslands that have been long-abandoned may be nutrient-enriched. Mowing and removal of cuttings will probably be required. In some extreme cases, topsoil removal may be needed.
- Invasive species: Abandonment and disturbance can lead to invasion by exotic plant species. Sometimes, the disturbance caused by restoration activities can open an ironic window to invasion. In an Irish context, Himalayan balsam and giant hogweed are likely to be two of the worst potential invaders in wet grasslands.
Abandonment of wet grasslands is a significant cause of biodiversity loss in Ireland as well as Europe. Changing patterns of land-use are largely responsible. If mechanisms can be found to reverse these changes, such as fit-for-purpose agri-environmental schemes, then it is possible to restore wet grasslands to good conservation status.
I will be running a small beginner’s bryophyte (mosses and liverworts) identification workshop tomorrow for the Clara Bog Visitors’ Centre. It filled up rapidly and there are no places left. Disappointing for those of you who aren’t able to attend, but a sign of great enthusiasm out there for getting to know bryos. The workshop will focus on learning some of the mosses and liverworts of Clara Bog, which are the real ecosystem engineers of the wetland. Maybe someday I’ll write about them in a little more detail, but not yet.
I’m a member of the British Bryological Society (BBS) “which exists to promote a wider interest in all aspects of bryology”. I’m also the regional recorder for County Offaly. That means it’s my responsibility to collect and manage biological records of mosses and liverworts from the county and more generally help the study and conservation of bryophytes. I decided to take on the role of regional recorder for Offaly for a few reasons. One is that trying to get to know the mosses and liverworts of a whole county is a great incentive for getting out there and learning more. Another reason is that Offaly’s bryophytes are very poorly recorded. That means that finding firsts, like first county records of a species, is pretty easy. So I don’t have to work too hard for the lovely warm feeling of accomplishment!
One of the under-recorded parts of Offaly is actually Clara Bog. When I started as regional recorder, the BBS only held records of seven mosses and liverworts from there! This low number of biological records is incredible, because the high conservation value of the bog has long been known. Ecologists have been visiting the bog for years, and it’s been the site of intensive research by Irish and Dutch ecologists and hydrogeologists since the late 1980s. Pages and pages of research reports based on Clara Bog have been produced, and these have resulted in only seven records properly collated in the BBS database. And because the National Biodiversity Data Centre mainly relies on the BBS for its biological records of bryophytes, that means there are only seven records for Clara Bog held by the national clearinghouse for information on biodiversity. Obviously, lots of people have neglected to hand in records of bryophytes (and probably lots of other organisms) to the relevant recording societies and the National Biodiversity Data Centre.
This is a huge problem. Without biological records telling us what species and habitats are present where, it makes it very difficult to make informed decisions. Good biological records are important for telling us what species are rare or declining and thus might need measures put in place to conserve them. Conversely, some species might be thought of as being rare and in need of special protection, when in fact they are simply under-recorded. Good biological records are also important for telling us what sites are of special conservation importance. We need this sort of information to prioritise conservation activities, even more so when the money is tight. If you were to decide whether Clara Bog was worth preserving based solely on bryophyte records, you might look at the seven mosses and liverworts listed as being present in the site and decide no, there’s nothing special there*. And you would be very wrong.
For those ecologists out there reading this, submit your records! All of us, including me, are guilty of sitting on biological records we’ve collected in the course of our work or recreation. Submit them to the National Biodiversity Data Centre or to the relevant recording society. For those of you reading this who hire ecologists, allow and encourage them to submit records from your development sites. The Chartered Institute of Ecology and Environmental Management encourages members to share biological records in its Code of Professional Conduct, as long as commercially sensitive and personal data are safeguarded.
Finally, if you’d really like to help do your bit for the mosses of Offaly, I’ll be leading another beginner’s day out on Saturday 12th October in Charleville Wood for the Offaly Naturalists’ Field Club and BBS Irish Regional Group.
* Well, no. Really you wouldn’t, because one of the records is for Tetraplodon angustatus, narrow cruet-moss, a legally protected species only found in one place in Ireland: Clara Bog. But you see what I mean, right?
Dún na Sí Amenity and Heritage Park
The Dún na Sí Amenity and Heritage Park in Moate, Co. Westmeath is having its official opening this Friday 20th September from 4.30pm. The park is the final work of a dedicated bunch of local volunteers – the Midlands Amenity Park Association – who have been planning this for years. The park has been developed on a bit of former common grazing now owned by Westmeath County Council. It was known as the Cow Park, and it will always be called that by a lot of the locals, though “the Cow Park Park” doesn’t really have that certain ring. You can find out more about the park and the opening on the park’s facebook page.
The amenity part of the park is in the middle of the site, bookended by the heritage parts. One of the heritage bookends is the Dún na Sí Heritage Centre, operated by the local branch of Comhaltas Ceoltóirí Éireann. In the Heritage Centre are replicas of megalithic monuments, traditional cottages, a hedge school, and traditional livestock, and céilís are regularly held there. The other bookend is a bit of dampish grassland that looks rather unassuming these days, but is really the jewel in the park’s heritage crown. It’s actually a turlough, a special type of transient wetland that is virtually unique to Ireland. The Cow Park turlough is one of the few to be found east of the Shannon and is the only confirmed example in Westmeath.
Turloughs are found in karst limestone landscapes, and their name is usually taken to be from the Irish tur lough meaning “dry lake”. In the summertime they are grasslands, usually grazed by cattle. In some turloughs, there is a permanent pond or wetland in the middle. In the wintertime, when the water table rises, turloughs turn into lakes. They fill quickly – over a matter of hours or days – via hollow, water-filled galleries in the bedrock that open out into one or more discrete swallow-holes. These can be hard to spot when the turlough is dry, and it’s unclear where all the Cow Park turlough’s swallow-holes are.
This specific hydrogeological system with its strong seasonality is virtually unique to Ireland (there are reports of a turlough in Wales and some karstic wetlands in Slovenia that are at least very turlough-like). Because of their unusual environmental conditions, they support very special ecosystems rich in plants and invertebrates. The importance of turloughs to European biodiversity is such that they are recognised as a priority habitat in the EU Habitats Directive. This means that many turloughs are officially designated as Special Areas of Conservation, though not the Cow Park (at least yet).
The Cow Park Turlough
It’s confession time here. My wife is from Moate and I spend a lot of time there. I used to go to the Cow Park years ago when I first moved to Ireland, armed with my (then) new copy of Webb’s An Irish Flora, trying to learn all the (to me) foreign plants. I still have a lot of the plants I collected then pressed in a binder (Veronica scutellata, marsh speedwell, is the prettiest of them). Once I got to know most of the plants in the Cow Park, I moved on to other pastures, and I never returned there for a serious look at the place. I knew it flooded in the winter, but so did a lot of places. I never realised it was a turlough. In my defence, though, I’m in good company. There have been a lot of surveys of the Cow Park carried out by competent botanists before and after me. (I’m not naming names here. You know who you are.) It wasn’t until Faith Wilson surveyed the site in December 2011 for an Appropriate Assessment of the amenity park project that she realised that the vanishing lake is really a turlough.
The Cow Park turlough isn’t very big, but it packs a lot in. In the centre is an area of rich fen dominated by bog bean (Menyanthes trifoliata), stoneworts (Chara vulgaris) and pondweeds (Potamogeton species). This is usually permanently wet, but with the wonderful summer we’ve had, it’s completely dry now. All the calcium carbonate that has precipitated out as the water evaporated, like limescale in a kettle, gives the vegetation a bleached look. Hopefully it will recover nicely when the autumn rains raise the water table! Around the central fen is a zone dominated by sedges (Carex nigra, C. disticha, C. hirta and others) with water horsetail (Equisetum fluviatile), lesser spearwort (Ranunculus flammula), water mint (Mentha aquatica) and others. Above this zone are stands of yellow flag (Iris pseudacorus) and species-rich wet grassland. A line of hawthorns (Crataegus monogyna) marks the upper water level. A total of 138 plant species, including stoneworts, mosses and liverworts, have been recorded from the Dún na Sí Amenity and Heritage Park site over different surveys, including my own.
The development of the park adjacent to such a valuable and sensitive ecosystem has meant a lot of challenges and compromises. I have been advising the Midlands Amenity Park Association strike this balance in creating a local recreational amenity while at the same time safeguarding and taking advantage of the natural heritage. For example, it was originally planned to excavate a permanent duck pond where it floods in winter. The discovery of the turlough put an end to that idea! A smaller pond was decided on instead, and some balancing between ecology and access was needed to determine where to place it. Mark Boyle of Murray & Associates has been very flexible with the landscape and planting plans, and I’ve been helping advise on what species are suitable to plant and where. Now that the turlough is no longer grazed by horses as it used to be, a long term management plan is being drawn up to maintain the biodiversity of the site.
Please do come along on Friday if you’re in the area, and see the new Dún na Sí Amenity and Heritage Park with its beautiful turlough yourself. I’ll be there to help show people around and to explain what a fantastic piece of natural heritage they have on their doorstep.