Tag Archives: biodiversity management
I’m delighted to announce that during a recent trip to explore Clara Bog, I discovered a small population of waved fork-moss (Dicranum undulatum), a plant up until then thought to be extinct in Ireland. It was previously known from only four other raised bogs in Offaly. Last seen in Ireland in 1960, its known sites have been seriously damaged by peat harvesting. The sites and other raised bogs in Offaly that were in reasonable condition were searched fruitlessly for the plant over 2005-2009. Because the only known populations could not be found again and because of the damage caused to raised bogs in the area due to turf cutting, waved fork-moss was judged to be extinct in Ireland in the recent book on the Rare and Threatened Bryophytes of Ireland.
Elsewhere in Europe, waved fork-moss is a plant with a northern distribution found in bogs, poor fens and peatland pine forests. Like Ireland, it is rare throughout most of Europe, except for Scandinavia, and is declining as a result of peat cutting, drainage and afforestation. In Britain, it also mainly grows in intact raised bogs, where it is considered Vulnerable to extinction. Waved fork-moss’s “reinstatement” in Ireland is very good news for nature conservation in Europe as well as Ireland.
The fact that waved fork-moss has been re-found gives us a second chance to conserve a species we thought was extinct. Opportunities like this don’t come around very often. The fact that it’s in Clara Bog makes the job of conservation a little easier, as the bog is a state-owned Nature Reserve and is managed by the National Parks and Wildlife Service. It may be that the work blocking drains and rewetting the bog that has already happened there is responsible for the survival of waved-fork moss.
This little plant is a perfect example of the biodiversity that can be lost if we fail to conserve and restore our raised bogs. Waved fork-moss and other bog specialists can only survive on wet, intact bogs, which are rapidly vanishing from the Irish landscape. The National Raised Bog Special Areas of Conservation Management Plan and the National Peatlands Strategy, soon to be finalised, may give us a second chance to conserve our raised bog resource. But they will only be up to the task if they are robust and properly implemented. We won’t have many more chances.
Special thanks to Gordon Rothero of the British Bryological Society for confirming my identification.
UPDATE: The Irish Times ran an article on this on 19 June, which you can see at this link.
UPDATE 2: And the Tullamore Tribune ran a nice article with some pictures. There was a nice closeup of the plant in the print version.
I love talk radio when it’s done well. You can really get a good insight into an issue pretty quickly if you have a knowledgeable and engaging contributor and a good host. It’s even better when the host (or his/her producers) knows a thing or two about the subject and can ask good, probing questions. But after the show comes the hangover. The text lines open, and every gobshite who can work a mobile sends in their opinions. Unfortunately, most are usually about as well considered as a toddler’s opinion on a suitable bedtime. Little gets added to the discussion, except maybe some extra ratings for the station.
To help make decisions about complicated problems, you need to have a good understanding of the issues. Ecologists and conservationists often wonder about how politicians and planners could let that development go there, when that place is so valuable for biodiversity. Oftentimes, bad decision making is the result of bad information. They’ve been told that the site only has an aul’ bunch of snails and swans and sure, can’t you find all the snails you want in your front garden? Other times, incomplete understanding of an issue can lead to unintended consequences. When overgrazing of woodlands becomes a problem, fencing out all the grazing animals is often the solution. But this usually leads to a new set of problems, like a takeover by bramble or holly at the expense of other plant species.
In the Spring 2014 issue of Irish Wildlife, there’s a letter I wrote taking the magazine to task for an article on forest management in an earlier issue. I hadn’t written it with publication in mind, though I did say I was happy for it to be published, and I’m not sure if my main point was well made. The nub of it was that I thought the earlier article wasn’t well-informed and was misleading on several points. And as I’ve been arguing, this sort of thing can be bad when trying to sort out complex issues, like sustainable forest management.
Sustainable forest management for production and biodiversity conservation is a complicated subject. There are lots of factors at work and a lot of tradeoffs to be made. If productivity is emphasised too much, then biodiversity suffers. If all forests are managed to maximise biodiversity then productivity will probably drop. The consequence of this is that we will need to import more of our timber and export the sustainability problem. If the forests we are importing from are sustainably managed, then great. But often times, imported timber comes from unsustainably managed tropical forests, or even temperate or boreal forests. The recent suspension of Forest Stewardship Council certification of Swedwood, an Ikea subsidiary, for unsustainable forestry practices in Russia is an example of poor forest management on our doorstep. Growing as much of our own timber in as sustainable way as we can is the most responsible solution.
This trick then is to balance biodiversity and productivity management, which isn’t a simple business. Take the old “conifers vs broadleaves” argument that I’d thought we’d moved past – that non-native conifers are bad for biodiversity and native broadleaves are good. You only need to think of red squirrels and their dependence on conifer forests in the parts of Ireland where grey squirrels have invaded to realise that it’s not that simple. And what about non-native broadleaves? Mature sycamore trees can support high abundances of invertebrates and a pretty good diversity of epiphytes, but sycamore is highly invasive in native woodlands. Native woodlands are undeniably better for biodiversity than plantation forests, but plantations of native trees are not really much better than plantations of non-natives. Generally it depends on what groups of plants, birds or invertebrates you’re interested in. Things like forest structure, age and landscape setting tend to be more important than crop species.
Another difficult decision is what should be the management priorities in which places? Should all the timber production happen in these forests and all the biodiversity conservation happen in those? Or should all forests be managed equally for productivity and biodiversity? Research from forests and a wide range of other ecosystems shows that the relationship between biodiversity and management intensity is not linear. Where biodiversity is high, a small increase in management intensity often results in a significant biodiversity decline. On the other hand, where biodiversity is fairly low, it will take a much greater decrease in management intensity, or increase in restoration conservation efforts, to significantly increase biodiversity. This suggests that it’s much more efficient to focus biodiversity management on conserving and restoring sites that are already in reasonably good shape than to bring all the species-poor sites up to a mediocre level of biodiversity. In sustainable forest management terms, this means conserving native woodlands and other habitats within forests, restoring areas with good potential and establishing new native woodlands in places where they can be readily colonised by nearby native species. This approach has been shown to be better for biodiversity than trying to make sure every hectare of forest has its 1500m2 (15%) biodiversity area.
In order to have the best forests we possibly can, we need to know as much as possible about how they work. The BIOFOREST and PLANFORBIO projects and other research have contributed significantly to the understanding of plantation forest biodiversity and sustainable forest management, but we still need more. Forest management needs to be based on hard evidence, rather than guesses and intuition. Just as importantly, those of us who are debating forest policy and management need to know what we’re talking about if we’re to shed light on the subject instead of blowing smoke.
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.
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.