Figure 2. Focal habitat and species restoration issues in the Irish national parks. (A) One of the last native stands of Scots pine (Pinussylves tris) woodland in Ireland and Lough Veagh at Glenveagh National Park. (B) Red deer (Cervus elaphus) stag, one of the first and most prominent and successful species restorations in Ireland. (C) Pontic rhododendron (Rhododendron ponticum, flowering evergreen shrub on right bank) invades a riparian forest, displacing native species at Killarney National Park. Pontic rhododendron is possibly the greatest threat to native biodiversity in the Irish national parks, because it competitively excludes most native plant species. (D) A golden eagle (Aquila chrysaetos) chick at Glenveagh National Park. Golden eagle introductions are the highest-profile species restoration in the last two decades in Ireland.
Because many of Ireland’s native predators were extirpated by the 19th century, species restorations have become a major conservation goal. National parks have been focal areas for the direct introductions of native wildlife, including the iconic red deer (Cervus elaphus, a close relative to the North American elk; fig. 2B). This species was restored to Glenveagh National Park in the late 19th century from populations in Britain and Ireland (GNP 2008). Raptor restoration has been a major focus in recent years, including the golden eagle (Aquila chrysaetos) at Glenveagh in 2001 (O’Toole et al. 2002), the white-tailed sea eagle (Haliaeetus albicilla) at Killarney National Park in 2007, and the red kite (Milvus milvus) in Wicklow Mountains National Park in 2007. To date, population recovery rates of most raptors are low. Major sources of mortality include poisoning, vehicle accidents, and illegal hunting. However, the first golden eagle chicks in more than a century fledged in 2007 at Glenveagh (fig. 2C), and scientists are hopeful that these native-born birds will fare better than introduced juveniles. Only time will tell.
Other restoration needs in the Irish national parks include active and passive approaches to wetland and riparian restoration, forest restoration, and control of invasive plant species. The introduced Pontic rhododendron (Rhododendron ponticum), which competitively excludes native plants, is perhaps the greatest threat to biodiversity in the Irish national parks, and it has proven to be a strong invader of forests, moorlands, and riparian environments (fig. 2D). In contrast, some introduced species and communities are yielding beneficial ecological surprises. Plantations of introduced conifers, such as Sitka spruce (Picea sitchensis), which are rightly viewed as ill-conceived by many because they are not native to the British Isles, apparently provide important surrogate habitat for some forest-dependent species, including the pine martin (Martes martes) and the hen harrier (Circus cyaneus). Such observations reinforce a need for precaution, but also provide hopeful signs that native biodiversity can be resilient.
In other cases, the restoration of native species has had substantial negative effects on some habitats. Restoration research at both Glenveagh and Ballycroy using grazing exclosures of varied sizes has demonstrated that red deer and livestock tend to decrease the abundance of ling heather (Calluna vulgaris) and expand the dominance of purple moor grass (Molinia caerulea), and that heather can recover with short-term exclusion of native grazers and introduced livestock (fig. 3). However, long-term exclusion of red deer has also been observed to favor increases in the cover of grazing-resistant purple moor grass, which forms a heavy thatch that limits recruitment of native trees (Millar, unpublished data) and has less habitat value than heather. Some of these grazing impacts may be due to the current lack of large predators (wolves) in the Irish landscape, which is unlikely to change anytime soon. Restoration of a full diversity of habitats, therefore, will likely require long-term commitments to wildlife population management as well as innovative grazing management through the use of exclosures, movement of animals, or targeted grazing with other ungulates (e.g., sheep, goats, or cattle).
[Photo of a research grazing exclosure at Ballycroy National Park. The dark vegetation is ling heather and the pale tufted grass around the exclosure is purple moor grass. Ling heather is critical habitat for the native red grouse, and research into the effects of both native (red deer) and nonnative grazers (sheep) on habitat availability helps the park balance rural livelihoods and native species conservation. Credit: Cameron Clotworthy]
Figure 3. A research grazing exclosure at Ballycroy National Park enabled scientists to understand the effects of grazing on vegetation by red deer. The dark vegetation in the exclosure is ling heather (Calluna vulgaris) and the pale tufted grass around the exclosure is purple moor grass (Molinia caerulea). Ling heather is critical habitat for the native red grouse (Lagopus lagopus scoticus), and research into the effects of both native (red deer) and nonnative grazers (sheep) on habitat availability helps the park balance rural livelihoods and native species conservation.
A marked decline in the populations of red grouse (Lagopus lagopus scoticus) across Ireland and in the approximately 25,622 hectares (63,313 ac) Owenduff/Nephin Complex Special Protection Area (CSPA) surrounding Ballycroy National Park is believed to have been caused by a combination of depredation and habitat loss. In particular, excessive grazing by domestic sheep has led to declines in ling heather height and cover, important dimensions of red grouse habitat (Murray et al. 2013). In 2006 the decision to remove sheep in winter for five months, split between late fall and early spring, allowed an improvement in habitat condition and a doubling in red grouse numbers (362–426 individuals in 2002 vs. 790–832 individuals in 2012) across the Owenduff/Nephin CSPA (Murray et al. 2013). The success of this innovative approach may have broad implications for red grouse habitat management in Ireland.
Implications for biodiversity
These examples provide only a brief sketch of the challenges of restoring biodiversity in long-settled lands such as Ireland. These are rarely settings where absolutes and complete solutions can be implemented successfully in one effort. In Ireland, initial work ranged from largely successful (red deer restoration) to highly challenging (raptor restorations). Of course, there are also unintended consequences of restoration that can be both good and bad. A critical element in such a comprehensive restoration program is the strategic pursuit of an adaptive research and long-term monitoring capacity to help park managers and partners track the success of their efforts. Current monitoring and research have focused on a subset of species (red deer) through agency and collaborative public and nongovernmental efforts (raptors). The first author con ducted the field research for this article in 2008 on a Fulbright Fellowship, just before the onset of the global economic crisis. Since that time, Ireland has endured great economic challenges, and is currently struggling to rebuild and expand its conservation research and monitoring capacity in a fiscally difficult time. Professional exchanges, in which scientists share ideas for inventory, monitoring, and research, are likely to be valuable for sharing insights and techniques in biodiversity restoration across differing environmental and cultural settings.
We conclude that national parks in long-settled lands like Ireland present interesting and compelling challenges for biodiversity conservation. They serve not only as important anchors of ecological restoration but also as windows on a vanished past and catalysts for human well-being today. Reestablished wildlife species and ecosystems provide potent and inspiring symbols of conservation for present and future generations. These examples from Ireland demonstrate the importance of park-based restoration programs to foster environmental awareness and conservation commitment in an ancient yet continuously evolving landscape. They also reinforce the importance of long-term commitment to inventory, monitoring, and adaptive research to ensure that such ef forts succeed and biodiversity is restored.
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About the authors
Daniel Sarr (firstname.lastname@example.org) developed this article while working with the National Park Service’s Klamath Network Inventory and Monitoring Program, Ashland, Oregon, USA, with support from the Irish American Fulbright Commission. He is now a research ecologist with the U.S. Geological Survey’s Grand Canyon Monitoring and Research Center in Flagstaff, Arizona. Cameron Clotworthy is with Ballycroy National Park, Westport, County Mayo, Ireland. Robbie Millar is with Glenveagh National Park, Churchill, Letterkenny, County Donegal, Ireland.