Holocene vegetation and flora dynamics of the west Cork/Kerry region, south-western Ireland

Vegetation History and Archaeobotany https://doi.org/10.1007/s00334-024-00998-6 ORIGINAL ARTICLE Holocene vegetation and flora dynamics of the west Cork/Kerry region, south‑western Ireland Michael O’Connell1 · Anette Overland1,2 Received: 29 November 2023 / Accepted: 14 April 2024 © The Author(s) 2024 Abstract Sediments from a small lake, Loch Beag, in Barrees, Beara peninsula, south-western Ireland, provide a record of vegetation history that spans most of the Lateglacial and Holocene (14–0.43 ka). The detailed part of the record relates to the Holocene, which is the focus of this paper. The investigations carried out include pollen and macrofossil analyses, loss-on-ignition measurements and 14C dating. As well as providing records for tree and shrub taxa, and especially Pinus, Quercus, Ulmus, Fraxinus and Taxus, other taxa mainly with Atlantic and/or Lusitanian distributions are also considered. These include Arbutus unedo (strawberry tree) and fern species such as Osmunda regalis, and the filmy ferns Hymenophyllum tunbrigense, H. wilsonii and Trichomanes speciosum (Killarney fern). Detailed records for a suite of bog/heath taxa, including ericoid species (Erica tetralix and E. cinerea), Narthecium ossifragum, Hypericum elodes and Myrica gale, are presented. The results of 14C dating of bog-pines from western Ireland are summarised. Results of other investigations, including key Holocene pollen diagrams, and charcoal and fossil-wood records from archaeological excavations that relate mainly to the Bronze Age in the wider west Cork/Kerry region, are reviewed. Vegetation dynamics, human impact and plant biogeography are discussed in the light of the considerable data now available for the region. Keywords Holocene · Pollen analysis · Macrofossil analysis · Woodland dynamics · Human impact · Plant biogeography · Ireland Introduction South-western Ireland, consisting of a series of peninsulas, is a distinctive region as regards climate, geomorphology, floristics and vegetation (Fig. 1). There is also substantial evidence for a human presence starting in the Mesolithic and particularly from the Neolithic/Bronze Age transition onwards (O’Brien 2009; Aalen et al. 2011). The region has a pronounced oceanic climate with mild winters, warm summers, infrequent frosts, and high precipitation distributed evenly throughout the year (see Study area). The geology Communicated by F. Bittmann. * Michael O’Connell 1 Palaeoenvironmental Research Unit, School of Geography, Archaeology and Irish Studies, University of Galway, Galway, Ireland 2 Present Address: Department of Natural History, University Museum, University of Bergen, Bergen, Norway is dominated by Devonian sandstone, often referred to as ‘Old Red Sandstone’ (Pracht 1997; Pracht and Sleeman 2002). There is a considerable exposure of Carboniferous limestone in the Killarney area including the Muckross peninsula, where the karstic limestone supports a Taxus (yew) woodland of some 25 ha (Kelly 1981). The upland character and north-east/south-west grain of the landscape was created by the Variscan (Armorican) orogeny towards the end of the Carboniferous period. This folding resulted in the creation of a metalliferous zone of copper, manganese and barites, that became the basis for Bronze Age and later copper mining in west Cork and Kerry (Kinnaird and Nex 2004). During the Weichselian, i.e. the last Ice Age (Midlandian in Ireland), the whole area was subject to severe glaciation that shaped and scoured the uplands, and resulted in considerable glacial deposits especially in the Killarney and Bantry areas (Ballantyne et al. 2011). The region is rich in periglacial features, and in the Beara peninsula solifluction lobes and involutions, of possible Younger Dryas age, are recognized (Coxon 1997; Harrison et al. 2010). Vol.:(0123456789) Vegetation History and Archaeobotany Fig. 1  A Map of Ireland. County boundaries and the study region shown in B are indicated. B The study region, i.e. part of Counties Kerry and Cork. Locations of the main pollen diagrams (including profiles by Vokes 1966; V1: Muckross Bog; V2: Ladies View) discussed in the text and selected prehistoric copper mines (Ross Island, Crumpane and Mount Gabriel; also Arderrawinny and Derrycarhoon) are indicated. Various geographical features, including roads, lakes and rivers, are shown. C Aerial photograph (detail of the Beara peninsula centred on Barrees; source: Google Earth, accessed November 2023) showing location of the pollen profiles, and archaeological sites for which charcoal data are available (sites are referred to by the letter given in parentheses). FF fulacht fiadh (burnt mound) As regards vegetation, the region is renowned for its Atlantic, temperate rainforests, including the yew woodlands at Muckross (see above) and especially the Quercus petraea-dominated woodlands that find best expression on sandstone in Killarney National Park, Ireland’s first and premier National Park (Kelly 1981; Cross 2006; Fig. 1). Pockets of fern and bryophyte-rich oak woodlands exist, such as at Glengarriff, and also in other parts of the Beara peninsula including that recently created as a result of the rewilding project by conservationist, Eoghan Daltun (2022). Bog, and especially blanket bog, forms extensive tracts throughout the region. Indeed, blanket bog and heath dominate most of the uplands. Vegetation History and Archaeobotany As regards floristics, the region is noted for its eu-Atlantic and Lusitanian elements (Webb 1983). Particularly noteworthy are the filmy ferns, Hymenophyllum tunbrigense, H. wilsonii and Trichomanes speciosum, i.e. the so-called Killarney fern (Richards and Evans 1972; Ratcliffe et al. 1993). Lusitanian species include Arbutus unedo (strawberry tree) which occurs in many of the oak (Quercus) and yew (Taxus) woodlands (e.g. Killarney, Glengarriff and elsewhere; Sheehy Skeffington and Scott 2021; Scott and Sheehy Skeffington 2022), Euphorbia hiberna, Saxifraga spathularis and Pinguicula grandiflora which are common, and the rare Simethis planifolia (S. mattiazzii) which, in Ireland and Britain, is known only from the Iveragh and Beara peninsulas (Lupton and Sheehy Skeffington 2020; Stroh et al. 2023). A recent discovery is the tropical fern, Stenogrammitis myosuroides (Sw.) Labiak, in Killarney National Park, the spores of which have probably been wind-transported from the Carribean (Hodd and Rumsey 2020). The main focus of this paper is the Beara peninsula which straddles the county boundaries of Cork and Kerry (Fig. 1). Nearby areas that share many of the same archaeological, geographical and vegetational features are also considered, and especially Iveragh peninsula to the north which includes the Killarney National Park, and Mizen peninsula to the south, a mainly upland area noted for its Bronze Age copper mines including those associated with Mount Gabriel (MG) (O’Brien 1994, 1999, 2003, 2004, 2009, 2015, 2022). The Beara (...truncated)