ABSTRACT We investigate the temporal and spatial distribution of pine ( Pinus sylvestris ) stumps preserved in peat deposits to test whether their occurrence can be used as an indicator of climatic shifts to drier conditions. Radiocarbon dates of sub‐fossil stumps were collected from the literature, along with environmental data throughout the island of Ireland. Data were analysed using non‐parametric statistical techniques. There was no distinct geographical pattern observed in the distribution of pine stumps on bog surfaces. Tree ages ranged from 66 to 500 years with 85.7 % of these <300 years. Pines occurred on bogs from ca. 8500 to 500 cal a BP. The temporal distribution during the Holocene was characterized as a mid‐Holocene peak in sites supporting pine, with two gaps either side of this peak. Our current understanding of past climate dynamics failed to explain this temporal distribution. The onset, mid‐Holocene peak and cessation of bog sites supporting the presence of bog pines appears to be driven by changes in pine seed and bog surface area availability during the Holocene rather than changes in climate. We conclude that variability in the occurrence of Irish bog pines is not a valid climate proxy as factors other than climate influence their presence and thereby disrupt the climate signals.
Abstract Aim Native Pinus sylvestris became extirpated in Ireland, during a massive population decline experienced throughout Europe. It was extensively replanted in Ireland during the 18th century from Scottish stock. We test the hypothesis that P. sylvestris in Rockforest Co. Clare did not become extirpated during the P. sylvestris decline, and persisted to present day independent of 18th century plantations. Location Rockforest, Co. Clare in Ireland. Methods Fossil pollen was counted from a terrestrial core. Radiocarbon dates and age‐depth modelling was used to ascertain the core chronology. Loss‐on‐ignition was carried out to investigate sediment accumulation history. Pollen was also counted from moss polster pollen traps to explore the deposition of P. sylvestris pollen in the surrounding landscape. Historical maps were consulted to investigate the longevity of other nearby P. sylvestris populations. Results A continuous record of P. sylvestris is reported. The core extends through the last two millennia, and reports a clear decline of P. sylvestris at c . 1550 cal bp . The P. sylvestris pollen curve recovers quickly after the decline event and persists at high levels up until the present day. The loss‐on‐ignition data reveal a stable accumulation of sediment with no major erosion events. The moss polster pollen traps show the core site is a suitable location for collecting pollen from the Rockforest P. sylvestris population. Historical maps demonstrate that none of the other nearby P. sylvestris populations extends further back than plantations in the early 18th century. Main conclusions The population of P. sylvestris in Rockforest Co. Clare survived the regional P. sylvestris decline, recovered and persisted right up to the present day, independent of introduction by human agency. Hence, we identify this microrefugium population of native Irish stock outside of the current understanding of the native range for this tree species.
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