Scots pine (Pinus sylvestris) dynamics in the Welsh Marches during the mid to late-Holocene

Dael Sassoon,Alastair Hotchkiss,Liting Feng,William J Fletcher,Fern Owen

doi:10.1177/0959683621994654

Abstract

Around 4000 cal yr BP, Scots pine ( Pinus sylvestris) suffered a widespread demise across the British Isles. This paper presents new information about P. sylvestris populations found in the Welsh Marches (western central Britain), for which the long-term history and origins are poorly known. Two new pollen records were produced from the Lin Can Moss ombrotrophic bog (LM18) and the Breidden Hill pond (BH18). The LM18 peat core is supported by loss-on-ignition, humification analysis and radiocarbon dating. Lead concentrations were used to provide an estimated timeframe for the recent BH18 record. In contrast to many other Holocene pollen records from the British Isles, analysis of LM18 reveals that Scots pine grains were deposited continuously between c. 6900–300 cal yr BP, at frequencies of 0.3–5.4%. It is possible that individual Scots pine trees persisted through the wider demise on thin soils of steep drought-prone crags of hills or the fringes of lowland bogs in the Welsh Marches. At BH18, the record indicates a transition from broadleaved to mixed woodland, including conifer species introduced around AD 1850 including Picea and Pinus. The insights from BH18 suggest that the current populations may largely be the result of planting. Comparison of the LM18 findings with other regional pollen records highlights consistent patterns, including a Mid-Holocene maximum (ca. 7000 cal yr BP), long-term persistence at low pollen percentages and a Late-Holocene minimum (ca. 3000 cal yr BP). These distinctive trends encourage further studies on refugial areas for Scots pine in this region and elsewhere.

Highlights

Since its arrival in the early Holocene after the onset of full interglacial conditions, between approximately 11,000–10,000 cal yr BP, Pinus sylvestris spread rapidly across the British Isles and reached its maximum extent ~4500 cal yr BP (Bennett, 1984; Birks, 1989; Birks et al, 1975; Kinloch et al, 1986)
This study aimed to improve understanding of the ecological history of Scots pine populations found in the area of the Welsh marches around Breidden Hill in Powys and Nesscliffe Hill in Shropshire
The LM18 pollen record includes a continuous curve for Pinus between 0.3% and 5.4%

Summary

Introduction

Since its arrival in the early Holocene after the onset of full interglacial conditions, between approximately 11,000–10,000 cal yr BP, Pinus sylvestris spread rapidly across the British Isles and reached its maximum extent ~4500 cal yr BP (Bennett, 1984; Birks, 1989; Birks et al, 1975; Kinloch et al, 1986). Palaeoecological data, shows that P. sylvestris suffered a widespread demise around 4000 cal yr BP (Gear and Huntley, 1991). While this demise was sudden in places, an increasing body of research has demonstrated that the timing and nature of this event are far from uniform (Blackford et al, 1992; Edwards et al, 1996; Edvardsson et al, 2016; Hall et al, 1994, 1996; Lageard et al, 1999, Payne et al, 2013). In the British Isles, one such debate revolves around the range of native P. sylvestris outside of the Scottish Highlands (Manning et al, 2010)

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