© University of Reading 2008 www.reading.ac.uk

UKAS 2011

2 May 2023

Holocene Hydrological and Vegetation Changes in Ombrotrophic Bogs in Central Ireland: Implications for our Understanding of Climate History and Human ActivitiesYoung, D., Stastney, P., Black, S., Branch, N., Pritchard, O., McCarroll, J. and Whitaker, J.

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Introduction

• Littleton Bog, Co. Tipperary

• Milled peat production bog

• Formerly an ombrotrophic, raised bog

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Littleton Bog• Type site for the

Holocene vegetation history of Ireland (Mitchell, 1956; 1965)

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UKAS 2011Raised peat bogs as archives• Sensitive to changes in

precipitation-evapotranspiration balance since they are ombrotrophic, or literally ‘cloud-fed’ systems free from the influence of groundwater

• So a record of bog surface wetness can be a record of climate (precipitation and temperature) change

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Archaeology

Plank trackway2972-2789 cal BP

Brushwood trackway1865-1596 cal BP

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Methods• Loss-on-ignition• Humification

• Radiocarbon dating • Plant macrofossils• Pollen• Testate amoebae• Oxygen, carbon and hydrogen isotopes

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ca. 5 yr/cm

ca. 42 yr/cm

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Results: Plant Macrofossils

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• Oligotrophic transitional bog during LTN 1, LTN 2

• Drier raised mire during LTN 3; Increasingly wet during LTN 4; drier in LTN 5; increased wetness during LTN 6

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Results: Pollen

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• Stable bog surface during pollen zone 1• Hazel/bog myrtle declines during 2a-2b,

grasses/Sphagnum increase• Sphagnum/grasses decline, increased heath, pine

during 2c

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Results: Testate Amoebae

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Reconstructed water table curve produced using Charman et al. (2007) transfer function, with thanks to Dan Charman, University of Exeter.

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Results: Stable Isotopes

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Composite diagram

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Medieval Warm Period

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Medieval Warm Period

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Bond events

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Bond events and trackways

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Dated archaeology at Littleton

• 13 structures dated:– 9 trackways– 4 platforms

• Apparently 2 main phases:– 3 earlier structures

are all constructed from Oak planks

– Later structures constructed from roundwood.

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Dated structures at Littleton

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Conclusions• Multi-proxy analysis from Littleton Bog shows

that evidence for climatic forcing of changes in the ecology of the bog.

• There is a link between changes in the circulation in the North Atlantic, and changes in effective precipitation at Littleton.

• These changes may have driven a series of bog bursts.

• Human activity on the bog adapted to these changes.

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