Mineral deficiency and the prescence of Pinus sylvestris on mires during the Mid- to Late Holocence: palaeoecological data from Cadogan's Bog, Mizen Peninsula, Co. Cork

Timothy Michael Mighall, J. G. A. Lageard, F. M. Chambers, M. H. Field, P. Mahi

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Abstract

Pollen records across parts of Ireland, England and northern Scotland show a dramatic collapse in Pinus pollen percentages at approximately 4000 radiocarbon years BP. This phenomenon has attracted much palaeoecological interest and several hypotheses have been put forward to account for this often synchronous and rapid reduction in pine from mid-Holocene woodland. Explanations for the 'pine decline' include prehistoric human activity, climatic change, in particular a substantial increase in precipitation resulting in increased mire wetness, and airborne pollution associated with the deposition of tephra. Hitherto, one largely untested hypothesis is that mineral deficiency could adversely affect pine growth and regeneration on mire surfaces. The discovery of pine-tree remains (wood pieces, stumps and trunks) within a peat located at Cadogan's Bog on the Mizen Peninsula, southwest Ireland, provided an opportunity to investigate the history of Pinus sylvestris and also to assess the importance of mineral nutrition in maintaining pine growth on mires. Pollen, plant macrofossils, microscopic charcoal and geochemical data are presented from a radiocarbon dated monolith extracted from this peat together with tree ring-width data and radiocarbon dated age estimates from subfossil wood. Analyses of these data suggest that peat accumulation commenced at the site around 6000 years BP when pine was the dominant local tree. Thereafter Pinus pollen percentages diminish in two stages, with the second decline taking place around 4160 +/- 50 years BP. Concomitant with this decline in Pinus pollen, there is a noticeable, short-lived increase in wet-loving mire taxa and a decrease in the concentration of phosphorus, potassium, magnesium, calcium, sodium, iron and zinc. These results suggest that increased mire surface wetness, possibly the result of a change in climate, created conditions unsuitable for pine growth c. 4000 years BP. Mire surface wetness, coupled with a period of associated nutrient deficiency, appears to be a possible explanation for a lack of subsequent pine-seedling establishment for most of the later Holocene.

Original languageEnglish
Pages (from-to)95-110
Number of pages15
JournalThe Holocene
Volume14
Issue number1
DOIs
Publication statusPublished - 2004

Keywords

  • Pinus sylvestris
  • pine decline
  • pine pollen
  • dendrochronology
  • subfossil wood
  • peat chemistry
  • mineral deficiency
  • Mizen Peninsula
  • southwest Ireland
  • Holocene
  • SCOTS PINE
  • NORTHERN SCOTLAND
  • VOLCANIC ACTIVITY
  • AGE CALIBRATION
  • LODGEPOLE PINE
  • SUBFOSSIL PINE
  • BRITISH-ISLES
  • TRACE-METALS
  • DRAINED PEAT
  • SW IRELAND

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