History of the <I>Pinus sylvestris </I>L. treeline at Creag Fhiaclach was investigated using a palynological approach. A modern pollen rain study demonstrated that the current treeline was detectable from a significant (p < 0.0001) reduction in the <I>Pinus/(Pinus </I>+ <I>Calluna vulgaris </I>(L.) Hull) pollen quotient. Heath vegetation typically has a P/(P + C) pollen quotient of less than 30%. Quotients higher than 30% represent <I>Pinus </I>woodland. A three year study on variation in <I>Calluna </I>flowering with altitude showed that the relative reduction in the <I>Pinus </I>pollen component at the treeline is caused primarily by changes in the density of <I>Calluna </I>flowering rather than <I>Pinus </I>pollen influx. The results have implications for the design of palynological studies, indicating the importance of replication, as well as aiding interpretation of fossil pollen data. Five replicate cores from six altitudes spanning the treeline were subjected to pollen analysis for the historical investigation. Twenty six palynomorphs including four Rhizopod taxa were described. Discriminant analysis was used in addition to quotients to classify the fossil pollen assemblages as either heath or forest types. The palynogical data were reduced using PCA and RDA and showed that a higher treeline may have been previously present at the more sheltered southern end of the treeline. However, an alternative hypothesis, of pollen assemblages similar to those of <I>Pinus </I>forest being produced by relatively infertile <I>Juniperus communis </I>L. canopies, was also tested by looking at the pollen spectra from transects across <I>Juniperus communis </I>patches. Dense patches of <I>Juniperus communis </I>result in pollen assemblages which cannot be distinguished from those of <I>Pinus sylvestris </I>woodland. <SUP>210</SUP>Pb and <SUP>14</SUP>C dates, while indicating stratigraphic validity, gave conflicting evidence for the ages of the peat deposit at Creag Fhiaclach. Evidence from dendrochronology on the site suggests that the <SUP>14</SUP>C dates are more correct and that the peat deposit dates from 1227-940 BP. A model of pollen distribution at the treeline on the basis of modern pollen deposition is proposed. The relative stability of this treeline poses interesting questions about how the treeline established and the inertia of this type of vegetation boundary to changes in climate.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:666125 |
| Date | January 1996 |
| Creators | McConnell, Jennifer |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11107 |
Page generated in 0.0135 seconds