Strong correlation between summer temperature and pollen accumulation rates for Pinus sylvestris, Picea abies and Betula spp. in a high resolution record from northern Sweden

• Published in: Journal of Quaternary Science
• Main Authors: Barnekow, Lena, Loader, Neil J., Hicks, Sheila, Froyd, Cynthia A., Goslar, Tomasz
• Format: Article in Journal/Newspaper
• Language: English
• Published: John Wiley & Sons Inc. 2007
• Subjects: Geology; temperature reconstruction; PAR; high resolution pollen record; Monolith; The Monolith; Northern Sweden
• Online Access: https://lup.lub.lu.se/record/740789; https://doi.org/10.1002/jqs.1096

Highly resolved pollen spectra analysed from a 47cm peat monolith recovered from a mire in northern Sweden exhibit climatic sensitivity in the pollen accumulation rates (PAR) of boreal treeline species. Robust temporal control, afforded through multiple AMS radiocarbon dating of the post atomic bomb-test period (AD1961-AD2002), provides a unique opportunity to compare pollen accumulation rates with the instrumental meteorological record. A series of strong correlations are observed between summer temperature and PAR for Pinus sylvestris, Picea abies and Betula spp. (excluding B. nana). Despite well constrained, contiguous (“annual”) sampling, the temporal resolution of the pollen signal preserved within each sample appears to be degraded to ca. 3-5 year resolution. This is likely to reflect processes occurring during peat accumulation and pollen deposition, as well as dating uncertainties and the effects of sub-sampling. These findings identify limitations to the maximum resolution that may realistically be recovered from the peat archive using high resolution sampling protocols and AMS 14C dating. We also identify the need for additional work to quantify the role of climate on peat accumulation and the resultant impact on assemblage based palaeoenvironmental reconstructions within mire sequences. The strongest climate association observed for Picea abies (r2adjusted = 0.53; n=36), was extended through the monolith beyond the 42 year period of “annual” sampling and the response successfully correlated with the Bottenviken historical instrumental record to AD1860. Although only presenting data from a single site, and requiring wider replication, we conclude that for sites close to the ecological limits of tree species, where levels of anthropogenic/non-climatic forcing on pollen production are low, well-dated records of PAR may potentially provide a proxy for reconstructing past summer temperature variability.