Conifer pollen abundance provides a proxy for summer temperature: evidence from the latitudinal forest limit in Finland

Abstract

Huusko, A. and Hicks, S. 2009. Conifer pollen abundance provides a proxy for summer temperature: evidence from the latitudinal forest limit in Finland.ABSTRACT: A 23-year record of pollen deposition (pollen accumulation rates: PARs) indicates that pollen production of the two most common northern boreal conifers -pine and spruce -varies dramatically from year to year and that high and low pollen years show consistency over the whole of northern Lapland. Testing for a calibration between the annual PARs of these two trees and a whole range of meteorological parameters reveals that the highest correlation is between pollen quantity and summer temperature centred around July of the year before pollen emission. Critical mean July temperature limits for the flowering of Pinus and Picea are 128C and 138C, respectively. This strong and region-wide relationship suggests that fossil Pinus and Picea PARs could be used as a proxy for summer temperature. Results are illustrated as maps showing the relationship between forest limits and July temperature and between PARs and the correlation coefficient with July temperature. It is noticeable, however, that although the climate signal is strong at the forest limit of the taxon in question, it is often weaker in the centre of its ecological range. This has implications when interpreting fossil pollen records. Temperature calibrations will vary spatially as the position of the forest limit changes.

Pollen–vegetation relationships for pine and spruce in southeast Poland on the basis of volumetric and Tauber trap records

“…This may indicate the strong influence of climatic conditions on spruce pollen production. The studies of Autio and Hicks (2004) and Huusko and Hicks (2009) in Finland and of Van der Knaap and Van Leeuwen (2003) in Switzerland produced comparable results. The latter authors found that summer drought was essential for abundant pollen deposition of Picea in the following year.…”

“…Annual pollen sums of both taxa demonstrate large year-to-year variation, which is controlled mainly by climatic factors such as summer temperature of the year before pollen emission (e.g. Hicks, 2001; Van der Knaap et al, 2001;Autio & Hicks, 2004;Pidek et al, 2008;Huusko & Hicks, 2009). On several occasions during pollen monitoring in Roztocze, as part of the PMP, no spruce pollen was recorded in the regional trap.…”

The effect of climate conditions on inter-annual flowering variability monitored by pollen traps below the canopy in Draved Forest, Denmark

“…In Finland (Hicks 2006;Huusko and Hicks 2009;Kuoppamaa et al 2009), Northern Sweden (Barnekow et al 2007) and the Alps (Kamenik et al 2009) efforts are made to use PAR from fossil records to reconstruct past climate, specifically summer temperatures. This requires high resolution records with good temporal control, because only near-annual variations in PAR can be expected to reflect variations in temperature or precipitation in the way pollen trap records do.…”

Pollen signals of ground flora in managed woodlands

“…Whilst these methods do reduce the effects of climate-related inter-annual variability in plant flowering (e.g. Huusko and Hicks, 2009;Jackson and Kearsley, 1998), they would have blurred the signal of the coppice cycle which we seek to study due to variability in the ground vegetation throughout a coppice cycle being greater than the climatic influence between consecutive years (e.g. Waller, at al.…”