Climate change during the past 1000 years: a high‐temporal‐resolution multiproxy record from a mire in northern Finland

Abstract

We present a record of peatland development in relation to climate changes and human activities from the Palomaa mire, a remote site in northern Finland. We used fine‐resolution and continuous sampling to analyse several proxies including pollen (for vegetation on and around the mire), testate amoebae (TA; for mire‐wetness changes), oxygen and carbon isotopes from Sphagnum cellulose (δ18O and δ13C; for humidity and temperature changes), peat‐accumulation rates and peat‐colour changes. In spite of an excellent accumulation model (30 14C dates and estimated standard deviation of sample ages <1 year in the most recent part), the potential to determine cause–effect (or lead–lag) relationships between environmental changes and biotic responses is limited by proxy‐specific incorporation processes below the actively growing Sphagnum surface. Nevertheless, what emerges is that mire development was closely related to water‐table changes rather than to summer temperature and that water‐table decreases were associated with increasing peat‐accumulation rates and more abundant mire vegetation. A rapid fen‐to‐bog transition occurred within a few years around AD 1960 when the water table decreased beyond the historical minimum, supporting the notion that mires can rapidly shift into bogs in response to allogenic factors. Copyright © 2012 John Wiley & Sons, Ltd.

Estimation of pollen deposition time-span in moss polsters with the aid of annual pollen accumulation values from pollen traps

“…Clymo and MacKay (1987) found that vertical water movement affected the distribution of pollen and spores in Sphagnum peat under laboratory conditions, but the results were difficult to extrapolate to the field. Recent investigations from high temporal resolution fossil pollen profiles (Finsinger et al 2013) provide strong evidence that movement of pollen down the profile does not occur. Cundill (1986) introduced another type of pollen trap with an artificial pollen collecting medium (galvanised steel wire mesh and acetate wool) that is as similar to a moss surface as possible and does not trap insects, mammals and amphibians (Cundill 1998).…”

Reconstructing climate change and ombrotrophic bog development during the last 4000years in northern Poland using biotic proxies, stable isotopes and trait-based approach

“…Within the Kusowo Sphagnum peat multiproxy approach presented here we wanted to test whether stable carbon isotopes of bulk Sphagnum peat can be used as qualitative indicator of mire surface wetness (Finsinger et al, 2013).…”

Environmental and taxonomic controls of carbon and oxygen stable isotope composition in &lt;i&gt;Sphagnum&lt;/i&gt; across broad climatic and geographic ranges

“…When not submerged, carbon isotope signals in bulk tissues or components such as cellulose depend mainly on the [CO2] in the chloroplast ([CO2]c), which alters isotope discrimination during biochemical fixation of CO2 and by fractionation caused by diffusion to the chloroplast (Farquhar et al 1989, O'Leary 1988. In mosses, [CO 2]c has been shown to be determined by temperature, light availability, CO2 partial pressure and, most importantly, plant water status (Finsinger et al 2013, van der Knaap et al 2011, Ménot and Burns 2001, Ménot-Combes et al 2004, Royles et al 2014, Skrzypek et al 2007a, Kaislahti Tillman et al 2013. When wet, external water films on leaf surfaces impede diffusion and…”