Development and refinement of proxy-climate indicators from peats

Abstract

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 11364 The Netherlands a b s t r a c t Peat, especially from acidic mires (bogs), is a natural archive of past environmental change. Reconstructions of past climate from bogs commenced in the 19th Century through examination of visible peat stratigraphy, and later formed the basis for a postglacial climatic scheme widely used in Northwest Europe. Nevertheless, misconceptions as to how bogs grow led to a 50-year lacuna in peat-climate study, before the concept of 'cyclic regeneration' in bogs was refuted. In recent decades, research using proxyclimate indicators from bogs has burgeoned. A range of proxies for past hydrological change has been developed, as well as use of pollen, bog oaks and pines and other data to reconstruct past temperatures. Most of this proxy-climate research has been carried out in Northern Europe, but peat-based research in parts of Asia and North America has increased, particularly during the last decade, while research has also been conducted in Australia, New Zealand and South America. This paper reviews developments in proxy-climate reconstructions from peatlands; chronicles use of a range of palaeo-proxies such as visible peat stratigraphy, plant macrofossils, peat humification, testate amoebae and non-pollen palynomorphs; and explains the use of wiggle-match radiocarbon dating and relationship to climate shifts. It details other techniques being used increasingly, such as biomarkers, stable-isotopes, inorganic geochemistry and estimation of dust flux; and points to new proxies under development. Although explicit protocols have been developed recently for research on ombrotrophic mires, it must be recognised that not all proxies and techniques have universal applicability, owing to differences in species assemblages, mire formation, topographic controls, and geochemical characteristics.

Re-assessing the vertical distribution of testate amoeba communities in surface peats: Implications for palaeohydrological studies

“…Sub-samples from one half were used to determine moisture content, bulk density and colorimetric peat humification, while those from the other half were stained using Rose Bengal and used for testate amoeba analysis. Samples were oven dried at 105°C for 24 hours and re-weighed to determine moisture content (Chambers et al 2011). A known volume of peat was also measured at 1 cm intervals and oven dried at 105°C for 24 hours, then weighed to determine bulk density (Tolonen et al 1992).…”

Comparative ecology of vascular plant, bryophyte and testate amoeba communities in four Sphagnum peatlands along an altitudinal gradient in Switzerland

“…This has led to their use in the study of primary (e.g. palaeoecological records, Chambers et al, 2012;Charman, 2001;McMullen et al, 2004) and secondary succession (Talbot et al, 2010). Testate amoebae are increasingly considered as a useful tool for peatland bio-monitoring and management (Davis and Wilkinson, 2004;Mitchell et al, 2008;Turner and Swindles, 2012).…”

Deciphering human–climate interactions in an ombrotrophic peat record: REE, Nd and Pb isotope signatures of dust supplies over the last 2500years (Misten bog, Belgium)

“…Peatlands (i.e., soils accumulating partially decomposed plant remains with above 50% of organic matter and greater than 30 cm deep, Clymo, 1987) are continental archives of particular interest because they are easy to date, have a high temporal resolution (decadal) and contain multiple measurable parameters dependent on environmental conditions including temperature and/or humidity, atmospheric circulation and wind strength (e.g., Chambers et al, 2012). In particular ombrotrophic bogs are commonly used to reconstruct Holocene climate variability (e.g., Dupont, 1986;Hong et al, 2000;Shotyk et al, 2002;Mauquoy et al, 2002;Chambers and Charman, 2004;Roos-Barraclough et al, 2004;Sapkota et al, 2007;Lamentowicz et al, 2008;Moschen et al, 2011;Kylander et al, 2013).…”