Refining CLAMP — Investigations towards improving the Climate Leaf Analysis Multivariate Program

Abstract

Abstract:CLAMP (Climate Leaf Analysis Multivariate Program) has been used for the past 17 years to estimate palaeoclimatic conditions. The reliability and applicability of this method, based on leaf physiognomic characters of fossil woody dicots, has been widely discussed over the same period. The present study focuses on some technical aspects of CLAMP, mainly on its robustness in the context of the theoretical unimodal requirements of Canonical Correspondence Analysis, and introduces "correction coefficients" for these aspects of the statistical approach as a new way of interpreting and improving on CLAMP estimates. This tool was tested on datasets derived from 17 European fossil floras ranging in age from the Late Oligocene to the Pliocene. Additionally, an objective statistical method for the selection of the best-suited modern vegetation dataset from 144 site (Physg3br) or 173 (Physg3ar) extant biotopes is proposed.

Regional chemostratigraphic key horizons in the macrofossil-barren siliciclastic lower Miocene lacustrine sediments (Most Basin, Eger Graben, Czech Republic)

“…This would assign the so-called micaceous facies (Kvaček & Teodoridis 2007, Teodoridis 2010, fossiliferous sediments just above the main coal seam at the Krušné Hory Mts edge, to be deposited isochronously with the uppermost part of the Holešice Member in the Bílina depocentre before the whole-basin Libkovice lake stage. Our findings and a new definition of the Holešice and Libkovice members can have relevance for the evaluation of palaeoenvironmental reconstructions made recently by Teodoridis (2010) and Teodoridis et al (2011). Teodoridis et al reconstructed higher mean annual temperatures from Břešťany flora than other floras from the Most Basin, mainly from sediments close to the top of the coal seam, although they probably all belongs to the top of the Holešice Member.…”

“…It is well known that to interpret any sediment record in terms of climate, chronostratigraphy basis and certain palaeogeographic frames for the sediment source area must first be established. The palaeoclimate reconstructions based on comparison of floras from individual sites in the Most Basin (Teodoridis 2010, Teodoridis et al 2011) also needs to refine yet uncertain stratigraphic assignment of those sites. These goals substantiate our effort in discussing an apparently "local problem" of the Most Basin stratigraphy.…”

“…Apparent lack of correlation horizons in the Most Basin fill and doubts about isochronicity of the coal formation (Hokr 1982, Elznic et al 1998 have hindered correlation of previous formal lithostratigraphic schemes for the different parts of the basin. Recent research in the Most Basin has included palaeobotany with environmental interpretations (Kvaček 1998, Kvaček et al 2004, Teodoridis & Kvaček 2006, Teodoridis 2010, Teodoridis et al 2011, sedimentology of fluvial and fluviodeltaic systems (Rajchl & Uličný 2005, Rajchl et al 2008) and basin development (Rajchl et al 2009), correlation of the main coal seam by geophysical logs (Mach 1997) and analysis of sulphur stable isotopes . A missing local stratigraphic frame for these studies is hence an obstacle, which hinders integration of that research and its palaeonvironmental interpretation.…”

Tracing the Eocene–Oligocene transition: a case study from North Bohemia

“…To verify the obtained estimates, the value of sampling errors (SE1) and (SE2) were calculated following Wilf (1997) Miller et al (2006) -SE 2 MAT = √([1 + ϕ (n-1) P(1-P)] × (P(1-P))/n), where the following symbols are used: c (slope of the MAT vs. leaf margin regression, equals 30.6 here), n (total species number), P (proportion of n species with entire margin, 0 < P < 1) and ϕ = 0.052 (dispersion factor). An updated version (see Teodoridis et al 2012) of the special tool developed by Teodoridis et al (2011c) was used to select relevant physiognomical datasets for using CLAMP, as characterized by e.g., Wolfe & Spicer (1999), Spicer et al (2009), andYang et al (2011). Physiognomic characteristics of the studied floras are presented in Appendix 1.…”

How to interpret palaeoclimate CLAMP estimates - is it a number value or an interval range?

“…CLAMP was first introduced by Wolfe (1993) and subsequently this technique has been refined mainly by Wolfe & Spicer (1999), Spicer (2000, 2007, Spicer et al (2004, 2009), and Teodoridis et al (2011 Braak (1986) performed by the software CANOCO for Windows Version 4.5 or automatically by an on-line application (see below), which reduces this multidimensional space (31 leaf physiognomic characteristics and 11 climatic parameters) to fewer, typically four-dimensional space and for each site is estimated vector score (AX1-4, ENV AX1-4), which represents its position in this space (position along the climate vector). The relationship between the climate vector scores and the observed climate values for those sites is represented by 2 nd order polynomial regression CLAMP physiognomic datasets from 144, 162, 173 and 189 modern sites mainly from SE Asia, Northern America and India and their relevant modern gridded meteorological calibration datasets corrected for the exact altitude of the sampling site (New et al 2002, Spicer et al 2009), i.e., Physg3ar, Physg3br, PhysgAsia1, PhysgIndia1, GRIDMet3a, GRIDMet3b, GRIDMetAsia1 and Teodoridis et al (2011Teodoridis et al ( , 2012) developed a special statistical tool, which helps to select relevant CLAMP physiognomic/meteorological datasets. All the mentioned reference files and datasets can be freely downloadable from the CLAMP website (Spicer 2011-2016) -see Appendix 1.…”