A pollen–climate calibration from western Patagonia for palaeoclimatic reconstructions

Abstract

Palaeoecological studies of sediment records from the western margins of southern South America have revealed vegetation dynamics to be under the influence of major regional climate drivers such as the Southern Westerly Winds, Southern Annular Mode and El Niño Southern Oscillation. Despite the substantial number of palynological records in this region, very few quantitative pollen‐based climate reconstructions using surface samples have been made. In this context, our objective was first to investigate the modern pollen–vegetation–climate relationships in the western Patagonian. The results show that the modern pollen dataset reflects the main vegetation types and that summer precipitation and winter temperature represent the main climate parameters controlling vegetation distribution. Secondly using this pollen–climate dataset we evaluate and compare the performance of two models (Weighted Averaging Partial Least Squares and Modern Analog Technique). We used these models to make climate reconstructions from two oceanic pollen records from western Patagonia. Compared with independent climate indicators, our pollen‐inferred climate reconstructions reveal the same overall trends, showing the potential of pollen–climate transfer functions applied to this region. This study provides much needed data for quantitative climate reconstructions in South America, but which also needs to be improved by enlarging the modern pollen dataset.

Early Holocene Thermal Maximum recorded by branched tetraethers and pollen in Western Europe (Massif Central, France)

“…4A) and the method seems unsuitable for our large-scale database containing more than 3000 pollen samples from ecosystems ranging from Mediterranean vegetation to tundra. A locally focused calibration may improve the performance of the model and the reliability of the reconstruction (Montade et al, 2019). To sum up, we suggest that the reconstruction of the climate signal for the period 10,000e8500 cal BP inferred from the MAT and the WAPLS can be improved.…”

A new modern pollen dataset describing the Brazilian Atlantic Forest

“…Bartlein et al, 2011;Mauri et al, 2015;Peyron et al, 2017;Zanon et al, 2018). However, very few studies using these techniques have been performed in the southern Hemisphere and especially in South America (but see Markgraf et al, 2002;Montade et al, 2019;Schäbitz et al, 2013;Tonello et al, 2009). Compiling a modern pollen data training set requires several steps: initially a wide range of modern pollen samples is required to span the range of environmental values likely to be represented by the main different vegetation types from a region.…”

cRacle: R tools for estimating climate from vegetation

“…1), a method analogous to the widely used coexistence approach (Mosbrugger and Utescher, 1997). Furthermore, the CRACLE results presented here compare favorably, although indirectly, to recent applications of the weighted average partial least squares (WA-PLS) model, commonly used for the analysis of fossil pollen samples, which uses modern analog communities to build proxy models (Montade et al, 2019). A direct comparison of the CRACLE and WA-PLS methods is necessary in future work.…”