Tree pollen representation in surface pollen assemblages  from different vegetation zones of European Russia

Novenko, Elena; Mazei, Natalia; Kusilman, M. V.

doi:10.12775/eq.2017.018

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…(Novenko, Mazei, & Kusilman, 2017; Paus, 2000; Siljamo et al., 2008) while the taxa that are likely to come from long‐distance transport are Picea spp., and Carpinus sp. (Latałowa & van der Knaap, 2006; Novenko et al., 2017). Fires themselves may have been a source of long‐distance pollen transport by air convection (Pisaric, 2002).…”

Section: Discussionmentioning

confidence: 99%

Did long‐term fire control the coniferous boreal forest composition of the northern Ural region (Komi Republic, Russia)?

Barhoumi

Ali

Peyron

et al. 2020

Journal of Biogeography

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Section: Discussionmentioning

confidence: 99%

Did long‐term fire control the coniferous boreal forest composition of the northern Ural region (Komi Republic, Russia)?

Barhoumi

Ali

Peyron

et al. 2020

Journal of Biogeography

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“…The bulk of the sites were derived from the European Modern Pollen Database (EMPD) v 3.0 (Davis et al, 2013) and the EMBSeCBIO (Eastern Mediterranean-Black Sea-Caspian corridor BIOmes) Initiative (Marinova et al, 2017). We included additional sites from various publications (Saadi and Bernard, 1991;de Klerk et al, 2009;Gruger and Jerz, 2010;Muller et al, 2010;Werner et al, 2010;Tarasov et al, 2011;Matthias et al, 2015;Niemeyer et al, 2015;Bell & Fletcher, 2016;Novenko et al, 2017) available from the European Pollen Database (http://www.europeanpollendatabase.net/) or Pangaea (https://www.pangaea. de/).…”

Section: Methods 21 Modern Pollen Datamentioning

confidence: 99%

Climate changes in interior semi-arid Spain from the last interglacial to the late Holocene

Wei

González-Sampériz

Gil‐Romera

et al. 2019

Preprint

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Abstract. The El Cañizar de Villarquemado sequence provides a palaeoenvironmental record from the western Mediterranean Basin spanning the interval from the last part of MIS6 to the late Holocene. The pollen and sedimentological records provide qualitative information about changes in temperature seasonality and moisture conditions. We use Weighted Averaging Partial Least-Squares (WA-PLS) regression to derive quantitative reconstructions of winter and summer temperature regimes from the pollen data, expressed in terms of the mean temperature of the coldest month (MTCO) and growing degree days above a baseline of 0 °C (GDD0) respectively. We also reconstruct a moisture index (MI), the ratio of annual precipitation to annual potential evapotranspiration, taking account of the effect of low CO2 on water use efficiency. We find a rapid summer warming at the transition to MIS5. Summers were cold during MIS4 and MIS2, but some intervals in MIS3 were characterized by summers as warm as the warmest phases of MIS5 or the Holocene. However, MIS3 was not significantly warmer in winter than other intervals, and there was a gradual decline in winter temperature from MIS4 through MIS3 to MIS2. The pronounced changes in temperature seasonality during MIS5 and MIS1 are consistent with changes in summer insolation. The ecophysiological effects of changing CO2 concentration through the glacial cycle has a significant impact on reconstructed MI. Conditions became progressively more humid during MIS5 and MIS4 was also relatively humid, while MIS3 was more arid. High MI values are reconstructed during the deglaciation and there was a pronounced increase in aridity during the Holocene. Changes in MI are anti-correlated with changes in GDD0, with increased MI during intervals of summer warming indicating a strong influence of temperature on evapotranspiration. Although our main focus here is on longterm changes in climate, the Villarquemado record also shows millennial-scale changes corresponding to Dansgaard-Oeschger cycles.

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“…Modern pollen data were obtained from the SMPDS dataset (the SPECIAL modern pollen dataset) [32], which contains pollen assemblages from 6458 terrestrial sites from Europe, the Middle East and northern Eurasia (figure 1a). The SMPDS data were derived from the European Modern Pollen Database (EMPD) v3.0 [33] and the EMBSeCBIO (Eastern Mediterranean-Black Sea-Caspian corridor BIOmes) Initiative [34], individual published records [35][36][37][38][39][40][41][42][43][44] obtained from the European Pollen Database (http://www.europeanpollendatabase.net/) or Pangaea (https:// www.pangaea.de/), and 73 modern surface samples from northern Spain. Counts for obligate aquatics, insectivorous plants, non-native species and cultivated plants are not included in the SMPDS since their abundance is assumed not to be primarily controlled by climate.…”

Section: (B) Implementationmentioning

confidence: 99%

An improved statistical approach for reconstructing past climates from biotic assemblages

et al. 2020

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Quantitative reconstructions of past climates are an important resource for evaluating how well climate models reproduce climate changes. One widely used statistical approach for making such reconstructions from fossil biotic assemblages is weighted averaging partial least-squares regression (WA-PLS). There is however a known tendency for WA-PLS to yield reconstructions compressed towards the centre of the climate range used for calibration, potentially biasing the reconstructed past climates. We present an improvement of WA-PLS by assuming that: (i) the theoretical abundance of each taxon is unimodal with respect to the climate variable considered; (ii) observed taxon abundances follow a multinomial distribution in which the total abundance of a sample is climatically uninformative; and (iii) the estimate of the climate value at a given site and time makes the observation most probable, i.e. it maximizes the log-likelihood function. This climate estimate is approximated by weighting taxon abundances in WA-PLS by the inverse square of their climate tolerances. We further improve the approach by considering the frequency ( fx ) of the climate variable in the training dataset. Tolerance-weighted WA-PLS with fx correction greatly reduces the compression bias, compared with WA-PLS, and improves model performance in reconstructions based on an extensive modern pollen dataset.

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Tree pollen representation in surface pollen assemblages from different vegetation zones of European Russia

Cited by 3 publications

References 9 publications

Did long‐term fire control the coniferous boreal forest composition of the northern Ural region (Komi Republic, Russia)?

Did long‐term fire control the coniferous boreal forest composition of the northern Ural region (Komi Republic, Russia)?

Climate changes in interior semi-arid Spain from the last interglacial to the late Holocene

An improved statistical approach for reconstructing past climates from biotic assemblages

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