Compositional turnover and variation in Eemian pollen sequences in Europe

Abstract

The Eemian interglacial represents a natural experiment on how past vegetation with negligible human impact responded to amplified temperature changes compared to the Holocene. Here, we assemble 47 carefully selected Eemian pollen sequences from Europe to explore geographical patterns of (1) total compositional turnover and total variation for each sequence and (2) stratigraphical turnover between samples within each sequence using detrended canonical correspondence analysis, multivariate regression trees, and principal curves. Our synthesis shows that turnover and variation are highest in central Europe (47-55°N), low in southern Europe (south of 45°N), and lowest in the north (above 60°N). These results provide a basis for developing hypotheses about causes of vegetation change during the Eemian and their possible drivers. Keywords Detrended canonical correspondence analysis • Extrinsic and intrinsic processes • Inertia • Last interglacial dataset • Multivariate regression trees • Neutral processes • Principal curves Communicated by F. Bittmann.

Snapshot isolation and isolation history challenge the analogy between mountains and islands used to understand endemism

“…The last interglacial (LIG, c . 129–116 ka; Felde et al., 2020) represents sea levels possibly equivalent to expectations if global temperatures rise by 1.5–2°C (2–6 m higher than present; Polyak et al., 2018). The LIG peak displayed deviates from that of Bintanja et al.…”

“…Some archipelagos, such as the continental islands of the Seychelles (Figure 4a ) , the atolls of Phoenix and Aldabra, largely submerged for a short period in the last interglacial (LIG, c . 129–116 ka; Felde et al., 2020; Norder et al., 2018). The consequences of sea‐level changes on isolation were less drastic for remote “hotspot volcanic oceanic islands” (Glossary), such as Hawai'i, the Canary Islands, Azores and Galápagos, which mainly lost land but maintained much of their original geographical configurations.…”

“…Glossary[Colour figure can be viewed at wileyonlinelibrary.com](LIG, c. 129-116 ka;Felde et al, 2020;Norder et al, 2018). The consequences of sea-level changes on isolation were less drastic for remote "hotspot volcanic oceanic islands" (Glossary), such as Hawai'i, the Canary Islands, Azores and Galápagos, which mainly lost land but maintained much of their original geographical configurations.…”

Neoglacial trends in diatom dynamics from a small alpine lake in the Qinling mountains of central China

“…For example, July air temperature and ice cover duration have both been shown to have a significant influence on the abundance of fragilarioids in the European Alps (Schmidt et al, 2004), while in a subalpine lake in the Eastern Sayan Mountains (Russia), insolation and Northern Hemisphere air temperatures played a strong role on modulating fragilarioid responses through the Holocene (Mackay et al, 2012). The early part of our record is dominated by Stauroforma exiguiformis, a species common in dystrophic lakes (Flower et al, 1996). Its high abundance may be related to relatively high carbon sequestration during the very early part of the record in zone 1 (Fig.…”

“…For example, estimating species turnover assumes that species are lost and gained over time in response to resource availability, competition, historical events, and environmental factors (Korhonen et al, 2010) over both recent (Smol et al, 2005) and long timescales (Leprieur et al, 2011). However, because the concept of beta diversity has so many meanings to different disciplines, we take the approach of Felde et al (2020) and just focus on directional compositional turnover, which is appropriate for palaeolimnological datasets from a single lake.…”