Forest history, peatland development and mid- to late-Holocene environmental change in the southern taiga forest of central European Russia

Understanding the long-term ecological dynamics of boreal forests is essential for assessment of the possible responses and feedbacks of forest ecosystems to climate change. New data on past forest dynamics and peatland development were obtained from a peat sequence in the southern Valdai Hills (European Russia) based on pollen, plant macrofossil, micro-charcoal, peat humification, and testate amoeba analyses. In terms of vegetation history, the results demonstrate a dominance of broadleaved forests in the study area from 7000 4000 cal yr BP. Picea was initially a minor component of this forest but increased in cover rapidly with climatic cooling beginning at 4000 cal yr BP, becoming the dominant species. Broadleaved species persisted until 900 cal yr, with evidence for intensified felling and forest management over recent centuries. Over the last four hundred years there is evidence for widespread paludification and the establishment of Picea-Sphagnum forests. These data demonstrate how modern wet woodlands have been shaped by a combination of climatic and anthropogenic factors over several millennia. The results also demonstrate the value of a multiproxy approach in understanding long-term forest ecology

Falkland Island peatland development processes and the pervasive presence of fire

Palaeoecological analyses of Falkland Island peat profiles have largely been confined to pollen analyses. In order to improve understanding of long-term Falkland Island peat development processes, the plant macrofossil and stable isotope stratigraphy of an 11,550 year Falkland Island Cortaderia pilosa (‘whitegrass’) peat profile was investigated. The peatland developed into an acid, whitegrass peatland via a poor fen stage. Macrofossil charcoal indicate that local fires have frequently occurred throughout the development of the peatland. Raman spectroscopy analyses indicate changes in the intensity of burning which are likely to be related to changes in fuel types, abundance of fine fuels due to reduced evapotranspiration/higher rainfall (under weaker Southern Westerly Winds), peat moisture and human disturbance. Stable isotope and thermogravimetric analyses were used to identify a period of enhanced decomposition of the peat matrices dating from ∼7020 cal yr BP, which possibly reflects increasing strength of the Southern Westerly winds. The application of Raman spectroscopy and thermogravimetric analyses to the Falkland Island peat profile identified changes in fire intensity and decomposition which were not detectable using the techniques of macrofossil charcoal and plant macrofossil analyses.</p

Falkland Island peatland development processes and the pervasive presence of fire

Acknowledgments RJP secured funding for this research from the Quaternary Research Association, University of York and the Russian Science Foundation (19-14-00102). We thank Paul Brickle and other members of the South Atlantic Environmental Research Institute for their help with logistics, David Large for valuable discussions about Falkland Islands peat and all landowners for access permission. This work is dedicated to Richard J. Payne who was tragically killed while climbing Peak 6477, a previously unclimbed subsidiary peak of Nanda Devi (Garhwal Himalayas) in May 2019. CRediT authorship contribution statement Dmitri Mauquoy: Conceptualization, Investigation, Writing - original draft, Writing - review & editing. Richard J. Payne: Conceptualization, Investigation. Kirill V. Babeshko: Investigation, Writing - original draft, Writing - review & editing. Rebecca Bartlett: Investigation, Writing - original draft, Writing - review & editing. Ian Boomer: Investigation. Hannah Bowey: Investigation. Chris D. Evans: Conceptualization, Writing - original draft, Writing - review & editing. Fin Ring-Hrubesh: Investigation. David Muirhead: Methodology, Investigation, Writing - original draft, Writing - review & editing. Matthew O’Callaghan: Investigation. Natalia Piotrowska: Investigation. Graham Rush: Investigation. Thomas Sloan: Investigation. Craig Smeaton: Methodology, Investigation, Writing - original draft. Andrey N. Tsyganov: Investigation, Writing - original draft, Writing - review & editing. Yuri A. Mazei: Investigation, Writing - original draft, Writing - review & editing.Peer reviewedPostprin

Significance testing testate amoeba water table reconstructions

Transfer functions are valuable tools in palaeoecology, but their output may not always be meaningful. A recently-developed statistical test ('randomTF') offers the potential to distinguish among reconstructions which are more likely to be useful, and those less so. We applied this test to a large number of reconstructions of peatland water table depth based on testate amoebae. Contrary to our expectations, a substantial majority (25 of 30) of these reconstructions gave non-significant results (P > 0.05). The underlying reasons for this outcome are unclear. We found no significant correlation between randomTF P-value and transfer function performance, the properties of the training set and reconstruction, or measures of transfer function fit. These results give cause for concern but we believe it would be extremely premature to discount the results of non-significant reconstructions. We stress the need for more critical assessment of transfer function output, replication of results and ecologically-informed interpretation of palaeoecological data

Climatic moisture conditions in the north-west of the Mid-Russian Upland during the Holocene

This study aimed to reconstruct the climatic moisture conditions of the Mid- Russian Upland through the Holocene. Surface moisture conditions in the study region were inferred from published pollen records from the Klukva peatland, in the north-west of the Mid-Russian Upland. Three climatic indices were derived from previously- published reconstructions of mean annual temperature and precipitation: the Climate Moisture Index, the Aridity Index and the Budyko Dryness Index. A simple modeling approach to reconstruct annual potential evapotranspiration and net radiation was developed and used to estimate the indices for different periods of the Holocene. The moisture indices were compared with independent proxies of climate moisture such as peatland surface wetness, reconstructed from testate amoebae and regional fire activity, reconstructed from charcoal. Results show that the surface moisture conditions in the study region were characterized by large variability. Periods of mild temperature and moderately wet conditions were followed by dry periods, which resulted in significant changes in palaeoenvironments. The method developed for calculation of potential evapotranspiration and indices of surface moisture conditions could be a useful tool for climate reconstructions. Our results demonstrate the detailed and nuanced palaeoclimate data which can be derived from pollen data

Peatland Development, Vegetation History, Climate Change and Human Activity in the Valdai Uplands (Central European Russia) during the Holocene: A Multi-Proxy Palaeoecological Study

Peatlands are remarkable for their specific biodiversity, crucial role in carbon cycling and climate change. Their deposits preserve organism remains that can be used to reconstruct long-term ecosystem and environmental changes as well as human impact in the prehistorical and historical past. This study presents a new multi-proxy reconstruction of the peatland and vegetation development investigating climate dynamics and human impact at the border between mixed and boreal forests in the Valdai Uplands (the East European Plain, Russia) during most of the Holocene. We performed plant macrofossil, pollen, testate amoeba, Cladocera, diatom, peat humification, loss on ignition, carbon and nitrogen content, &delta;13C and &delta;15N analyses supported by radiocarbon dating of the peat deposits from the Krivetskiy Mokh mire. The results of the study indicate that the wetland ecosystem underwent a classic hydroserial succession from a lake (8300 BC&ndash;900 BC) terrestrialized through a fen (900 BC&ndash;630 AD) to an ombrotrophic bog (630 AD&ndash;until present) and responded to climate changes documented over the Holocene. Each stage was associated with clear changes in local diversity of organisms responding mostly to autogenic successional changes during the lake stage and to allogenic factors at the fen-bog stage. The latter can be related to increased human impact and greater sensitivity of peatland ecosystems to external, especially climatic, drivers as compared to lakes