A major hydrobiological change in Dasht-e Arjan Wetland (SW Iran) during the late glacial-early Holocene transition revealed by subfossil chironomids

The late glacial-early Holocene transition is a key period in the Earth’s history. However, although this transition is well studied in Europe, it is not well constrained in the Middle East and palaeohydrological records with robust chronologies remain scarce from this region. Here we present an interesting hydrobiological record showing a major environmental change occurring in the Dasht-e Arjan Wetland (SW Iran, near to Persepolis) during the late glacial-early Holocene transition (ca. 11,650 years cal BP). We use subfossil chironomids (Insecta: Diptera) as a proxy for hydrological changes and to reconstruct lake-level fluctuations. The Arjan wetland was a deep lake during the Younger Dryas (YD) marked by a dominance of Chironomus plumosus/anthracinus-type, taxa adapted to anoxic conditions of deep waters. At the beginning of the Holocene a drastic decrease (more than 80% to less than 10%) of Chironomus plumosus/anthracinus-type, combined with diversification of littoral taxa such as Polypedilum nubeculosum-type, Dicrotendipes nervosus-type and Glyptotendipes pallens-type suggest a lake-level decrease and a more vegetalized aquatic environment. We compare and contrast the chironomid record of Arjan with a similar record from northwestern Iran. The palaeoclimatic significance of the record, at a local and regional scale, is subsequently discussed. The increase in northern hemisphere temperatures, inferred by geochemical data from NGRIP, at the beginning of the Holocene best explains the change from the YD highstand to early Holocene lowstand conditions in the Dasht-e Arjan wetland. However, a contribution of the melt-water inflow from small local glaciers in the catchment basin is not excluded

Are morphological characteristics of Parrotia (Hamamelidaceae) pollen species diagnostic?

Parrotia persica is one of the most notable endemic relict tree species growing in the Hyrcanian forest at the southern Caspian Sea. The recent discovery of sibling species Parrotia subaequalis, occurring in the temperate for-ests of south-eastern China, offers the opportunity to compare their morphology and ecological preferences and to dig deeper into the paleophytogeographic history of the genus from a perspective. Since pollen morphology of these species would be essential to unravel the origin and evolution of these Arcto-Tertiary species, the present study aimed to investigate whether it is possible to segregate pollen from these two species. Therefore, a detailed combined light-and scanning electron microscopy-based pollen-analysis of each taxon was conducted, the pol-len was described, measured, and compared using statistical approaches and principal component analyses to es-tablish unbiased results. The correlation-based principal component analysis achieved for each species shows an overall good superposition of pollen grains measured in equatorial and polar views in the first principal plane, revealing that the P. persica pollen is morphometrically as homogeneous as that of P. subaequalis. Then, the sig-nificant difference, mainly driven by lumen density, has been highlighted between the two species. Ultimately, the cross-validation of the resulting two-species linear discriminants classifier shows that based upon this refer-ence dataset, (sub)fossil pollen grain can now be confidently assigned to either of the two species with an 85.8% correct-assignment rate. This opens new doors in the affiliation of fossil Parrotia pollen and suggests that previous pollen records need to be revised.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).Peer reviewe

Early Sasanian landscape modification: New geoarchaeological evidence from the Ardashir Pond in southwest Iran (Palace of Ardashir, third century CE)

The Sasanian period (224–651 CE) marked an era of large‐scale urban projects insouthwest Asia, including Iran's semi‐arid highlands, with particular efforts to ma-nipulate water bodies. This study presents a recent interdisciplinary investigation ofa spring‐fed pond at the entrance of the Palace of Ardashir (Firuzabad plain,southwest Iran), part of a recently registered World Heritage site. Historical ac-counts suggest that the entire water system of the plain, including the pond, un-derwent a hydraulic re‐organization at the beginning of the Sasanian period, a factthat has never been investigated geoarchaeologically. A series of sediment coreswere retrieved from the pond to probe its evolution and examine the extent of itslandscape modification. The cores were sedimentologically described andradiocarbon‐dated with age–depth models established based on 57 AMS (accel-erator mass spectrometry)14C dates to understand the basin's depositional history.The results indicate that (i) Ardashir Pond has existed as part of a larger wetlandcomplex since at least 4500 years ago, (ii) it was substantially enlarged at the be-ginning of the Sasanian era, and (iii) it was abandoned at the end of the Sasanianperiod. The Ardashir Pond is one of the first geoarchaeologically investigated casestudies to demonstrate the Sasanian landscape in the framework of the“Iranshahr”sociopolitical concept

20,000 years of societal vulnerability and adaptation to climate change in southwest Asia.

The Fertile Crescent, its hilly flanks and surrounding drylands has been a critical region for studying how climate has influenced societal change, and this review focuses on the region over the last 20,000 years. The complex social, economic, and environmental landscapes in the region today are not new phenomena and understanding their interactions requires a nuanced, multidisciplinary understanding of the past. This review builds on a history of collaboration between the social and natural palaeoscience disciplines. We provide a multidisciplinary, multiscalar perspective on the relevance of past climate, environmental, and archaeological research in assessing present day vulnerabilities and risks for the populations of southwest Asia. We discuss the complexity of palaeoclimatic data interpretation, particularly in relation to hydrology, and provide an overview of key time periods of palaeoclimatic interest. We discuss the critical role that vegetation plays in the human-climate-environment nexus and discuss the implications of the available palaeoclimate and archaeological data, and their interpretation, for palaeonarratives of the region, both climatically and socially. We also provide an overview of how modelling can improve our understanding of past climate impacts and associated change in risk to societies. We conclude by looking to future work, and identify themes of "scale" and "seasonality" as still requiring further focus. We suggest that by appreciating a given locale's place in the regional hydroscape, be it an archaeological site or palaeoenvironmental archive, more robust links to climate can be made where appropriate and interpretations drawn will demand the resolution of factors acting across multiple scales. This article is categorized under:Human Water > Water as Imagined and RepresentedScience of Water > Water and Environmental ChangeWater and Life > Nature of Freshwater Ecosystems

The Eurasian Modern Pollen Database (EMPD), version 2

The Eurasian (née European) Modern Pollen Database (EMPD) was established in 2013 to provide a public database of high-quality modern pollen surface samples to help support studies of past climate, land cover, and land use using fossil pollen. The EMPD is part of, and complementary to, the European Pollen Database (EPD) which contains data on fossil pollen found in Late Quaternary sedimentary archives throughout the Eurasian region. The EPD is in turn part of the rapidly growing Neotoma database, which is now the primary home for global palaeoecological data. This paper describes version 2 of the EMPD in which the number of samples held in the database has been increased by 60 % from 4826 to 8134. Much of the improvement in data coverage has come from northern Asia, and the database has consequently been renamed the Eurasian Modern Pollen Database to reflect this geographical enlargement. The EMPD can be viewed online using a dedicated map-based viewer at https://empd2.github.io and downloaded in a variety of file formats at https://doi.pangaea.de/10.1594/PANGAEA.909130 (Chevalier et al., 2019)Swiss National Science Foundation | Ref. 200021_16959

The Eurasian Modern Pollen Database (EMPD), version 2

The Eurasian (nee European) Modern Pollen Database (EMPD) was established in 2013 to provide a public database of high-quality modern pollen surface samples to help support studies of past climate, land cover, and land use using fossil pollen. The EMPD is part of, and complementary to, the European Pollen Database (EPD) which contains data on fossil pollen found in Late Quaternary sedimentary archives throughout the Eurasian region. The EPD is in turn part of the rapidly growing Neotoma database, which is now the primary home for global palaeoecological data. This paper describes version 2 of the EMPD in which the number of samples held in the database has been increased by 60% from 4826 to 8134. Much of the improvement in data coverage has come from northern Asia, and the database has consequently been renamed the Eurasian Modern Pollen Database to reflect this geographical enlargement. The EMPD can be viewed online using a dedicated map-based viewer at https://empd2.github.io and downloaded in a variety of file formats at https://doi.pangaea.de/10.1594/PANGAEA.909130 (Chevalier et al., 2019).Peer reviewe