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Several techniques are commonly used for quantitative climate reconstructions based on plant information from lake sediments. One of these is the creation of transfer functions that link current climate to current plant distributions and apply the results to pollen information from sediment cores. However, one challenge is to combine this information with that of other proxies. Therefore, we have developed a new algorithm that automatically creates a compromise from all available proxy information. This technique has already been successfully tested on over 500 sediment cores throughout Europe and the Middle East. Moreover, it allows us to reconstruct not only the climate of the last centuries, but also that of several glacial-interglacial cycles. In this context, the following proxies were used: Plant information from lake sediment cores, isotopic information from speleothems, marine cores, and ice cores.To achieve this, we need to solve four major tasks. First, we conducted a machine learning competition to find the best generalized transfer functions linking current climate to vegetation data. Second, we developed a Bayesian-based age-depth/distance transformation that allows us to construct a regular temporal grid not only for sediment cores but also for speleothems. This computationally fast and easy-to-implement transformation allows us to include all age uncertainties in our reconstruction method. Third, if the proxies are to be considered in spectral space rather than temporal space, this can be achieved by our method using wavelet power spectra. Fourth, we have designed a fast algorithm that combines all inserted proxy information. This was made possible through the use of a Markov chain Monte Carlo method that derives specific weights for each taxon based on the included proxy information. In addition, this flexible technique can be enhanced by incorporating direct climate information, e.g., from instrumental meteorological measurements, from results of paleoclimate simulations, and/or from historical records. If the human influence on a proxy in a given period is not negligible, the algorithm ignores it and focuses on the remaining proxies to minimize this effect. Therefore, the procedure can be easily extended with further proxy information such as CO2 and/or solar insolation.In summary, our new method provides quantitative paleoclimate reconstructions that approximate proxies not only in temporal space but also in spectral space, and can be further constrained by climate anchor points.

Throughout the Mediterranean biome, fire has been a dominant natural agent of change and a primary tool for anthropogenic landscape modifications. This research explores linkages among fire, vegetation, and human agricultural practices in the Eastern Mediterranean region, a region with limited evidence of the role these processes have in shaping the landscape.Olive horticulture is among the oldest and most widespread agricultural forms in the Mediterranean Basin. The first major olive cultivation can be traced back in time with pollen evidence. In the Sea of Galilee, the earliest palynological evidence for olive horticulture suggest cultivation began approximately 7000 cal yr BP.Here, we present a new high-resolution macro-charcoal dataset from the Sea of Galilee prior and during the first olive cultivation. Charcoal morphotypes were identified and are used to characterize fuel types. We also compare our data with a new multi-proxy dataset from the same record indicating the timing and impact of olive cultivation and related vegetation and climate changes.The following questions are discussed: What was the natural fire regime (pre-large scale agriculture) around the Sea of Galilee basin? What role did fire play as a potential tool for clearing and fertilizing landscapes as the first olive orchards developed? How did fire regimes change once olive orchards were planted? Finally, can charcoal morphotypes provide novel insights into understanding paleofire regimes?This study allows a new perspective into natural fire regimes in the Levant and an increased understanding of the role of fire during early horticulture practice. Moreover, it can serve as a basis for future fire management plans.

In this report, we present the contributions, outcomes, ideas, discussions and conclusions obtained at the PaleoMaps Workshop 2019, that took place at the Institute of Geography of the University of Cologne on 23 and 24 September 2019. The twofold aim of the workshop was: (1) to provide an overview of approaches and methods that are presently used to incorporate paleoenvironmental information in human–environment interaction modeling applications, and building thereon; (2) to devise new approaches and solutions that might be used to enhance the reconstruction of past human–environmental interconnections. This report first outlines the presented papers, and then provides a joint protocol of the often extensive discussions that came up following the presentations or else during the refreshment intervals. It concludes by adressing the open points to be resolved in future research avenues, e.g., implementation of open science practices, new procedures for reviewing of publications, and future concepts for quality assurance of the often complex paleoenvironmental data. This report may serve as an overview of the state of the art in paleoenvironment mapping and modeling. It includes an extensive compilation of the basic literature, as provided by the workshop attendants, which will itself facilitate the necessary future research.

Despite ongoing discussions on hydroclimatic conditions in the southern Levant during the Last Glacial, detailed knowledge about the Levantine paleovegetation, which is an important indicator for the paleoclimate, is limited. To investigate the paleovegetation in northern Israel, we analyzed the pollen assemblage of a sediment core that was drilled at the Ohalo II archaeological site on the southwestern shore of the Sea of Galilee (Lake Kinneret). We refined the lithology and the age-depth model with the help of five new radiocarbon dates. The core comprises a continuous sediment profile of mainly laminated authigenic calcites and detrital material that deposited between ca. 28,000 and 22,500 years before present, when the Sea of Galilee rose above the modern lake level stand and temporarily merged with Lake Lisan, the precursor of the Dead Sea. The well-dated and high-resolution pollen record suggests that steppe vegetation with grasses, other herbs, and dwarf shrubs predominated in northern Israel during the investigated period. In contrast to the Holocene, there was no continuous vegetation belt of the Mediterranean biome in the vicinity of the Sea of Galilee. Mediterranean elements such as deciduous oaks only occurred in limited amounts and were probably patchily distributed. These results disagree with previous pollen-based hypotheses from the region that assumed the spread of Mediterranean forest during glacial periods. While the pollen data may indicate semiarid conditions in northern Israel and give no evidence of increased effective moisture, previous hydroclimatic studies suggested increased precipitation rates that are consistent with high lake levels (Sea of Galilee/Lake Lisan). Thus, we discuss factors influencing the pollen assemblage and the plant cover.

Olive (Olea europaea L.) was one of the most important fruit trees in the ancient Mediterranean region and a founder species of horticulture in the Mediterranean Basin. Different views have been expressed regarding the geographical origins and timing of olive cultivation. Since genetic studies and macro-botanical remains point in different directions, we turn to another proxy - the palynological evidence. This study uses pollen records to shed new light on the history of olive cultivation and large-scale olive management. We employ a fossil pollen dataset composed of high-resolution pollen records obtained across the Mediterranean Basin covering most of the Holocene. Human activity is indicated when Olea pollen percentages rise fairly suddenly, are not accompanied by an increase of other Mediterranean sclerophyllous trees, and when the rise occurs in combination with consistent archaeological and archaeobotanical evidence. Based on these criteria, our results show that the southern Levant served as the locus of primary olive cultivation as early as similar to 6500 years BP (yBP), and that a later, early/mid 6th millennium BP cultivation process occurred in the Aegean (Crete) - whether as an independent large-scale management event or as a result of knowledge and/or seedling transfer from the southern Levant. Thus, the early management of olive trees corresponds to the establishment of the Mediterranean village economy and the completion of the 'secondary products revolution', rather than urbanization or state formation. From these two areas of origin, the southern Levant and the Aegean olive cultivation spread across the Mediterranean, with the beginning of olive horticulture in the northern Levant dated to similar to 4800 yBP. In Anatolia, large-scale olive horticulture was palynologically recorded by similar to 3200 yBP, in mainland Italy at similar to 3400 yBP, and in the Iberian Peninsula at mid/late 3rd millennium BP.

International audience; This paper explores long-term trends in human population and vegetation change in the Levant from the early to the late Holocene in order to assess when and how human impact has shaped the region’s landscapes over the millennia. To do so, we employed multiple proxies and compared archaeological, pollen and palaeoclimate data within a multi-scalar approach in order to assess how Holocene landscape dynamics change at different geographical scales. We based our analysis on 14 fossil pollen sequences and applied a hierarchical agglomerative clustering and community classification in order to define groups of vegetation types (e.g. grassland, wetland, woodland, etc.). Human impact on the landscape has been assessed by the analysis of pollen indicator groups. Archaeological settlement data and Summed Probability Distribution (SPD) of radiocarbon dates have been used to reconstruct long-term demographic trends. In this study, for the first time, the evolution of the human population is estimated statistically and compared with environmental proxies for assessing the interplay of biotic and abiotic factors in shaping the Holocene landscapes in the Levant.

Quaternary science reviews 214, 98-116 (2019). doi:10.1016/j.quascirev.2019.04.033 special issue: "The ICDP Dead Sea Deep Drilled Core: Window into the Late Quaternary Hydro-climate and Seismic History of the East Mediterranean-Levant / Edited by Mordechai Stein, Steve Goldstein", Published by Elsevier, Amsterdam [u.a.]

The Marmara region in northwestern Turkey provides a unique opportunity for studying the vegetation history in response to climate changes and anthropogenic impacts because of its location between different climate and vegetation zones and its long settlement history. Geochemical and mineralogical investigations of the largest lake in the region, Lake Iznik, already registered climate-related changes of the lake level and the lake mixing. However, a palynological investigation encompassing the Late Pleistocene to Middle Holocene was still missing. Here, we present the first pollen record of the last ca. 31 ka cal BP (calibrated kilo years before 1950) inferred from Lake Iznik sediments as an independent proxy for paleoecological reconstructions. Our study reveals that the vegetation in the Iznik area changed generally between (a) steppe during glacials and stadials indicating dry and cold climatic conditions, (b) forest-steppe during interstadials indicating milder and moister climatic conditions, and (c) oak-dominated mesic forest during interglacials indicating warm and moist climatic conditions. Moreover, a pronounced succession of pioneer trees, cold temperate, warm temperate, and Mediterranean trees appeared since the Lateglacial. Rapid climate changes, which are reflected by vegetation changes, can be correlated with Dansgaard-Oeschger (DO) events such as DO-4, DO-3, and DO-1, the Younger Dryas, and probably also the 8.2 event. Since the mid-Holocene, the vegetation was influenced by anthropogenic activities. During early settlement phases, the distinction between climate-induced and human-induced changes of the vegetation is challenging. Still, evidence for human activities consolidates since the Early Bronze Age (ca. 4.8 ka cal BP): cultivated trees, crops, and secondary human indicator taxa appeared, and forests were cleared. Subsequent fluctuations between extensive agricultural uses and regenerations of the natural vegetation become apparent.

The Marmara region in northwestern Turkey provides a unique opportunity for studying the vegetation history in response to climate changes and anthropogenic impacts because of its location between different climate and vegetation zones and its long settlement history. Geochemical and mineralogical investigations of the largest lake in the region, Lake Iznik, already registered climate related changes of the lake level and the lake mixing. However, a palynological investigation encompassing the Late Pleistocene to Middle Holocene was still missing. Here, we present the first pollen record of the last ca. 31 ka cal BP (calibrated kilo years before 1950) inferred from Lake Iznik sediments as an independent proxy for paleoecological reconstructions. Our study reveals that the vegetation in the Iznik area changed generally between steppe during glacial/stadial conditions, forest-steppe during interstadial conditions, and oak dominated mesic forest during interglacial conditions. Moreover, a pronounced succession of pioneer trees, cold temperate, warm temperate, and Mediterranean trees appeared since the Lateglacial. Rapid climate changes, which are reflected by vegetation changes, can be correlated with Dansgaard–Oeschger (DO) events such as DO-4, DO-3, and DO-1, the Younger Dryas, and probably also the 8.2 event. Since the mid-Holocene, the vegetation was influenced by anthropogenic activities. During early settlement phases, the distinction between climate-induced and human-induced changes of the vegetation is challenging. Still, evidence for human activities consolidates since the Early Bronze Age (ca. 4.8 ka cal BP): cultivated trees, crops, and secondary human indicator taxa appeared, and forests got cleared. Subsequent fluctuations between extensive agricultural use and regeneration of the natural vegetation become apparent.