Grass-dominated ecosystems, encompassing steppe, forest-steppe, savanna, woodlands, and shrublands, cover approximately 40% of the global land surface and are critical for biodiversity, carbon storage, livelihoods, and culture. Grassland ecosystems are often assumed to be dominant in regions that are too cold or dry for tree growth and have limited soil development. Many grassy ecosystems are, however, found in warm and wet climates that could support forests. This pattern may be explained by grassy ecosystems also maintained by consumers of biomass, such as fire and herbivores, which tip the competitive balance in favor of grasses. Central Eastern Europe hosts some of the largest expanses of open ecosystems, notably steppe and forest-steppe woodlands, which humans have heavily impacted for millennia. Despite the critical roles fire may have had in these landscapes, our understanding of grassland fire frequency and intensity relies on contemporary ecological studies and remote sensing. The few long-term fire regime reconstructions worldwide based on charcoal records in grasslands have revealed that many assumptions about fires in grassy ecosystems rely on extrapolations from forested environments, revealing gaps in our knowledge regarding the natural occurrence and intensity of fires to climate, vegetation composition, and biomass dynamics in grassy ecosystems. To address these gaps, we conducted palaeoecological analyses, including pollen, charcoal morphologies, and morphometrics (L/W), in two contrasting grassy ecosystems in south-eastern Romania—Lake Oltina in the forest-steppe and Mangalia Herghelie in the steppe. Our research aims are to explore: i) the variation in biomass burning, fire frequency, and severity of fire over time in response to climate, vegetation changes, and human activities; ii) to compare trends in fire regime between ecosystems with (forest-steppe) and without (steppe) tree cover; and ii) to assess deviations in modern fire regimes from long-term trends. Additionally, we examine charcoal morphological and morphometrical assemblages as signals for reconstructing vegetation composition changes in regions with poor pollen preservation. Our analysis seeks to unravel the intricate interactions and feedback among fire, climate, and vegetation dynamics. Frequent fires in grass-dominated ecosystems act as a bottleneck for tree recruitment, sustaining the dominance of grasslands. We hypothesize that fire activity increases with decreasing rainfall but decreases with increasing rainfall, potentially influencing the transition from steppe to forest-steppe to woodland. The fire regime characteristics are expected to change during this transition, with decreasing fire frequency and increasing severity due to elevated fuel loads and reduced flammable grasses. In the long term, this may lead to a shift towards a landscape dominated by woody vegetation, accompanied by lower frequency but higher severity fires. Human ignitions and the use of fire for land management alter these dynamics. Insights from this feedback and interaction will guide us in identifying thresholds in tree cover as indicators for a fire regime shift and determining tipping points in the balance between vegetation and fire. This study adds valuable knowledge to refine our understanding of the nuanced interplay between fire, climate, and vegetation dynamics in temperate European grasslands.

Southeastern Europe is home to remnants of highly diverse open ecosystems, including grasslands and forest- steppe. To understand the impacts of climate changes, fire disturbance, and herbivory on forest-grassland coexistence in this region, we integrated new and published paleoecological data from two sedimentary records in southeastern Romania with information on herbivore population dynamics and dietary habits. Our findings indicate that fluctuations in forest-grassland cover closely mirrored changes in regional growing season moisture availability in the Black Sea region. During periods with increased moisture availability (e.g. 6000-3800 cal yr BP), diverse broadleaved forest dominated by Quercus expanded. Conversely, more drought- tolerant herbaceous cover increased during drier intervals (7200-6800 and 3800-2000 cal yr BP). We identified a critical tree cover of 25-40% at Mangalia Herghelie and 25-55% at Lake Oltina where neither forest nor grassland dominated. Stable forest states emerged above 40% tree cover and 55% respectively, while grassland- dominated states had tree cover below 25%. Disturbances by fire and herbivores fluctuated over time, and were further influenced by human activity, which along with deforestation, altered the composition and extent of steppe and forest-steppe vegetation. High fire severity occurred during intermediate moisture conditions and tree cover (6800-5500, 3800-2800 cal yr BP), while low fire severity was observed when herbaceous biomass dominated (7200-7000, 2800-2000 cal yr BP) or under greater tree cover (5500-3800 cal yr BP). Herbivore dynamics shifted from large-bodied grazers in the Neolithic and early Eneolithic (7650-6550 cal yr BP; Prehamangia and Hamangia cultures) to a more diverse array of feeding types involving smaller domestic and wild herbivores along with sedentary agriculture during the flourishing Eneolithic (6550-5850 cal yr BP; Gumelnita culture), before returning to larger domestic grazers as well as omnivores in the Bronze and Iron Ages (3500-2000 cal yr BP). Large-bodied herbivores with selective diets (primarily grazers) had a more substantial effect on grasses compared to mixed feeders with bulk diets, whereas domestic herbivory was associated with increased apophyte abundance and diversity. Our findings underscore the essential factors for sustainable management of forest-grassland mosaics under changing climate conditions with projected accelerating aridification. They also highlight the need for continued research to enhance our understanding of these biodiverse, sensitive open ecosystems to inform effective management strategies.

Sea level reconstructions in the Black Sea basin and elsewhere rely on the identification of sea level markers and on the understanding of their post-genetic vertical movements. We present here evidence of a fast, bi-directional vertical displacement on the western Black Sea shore at Mangalia, Romania. We argue that an area situated near the shoreline was submerged 4 m, subsequently filled with marine silts and sands, then uplifted by 10 m, where it currently stands. Radiocarbon dating of several types of materials from the infill, as well as archaeological evidence, indicate that this displacement occurred during the eighteenth to nineteenth centuries. Mollusc shells found in anatomical connection close to the top of the sediment sequence have a 14C reservoir age offset of 900 years, probably due to the hard water effect. This is much larger than the 400 year offset that is generally considered for the Black Sea and highlights the problematic dating of Black Sea coastal sediments. The findings of this study offer strong evidence of short-term, local tectonic movements that should be considered when past sea levels are calculated, while at the same time serve a warning for urban and marine development planners.

This study reconstructs the paleoecological settings of Chilia/Licostomo, the most important Genoese colony in the Danube delta. Our paleoenvironmental data (i.e., sedimentology, pollen, charcoal, radiocarbon ages) corroborate historical and archaeological information over the last seven centuries to document the habitation at Chilia and its military and socioeconomic activity during ca. 14th–19th centuries A.D. Palynological data show the continuous presence of humans, with anthropogenic pollen index calculation (API) values between 2% and 16% during the last five centuries. The variability of API, corroborated with the major peaks of the charcoal concentration, matches the documented military conflicts and population changes in the area: the Ottoman conquest of Dobrugea (15th century A.D.), the Zaporozhians Cossaks raids (17th century A.D.), and the Russian–Ottoman wars (18th–19th centuries A.D.). The presence of coprophilous fungi fits the Ottoman tradition of animal husbandry, whereas their appearance after the Zaporozhians Cossacks raids and their good correlation with open land vegetation suggest that the Chilia loess island was temporally used as a refuge from multiple menaces (e.g., wars, administrative crisis). These paleoecological data, together with the rare archaeological findings, exclude human habitation of the Chilia Plain earlier than the documented arrival of the Lipovans during the late 18th century A.D. The critical assessment of the correspondences between the paleoecological and historical data shows the relevance of the approach in deltaic environments, when applied to lagoon/lacustrine sediments, yet often limited to chronologically disparate, decennial‐ to multicentennial‐scale temporal frameworks.

Recent developments in morphological and morphometric analyses of charcoal particles have improved our ability to discern characteristics of burnt plant fuel and interpret fire-type changes. However, burning experiments linking known plants to these metrics are limited, particularly in open ecosystems. This study presents novel analyses of laboratory-produced charcoal of 22 plant species from the steppe regions of Eurasia (Romania and Russia), along with selected samples from three Holocene charcoal and pollen records from the same areas. We characterise charcoal production, morphologies and morphometrics in these grass-dominated environments, thereby enabling more robust interpretations of fuel sources and fire types for palaeofire research. Our experiments demonstrate that fire temperature can introduce biases in charcoal produced among species. Grass charcoal production was significantly lower and decreased more strongly with fire temperature compared to forbs. This suggests an underrepresentation of terrestrial graminoids in sedimentary charcoal assemblages. Morphometric analyses revealed that graminoid charcoal particles were more elongated (length-to-width ratio L/W=4) and narrower (width-to-length ratio W/L=0.38) than forbs (L/W=3.1 and W/L=0.42, respectively), in agreement with a global compilation for graminoids (L/W=4.3 for grass 5.4 grass and wetland graminoids) and forbs (L/W=2.9). However, overlapping L/W values present a challenge for establishing cut-off values for fuel type identification in charcoal assemblages with mixed fuel sources. Based on our analyses and compiled datasets from experimental burns, L/W values above 3.0 may indicate predominantly herbaceous morphologies in temperate grassland-dominated ecosystems, though values are likely to be higher for grass than forb-dominated grasslands. Notably, terrestrial grasses exhibit shorter aspect ratios (L/W=4.3) than wetland graminoids (L/W=6.4), highlighting that the aspect ratio needs tailoring to the specific environment of its application, i.e. wetland vs. terrestrial ecosystems. The long forms of graminoid charcoal particles also suggest their potential for atmospheric longer-distance transport compared to more spherical particles, meaning they likely provide insights into regional fire history. An important finding is that charcoal of herbaceous plants closely corresponded to the pollen record, highlighting a solid link between the dominant vegetation and fuel burnt in grassland-dominated environments. However, the relationship between woody charcoal and tree pollen may be more complex, as tree pollen can travel atmospherically longer distances compared to woody charcoal. Our results also highlight the complex interplay between local vegetation and charcoal composition with human fire use that needs to be considered when interpreting charcoal morphological records. A critical takeaway from this study is the importance of not assuming the universality of previous research findings and instead employing experimental approaches to characterise charcoal particles in new ecosystems prior to the application of these techniques. Furthermore, this study also highlights recommendations for further research in new geographical areas and proposes methodological adjustments to enhance the usefulness of charcoal analysis in fire research.

The Danube Delta is Europe's largest wetland system and of unique biogeographical character. Whilst its geomorphological evolution is relatively well-known its ecological history is poorly understood, including the history of human impact, as a result of the dynamic nature of deltaic systems, and the scarcity of reliably dated successions. In this paper, we report a multi-proxy record of palynology, sediment texture, geochemistry, and ostracods from the upper reaches of the Danube Delta. We use these data to reconstruct a mid-to-late Holocene history of vegetation and environmental changes at local and regional scales, which serve as a model for understanding baseline conditions in delta apex regions. From 7500 to 6200 ​cal ​yr BP, the study site was part of an inter-distributary channel-levee system connected to coastal lagoons and sensitive to sea-level fluctuations but transitioned to a partially-disconnected lacustrine environment after 5700 ​cal ​yr BP. These geomorphologically-driven landscape changes strongly influenced the pollen source area making it complex to interpret palynoassemblages. Prior to 5700 ​cal ​yr BP, palynoassemblages were predominantly river-transported, reflecting widespread hinterlands, and providing information for the regional reconstruction of the vegetation history in the northern Dobrogea region. These data reveal the early presence of Carpinus and Fagus in southeastern Romania, prior to their spread through the Carpathian Basin. After 5700 ​cal ​yr BP, initiated by a slowdown in the relative rate of rise of the Black Sea, peat accumulation commenced within the shallow lake depocentre and airborne pollen became the dominant source. These pollen data record an expansion of herbaceous taxa and highly diverse marsh and aquatic taxa. Tree cover became dominated by Quercus, with low percentages of Carpinus, Betula, Ulmus, and Tilia. The earliest pollen evidence indicative of human impact commences c. 6500 ​cal ​yr BP) and, after 3200 ​cal ​yr BP, the decline in Quercus and a synchronous rise in archaeological artifacts, points to an opening of the landscape by forest clearance and an enlargement of arable areas. In particular, clearance and agriculture during the development of the Hallstattian Babadag culture (c. 3200-2800 ​yr BP) reflects an increase in population and settlement density during that late interval. Our paper comprises the first mid-to-late Holocene palynological record for the Danube Delta and highlights how human activity has profoundly altered the dryland region, creating landscapes comparable to today from around 3200 years BP, while the local deltaic landscape retained its character over the last six millennia.

The stratigraphy of the lower reaches and floodplains store mineral sediments, organic matter, pollen, and charcoal which are important proxies for understanding the environmental evolution that directly interacts with human activity. The present study is based on four sediment cores (7 to 19 m long) from the Lower Danube floodplain in NW Dobrudgea, close to Galați-Măcin area. The cores were carefully described and sampled for grain size, loess on ignition, magnetic susceptibility, charcoal, pollen and radiocarbon dating to reconstruct the paleoenvironmental changes in a key region for Neolithic cultures dispersal across SE Europe. The results of these combined analyses from the four cores with a special focus on Jijila mastercore (placed in a lake derived from a former embayment) bring new data about the mid and late Holocene floodplain environmental changes and a new perspective regarding the first settlements emplacement in the study area. Lower Danube floodplain inhabitation is still a hotly debated subject. The archaeological findings suggest the first settlements date from the Bronze Age (La Grădini – Jijila; Brăila), whereas recent human bones datings point to an earlier inhabitation during the Mesolithic-Neolithic period (Brăiliţa). The newly obtained charcoal and pollen profiles on Jijila core show two intervals of higher intensity human activity, the first during the Neolithic period and the second during the mid and late Bronze Age. Both periods are highlighted with peaks in charcoal particles and pollen grains (cereals) indicative of human activity.

The Danube delta is Europe’s largest wetland system and of unique biogeographical character. Whilst its geomorphological evolution is relatively well-known its ecological history is poorly understood. This paper provides the first multi-proxy record, combining pollen, spores, sediment texture, geochemistry, and ostracod data from the upper Danube delta, reconstructing a series of well-defined environmental changes during the mid and late Holocene. Results indicate significant geomorphological transformations during the last 7500 cal yr BP: the study site had been part of a channel-levee system connected with the coastal lagoons nearby, sensitive to sea-level fluctuations until c. 6200 cal yr BP, and then transitioned to a largely disconnected lacustrine environment after 5700 cal yr BP. These geomorphologically-driven landscape changes strongly influenced the pollen source area and thus the pollen spectra. Prior to 5700 cal yr BP, the pollen was predominantly transported by river water, reflecting a large-scale pollen source area. Nevertheless, the data give a general picture of the vegetation composition in the region (northern Dobrogea) and support the early presence of Carpinus and Fagus in southeastern Romania, prior to their spread along the Carpathian Basin. At 5700 cal yr BP, initiated by the Black Sea level rise slow down, peat started to accumulate in the shallow lake and sub-regional airborne pollen becomes the dominant source. The pollen data shows a remarkable expansion of herbaceous taxa, particularly Poaceae, as well as high and diverse marsh and aquatic taxa. Tree cover became dominated by Quercus, with low percentages of other tree taxa such as Carpinus, Betula, Ulmus, and Tilia. Although the first pollen evidence of human impact is recorded in the Eneolithic (c. 6500 cal yr BP), from 3200 cal yr BP, the decline in Quercus is synchronous with more significant human indicators suggesting an opening of the landscape by forest clearance and enlargement of arable areas during the Late Bronze Age and Early Iron Age, especially during the Hallstattian Babadag culture (11-8th c. BC) which reflected a net increase in population and settlement density. This first continuous record for the mid-late Holocene from the Danube Delta shows that although local environmental change is strongly registered it is still possible to gain regional data on changing vegetation and human impact which has profoundly altered the Dobrogean region, creating landscapes comparable to today from around 3200 years BP.

This study confronts local environmental proxies (i.e., pollen, charcoal, paleofauna) with ancient sources documenting Kilia/Lycostomo Byzantine-Genoese settlement at the mouth of the northern Danube's distributary to reconstruct environmental changes which render difficult the localization of the Middle Age settlement. Historical data seem contradictory, while systematic archaeological research has been extremely difficult on the Chilia branch, the modern border between Romania and Ukraine. Yet, after the complete reevaluation of all the sources in relationship with their reconstructed paleoenvironments, we propose to locate the major Byzantine and Early Modern trading centre Lykostomion/Licostomo as well as Chilia at Kilija/New Chilia (now in Ukraine), on the Bugeac plateau, on the left bank of the Danube’s northern branch (itself called Chilia, former Lykostoma). Old Chilia (now in Romania), whose name was always taken as proof of the location of the famous historical city of Chilia, lacks archaeological traces of urban occupation before the 19th-20th century. In fact, this loess island in the delta, on the southern shore of the Chilia branch, has been used only for subsistence activities (fisheries, agriculture, husbandry) and for supporting the storage capacities of the main harbour of Lykostomion/Licostomo-Chilia, situated under the modern harbour of New Chilia. Besides texts and some scarce archaeological reports, this localisation is now supported by two sedimentary cores (PAR 1 and KIL 1) which allow the reconstruction of the Chilia branch progradation, with an absolute chronology based on 14C dates. Vegetation, charcoal and microfauna occurrence in the KIL 1 sediments of the last ca. 700 yrs are excellent proxies for the high-resolution study of the local deltaic dynamics under natural and human pressure. For the first time, they reveal information about the maritime and riverine milieux developing at the place where this trading hub was founded, the living conditions (food, housing, heating) of its inhabitants and the ecological changes related to their demographic fluctuations. Most interestingly, they show the environmental impact of the military conflicts and urban re-foundations, which occurred in the 13th, 15th and 18th centuries at this major gate of SE Europe.

The Carpathian island-type glaciokarst has a great potential of preserving signals of past environments, archived in cave deposits like speleothems and clastic infills. We present here the geomorphology and structural control of several relict alpine caves and the surrounding glaciated marble karst in the Fagara. Mountains. Four truncated and partially unroofed caves remained on the ridge-top of Museteica Mountain, above the glacial cirque, while a ponor cave that developed on the cirque bottom could be related to the Last Glacial Period. Structural measurements and cave morphology showed that the conduits formed at the intersection of foliation planes and tectonic fractures on the NE-SW and NW-SE directions. Cave development reflects three speleogenetic stages: 1) texture- and fabric-controlled dissolution and distension; 2) structurally-controlled breakdown; and 3) truncation, unroofing, and cave infilling with sediments. Slow diffuse dissolution was typical for the ridge-top caves, whereas M1 Cave developed by pressure flow. Further, we report the first U-Th speleothem ages, related to the evolution of alpine caves and island glaciokarst in the South Carpathians during the Middle and Late Pleistocene. Dating results show a minimum estimated age of similar to 560 ka for the ridge-top caves, and that speleothem deposition met optimal conditions only during warmer periods, largely corresponding to interglacials. Stable carbon isotope values in speleothems range between-9.96% and-4.11%, indicating the presence of plant and soil organic activity at the time of deposition. In total, five speleothem growth phases were distinguished during the last similar to 560 ka. We excavated the sediment infill of a ridge-top doline down to a 2-m depth. Radiocarbon dating revealed that it was deposited during the Late Holocene, and preliminary pollen analysis identified a plant assemblage dominated by grasses. Using the relationships between karst development, glaciation, and cave sedimentary archives, we present a time slice chronology of alpine landscape evolution at >560 ka, similar to 400 ka, similar to 330 ka, the Last Glacial Period (70-12 ka), and the Late Holocene. Our geomorphological, isotopic, and geochronological results also support the existing hypothesis that the South Carpathians may have experienced at least two glacial phases during the Pleistocene. Glacial erosion rate during the Last Glacial Period, and most likely during the penultimate glaciation, averages around 0.6 mm yr(-1). (C) 2020 Elsevier B.V. All rights reserved.

Future patterns of European ecosystem services provision are likely to vary significantly as a result of climatic and socio-economic change and the implementation of adaptation strategies. However, there is little research in mapping future ecosystem services and no integrated assessment approach to map the combined impacts of these drivers.Map changing patterns in ecosystem services for different European futures and (a) identify the role of driving forces; (b) explore the potential influence of different adaptation options.The CLIMSAVE integrated assessment platform is used to map spatial patterns in services (food, water and timber provision, atmospheric regulation, biodiversity existence/bequest, landscape experience and land use diversity) for a number of combined climatic and socio-economic scenarios. Eight adaptation strategies are explored within each scenario.Future service provision (particularly water provision) will be significantly impacted by climate change. Socio-economic changes shift patterns of service provision: more dystopian societies focus on food provision at the expense of other services. Adaptation options offer significant opportunities, but may necessitate trade-offs between services, particularly between agriculture- and forestry-related services. Unavoidable trade-offs between regions (particularly South-North) are also identified in some scenarios.Coordinating adaptation across regions and sectors will be essential to ensure that all needs are met: a factor that will become increasingly pressing under dystopian futures where inter-regional cooperation breaks down. Integrated assessment enables exploration of interactions and trade-offs between ecosystem services, highlighting the importance of taking account of complex cross-sectoral interactions under different future scenarios of planning adaptation responses.

Histria (Istros) is one of the earliest Milesian colonies founded on the Black Sea coast during the archaic period (7th c. BC). Its remains are located within what is today the Razelm-Sinoe lagoon system which forms the southern part of the Danube Delta. During its 13 centuries of existence, Histria experienced an environment favourable for a prosperous economy (e.g. fishery, farming, grazing, pottery, marine trades) as indicated by numerous archeological finds from both in situ and elsewhere in the Black Sea and Mediterranean Sea basins. Moreover, it benefited from a strategic position on an open-coast, which was easy to defend. Important environmental changes occurred both during and after the existence of the ancient city, and the most significant are related to major shoreline displacement. This study reports Late Holocene coastal landscape changes, from the open-coast stage to the present-day lagoon system, based on numerical age determination of the paleoshorelines, stratigraphic records by cores in lagoons and beach ridges and topographic surveys. A new chronological framework is established which reports younger ages than previously suggested for the coastal morphosedimentary units of the Histria region. Further, the findings shed new light upon the evolution of the southern part of the Danube delta. The results point to the development of an ancient deltaic lobe (Dunavatlobe, 2000-1300 BP, associated with the southernmost Danube distributary) which was situated 10-20 km north of the settlement. The lobe was subsequently reworked by waves, providing sediments which were accumulated downdrift (southward) as a continuous beach ridge plain (Saele-Chituc) in front of the city, leading to its isolation from the sea. The abandonment of Histria (7th c. AD) coincides with the decoupling of the city from the open coast as a consequence of the shoreline progradation. The new beach ridge plain (Saele-Chituc) is affected by intense neotectonic movements which led to the recent drowning of its central part and the formation of Sinoe lagoon; the same processes affected the downdrift part of the Dunavat lobe and Histria and Nuntasi Lakes. The new sea-level curve obtained for the Histria region shows relative stability within the last four millennia, with oscillations within 0 to -2 m of the current level. This contradicts the concept of a marine regression (Phanagorian) which is suggested to have occurred during the 1st millennium BC. However, a few areas containing archeological remains are currently below sea-level owing to local neotectonics. (C) 2012 Elsevier Ltd and INQUA. All rights reserved.

Histria (Istros) is a Milesian colony founded on the Black Sea coast during the 7th c.BC. Nowadays, the remains of the ancient city are located 8 km inland form the Black Sea coast, on the continental edge of the Razelm-Sinoe lagoon system which forms the southern part of the Danube Delta. Significant environmental changes occurred during and after the ancient city's lifetime, particularly related to dramatic shoreline displacement. The present study deals with the Late-Holocene coastal landscape transformation from the open-coast stage to the present-day lagoon system. Our research includes stratigraphic records by Ground Penetrating Radar scanning of the beach ridges, cores in lagoons and beach ridges and absolute age determination of the paleoshorelines. The study shows that the ancient city decoupling from the sea was due to the beach ridge plain development southward and eastward of the acropolis. The decline of the Histria city, documented during the 7th c. AD, temporally coincides with the decoupling of the city from the open coast as a consequence of the shoreline progradation. Discontinuous chronology and discordant stratigraphy obtained by OSL dating and GPR scanning of successive ridges document intense neotectonic movements which affected Saele-Chituc beach ridge plain. The seismic activity led to the recent drowning of its central part and the formation of the Sinoe lagoon; the same processes acted at the downdrift part of the Dunavat lobe and also in the areas presently occupied by Histria and Nuntasi Lakes. Several areas containing archeological remains are currently below sea-level due to local neotectonics.