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We conducted multi-proxy analyses in two subalpine lakes, Lake Gropile, in the Rodna Mountains and Lake Vinderelu in the Maramureș Mountains, the Eastern Carpathians, Romania, to investigate the effect of different land-use practices on landscape composition, diversity and slope erosion. In the case of Lake Gropile, results evidenced a more extended tree and shrub cover and high fire activity between 6400 and 2800 cal yr BP, accompanied by reduced soil erosion, which appeared more strongly regulated by climatic conditions. Anthropogenic impact became evident 2800 years ago, when landscape openness, pasturing, and disturbance of soil cover increased and intensified over the last four centuries. In the case of Lake Vinderelu, intensified burning was followed by grazing around 1200–1100 cal yr BP and continued throughout the last millennium. Results also highlight the site-specific effects of land-use on vegetation composition and landscape diversity. For Lake Vinderelu, a combined effect of local burning and grazing in removing shrub cover appear to be the main drivers of changes in landscape diversity and structure. At Lake Gropile, fire was more connected to shrub cover changes while grazing to herbaceous cover diversity. Moderate to low grazing appeared to benefit both subalpine ecosystems, creating rich grassland-shrub mosaic communities, while overgrazing reduced landscape diversity and exacerbated erosion. Our findings document the millennial-scale legacy of land-use practices on the subalpine landscapes in this region. We propose that these semi-natural ecosystems hold important ecological and cultural value, and recommend their maintenance through controlled, low intensity pasturing and/or burning. [ABSTRACT FROM AUTHOR]

Despite the increasing interest in spring-fed fens' sediments as a palaeoenvironmental archive, their potential as high-precision climatic records is rarely used to its full extent. Here, we present a detailed early to mid-Holocene record of environmental changes in the Turtul hanging spring-fed fen, northeastern Poland, to test whether the well preserved and accurately subsampled alternating peat and tufa sediments allow us to recognise short-duration local and regional climatic changes. Our reconstructions are based on a loss-on-ignition analysis of the sediment, carbon and oxygen stable isotope values of tufa, and biotic proxies: plant macrofossil and malacological analyses. A detailed environmental reconstruction was possible due to the combination of detailed sampling (1 cm intervals) and high sediment accumulation rates. The two sediment sequences collected from the fen revealed the congruent palaeoenvironmental history; however, the temporal shift associated with the distance of the coring site from the water outflow was also apparent, stressing the need for careful selection of the coring site in palaeoenvironmental research. Peat deposition at Turtul started at 10,300 cal yr BP; however, tufa precipitation did not begin before 9250 cal yr BP. During the most active tufa deposition, from 7850 to 6100 cal yr BP, a high sedimentation rate was observed (0.11–0.25 cm yr−1). We found several abrupt and short-duration declines in carbonate deposition corresponding to climatic fluctuations recorded in geological archives from the southeastern Baltic region. The carbonate drops at 8200–8130, 7900–7850, 7400–7300, 6600–6500, 5980–5870 and 5400 cal yr BP were associated with climate cooling or drying, whereas those at 10,200–9250, 8450–8340 and 6160–6100 cal yr BP can be attributed to drying with no cooling. We conclude that the evident sensitivity of the Turtul fen to climatic shifts that emerge from our high-resolution (one sample every 17 years on average) reconstruction complements the still rare high-resolution palaeoenvironmental records in the area. [ABSTRACT FROM AUTHOR]

Long-term ecological studies can provide useful information on forest ecosystem resilience against past climatic change and human caused disturbances. Here, we present a high-resolution 2200-year-long record of forest development in north-eastern Poland, Suwalki region, using paleobotanical proxies (pollen, plant macrofossils, and charcoal). We show that the pollen abundance of deciduous trees was higher than that of coniferous trees, indicating a near pristine state until 900 AD and a semi-natural forest state until 1500 AD. After 1500 AD, the proportion of coniferous tree taxa surpassed that of deciduous trees and have since remained the dominant forest component. The 17th century experienced massive deforestation coupled with a new phase of human colonization in the area that led to the continued and significant decline of deciduous tree cover, for example, Carpinus, Quercus, and Tilia. Cooling associated with the Little Ice Age may have played a role in Picea's expansion in this area after 1450 AD. Despite significant climatic shifts associated with the warmer Roman Period or Medieval Climate Anomaly and colder Migration Period, as well as a more sustained human impact, Quercus remained a stable forest component until 1500 AD. The stability of Quercus is an important aspect for forest management strategies as future projections suggest warmer conditions and increased frequency of climate extremes will impact forest composition and structure. Our long-term data suggest that forests in the Suwałki region should contain more abundant deciduous tree species, that is, Quercu s, whereas conifer cover should be reduced. We also show clear regional differences in the forest development in the Suwałki region, highlighting the importance of local hydrology, geomorphology, and degrees of human activity on the forest composition. [ABSTRACT FROM AUTHOR]

Mountain regions harbour high biodiversity; however, in numerous areas, they are strongly degraded by human activity. Our study reconstructs the development of the submontane forest belt (400 and 650 m a.s.l.) in the Beskid Wyspowy Mountains (Western Carpathians, Central Europe) affected by climate, humans, fire, and parasitic fungi during the Holocene. This forest belt is considered the most transformed by the human in the Carpathian region. Our multi-proxy study included analyses of pollen, non-pollen palynomorphs (NPPs), plant macrofossils, micro- and macrocharcoal (size fraction >100 µm, analysed in contiguous sampling), geochemical, and sedimentological markers. The results revealed that Picea abies dominated on the fen subjected to study at ca. 8510–5010 cal. BP. Tilia cordata was a substantial component of the submontane forest between ca. 8510 and 2970 cal. BP and it survived a probable Kretzschmaria deusta outbreak, as well as a period of increased fire activity (ca. 6000 cal. BP). The final retreat of forests with a substantial contribution of Tilia was induced by the expansion of Abies alba, Fagus sylvatica, and partly Carpinus betulus and was preceded by the period of increased fire activity and erosion. From ca. 900 cal. BP human-induced deforestations and agricultural and pastoral activity increased. The modern presence of woodlands with Pinus sylvestris and Larix decidua, in the submontane zone in the Beskid Wyspowy Mountains, is a result of sub-recent anthropogenic afforestation on overgrazed areas. The example of the Zbludza site reveals that changes related to fire and pathogen infections, if they have low magnitudes and new competitive taxa are absent, may be reversible in a forest composed of fire-intolerant tree taxa as Tilia. Nonetheless, the widespread submontane ecosystem degradation and the introduction of alien species hamper the regeneration of forest vegetation typical of the submontane zone. [ABSTRACT FROM AUTHOR]

Landslide mountain fens formed in landslide depressions are dynamic environments as their development is disturbed by a number of factors, for example, landslides, slopewash, and surface run-off. These processes lead to the accumulation of mineral material and wood in peat. Disturbed peatlands are interesting archives of past environmental changes, but they may be challenging for providing biotic proxy-based quantitative reconstructions. Here we investigate long-term changes in testate amoeba communities from two landslide mountain fens – so far an overlooked habitat for testate amoeba investigations. Our results show that abundances of testate amoebae are extremely low in this type of peatlands, therefore not suitable for providing quantitative depth-to-water table reconstructions. However, frequent shifts of dominant testate amoeba species reflect dynamic lithological situation of the studied fens. We observed that high and stable mineral matter input into the peatlands was associated with high abundances of species producing agglutinated (xenosomic) as well as idiosomic shells which prevailed in the testate amoeba communities in both analyzed profiles. This is the first study that explores testate amoebae of landslide mountain fens in such detail, providing novel information about microbial communities of these ecosystems. [ABSTRACT FROM AUTHOR]

A better understanding of past long-term environmental changes in the subarctic region is crucial for mitigation of the possible negative effects of climate warming in this vulnerable region. This study provides a new multi-proxy reconstruction of regional vegetation changes and peatland development for north-eastern Fennoscandia (Russia) during most of the Holocene. To that purpose, we performed plant macrofossil, pollen, testate amoebae, peat humification, loss on ignition and radiocarbon analyses of the peat deposits from a mire around Vodoprovodnoe Lake (the Kindo Peninsula, the Republic of Karelia). Our data indicate that the peat deposits started accumulating before 9147 ± 182 cal. yr. BP. The vegetation cover in the area was mainly typical for the northern taiga zone, except for the period ~7800–5600 cal. yr. BP, when it generally resembled the middle taiga zone. The vegetation cover and peatland were greatly affected by reoccurring fires, which can be partly related to human activity. These events were associated with an increased proportion of birch in the vegetation cover (as a pioneer species) and/or water level decreases. By 600 cal. yr. BP, the peatland and the surrounding vegetation reached its current state and only minor changes had been recorded since that time. Overall, our results suggest a considerable and unexpected role of fires in the postglacial dynamics of subarctic peatlands. [ABSTRACT FROM AUTHOR]

Although several studies provide a broad overview of vegetation changes in the Carpathian Basin during the Holocene, stand-scale vegetation changes are lesser known because of the rarity of suitable sampling sites. In this study we investigated the sediment of a small closed-canopy site (Nagy-forrás forest hollow, 685 m a.s.l., 0.1 ha), located in the Mátra Mountains, on the north facing slope of Kékes (1014 m a.s.l.). We carried out detailed pollen, conifer stomata and plant macrofossil analyses, as well as radiocarbon dating to examine Late Glacial and Holocene dynamics of vegetation development. The site dates back to ca. 15,500 cal yr BP, when open boreal forests and wet tundra-like habitats occurred around the hollow. Closed forest cover developed around 14,600 cal yr BP, when a boreal European larch-Swiss stone pine (Larix decidua-Pinus cembra) forest surrounded the hollow. This vegetation type remained stable up to 7700 cal yr BP. We observed a hiatus between 7700 and 2710 cal yr BP, followed by a beech (Fagus sylvatica) dominated mixed temperate deciduous forest. Our results confirmed that the area was covered by a primary forest, as human influence was visible only from 175 cal yr BP. The relatively long lasting persistence of Pinus cembra in the Holocene at relatively low altitude was documented, which has never been found in Holocene sediments in the Pre-Carpathians before. We hypothesize that the north facing slope acted as a cold-stage refugium in the Early Holocene and could play the same role for the present-day beech forest that is threatened by recent climate change. [ABSTRACT FROM AUTHOR]

In this article, we examined the indicative value of a relationship between two non-pollen palynomorphs (NPPs), fungal HdV-10, related to the presence of Calluna vulgaris, and HdV-31A, which is testate amoeba – Archerella flavum. Both are frequently present on slides designated for pollen analysis, prepared from Sphagnum peat. We analysed three profiles from three extensive ombrotrophic peatlands in northern Poland, in which the content of testate amoebae (TA) was examined and TA-inferred depth to the water table (DWT) was reconstructed. The new analysis of palynological samples regarding NPPs revealed that strong increases in HdV-10 content were mostly simultaneous to HdV-31A declines. However, the relations between both types were not statistically significant. The rapid increases in HdV-10, despite the fact that this type of conidiospores is related to drier habitats on peatlands, were tentatively interpreted as an indicator of rapid rises in the water table level which, in consequence, might have stimulated the production of these spores by fungi. In addition, a negative correlation between HdV-31A and Arcella discoides and positive one, but weaker, in case of HdV-10 (attributed by some authors to species Trichocladium opacum (Corda) S Hughes) and A. discoides show a link between mutual fluctuations of both NPPs and hydrological instabilities on peatland. The Bagno Kusowo bog, the westernmost peatland subjected to the study, displayed an intriguing agreement between the presence of peat sections with strong increases in HdV-10 and cold climate events affecting Europe. Our study reveals that counting even a limited number of NPP types during the standard pollen analysis of Sphagnum peat may support the interpretation of results, especially, in cases when the investigation lacks testate amoeba analysis. When the reconstruction of TA-inferred DWT is provided, it may introduce additional information about the patterns of hydrological dynamics. [ABSTRACT FROM AUTHOR]

Sediments from an oxbow lake located in the Prosna River valley (Poland) were analysed to investigate the developmental history of the wetland ecosystem and any response to abrupt climatic changes. High resolution plant macrofossil analysis and radiocarbon dating were undertaken on two cores, with lower resolution geochemical analysis conducted on one of these cores. We provide evidence of a palaeolake with a late Glacial origin (older than 12,500 years). Abundant fossil presence of macrophytes (e.g. multiple Potamogeton species) in the studied palaeomeander may indicate that the north–south orientation of the Prosna valley made it an important route for the spreading of aquatic plants during the late Glacial. Chara sp., Batrachium sp. and Potamogeton spp. were the pioneer plants that colonised cold water with a high Ca2+ content. Early Holocene warming trigged a decrease in water level at the oxbow lake and facilitated the expansion of thermophilous water plants, for example, Ceratophyllum demersum, Typha sp. and Lemna trisulca, which usually occur in shallow water. A decreasing water level resulted in the gradual isolation of the study site from the influence of groundwater, leading to acidification of the habitat and the development of a Sphagnum population, with S. contortum and S. teres as dominant species. The presence of S. contortum (the oldest occurrence in the European lowlands) and S. teres during the early Holocene may indicate that river valleys and the peatlands that developed in this region acted as an important habitats (and possibly refugia) for some minerotrophic Sphagnum species. [ABSTRACT FROM AUTHOR]

Fire is a major disturbance agent in the boreal forest, influencing many current and future ecosystem conditions and services. Surprisingly few studies have attempted to improve the accuracy of fire-event reconstructions even though the estimates of the occurrence of past fires may be biased, influencing the reliability of the models employing those data (e.g. C stock, cycle). This study aimed to demonstrate how three types of fire proxies – fire scars from tree rings, sedimentary charcoal and, for the first time in this context, fungal spores of Neurospora – can be integrated to achieve a better understanding of past fire dynamics. By studying charcoal and Neurospora from sediment cores from forest hollows, and the fire scars from tree rings in their surroundings in the southern Fennoscandian and western Russian boreal forest, we produced composite fire-event data sets and fire-event frequencies, and estimated fire return intervals. Our estimates show that the fire return interval varied between 126 and 237 years during the last 11,000 years. The highest fire frequency during the 18th–19th century can be associated with the anthropogenic influence. Importantly, statistical tests revealed a positive relationship between other fire event indicators and Neurospora occurrence allowing us to pinpoint past fire events at times when the sedimentary charcoal was absent, but Neurospora were abundant. We demonstrated how fire proxies with different temporal resolution can be linked, providing potential improvements in the reliability of fire history reconstructions from multiple proxies. [ABSTRACT FROM AUTHOR]

The Central European area has been extensively studied using qualitative reconstruction techniques focusing on the development of peatlands in the past; however, research based on quantitative techniques is still lacking, especially in relation to highlands and mountainous areas. In this study, we focused on the hydrological changes and human-induced disturbances that affected two raised bogs from the Orawa-Nowy Targ Basin (Carpathian region): Puścizna Krauszowska and Puścizna Mała. We aimed to reconstruct the development of peatlands and changes in water table under different intensities of human activities. Two peat sequences from two different bogs, both possessing absolute chronologies based on high-resolution 14C dating, were examined in terms of pollen, non-pollen palynomorphs, plant macrofossils and testate amoeba records. We detected an asynchronous decrease in the water table level on the bogs that took place between the 4th and the 7th century ad, which occurred simultaneously with a global cold period ad 300–600 (Migration Period) in case of the Puścizna Mała bog. A concurrent but insignificant human impact on bogs was recorded. A distinct wet shift corresponding to the Wolf solar minimum (ca. ad 1280–1340) in Puścizna Mała was detected during ca. ad 1300–1350. The effect of this climatic event on bog hydrology is difficult to estimate because of the simultaneous human-induced deforestation. Drainage and substantial acceleration of peat extraction in the 19th and the 20th century ad led to the significant disturbances in peatland; however, these bogs were still susceptible to dry climatic events. [ABSTRACT FROM AUTHOR]

It is commonly assumed that the majority of buried ice-blocks in Europe melted at the end of Late Glacial period and during the first part of the early- Holocene. We show, however, that scattered dead-ice-blocks may have been preserved in the ground until 8500 cal. yr BP. We analysed thermokarst features in Lake Ķikuru, western Latvia, by means of a multi-proxy approach (pollen, non-pollen palynomorphs, plant macrofossils, diatoms, loss-onignition, magnetic susceptibility, C:N ratio, carbon accumulation rate and radiocarbon dating). Abiotic and biotic processes following the ice-block meltdown suggests abrupt development of a thermokarst from 8500 to 7400 cal. yr BP. Important changes in local vegetation occurred with the deepening of a kettle-hole during the transition from a fen to a lake that nearly coincided with the appearance of the first fish at 7800 cal. yr BP, thus forming a clear indication of a lacustrine environment. Our study shows that a thin peat layer formed at first and, due to the meltdown of the ice-block, it gradually lowered to the bottom of the kettle-hole, and gyttja begun to accumulate afterwards. Given that thermokarst arise when the mean summer air temperature gradually increases to a value above the present-day temperature, we must assume that the local conditions must have been exceptional to secure ice-block from the meltdown for so long. Therefore, the legacy of the last ice age was still evident even ca. 5500 years after the Weichselian ice retreat from the eastern Baltic. [ABSTRACT FROM AUTHOR]

Wetlands are very vulnerable ecosystems and sensitive to changes in the ground water table. For the last few thousand years, hydrological balance has also been influenced by human activity. To improve their cropping features, drainage activity and fertilizing were applied. The drainage process led to an abrupt change of environment, the replacement of plant communities and the entire ecosystem. The problem of carbon sequestration is very important nowadays. A higher accumulation rate is related to higher carbon accumulation, but the intensity of carbon sequestration depends on the type of mire, habitat, and climatic zone. The main aim of this article was an examination of the changes in poor-fen ecosystem during the last 200 years in relation to natural and anthropogenic factors, using paleoecological methods (pollen and macrofossils). The second aim was a detailed investigation of the sedimentary record to aid our understanding of carbon sequestration in the poor fen of temperate zone. This case study shows that fens in temperate zones, in comparison with boreal ones, show higher carbon accumulation rates which have been especially intensive over the last few decades. To reconstruct vegetation changes, detailed palynological and macrofossil analyses were done. A 200-year history of the mire revealed that it was influenced by human activity to much degree. However, despite the nearby settlement and building of the drainage ditch, the precious species and plant communities still occur. [ABSTRACT FROM AUTHOR]

This study explores the history of the development of Sphagnum communities in an ombrotrophic peatland – Bagno Kusowo – over the past 650 years, based on high-resolution plant macrofossil and testate amoebae analysis. Our research provided information related to the length of peatland existence and the characteristics of its natural/pristine state before the most recent human impacts. Changes in the Sphagnum communities before human impact could have resulted from climate cooling during the ‘Little Ice Age’ (LIA). In this cold and unstable hydrological period, among vascular plants, Eriophorum vaginatum and Baeothryon caespitosum dominated in the peatland vegetation. Peat-forming Sphagnum communities survived the drainage conducted during the 20th century at the Bagno Kusowo bog. We provide three important messages through this study: (1) testate amoebae reflect similar hydrological trends in two peat cores despite considerable microhabitat variability, (2) average long-term water level 10 cm below the surface should be a target for active bog conservation and (3) sites like Bagno Kusowo are extremely important to preserve the remains of pristine biodiversity (including genetic diversity of plants and protists) that was completely removed from most of the raised bogs in Europe due to human activities, for example, drainage. [ABSTRACT FROM AUTHOR]

Peat deposits from an ombrotrophic bog (north-eastern Poland) were analysed to reconstruct peatland development and environmental changes. This paper presents reconstructions of hydrological changes and plant succession over the last 6000 years. The methods included the high-resolution analysis of plant macrofossils, pollen and testate amoebae, supported by radiocarbon dating. Three main phases were identified in the history of the bog and surrounding woodland vegetation: 4000–400 BC, 400 BC–AD 1700 and AD 1700–2011. Except for terrestrialisation and the fen-to-bog transition phase, the development of bog vegetation was mainly dependent on the climate until approximately AD 1700. The dominant taxon in Gązwa bog was Sphagnum fuscum/rubellum. Woodland development was significantly affected by human activity at several time periods. The most visible human activity, manifested by the decline of deciduous species, occurred ca. 350 BC, ca. AD 250, ca. AD 1350 and after AD 1700. These events correspond to phases of human settlement in the area. During 400–300 BC, the decline of deciduous trees, primarily Carpinus, coincided with an increase in indicators of human activity and fire frequency. At ca. AD 200, Carpinus and Tilia abundance decreased, corresponding to an increased importance of cereals (Secale and Triticum). Since ca. AD 1350, the impact of Teutonic settlement is apparent, and after AD 1700, deciduous forests largely disappeared. [ABSTRACT FROM PUBLISHER]

Fens are underestimated carbon sinks. Knowledge about their role in the sequestration of CO2 in the past is limited. The research reported here focused on identifying long-term carbon accumulation rates (CARs) in a drained fen (Bagno Bruch) and a waterlogged fen (Bagno Mikołeska) in southern Poland. On the basis of 210Pb and AMS 14C dates and age–depth modeling, 7000- and 2000-year records of changes in bulk composition and carbon and sulfur content are presented and discussed. Strong human impact is detected, especially in Bagno Bruch. However, minor climatic signals linked to the ‘Little Ice Age’ and to the influence of wind-blown sands are also evident. The sand may have influenced the plant composition, peat accumulation rates (PARs), and CARs, in addition to the bulk composition at Bagno Mikołeska. The mean value of the CAR in the youngest peat layers spanning the last 200 years is generally lower in two cores from Bagno Bruch (c. 85 and 86 g/m2/yr) than in two cores from Bagno Mikołeska (c. 140 and 142 g/m2/yr). The fens are characterized by higher CARs compared with boreal peatlands. The reproducibility of the CAR values is the most promising result, suggesting the low mobility of 210Pb and the reliability of this method in assessing the chronology of fens. [ABSTRACT FROM PUBLISHER]

Here, we present results from the most comprehensive compilation of Holocene peat soil properties with associated carbon and nitrogen accumulation rates for northern peatlands. Our database consists of 268 peat cores from 215 sites located north of 45°N. It encompasses regions within which peat carbon data have only recently become available, such as the West Siberia Lowlands, the Hudson Bay Lowlands, Kamchatka in Far East Russia, and the Tibetan Plateau. For all northern peatlands, carbon content in organic matter was estimated at 42 ± 3% (standard deviation) for Sphagnum peat, 51 ± 2% for non-Sphagnum peat, and at 49 ± 2% overall. Dry bulk density averaged 0.12 ± 0.07 g/cm3, organic matter bulk density averaged 0.11 ± 0.05 g/cm3, and total carbon content in peat averaged 47 ± 6%. In general, large differences were found between Sphagnum and non-Sphagnum peat types in terms of peat properties. Time-weighted peat carbon accumulation rates averaged 23 ± 2 (standard error of mean) g C/m2/yr during the Holocene on the basis of 151 peat cores from 127 sites, with the highest rates of carbon accumulation (25–28 g C/m2/yr) recorded during the early Holocene when the climate was warmer than the present. Furthermore, we estimate the northern peatland carbon and nitrogen pools at 436 and 10 gigatons, respectively. The database is publicly available at https://peatlands.lehigh.edu. [ABSTRACT FROM PUBLISHER]

A high-altitude lake sediment sequence (Buhăiescu Mare, 1918 m a.s.l.) in the subalpine zone of the Rodna Mountains was analysed through a multi-proxy approach to determine the sensitivity of high mountain habitats to climate, fire and land use changes. The early Holocene regional forests were dominated by Pinus (sylvestris and mugo) and replaced by Picea abies from 9800 cal. yr BP. After an extended hiatus in the profile (c. 9800–4200 cal. yr BP), probably because of the physical removal of sediments through avalanche or high-flow events, P. abies, Abies alba and Fagus sylvatica forests developed after 4200 cal. yr BP. The timberline and treeline reacted sensitively to past changes in climate and human impact. The site was probably situated above the treeline throughout most of the investigated period. However, a treeline ecotone or krummholz zone may have sporadically reached the lake’s elevation in the early Holocene. A decline in timberline and treeline elevation was noted during the last 1200 years, and more evidently over the past 200 years, with replacement by subalpine shrubs (Alnus viridis) and alpine herbaceous communities. Because these vegetation changes were associated with an increased prevalence of pollen-based anthropogenic indicators, charcoal particles and abiotic indicators, human-induced fires and clearance and resultant erosion inputs to the lake are implied. Effects of current warming on the altitude range of trees are not yet visible, probably because land use has more strongly contributed to changes in land cover than the climate fluctuations of the last millennium in the Rodna Mountains. [ABSTRACT FROM PUBLISHER]