Pollen reveals the diet and environment of an extinct Pleistocene giant deer from the Netherlands

Pollen analysis of five teeth (two premolars, three molars) from a single maxilla of a giant deer (Megaloceros giganteus) found in Pleistocene deposits in The Netherlands reflects the diet and the landscape of the specimen that lived in eastern Doggerland. Apiaceae (among which Anthriscus sylvestris, Heracleum and Hydrocotyle), Asteraceae (among which Anthemis-type, Senecio-type and Cichorioideae), Filipendula, Poaceae and Symphytum were among the ingested plants. The landscape had dense, species-rich tall-herb vegetation and an open tree layer of Alnus and Betula, whereas thermophilous tree taxa were absent. Climate was probably cool-temperate, semi-dry, sub-continental. A radiocarbon date of the maxilla is beyond the 14C detection limit. We conclude that our giant deer most likely lived during the early Eemian or during an early Weichselian interstadial.</p

The effect of climate variability on pollen productivity, AD 1975-2000, recorded in a Sphagnum peat hummock

Pollen accumulation rates and pollen percentages from a Sphagnum peat hummock in the Jura Mountains were used to determine past pollen deposition. Post-bomb calibrated radiocarbon dates allowed estimations of annual variability in pollen productivity AD 1975-2000. Percentages of abundant taxa were modified (downweighted) to reduce the influence of plant cover, mean pollen productivity, and interdependence of the variables. Significant correlations with seasonal climatic parameters (tested with simple linear regression) were found both for pollen accumulation rates and for modified pollen percentages. Winter temperature is an important factor for pollen productivity of several tree species. The climatic effect on the modified pollen assemblage is best explained by a wet/warm to cold/dry gradient, but seasonal influence is considerable (ordination by PCA, RDA). Modified pollen percentages showed similarities in annual fluctuations between sites in the Jura Mountains, the Western Alps and the Eastern Alps

Holocene tree immigration and the chironomid fauna of a small Swiss subalpine lake (Hinterburgsee, 1515 m asl).

Early Holocene reforestation by stone pine (Pinus cembra) and tree birch (Betula pubescens) took place ca. 500 years after the end of the Younger Dryas at Hinterburgsee, a small subalpine lake in the northern Swiss Alps. During the next ca. 3000 years the local vegetation consisted of open woodlands with many pioneer dwarf shrubs and herbs. The expansion of silver fir (Abies alba) at ca. 7400 calibrated radiocarbon years before present (cal. BP) and Norway spruce (Picea abies) at ca. 6000 cal. BP in Hinterburgsee's catchment led to a closing of the local forests with a successive decrease in erosion and a distinct change in Hinterburgsee's sediment composition. First signs of probably human-induced openings of the catchment forest are apparent at ca. 2500 cal. 13P, but it is not until the past ca. 800 years that pollen analysis suggests strong local and regional anthropogenic activity. The strongest and most abrupt changes in the Holocene development of Hinterburgsee's chironomid fauna took place at ca. 11500 cal. BP and at ca. 10 000 cal. BP, when parts of the alpine taxa that were dominant during the Younger Dryas disappeared from the lake. The first change is most likely related to the increasing temperatures after the end of the Younger Dryas, the second possibly to decreasing lake depth and increasing summer insolation in the early Holocene that may have led to warmer bottom water temperatures in the lake. No clear relationship between the changes in catchment vegetation and the development of the chironomid fauna was found. Possibly the increase in sediment organic matter associated with the denser catchment forests was responsible for a succession in the chironomid stratigraphy between 7000 and 4500 cal. BP. However, due to the high sedimentation rates in Hinterburgsee this trend could also be a consequence of, or be promoted by, the sediment infilling of the lake basin. This conjecture is supported by the increasing importance of Tanytarsus lugens-type, a chironomid taxon dominant in the extant chironomid assemblages of shallow mountain lakes in Switzerland. The only shift in the chironomid fauna that clearly parallels a change in catchment vegetation is found during the past ca. 800 years. We discuss possible reasons for the comparatively weak influence of catchment vegetation on the chironomid fauna of Hinterburgsee and the implications of our results for multi-proxy studies on past climate involving both palaeobotanical and chironomid-based reconstructions

The occurrence of an upper decomposed peat layer, or “kultureller Trockenhorizont”, in the Alps and Jura Mountains

Many European mires show a layer of increased decomposition and minerogenic content close to the mire surface. Although the phenomenon is widely recognised, there have been few investigations of its distribution, cause and effect. In this study, nine peat profiles from the Alps and Jura Mountains in central Europe were studied to assess general trends in the upper peat stratigraphy. Analyses of pollen and fungal spore content in two profiles indicates that near-surface changes in decomposition are related to recent historical changes in grazing intensity of the surrounding landscape. Reduced trampling pressure and/or decreased nutrient input allowed partial Sphagnum regeneration in the western Alps and Jura Mountains from AD 1940–60, and in the eastern Alps from AD 1820–60. The results are considered in the context of climate and land use, and future implications for mire development in a changing environment are discussed. Many high-altitude mires in the area are now in a Sphagnum peat re-growth state, but future land use and climatic change will determine whether they will develop towards raised bog or forest carr

Pollen and spores from molar folds reflect food choice of late Pleistocene and Early Holocene herbivores in The Netherlands and the adjacent North Sea area

Molars of eight large herbivore species (Megaloceros giganteus, Cervus elaphus, Rangifer tarandus, Alces alces, Bison priscus, Ovibos moschatus, Coelodonta antiquitatis and Stephanorhinus kirchbergensis) were collected ex situ from Pleistocene and Holocene sands dredged in the North Sea, and from Dutch inland sites. Folds in many molars contained compacted masticated plant remains, and also microfossils. We identified pollen, spores, and non-pollen palynomorphs and discuss and interpret food preferences, represented flowering seasons, or parts of flowering seasons, and we discuss effects of changing vegetation composition in relation to climate and age of the molars, based on the pollen spectra. Various confounding factors have contributed to the recorded pollen composition, but nevertheless the pollen spectra show valuable aspects of vegetation composition, food choice, age, and landscapes, from subarctic open areas to interglacial forest. Ecological and statistical analysis of the results shows dietary differences between the mammal species analyzed

Paleolimnological evidence for increased landslide activity due to forest clearing and land-use since 3600 cal BP in the western Swiss Alps.

Schwarzsee is located in the western Swiss Alps, in a region that has been affected by numerous landslides during the Holocene, as evidenced by geological surveys. Lacustrine sediments were cored to a depth of 13 m. The vegetation history of the lake's catchment was reconstructed and investigated to identify possible impacts on slope stability. The pollen analyses record development of forest cover during the middle and late Holocene, and provide strong evidence for regional anthropogenic influence such as forest clearing and agricultural activity. Vegetation change is characterized by continuous landscape denudation that begins at ca. 4300 cal. yrs BP, with five distinct pulses of increased deforestation, at 3650, 2700, 1500, 900, and 450 cal. yrs BP. Each pulse can be attributed to increased human impact, recorded by the appearance or increase of specific anthropogenic indicator plant taxa. These periods of intensified deforestation also appear to be correlated with increased landslide activity in the lake's catchment and increased turbidite frequency in the sediment record. Therefore, this study gives new evidence for a strong influence of vegetation changes on slope stability during the middle and late Holocene in the western Swiss Alps, and may be used as a case study for anthropogenically induced landslide activity

A multi-proxy, high-resolution record of peatland development and its drivers during the last millennium from the subalpine Swiss Alps

We present a record of peatland development during the last 1000 years from Mauntschas mire in the eastern Swiss Alps (Upper Engadine valley; 1818 m a.s.l.) inferred from testate amoebae (pH and depth to the water table (DWT) reconstructions), stable oxygen isotopes in Sphagnum (δ18O; proxy for water vapour pressure) and carbon isotopes in Sphagnum (δ13C; proxy for mire surface wetness), peat accumulation rates, charcoal (indicating local burning), pollen and spores (proxies for human impact), and plant macrofossils (reflecting local vegetation and trophic state). Past human impact on the local mire conditions was strong but fluctuating during AD 1000–1570 (±50 yr; depth–age model based on 29 14C AMS dates) with local irrigation of nutrient-enriched water and grazing. Human impact was minor AD 1570–1830 (±30 yr) with partial recovery of the local mire vegetation, and it was absent AD 1830 (±30 yr)–present when hummock formation took place. Correlations among DWT, pH, δ13C, and δ18O, carried out both with the raw data and with linear trends removed, suggest that the factors driving peatland development changed over time, since only testate amoeba-based pH and DWT co-varied during all the three aforementioned periods. δ18O correlates with δ13C only in the period AD 1830–present and with DWT only during AD 1570–1830, δ13C correlates with DWT only during AD 1000–1570. Part of this apparent instability among the four time series might be attributed to shifts in the local mire conditions which potentially formed very different (non-analogue) habitats. Lack of analogues, caused, for example, by pre-industrial human impact, might have introduced artefacts in the reconstructions, since those habitats are not well represented in some proxy transfer functions. Human impact was probably the main factor for peatland development, distorting most of the climate signals