Description: Modern pollen spectra can improve the interpretation of fossil pollen records used to reconstruct past vegetation, climate and human impacts. It is important, therefore, to carefully examine the relationships between modern pollen spectra, vegetation, climate and human activity. Here, we present the results of an analysis of the pollen spectra of 143 surface pollen samples from farmland, wasteland, desert, steppe/meadow, forest and river valley along a transect from Lanzhou to Urumqi, in northwestern China. The modern pollen assemblages are mainly composed of Amaranthaceae, Artemisia , Poaceae, Asteraceae, Ephedra and Nitraria . The results indicate that in general the surface pollen assemblages of different vegetation types reliably represent the modern vegetation in terms of the composition of the main taxa and the dominant types. Farmland is dominated by cereal-type (≥ 15%) and Amaranthaceae (≥ 20%), while the pollen assemblages of wasteland (i.e. the vegetation immediately surrounding farmland) are mainly composed of Amaranthaceae (≥ 25%), Artemisia (≥ 20%), Poaceae (≥ 10%), Asteraceae (≥ 5%) and Cyperaceae (≥ 5%). Amaranthaceae (≥ 45%) and Ephedra (≥ 10%) are the most important taxa in desert, and Cyperaceae (≥ 35%) and Thalictrum (≥ 2%) are the dominant pollen types in steppe/meadow. Forest and river valley samples are characterized by high frequencies of Picea (≥ 10%) and Cyperaceae (≥ 20%). Both constrained and partial canonical ordination techniques (RDA and partial RDA) of the main pollen types and environmental variables show that the modern pollen spectra are primarily controlled by mean annual precipitation (MAP). Cyperaceae, Thalictrum and Brassicaceae are positively correlated with MAP and negatively correlated with mean July temperature (T July ), while the representation of certain other types, such as Amaranthaceae, Ephedra and Nitraria , is negatively correlated with MAP and positively correlated with T July . The Human Influence Index (HII) is significantly correlated with cereal-type pollen, and it can also differentiate human-influenced and natural vegetation. Our results provide a basis for improving the interpretation of fossil pollen records from arid northwestern China and similar regions.

Description: In the late spring of the year ad 1295 a landslide devastated the village of Onoldswil in the Swiss Jura mountains. During recent construction work, a small area of the original land surface was unearthed. The 5 m of compacted clay deposited by the landslide had caused the complete exclusion of oxygen and underneath it the excavators came upon mosses, blades of grasses and other plants that were still green. Below the vegetation cover the humus horizon with subterranean plant parts appeared. Samples were taken for plant macro- and microfossil and geoarchaeological analyses. This offered the rare opportunity to study the vegetation and the topsoil of a small area of land preserved in situ as an autochthonous palaeobiocoenosis, the preserved original combination of the plant community which grew there. Grassland taxa dominated the pollen and macrofossil spectra. Compacted zones within the humus horizon, the plant taxa composition and the presence of spores of coprophilous fungi showed that this place had once been a nutrient-rich pasture. Grazing animals had favoured the spread of juniper. Manuring seems to have taken place. The slopes of the surrounding mountains had been largely cleared of woodland, which may have been the cause of the landslide. The disaster probably happened in late spring, because entire fruiting capitula of Taraxacum officinale (dandelion) were found. Landslides are catastrophic events, destroying the soils and everything that lives in and on them on their way downhill. In places, however, they can also blanket the original land surface and its vegetation and create an archive of ancient life.

Description: This essay is a contribution to the historiography of Lennart von Post and the early development of quantitative pollen analysis. Based on von Post’s own publications and source material from the archives of Stockholm University College, where he was appointed professor in 1929, the essay offers four points on von Post’s scientific identity and the collective work through which quantitative pollen analysis, or “pollen statistics”, came into being. The four points are, first, that von Post made his career as a geologist; second, that he framed pollen analysis as a means to tackle Quaternary geological issues; third, that his work benefitted from collective work, both in the field and in the laboratory; and fourth, that quantitative pollen analysis was not accepted without criticism, taking some years to break through beyond the Geological Survey, where von Post worked before he became professor.

Description: Quantification of vegetation cover from pollen analysis has been a goal of palynologists since the advent of the method in 1916 by the great Lennart von Post. Pollen-based research projects are becoming increasingly ambitious in scale, and the emergence of spatially extensive open-access datasets, advanced methods and computer power has facilitated sub-continental analysis of Holocene pollen data. This paper presents results of one such study, focussing on the Mediterranean basin. Pollen data from 105 fossil sequences have been extracted from the European Pollen database, harmonised by both taxonomy and chronologies, and subjected to a hierarchical agglomerative clustering method to synthesise the dataset into 16 main groupings. A particular focus of analysis was to describe the common transitions from one group to another to understand pathways of Holocene vegetation change in the Mediterranean. Two pollen-based indices of human impact (OJC: Oleaceae, Juglans, Castanea ; API: anthropogenic pollen indicators) have been used to infer the degree of human modification of vegetation within each pollen grouping. Pollen-inferred cluster groups that are interpreted as representing more natural vegetation states show a restricted number of pathways of change. A set of cluster groups were identified that closely resemble anthropogenically-disturbed vegetation, and might be considered anthromes (anthopogenic biomes). These clusters show a very wide set of potential pathways, implying that all potential vegetation communities identified through this analysis have been altered in response to land exploitation and transformation by human societies in combination with other factors, such as climatic change. Future work to explain these ecosystem pathways will require developing complementary datasets from the social sciences and humanities (archaeology and historical sources), along with synthesis of the climatic records from the region.

Description: The development of palynology since its recognised launch in 1916 by Lennart von Post is examined in terms of its historiography, the biographies of pollen analysts and the role of those who have influenced the discipline. Emphasis is placed upon research beginnings in Scandinavia (especially Sweden), Great Britain and Ireland. Within an analytical narrative which includes archival and published sources, special consideration is given to a ‘proclamation’ on methodology which appeared in 1909, on a supposed geology/botany dichotomy stemming from von Post’s background, on the forgotten early practitioners in Britain and Ireland and their connections, on the role of women up to the end of the Second World War and on issues related to wartime hostilities. Present day palynology can trace a continuity from von Post and palynologists are part of an extended disciplinary genealogy. Ignorance of these can be seen as a loss of heritage and to represent an intellectual impoverishment.

Description: The reaction of vegetation to past climate change provides important insights for vegetation responses to future climate change. A key problem for projections into the future is obtaining estimates of the rates at which plants are able to spread as their environment changes. To address this uncertainty, we review the palaeoecological and phylogeographic literature to estimate the range of observed rates of spread for the major European trees and discuss aspects of their postglacial spread. The review is illustrated with isochrone maps depicting the time when particular thresholds in pollen proportion were reached in pollen diagrams available from the European Pollen Database. We find that rates of at least 1,000 m year −1 were realised by early colonisers including Corylus and Ulmus , while trees spreading later into established woodlands, e.g. Quercus and Tilia , achieved rates of around 500 m year −1 . Phylogeographic investigations are available for most of the abundant European trees, often indicating that populations in the central and southern parts of the three south European peninsulas were not the origins for the postglacial colonization of central and northern Europe. In some cases, the results of these studies clearly show the direction of postglacial spread, while generally providing new information to help in interpreting pollen data. Phylogeographic results for Alnus suggest that the high apparent rates of postglacial spread are due to an initial spread at low population density and a later expansion. This decoupling between spread and population expansion is also seen for late expanding trees such as Picea, Fagus and Carpinus . Here, population expansion was probably not delayed by dispersal, but by a limiting climate as assumed by von Post. While the late Holocene expansion of Picea and Fagus in Sweden was important as a dating tool in the development of pollen analysis by von Post 100 years ago, we remain unable to determine which particular driver caused the late expansion of these two trees.

Description: In the early 1980s Naomi Miller changed the field of palaeoethnobotany; her research into whether the ancient seed eaters of southwest Asia were human or herbivore opened an ongoing debate over the impact that burning of animal dung had on the formation of archaeobotanical assemblages, and how researchers can differentiate between human and animal food remains. As the number of systematic archaeobotanical studies across West Asia and many other parts of the world increase, we are continually confronted with the question of the significance of dung burning. Herd animal dung is the dominant fuel source in many parts of West Asia today and the high densities of seeds of wild plants in archaeobotanical assemblages suggest that people were using dung as fuel across Inner Asia for millennia. Seed assemblages that represent herd animal dung are assisting scholars in understanding palaeoecology and herd animal diet in the past as well as human economy and pasturing practices. However, interpreting these assemblages is not always simple and there are predictable biases that need to be taken into account, notably an overrepresentation of endozoochoric seeds (seeds dispersed through animal ingestion). In West Asia, the most prominent of such seeds in dung assemblages are from the Amaranthaceae family, notably Chenopodium .

Description: Modern soil phytoliths can potentially provide analogues for phytolith assemblages from archaeological and palaeoecological contexts. To assess the reliability of soil phytoliths for representing different plant communities, we analysed phytoliths in surface soils and parent plants at 65 sites representing five types of regional vegetation in Northeast China. The results demonstrated that surface soil phytolith assemblages could clearly differentiate samples from herbaceous and woody communities, and samples from Poaceae and non-Poaceae communities could be separated statistically. In addition, woody communities could be differentiated into a broadleaf-Poaceae community, a broadleaf-non-Poaceae community and a conifer and broadleaf-non-Poaceae community, except for some overlapping samples. Soil phytolith assemblages are thus able to differentiate regional vegetation types into different plant community types. In the present study, soil phytoliths represented about 30% of the phytoliths present in the aboveground vegetation. In addition, soil phytoliths from different communities reflected the aboveground vegetation with slightly different degrees of accuracy, and in addition different morphotypes exhibited different degrees of representational bias. Some morphotypes (e.g. rondel, elongate psilate, lanceolate) overrepresented the abundance of the associated plant taxa; morphotypes such as tracheid, conical epidermal, stomata and others under-represented the original plant richness; and other morphotypes, e.g. saddle, trapeziform sinuate, scutiform, were in good agreement with the numbers of plant taxa in the plot inventory. Thus, any quantitative palaeovegetation reconstruction using phytoliths should begin with the calibration of soil phytolith assemblages. We conclude that our findings provide improved phytolith analogues for different plant communities, with applications in palaeoenvironmental reconstruction, and they also provide additional insights into the mechanisms of phytolith production and deposition.

Description: The initial relationships between the first human colonizers and the native vegetation of Isla San Cristóbal, Galápagos, were studied by the analyses of wood charcoal, plant macro-remains, phytoliths and historical records. Archaeological and modern botanical samples were collected from four archaeological sites within the former farmland of the 19th century Hacienda El Progreso, a sugar plantation located in the moist highlands of the island. The archaeobotanical remains show the use of native timber, the introduction of crops and weeds, some aspects of local diet, and evidence of vegetation clearance. Ecological impact is shown by the changes to the native vegetation caused by human colonization of the island and the expansion of agricultural land for the plantation enterprise. This paper provides a synthesis of the archaeobotanical study at El Progreso which forms a baseline for future research in the Galápagos islands.