Soil Pollen Research Articles

Pollen assemblages of tauber traps and surface soil samples in steppe areas of China and their relationships with vegetation and climate

Abstract We use 86 pollen trap and surface soil pollen samples in steppe areas of China to explore the relationships between modern pollen, vegetation, and climate. The modern pollen spectra from both sources have comparable compositions with regard to the major pollen taxa. However, the number of taxa in the traps was higher than in the surface soil samples. Both pollen accumulation rates and pollen concentrations are higher in the typical steppe areas than in the desert steppe areas. Discriminant analysis indicates that pollen spectra from trap and surface soil samples roughly reflect the vegetation zones of desert steppe and typical steppe, especially in the case of the trap samples. Detrended canonical correspondence analysis suggests that pollen assemblages have a significant relationship with the temperature of the coldest month and the mean annual precipitation.

Decomposition in soil and chemical characteristics of pollen

SummaryThe input to soils made by pollen and its subsequent mineralization has rarely been investigated from a soil microbiological point of view even though the small but significant quantities of C and N in pollen may make an important contribution to nutrient cycling. The relative resistance to decomposition of pollen exines (outer layers) has led to much of the focus of pollen in soil being on its preservation for archaeological and palaeo‐ecological purposes. We have examined aspects of the chemical composition and decomposition of pollen from birch (Betula alba) and maize (Zea mays) in soil. The relatively large N contents, small C‐to‐N ratios and large water‐soluble contents of pollen from both species indicated that they would be readily mineralized in soil. When added to soil and incubated at 16°C an amount of C equivalent to 22–26% of the added pollen C was lost as CO2 within 22 days, with the Z. mays pollen decomposing faster. For B. alba pollen, the water‐soluble fraction decomposed faster than the whole pollen and the insoluble fraction decomposed more slowly over 22 days. By contrast, there were no significant differences in the decomposition rates of the different fractions from Z. mays pollen. Solid‐state 13C nuclear magnetic resonance (NMR) revealed no gross chemical differences between the pollen of these two species, with strong resonances in the alkyl‐ and methyl‐C region (0–45 p.p.m.) indicative of aliphatic compounds, the O‐alkyl‐C (60–90 p.p.m.) and the acetal‐ and ketal‐C region (90–110 p.p.m.) indicative of polysaccharides, and the carbonyl‐C region indicative of peptides and carboxylic acids. In addition, both pollens gave a small but distinct resonance at 55 p.p.m. attributed to N‐alkyl‐C. The resonances attributed to polysaccharides were lost completely or substantially reduced after decomposition.

Changes in soil pollen assemblages on footwear worn at different sites

The application of palynology to forensic investigations relies on the similarity of pollen assemblages from forensic items, such as footwear, with control samples from a crime scene. The pollen from material adhering to footwear is likely to reflect some combination of pollen from the locations where the boots/shoes have been worn most recently. This study investigated the changes in pollen assemblages on footwear that had been worn at different sites. Six rural sites in the East Midlands of England, United Kingdom were visited wearing pristine boots (i.e. no mixing), and boots that were previously worn at other localities (i.e. potential mixing). Samples of adherent soil from these items of footwear, and control samples, were analysed palynologically in order to assess the degree and significance of mixing of the pollen assemblages. With the exception of one sample, the pollen adherent to footwear or in the soil samples from each of the six sites (no mixing) had a characteristic signature. This supports the general distinctiveness of pollen from individual sites, the concept of widespread palynological heterogeneity, and the utility of palynology in forensic geoscience. The data from this study show that when mixing occurs from wearing footwear at different sites, the pollen/spore content of the boots etc. dominantly reflects that of the last site. This was evident from a visual examination of the raw data, and was confirmed using detrended correspondence analysis applied to the eleven dominant taxa. These data showed clustering of samples based on the last site visited. The more abundant the pollen/spores, the closer the samples were clustered. The clustering was less convincing at localities that yielded relatively sparse palynomorphs. However, sample material from footwear that was potentially contaminated with soil from previous localities typically exhibited some subtle differences. These were normally slight increases in diversity, and small variations in certain pollen types. The relative insignificance of these differences means that they would be difficult to discern consistently and quantify. It is thus critical that, in relevant forensic investigations, footwear belonging to suspects is seized as soon as possible after a crime is committed.

A transfer-function model developed from an extensive surface-pollen data set in northern China and its potential for palaeoclimate reconstructions

A total of 237 surface soil pollen samples were collected from less disturbed zonal communities, and a new surface pollen data set has been established in northern China. Pollen—climate parameter transfer functions using weighted-averaging regression and calibration partial least squares (WA-PLS) model as a tool to reconstruct past climate changes from pollen data, were tested with this new surface pollen data set. The results of cross-validation showed that the method worked very well with precipitation ( R = 0.94, R2jack = 0.89, RMSEPjack = 69 mm, the safe dynamic range of the reconstruction was 40 mm~800 mm) and worked well with temperature ( Tann: R = 0.84, R 2jack = 0.71, RMSEPjack = 2.0°C, the safe dynamic range of the reconstruction was −4°C~13°C; MTwa: R = 0.79, R2jack = 0.63, RMSEPjack = 2.5°C, and the safe dynamic range of the reconstruction was 8°C~26°C), indicating that the surface pollen data set and WA-PLS reconstruction technique in this paper have strong potential for palaeoclimatic reconstruction.

The Bronze Age landscape of the Bjäre peninsula, southern Sweden, and its relationship to burial mounds

Palaeoecological analyses from a small fen deposit, combined with pollen analysis from buried soil profiles under prehistoric burial mounds, have been used to investigate the timing and vegetation change associated with the Holocene development of a cultural landscape in southern Sweden. Traditional pollen analysis is complemented with plant macrofossil analysis and soil pollen analysis from within and in close proximity to the burial mounds in the coastal Bjäre peninsula, well known for its high density of well-preserved Bronze Age monuments. The vegetation development is linked to the construction of the burial mounds. A marked increase of cultural impact on the landscape is recorded during the Neolithic–Bronze Age transition and estimates of landscape openness suggest that by the onset of the Bronze Age, forest cover was only 20–40%, falling to 10% in the immediate vicinity of the burial mounds themselves. The coastal strip appears to have been affected by human activity to a greater extent and at an earlier date than sites from further inland in southern Sweden and the Bronze Age burial mounds were most likely designed to be visible in a largely deforested landscape.

A molecular approach to species identification of Chenopodiaceae pollen grains in surface soil

Pollen identification and classification are important not only for palynologists, but also for systematists and ecologists. Because palynological methods for the identification of pollen in surface soil until now could resolve at best to the generic level, we have developed a molecular approach to species-level identification of Chenopodiaceae pollen in surface soils. Surface soil samples were collected in the central area of Junggar Desert Basin, Xinjiang, China. Fresh leaves of 19 Chenopodiaceae species were sampled for DNA sequencing, establishing a database of internal transcribed spacer (ITS) regions of nuclear ribosomal DNA for Chenopodiaceae. Individual chenopod pollen grains in a soil sample were separated from the soil and the ITS1 region of each pollen grain was amplified using nested PCR and sequenced. By comparing the amplified ITS1 sequences to those in the Chenopodiaceous database, we identified the pollen in the soil samples to the level of species. The new method provides a technical reference for species identification of soil surface pollen for other families. This work is necessary for further efforts to interpret the relationship of surface soil pollen to vegetation characteristics. It also has significant potential for enhancing the ability to identify pollen in clinical airborne allergen or criminological studies.

Environmental impacts of the Norse settlement: palaeoenvironmental data from Myvatnssveit, northern Iceland

Lawson, I. T., Gathorne‐Hardy, F. J., Church, M. J., Newton, A. J., Edwards, K. J., Dugmore, A. J. & Einarsson, Á. 2007 (January): Environmental impacts of the Norse settlement: palaeoenvironmental data from Mývatnssveit, northern Iceland. Boreas, Vol. 36, pp. 1–19. Oslo. ISSN 0300–9483.The first stratigraphically continuous pollen profile spanning the Norse and Medieval periods from the archaeologically‐rich Mvatnssveit region of northern Iceland is presented. Detailed analyses were made of the tephra, sediment characteristics, pollen and chironomids of a 3 kyr sediment sequence from Helluvastjörn, a small, shallow lake. The pollen data show a steady decline in the percentage abundance of tree birch (Betula pubescens) pollen between the Norse settlement (landnám, c. AD 870) and c. AD 1300, a pattern that contrasts with the abrupt fall in birch pollen percentages immediately following the Norse colonization at almost all previously studied sites in Iceland. Some lines of evidence suggest that the gradual birch decline could be a result of reworking of soil pollen, but independent evidence suggests that this may not necessarily be the case. The pollen record indicates that birch woodland was replaced by acidophilic taxa (notably Empetrum nigrum and Sphagnum), again contrasting with the more usual pattern of Poaceae expansion seen in post‐landnám pollen diagrams from mires close to farm sites. Chironomid and Pediastrum accumulation data show that the limnic environment became more productive immediately after landnám, probably because of anthropogenic disturbance. An increase in sedimentation rate after landnám appears initially to have been caused by increased lake productivity, while reworked inorganic soil materials became a significant contributor to the sediments after c. AD 1200. The data suggest that the impact of settlement on terrestrial vegetation may have been more variable than previously thought, while freshwater ecosystems experienced significant and rapid change.

Vegetation and Climate Variations at Taibai, Qinling Mountains in Central China for the Last 3 500 cal BP

Abstract: Pollen records of two swamp sections, located at Taibai Mountain, the highest peak in the Qinling Mountains of central China, show variations of vegetation and climate for the last 3 500 cal BP. The pollen assemblage at the Foyechi and Sanqingchi sections and the surface soil pollen allowed us to reconstruct a high-altitude vegetation history at Taibai Mountain for the first time. The data indicated that there was a cold-dry climate interval between 3 500 and 3 080 cal BP and a relatively warm and wet period compared with the present from 3 080 to 1 860 cal BP. The warmest period in the late Holocene on Taibai Mountain was from 1430 to 730 cal BP, with an approximate 2 °C increase in mean annual temperature compared with today. There was a relatively cool-dry climate interval from 730 to 310 cal BP. After 310 cal BP, a mountain tundra vegetation developed again and the position of the modern tree line was established. (Managing editor: Ya-Qin HAN)

Sub-Local Differences in Late Holocene Land Use at Orstad, Jæren in SW Norway, revealed by Soil Pollen Stratigraphy

Four soil profiles along an 84 m transect through a clearance cairn field on podsol soils at Orstad, Jæren, SW-Norway, were investigated. By relating pollen-analytical results to soil stratigraphical and morphological features, it was possible to reconstruct the landuse history of the site, and to reveal differences along the transect, although pollen preservation was poor. Human activity at Orstad began about 4500 uncalibrated 14C years BP. The reason for an intermediate abandonment of the site between about 4000 and 3600 uncalibrated 14C years BP was presumably a higher ground-water level, caused by local deforestation and/or by a climatic change. After that period, people seem to have grown cereals (Triticum and Hordeum) on at least two different field patches on the site. This land use was presumably occasional, and related to extraordinary needs. Fire-clearance seems to have been practised to prepare the fields for cultivation after long fallow periods. Between 2900 and 3200 uncalibrated 14C years BP, Orstad was possibly permanently inhabited. The agricultural fields were moved to higher levels, as the initial fields had become nutrient-depleted and too moist. Thin black layers in the profile may be remains of manure.

Sub-Local Differences in Late Holocene Land Use at Orstad, Jæren in SW Norway, revealed by Soil Pollen Stratigraphy

Four soil profiles along an 84 m transect through a clearance cairn field on podsol soils at Orstad, Jæren, SW-Norway, were investigated. By relating pollen-analytical results to soil stratigraphical and morphological features, it was possible to reconstruct the landuse history of the site, and to reveal differences along the transect, although pollen preservation was poor. Human activity at Orstad began about 4500 uncalibrated 14C years BP. The reason for an intermediate abandonment of the site between about 4000 and 3600 uncalibrated 14C years BP was presumably a higher ground-water level, caused by local deforestation and/or by a climatic change. After that period, people seem to have grown cereals (Triticum and Hordeum) on at least two different field patches on the site. This land use was presumably occasional, and related to extraordinary needs. Fire-clearance seems to have been practised to prepare the fields for cultivation after long fallow periods. Between 2900 and 3200 uncalibrated 14C years BP, Orstad was possibly permanently inhabited. The agricultural fields were moved to higher levels, as the initial fields had become nutrient-depleted and too moist. Thin black layers in the profile may be remains of manure.

Pollen–vegetation relationships in Bay of Fundy salt marshes

We examined the distribution of vegetation and pollen in surface soils of three salt marshes on the outer Bay of Fundy to assess the value of pollen in paleoenvironmental reconstructions. We examined the relationship of pollen to vegetation using linear regression at two scales: vegetation zones dominated by graminoids and forb patches within these zones. Of the dominant graminoids, only pollen of Cyperaceae was a dependable indicator of source vegetation. In contrast, at least seven common forbs were significantly represented by their pollen at one or both scales. Because forbs are more abundant in northern marshes, increases in forb pollen abundance in buried sediments of southern marshes could signal colder climate regimes. Other studies have shown Plantago maritima L. and Ligusticum scoti cum L. to be associated with distinct ranges in elevation, and Triglochin maritima L. with soil anoxia. Thus, shifts in forb pollen abundance may indicate changes in tidal flooding frequency and sea levels.Key words: Potentilla anserina, Glaux maritima, Spergularia canadensis, wetland, palynology.

Vitis pollen dispersal in and from organic vineyards : I. Pollen trap and soil pollen data

The recent discovery of Roman vineyards in Britain [Antiquity 75 (2001) 745] based on both archaeological and palynological data has raised questions concerning the palynological record of viticulture in NW Europe. This paper presents data collected from 30 pollen traps and 29 soil pollen samples from within, and around, three organic vineyards in England. The soil trap data were collected over one flowering season. Within-vineyard pollen accumulation is compared with off-site accumulation and the soil pollen data. Although there is extremely high intravineyard variation in Vitis accumulation, the data confirm the role of stemflow transport and the exponential decrease in Vitis pollen accumulation with distance away from the vineyard. Pollen trap values of over 2% total pollen (TP) Vitis and soils with over 0.2% TP (based on 1000+ pollen sum) are likely to indicate the on-site presence of a vineyard. This is in accordance with the values recorded from known Roman vineyards in the Nene Valley. A compilation of occasional finds of Vitis pollen in England reveals typical values of 0.2% or less; although higher values are recorded, they are generally an artefact of a low total pollen count. However, the clustering of these occasional finds into the Roman and high Medieval periods suggests that long-distance Vitis influx increased during periods of widespread viticulture in NW Europe including England. The monitoring of Vitis pollen dispersal suggests that where encountered as part of routine pollen counting, the total pollen sum should be increased to ca. 1000 TP in order to establish a better estimate of the frequency of occurrence. This will allow palynology to play a less ambiguous part in the mapping of ancient viticulture.

Quantitative Relationship Between Pollen in the Surface Soil and Vegetation in the Yanshan Area

This study explored the quantitative relationship between pollen in the surface soil and vegetation in the Yanshan area. Data were collected from the region between about 39°00′-40°50′ N and between 117°10′-119°50′ E from 2 082 m elevation in the Yanshan Mountains to 0 m at the seashore of the Bohai Sea. The samples of pollen in the surface soil were collected from 53 locations at about 100 m elevational intervals in Yanshan Mountainous area and at about 20 km level intervals in the plain between Yanshan mountain and Bohai Sea seashore. At the same time of pollen sampling in the surface soil, investigation of the vegetation was also done. Then, R value (representation of pollen) was calculated with pollen percentage and vegetation investigation. According to sampling of pollen in surface soil and vegetation investigation, the relationship between soil surface pollen and modern vegetation was quantitatively analyzed. Results showed that the surface pollen assemblages of all vegetation zones in Yanshan area basically represent vegetation composition, but the pollen assemblages are not equal to the vegetation composition. This is due to the influences of pollen preservation, pollen production, foreign pollen and pollen identification. The representation of pollen in surface soil is very different in families and genera. The tree pollens such as Pinus, Betula, Juglans and Castanea are over_represented, but Quercus, Carpinus and Populus are under_represented; the shrub pollen such as Zanthoxylum is over_represented, Rosaceae and Corylus are under_represented; the herb pollens such as Artemisia, Chenopodiaceae, Typha, Labiatae, Polygonaceae, Ranunculaceae, Umbelliferae and Thalictrum are over_represented, while others such as Gramineae, Saxifragaceae, Humulus, Cyperaceae, Leguminosae, Caryophyllaceae and Convolvulaceae are under_represented. The same pollen in different vegetation zones has different R value. Generally, R value of the pollen in the vegetation zones far away from the main pollen sources is lower than that in the places of main pollen sources. The change of R value is also influenced by pollen preservation, pollen production, and foreign pollen.

Evaluation of Holocene pollen records from the Romanian Plain

This study is a critical review of pollen analyses carried out on Holocene sequences from 15 sites in and near the Romanian Plain. Three sites come from natural sediments, 10 sites are from anthropogenic deposits and two are from both anthropogenic and natural settings. The general reconstruction is of a steppe–forest–steppe vegetation through the Holocene. The nature of the deposits, however, casts doubts on this reconstruction. Deposits of archaeological sites generally yield pollen spectra that are influenced by human activities and thus unsuitable for vegetation reconstructions. Loess deposits are also unfavorable for pollen preservation because of high pH and porosity. Consequently, pollen spectra from loess deposits are strongly biased by selective pollen destruction. Research and experiments carried out by several authors suggest that spectra dominated by Asteraceae, Poaceae, Chenopodiaceae or Pinus pollen in soils and loess are a result of selective pollen destruction, especially if low pollen concentrations, progressive pollen deterioration or high frequencies of deteriorated or unidentifiable pollen are evidenced. The fact that pollen records from the Romanian Plain come from loess, alkaline peat or archaeological sites reduces their reliability for reconstructions of vegetation. The vegetation history of similar regions in Hungary, Bulgaria and Turkey suggests that early Holocene steppe vegetation was gradually replaced by forest or forest–steppe vegetation in the late Holocene. Records from lake sediments are required to find out whether the Holocene vegetation history of the Romanian Plain was similar.

Landscape scale soil pollen analysis

Whatever the potential of soil pollen analysis, the medium has not been exploited to the same extent as ‘conventional’ approaches involving lake and peat deposits. Problems endemic to soil pollen studies may, however, be preventing the realisation of investigations which might otherwise be carried out, especially those at the ‘landscape’ scale. Spatially-based pilot studies focusing upon sub-peat podsols in Sussex (England) and Jura (Scotland) provide encouragement for the use of soil pollen analyses in broader scale inquiries of settlement and the wider landscape. A newly-instigated application of the approach is introduced for part of Shetland (Scotland).

Landscape scale soil pollen analysis

Landscape scale soil pollen analysis

The use of micromorphology in soil pollen analysis: The interpretation of the pollen content of slope deposits in Galicia, Spain

Humic horizons of soil profiles often contain pollen and spores. Comparison of the sequence of pollen associations of soil profiles with pollen zones of reference diagrams offers palyno-ecological information, relevant for reconstruction of landscape ecological development. In palynological studies of semiterrestrial and aquatic deposits, pollen is considered to be part of the sediment and anaerobic conditions in water-saturated deposits promote its conservation. This is not true for pollen in soils. Aerobic conditions in drained soils result in bio-oxidation of unprotected pollen grains. Interpretation of soil pollen associations requires knowledge of the processes of infiltration and conservation of pollen grains in the soil material. Micromorphology is an important technique to investigate these processes. This is demonstrated in a case study of polycyclic slope deposits in Galicia (Spain). The buried cambisols, in pleistocene solifluction deposits, contain post-sedimentary infiltrated pollen. The pollen associations reflect successive phases in soil ecological development. The holocene colluvial deposits contain syn-sedimentary incorporated pollen. The pollen associations reflect environmental conditions during the deposition of colluvial layers.

Analysis of pollen in soils: processes of incorporation and redistribution of pollen in five soil profile types

In order to interpret soil pollen diagrams, knowledge on the processes of pollen incorporation and redistribution is essential. It has been suggested, with little direct supporting evidence, that pollen can move in soils through association with translocated organic matter, with soil water or as a result of soil faunal activity. We report the results of investigating pollen redistribution in a range of soil types through micromorphological analysis. It was possible to categorise, using fluorescent microscopy, the location of pollen grains within soil thin sections. The overall conclusion is the key role of soil fauna in causing the redistribution of pollen. It is only in accumulating organic horizons of peaty soils or podzols that pollen can be stratified and thus interpreted for palaeoenvironmental reconstruction.

Fine Resolution of Pollen Patterns in Limited Space: Differentiating a Crime Scene and Alibi Scene Seven Meters Apart

Abstract In an alleged rape case, the pollen content of soil samples from the suspect's clothing was compared with that of soil samples from the alleged crime scene (an alleyway) and from the alibi scene (next to a driveway) to determine whether or not the suspect had been at the alleged crime scene. Although only 7 m apart, the two scenes had significantly different soil pollen representations due to their different vegetation. Because of this close proximity, however, these differences in pollen representation were in the amounts of the same pollen types rather than in the numbers of different pollen types. The clothing samples showed a very strong correlation with each other and with the sample from the alleged crime scene in the amounts of pollen types present, very strongly supporting the contention that the suspect had been at the alleged crime scene.

A 6000‐year soil pollen record of subalpine meadow vegetation in the Olympic Mountains, Washington, USA

1 Subalpine meadow communities are influenced by edaphic and microclimatic gradients, and should be affected by climate change that affects these local controls. We used pollen preserved in meadow soils to investigate the long‐term interaction of these factors in a 1‐ha subalpine meadow in the Olympic Mountains, Washington, USA. 2 To describe the spatial scale at which soil pollen is related to neighbouring vegetation, pollen in 46 soil surface samples was compared with plant cover within concentric circular plots (0.5–1 m radii). Regression analysis of percentage pollen with plant cover at different distances from the surface sample had the highest correlation with radii < 1 m, confirming that entomophilous meadow species have very small relevant pollen source areas. 3 We analysed pollen records in soil columns at three sites representing a range of growing season lengths and community types within the meadow. Soils had aggraded by the deposition of eolian silt. Radiocarbon dates of pollen concentrates were similar to or older than radiocarbon dates on charcoal pieces at the same depth, suggesting negligible downwards movement of pollen in the soil profile. 4 The oldest soil pollen profile was from the wettest microsite, currently dominated by a snowbed Carex nigricans community. This site was occupied by a dry Juniperus community prior to c. 6000 bp (before present), when it shifted to more mesic communities dominated by Poaceae and Polemonium. The first appearance of a snowbed Carex nigricans community at this site, c. 2500–1500 bp, suggests a change to cooler and/or wetter regional climate. 5 High levels of Polygonum bistortoides at all sites indicated a shift to long snow‐free periods and mesic summer conditions during an interval corresponding to the Medieval Warm Period (c. 1200–700 bp). After 500 bp (during the Little Ice Age) Carex nigricans re‐established in the wet microsite, while relatively little change occurred at the other two sites. Overall, the greater magnitude of change at this microsite than at the longer growing‐season sites indicates that, in these subalpine meadows, short growing season sites are most sensitive to regional climate change.