			Home About us Contact

Modern Pollen (modern + pollen)

Distribution by Scientific Domains

Humanities and Social Sciences	40%

Selected Abstracts

Modern pollen,vegetation relationships in subarctic southern Greenland and the interpretation of fossil pollen data from the Norse landnám

JOURNAL OF BIOGEOGRAPHY, Issue 3 2007
J. Edward Schofield
Abstract Aim, The objective of this paper is to explore the relationships that exist between vegetation and modern pollen rain in the open, largely treeless landscape of subarctic Greenland. The implications of these results for the interpretation of fossil pollen assemblages from the time of the Norse landnám are then examined. Location, The study area is the sheep farming district of Qassiarsuk in the subarctic, subcontinental vegetational and climatic zone of southern Greenland (61° N, 45° W). Between c.ad 1000,1500 this region was contained within the Norse Eastern Settlement. Methods, Detrended Correspondence Analysis (DCA) of harmonized plant,pollen data sets is used to compare plant cover in 64 vegetation quadrats with pollen assemblages obtained from moss polsters at matching locations. Presence/absence data are also used to calculate indices of association, over- and under-representation for pollen types. Results, Good correspondence between paired vegetation,pollen samples occurs in many cases, particularly in locations where Salix glauca,Betula glandulosa dwarf shrub heath is dominant, and across herbaceous field boundaries and meadows. Pollen samples are found to be poor at reflecting actual ground cover where ericales or Juniperus communis are the locally dominant shrubs. Dominant or ubiquitous taxa within this landscape (Betula, Salix and Poaceae) are found to be over-represented in pollen assemblages, as are several of the ,weeds' generally accepted as introduced by the Norse settlers. Main conclusions, Due to their over-representation in the pollen rain, many of the Norse apophytes and introductions (e.g. Rumex acetosa and R. acetosella) traditionally used to infer human activity in Greenland should be particularly sensitive indicators for landnám, allowing early detection of Norse activity in fossil assemblages. Pteridophyte spores are found to be disassociated with the ground cover of ferns and clubmosses, but are over-represented in pollen assemblages, indicating extra-local or regional sources and long residence times in soil/sediment profiles for these microfossils. A pollen record for Hordeum -type registered in close proximity to a field containing barley suggests that summer temperatures under the current climatic regime are, at least on occasion, sufficient to allow flowering. [source]

Developing a modern pollen,climate calibration data set for Norway

BOREAS, Issue 4 2010
ANNE E. BJUNE
Bjune, A. E., Birks, H. J. B., Peglar, S. M. & Odland, A. 2010: Developing a modern pollen,climate calibration data set for Norway. Boreas, Vol. 39, pp. 674,688. 10.1111/j.1502-3885.2010.00158.x. ISSN 0300-9483. Modern pollen,climate data sets consisting of modern pollen assemblages and modern climate data (mean July temperature and mean annual precipitation) have been developed for Norway based on 191 lakes and 321 lakes. The original 191-lake data set was designed to optimize the distribution of the lakes sampled along the mean July temperature gradient, thereby fulfilling one of the most critical assumptions of weighted-averaging regression and calibration and its relative, weighted-averaging partial least-squares regression. A further 130 surface samples of comparable taphonomy, taxonomic detail and analyst became available as a result of other projects. These 130 samples, all from new lakes, were added to the 191-lake data set to create the 321-lake data set. The collection and construction of these data sets are outlined. Numerical analyses involving generalized linear modelling, constrained ordination techniques, weighted-averaging partial least-squares regression, and two different cross-validation procedures are used to asses the effects of increasing the size of the calibration data set from 191 to 321 lakes. The two data sets are used to reconstruct mean July temperature and mean annual precipitation for a Holocene site in northwest Norway and a Lateglacial site in west-central Norway. Overall, little is to be gained by increasing the modern data set beyond about 200 lakes in terms of modern model performance statistics, but the down-core reconstructions show less between-sample variability and are thus potentially more plausible and realistic when based on the 321-lake data set. [source]

Seasonality of modern pollen and sediment deposition in an estuarine context: the Severn Estuary Levels, southwest England,

JOURNAL OF QUATERNARY SCIENCE, Issue 3 2008
J. R. L. Allen
Abstract Recent sedimentological and palynological research on subfossil Holocene banded sediments from the Severn Estuary Levels suggested seasonality of deposition, registered by variations in mineral grain-size and pollen assemblages between different parts of the bands. Here we provide data that strengthen this interpretation from sampling of modern sediments and pollen deposition on an active mudflat and saltmarsh on the margin of the Severn Estuary, and comparison with a vegetation survey and contemporary records of climate, river and tidal regimes. The results of grain-size analysis indicate deposition of comparatively coarse-grained silts during the relatively cool and windy conditions of winter and comparatively fine-grained sediments during relatively warm and calm summer months. Pollen analysis demonstrates the significance of long-term storage of pollen grains and fern spores in the estuarine waterbody, superimposed on which seasonal variations in pollen inputs from local and regional vegetation remain detectable. Copyright © 2007 John Wiley & Sons, Ltd. [source]