Spore Taxa Research Articles

Modern pollen spectra and vegetation in southern Ontario, Canada

A weekly census of air borne pollen grains was conducted for three years (1983–1985) at four sampling stations (from north to south: Sudbury, Peterborough, Toronto and London) in the Great Lakes region, southern Ontario, Canada.A Cour volumetric vane sampler was used at each site, located at the respective meteorological station, providing pollen spectra from an area of surrounding vegetation with an estimated radius of 40 km. Filter samples were processed by a standard, established procedure.The study area forms part of the Upper Canada Peninsula vegetation region. Two sites, Sudbury and Peterborough, occur in one of the two major vegetation zones, the Mixed-Hardwood; the others, Toronto and London, are located in the second zone, the Deciduous Forest.Previous studies of pollen-vegetation relations in this region were based on analysis of moss polsters. The pollen trap method used here provides a more sensitive registration of regional pollen and while the seven most important taxa quantitatively are found in the both data sets, such important taxa as Cupressaceae and Populus are under-represented or absent in polster data because of poor preservation, but well represented in the trap analyses (Cupressaceae at 9% and Populus at nearly 3%). Similarly, some spore taxa that are absent from previously published results occur in the present data in significant frequencies (Lycopodium at 4% from Sudbury and Sphagnaceae from all stations).The results of statistical analyses show the predictable major change in the regional pollen spectra between Sudbury and Peterborough.

Late quaternary pollen transport processes, western North Atlantic: Data from box models, cross-margin and N-S transects

Surface pollen assemblages in coastal and neritic sediments of the western North Atlantic compare well with eastern North American vegetation zones, and late Quaternary pollen in marginal marine sediments clearly correlate with changes in terrestrial vegetation and paleoclimates. In contrast, offshore assemblages are strongly affected by differential adaptation of pollen to long distance transport by wind and water. Marine pollen transport processes were studied by measuring air and water inputs to a coast-shelf box model, and by study of surface samples from cross-margin transects in three different climatic and oceanographic regions at approximately 38°, 45° and 55°N latitude. The box model shows that aerial transport is the main process by which pollen moves across the continental margin off Nova Scotia. Two clear seabed distribution patterns were found: Betula, Quercus, and herb pollen decrease rapidly offshore in abundance (grains per cubic centimetre) and in relative abundance (percentage); Pinus and Picea have abundance peaks on the continental margin, but percentages increase further offshore. Distributions of the main pollen and spore taxa were compared for late Wisconsinan glacial (oxygen isotopic stage 2, 12–28 ka), terminal Pleistocene (10–12 ka) and Holocene sediments at 5 continental margin and 3 deep-sea sites. The largest changes were found in percentages of Pinus, Picea, and herb pollen during the late Wisconsinan glacial and terminal Pleistocene intervals at subpolar latitudes. These data can be related to shifts in paleo-vegetation, -winds and -hydrology that accompany global climate change.

Petrology and palynology of the No. 5 block coal bed, northeastern Kentucky

The upper Middle Pennsylvanian (middle Westphalian D equivalent) No. 5 Block coal bed (Eastern Kentucky Coal Field of the Central Appalachian Basin) is a low-sulfur, compliance coal resource, dominantly comprised of dull, inertinite-rich lithotypes. Ash yields tend to be highly variable in the No. 5 Block, as does bed thickness and frequency of bed splitting. This study describes the petrographic, palynologic and geochemical characteristics of the No. 5 Block coal bed, and reports on some temporal and spatial trends among these parameters in eastern-northeastern Kentucky. Petrographically the No. 5 Block coal is predominated by dull, often high-ash lithotypes, with inertinite contents commonly exceeding 30% (mmf). The coal thins to the north-northwest where it tends to be higher in vitrinite and sulfur content. Representatives of large and small lycopsids and ferns (both tree-like and small varieties) dominate the No. 5 Block coal bed palynoflora. Calamite spores and cordaite pollen also occur but are less abundant. Small lycopsid ( Densosporites spp. and related crassicingulate genera) and tree fern (e.g. Punctatisporites minutus, Laevigatosporites globosus) spore taxa are most abundant in dull lithotypes. Bright lithotypes contain higher percentages of arboreous lycopsid spores ( Lycospora spp.). Regionally, the No. 5 Block coal contains abundant Torispora securis, a tree fern spore specially adapted for desiccation prevention. This, along with overall high percentages of inertinite macerals, suggest that peat accumulation may have taken place in a seasonally dry (?) paleoclimate. The No. 5 Block coal bed thickens rather dramatically in a NW-SE direction, as does the frequency of coal bed splitting. This phenomenon appears to be related to increased accomodation space in the southeastern portion of the study area, perhaps via penecontemporaneous growth faulting. Maceral and palynomorph variations within the bed correspond with these changes. Thin coal along the northwestern margin tends to be vetrinite rich and contains abundant Lycospora, perhaps reflecting relatively stable peat-forming conditions. Thicker coal to the southeast contains more inertinite, high-ash coal layers, and inorganic partings. Spore floras contain more small lycopsid and tree fern components and are temporally variable, perhaps indicating a more unstable peat-forming environment.

Mid- and late-Holocene vegetation history of Quidenham Mere, Norfolk, UK interpreted using recurrent groups of taxa

The results of pollen analyses from the top 8 m of sediment retrieved from Quidenham Mere, Norfolk, UK are presented. These, together with the results of charcoal analyses and the numerical classification of the pollen and spore taxa into ‘recurrent groups’ using simple discriminant function analysis, are used to reconstruct the vegetation history of the Quidenham Mere catchment over approximately the last 8000 years and to infer anthropogenic effects on the landscape. After some minor woodland clearance in the Bronze Age and further clearance in the Iron Age, it was only in the Anglo-Saxon period that most of the woodland was cleared. Although arable farming was important, it appears that there was also a considerable amount of land used for grazing, with grazed woodland and wood pasture. Towards the top of the sequence, within the past 200 years, there is evidence of the foundation and development of the Quidenham Hall parkland adjacent to the site, with the planting of native and exotic species of trees. A comparison is made between the vegetation histories and anthropogenic effects on the landscapes of Quidenham Mere and Diss Mere, a similar lake about 10 km from Quidenham. Both sites reflect the agricultural practices occurring in their catchments from early times. Exceptionally high values of Cannabaceae grains are indicative of retting of hemp during the past 1500 years. Rarefaction analysis is used to compare the pollen richness of the two sites.

Vegetation change on Papa Stour, Shetland, Scotland: a response to coastal evolution and human interference?

The first palynological and related sedimentological studies from Papa Stour, Shetland are presented and supplement the limited data available for the study of Holocene vegetation change from the Northern Isles of Scotland. Two pollen sites were located on an isthmus which has experienced the marked influences of waterlevel changes, inundation by blown shell sand, and probable grazing and arable activity. In spite of the unpromising, calcareous nature of the mineral materials at the sites, very rich suites of pollen and spore taxa were recovered including those of taxa now absent from, or rare in the islands. The assemblages indicate a strong interplay between two major habitat types, maritime heath and grassland. In addition, the sites demonstrate the effects of intermittent pool formation. The study shows that the vegetational and geomorphological landscapes of the study area are both dynamic and closely linked.

Late Holocene vegetational changes on the Illawarra coastal plain, New South Wales, Australia

Palynological evidence is presented which supports the view that Illawarra was not entirely covered by dense rainforest at the time of European settlement. In the environs of Jamberoo and Kiama, there may have been wet sclerophyll forest and subtropical rainforest in existence during the last five millennia of the Holocene. The palynological data are unable to substantiate estimates of the amount of rainforest prior to its clearance by Europeans. However, in view of both the number of pollen and spore taxa from plants now characteristic of regional sub-tropical rainforest, and the almost certain under-representation of these taxa in the palynological record, it is feasible that such vegetation occupied a considerable part of this area, with wet sclerophyll present on less climatically and edaphically favoured sites. Local wetland vegetation dynamics seem to have involved saline being replaced by freshwater marsh c.2600 B.P. The reduction in marine influence responsible for this seral change may have either been caused by a fall in sea-level, or a more effective coastal barrier.

Pollen and spores transport into the Antarctic

Pollen deposition in a 7 cm thick moss turf (Polytrichum juniperinum) from a site in Admiralty Bay (King George Island, maritime Antarctic zone) and in three cushions of Schistidium antarcticum (1–3 cm thick) from Bailey and Clark Peninsula (Wilkes Land, Greater Antarctica) were investigated. Twenty-four pollen and spore taxa were identified from a total of 1094 grains in the sample from Admiralty Bay. By contrast, the 3 samples from Wilkes Land contained only 10 grains (5 taxa). While the former sample was poor in lichen-mycobiont spores the latter revealed very many. Pollen deposition appears to be a good indicator of direction and frequency of immigration of cryptogamic propagules. It seems that the presence of cryptogamic species in the maritime Antarctic zone is predominantly the result of long-distance transport from neighbouring South America and a selection by climatic factors. The low frequency of pollen in Wilkes Land indicates a separation of this part of Antarctica from propagule exchange with other continents and the cryptogams of most of the Antarctic continent may represent a largely relictual flora which survived in ice-free refugia.

A New Design of Pollen Trap for Modern Pollen Studies

The design of a simple and robust pollen trap is described. The pollen trap was tested at three locations in the Morton Lochs Nature Reserve, Fife, Scotland, and samples were collected at monthly intervals for the 3-year period April 1980 to April 1983. The resulting pollen diagrams show that there is a clear link between major pollen and spore taxa and the dominant plant species of the area. The study shows that this new design of pollen trap produces reliable and consistent results and overcomes some of the problems encountered with other designs of trap.

Objective paleoecological and biostratigraphic interpretation of tertiary palynological data by multivariate statistical analysis

Abstract Analysis of conventional percentage frequency data from 167 palynomorph‐rich samples from the Eocene of southern Britain by principal components analysis and cluster analysis is making it possible to disentangle the effects of pollen transport and catchment and other facies‐related perturbations from real ecological information. Three major natural groups of pollen and spore taxa have been recognized within these assemblages whose internal ecological homogeneity suggests that they record groups of plant communities that are identified as Eocene versions of deciduous forest, fern and conifer forest, and paratropical rain forest. The paleoecological structure of the three communities is explained and their change during the Eocene is recorded. By analogy with temperature of modern vegetation types this method of analysis of palynological data is used to reconstruct Tertiary climatic changes.

TETRAXYLOPTERIS SCHMIDTII: ITS FERTILE PARTS AND ITS RELATIONSHIPS WITHIN THE ANEUROPHYTALES

The fertile branching system of Tetraxylopteris is composed of successive “nodes” bearing opposite and decussately arranged, upcurved sporangial complexes. By means of the transfer technique the morphology of the sporangial complex was revealed. It consists of a main stalk which dichotomizes twice producing four major branches. Each of the four branches is further subdivided three times, the subdivisions being arranged alternately and pinnately. The ultimate divisions bear the sporangia singly and terminally. The sporangial complexes decrease in size distally and are more tightly curved at the apex. The sporangia are oblong‐oval with an acute apex. The spores are identical to the dispersed spore taxon Rhabdosporites langii, Richardson. They are spherical, trilete and pseudosaccate with a fine granular ornament on the pseudosaccus. They are 75–176 μ in diameter and show developmental stages from young tetrads to separated, fully mature spores depending on the age of the sporangium from which they were obtained. This is the first account of spores in sporangia of Tetraxylopteris. The diagnosis of the genus and species are emended to include the new information and the order Aneurophytales is redefined.

Palynological studies on Late Cretaceous-Palaeogene floral history and stratigraphy

The biostratigraphical importance of spore-and-pollen analysis is determined by the possibility of distinguishing sporae dispersae from synchronous marine and continental deposits. A great variety of pollen and spore taxa from the Upper Senonian and Paleocene have a regional and general biostratigraphical significance. According to palynological data the last fundamental rearrangement of the flora and its complete renovation took place at the Late Cretaceous-Palaeogene boundary. The Early Palaeogene flora was differentiated (European, East-Siberian, and Primorsko-Sakhalinskaia floristic areas; Tourkmeno-Kazakhstanskaia province), but the dominating taxa in each of the floristic areas are different from those in Maastrichtian times. By the end of the Palaeogene, changes in the climatic zones caused rearrangements within the floristic areas and a degradation of the polychronous floras of the Northern Hemisphere. For this reason, Upper Palaeogene (Oligocene) palyno-stratotypes are mainly of regional importance.