The vegetation in the upper half seems more humid, with more forbs represented, especially Polygonum and Stellaria/Cemstium and fewer Betula. The effect of the recent grazing is clearly reflected in the soil parameters (Fig. The higher frequencies of grass pollen in the recent samples (A; and /) compared to those of the centre (h) can be explained by less intensive grazing which enabled the grasses to flower.The soil analyses of both profiles (Figs 12 and 13) indicate that grazing began quite recently. D.), whereas the shallower sample, taken from a depth of 4-5 cm, could not be dated because of the risk of contamination with modern 14 It gave the average date of the sample as being around AD 1956.
One of the most common soil types, especially on south-facing slopes, consists of two layers of aeolian sediments resting on till or bedrock. Palaeogeography, Palaeoclimatology, Palaeoecology (Global and Planetary Change Section) 82. climatic changes during the late Holocene, and the utilization of the area by caribou. P., during the mid-Holocene warm period, the Inland Ice margin reached its present position, only to withdraw further east (Kelly, 1985; Weidick et al. During the following millennia, several colder and/or more humid periods are registered in the vegetation sequence as well as in the Ice Cap cores (Dansgaard et al. Their water levels depend on the ratio of precipitation to evaporation. Singles rödental Thus, at the edge of one of the many saline lakes, Store Saltsø, to the south of Kangerlussuaq airport, a series of peat ridges formed mainly by Drepanocladus aduncus, with an alternatingcontent of loess, indicates that former lake levels used to be several metres above the present height (Hansen, 1970). Plant and animal remains indicate less alkaline/saline water at that time.Analyses of pollen content and chemical composition in soil profiles confirm the hypothesis of their formation being a result of grazing.The original vegetation types were Salix gla uca scrubs or grassy Betula nana heaths. Due to a recent pronounced decline in the caribou population, the greens are now changing with Poa pratensis flowering vigorously as a result of little or no grazing, and Euphrasia frigida is spreading.
40 dating Glostrup
The soil underneath contained seeds of waterplants, proving it to be a dried-up pond. (1988): Till genesis in areas of crystalline bedrock with undulating topography. University of Stockholm, Department of Quaternary Research, Report 11. However, around 1970, it became a pond once again as a result of a climatic oscillation towards more humid conditions. A peat sample from the upper ridge has been dated at 2,330 ± 120 B. The lowering of temperature and increasing precipitationin past decades reflect such oscillations as other nearby lakes bear evidence of past vegetation, mainly willow, on former banks which have since been drowned. kristen dating Fredericia Correspondingly, a shallow depression at the head of Godthåbsfjord 300 km to the south was covered in 1960 by an open, almost one metre high Salix glauca copse (Fredskild, 1973).The results are discussed in relation to former and present grazing as well as to the holocene environmental history of the area. Apart from the few centimetres thick, humus, surface layer, the soil is loess-like, with thin layers of former surface humus. The following were measured: exchangeable Ca, Mg, Mn, Kjeldahl N, loss on ignition, conductivity (soil:water -1:5) and p H.
The investigated area is situated NE of the head of Kangerlussuaq (Søndre Strømfjord) close to the Inland Ice just north of the Arctic Circle (Fig. Most of the area is a lowland with E-W running, rounded, gneissic ridges only exceptionally exceeding 500 m.a.s.l. Most pollen samples were taken from these thin humus layers which occurred at irregular intervals. The degree of cover in five moist and four dry greens is summarized in Table 1. Other species are Ceratodon purpureus (Hedw.)Brid., Climacium dendroides (Hedw.)Web. In dry greens Drepanocladus aduncus and Polytrichum alpinum dominate. The only other phanerogams are Ranunculus hyperboreus Rottb., Equisetum arvense L., Cerastium alpinum and Polygonum viviparum L. 4) virtually all the pollen, except Cyperaceae, had been almost totally destroyed, and much was too poorly preserved for determination.Following a population peak, the now decreasing caribou density and grazing allow for an alteration to a more diverse vegetation. The analyses also include frequencies of the testate amoeba Assulina (possibly including some Euglyphd) of; fruit bodies of the primitive Ascomycete Microthyrium, labiae of Chironomidae larvae, the algae Pediastrum and Botryococcus.In order to elucidate the vegetation history, soil profiles in selected greens were sampled at different depths and analyzed for pollen and chemical composition. The soil samples were taken from vertical profiles, the digging of which was sometimes hindered by permafrost.At what level grazing began is not clear, most likely not until quite recently.This is confirmed by the soil analyses which indicate former grazing (Fig. The lower half of the profile (a-d) under the copse (Fig.