Reconstruction and Interpretation of the Local Vegetational Succession of a Lateglacial Deposit From Usselo (The Netherlands), Based on the Analysis of Micro- And Macrofossils

Abstract

Analysis of plant micro-and macrofossils from a sequence from Usselo (The Netherlands) allows a detailed reconstruction oflocal developments during a period of more than one and a half millennia, starting before the Belling period and lasting till the end of the Altered period. The sequence started in an oligotrophic shallow pool with a very low organic production in a barren sandy landscape. An early phase with G/oeotrichia type may be connected with the ability of N-fixation of these blue-green algae. This capacity may have initiated nutrient availability. Characeae played an important role on the initially sandy substrate. These pioneers opened up the site for other aquatics and helophytes, e.g. Potamogeton a/pinus, Carex rostrata, Phragmites australis, Equisetumfluviatile, followed by Menyanthes trifoliata, Myriophyllum spicatum and various Carex species. This sequence indicates a gradual eutrophication of the site, accompanied by an increase in production of organic matter (interrupted during the Older Dryas), as substantiated by the organic/inorganic ratio of the substrate. The tendency towards eutrophication ended when the vegetation at the mire surface lost its contact with the ground water. The sequence ended with a vegetation type dominated by Sphagnum and the occurrence of oligotraphentous Thecamoeba.These changes in local vegetation are explicable without resort to temperature fluctuations. The nutrient status of the habitat, and the water level(the latter influenced by sand and organic sediment deposition) were apparently the most important factors in the vegetation succession.

Fossil akinetes of Aphanizomenon and Anabaena as indicators for medieval phosphate-eutrophication of Lake Gosciaz (Central Poland)

“…The analysis of fossil remains of Cyanobacterla has shown to be worthwhile because it allows a better understanding of the changing local environments in lakes and pools during the past Van Geel et al (1984 recorded Gloeotrtehta as a pioneer during the early part of the Late glacial period. These records from the type section at Usselo were of crucml importance for the understanding of the vegetation development dunng the early part of the Late glacial period: Cyanobacterla of the Gloeotrwhta-type apparently played a pioneer role m nutnent-(nltrogen)poor s~tuations thanks to their ability to fix nitrogen and thus making conditions statable for other aquatic plants…”

“…The exploration of "extra" paleoenvironmental indicators In palynology is one of the topics in the palynologlcal research program at the Hugo de Vrles-Laboratory of the University of Amsterdam. Among the "extra" fossils are, a.o., fungal and algal spores and remains of Cyanobacterla (for-0034-6667/94/$7 00 © 1994 Elsevier Science B V All rights reserved SSDI 0034-6667(94)00051-K merly named Blue-green Algae) (Van Geel et al, 1983, 1984Batten andVan Geel, 1985, Cronberg, 1986;Van Geel, 1986). The present paper deals with the fossil record and interpretation of akinetes of Cyanobacterla (Aphanizomenon and Anabaena) In the holocene deposits of Lake Goscaaz in Central Poland.…”

A review of the use of non-pollen palynomorphs in palaeoecology with examples from Australia

“…They are also known to be predominant in eutrophied systems (Hutchinson 1957) but decline when hypertrophic and higher turbidity levels are reached owing to a lack of energy (light) available to drive the nitrogen fixation process (Zevenboom and Mur 1980). Van Geel et al (1984, 1989 found that Gloeotrichia was of great importance at a Late Glacial type section at Usselo, the Netherlands, where, by undertaking nitrogen fixation in pools of the earliest phase of the Late Glacial, it made conditions suitable for the reestablishment of other aquatic vegetation. The authors also report from modern observation of the taxon that, each year during late summer at a sandy pool dug in a Dutch coastal dune area, G. echinulata plays a pioneering role in re-establishing aquatic plant life.…”

Reconstruction of the vegetation at A.D. 915 at Ohse-yachi Mire, northern Japan, from pollen, present-day vegetation and tephra data

“…Van der Molen and Hoekstra 1988;Van Geel 1978;Van Geel et al 1984). Van der Molen and Hoekstra 1988;Van Geel 1978;Van Geel et al 1984).…”