In pollen preparations other microfossils
of various origin are also preserved. Among the 'extra' microfossils
in raised bog peat are spores of fungi, remains of algae and invertebrates.
In a series of papers the descriptions and illustrations of many
non-pollen palynomorphs (NPP, or 'Types') were published and their
indicator value was discussed (for references see van Geel, 2001).
Morphological descriptions were always combined with stratigraphic
information, often in the form of pollen and macrofossil diagrams.
Several hundred Types have now been distinguished, each one with
a Type-number. In most cases there was initially no, or hardly
any taxonomic/ecological knowledge about the distinguished Types.
The identification of the fossils was attempted with the aid of
literature and by consulting colleagues in invertebrate zoology,
phycology and mycology. Among the NPP there still are many taxa
which are not properly identified, but some of them nevertheless
can be used as palaeoenvironmental indicators. In such cases,
the ecological information was inferred from the co-occurrence
(curve matching) with identified taxa.
For Types in raised bog peat the publication by van Geel (1978)
is relevant. For the ACCROTELM project only a selection of Types
with a clear indicator value will be recorded (see below).
Many different fungal 'Types' occur in peat
deposits, especially in peat layers which were formed under relatively
dry conditions. In peat which was formed under very wet conditions
fungal remains occur rarely.
From the various studies of fossil fungal spores, it became clear
that the recorded spores in most cases are of strictly local occurrence.
They were fossilised at, or near the place where they had been
produced, or the spores were deposited only a short distance from
the place where sporulation took place. A relevant selection of
raised bog fungi is given here. ACCROTELM partners responsible
for pollen analysis will receive an illustration showing the
following NPP:
- Gelasinospora
spores (Types 1 and 2) indicate relatively dry conditions.
Spores are ellipsoidal, 22-30(-37) x 14-20(-24) µm. Spore
surface almost black, evenly ornamented with ca 1 µm wide
round, or ellipsoidal hyaline pits.
- Type 10 is an indicator
for relatively dry conditions. It occurs on the roots of Calluna
vulgaris.
Spores transversely (1-)2-3(-6) septate, (10-)20-30(-50) µm
long and (7-)9-10(-12) µm wide, formed at the ends of septate,
pigmented, (1-)1.5(-2) µm wide hyphae; basal cells paler
(thinner-walled) than the others; not constricted at the septa
or hardly so. In each septum a ca 0.3 µm wide pore.
- Type 12 is also a dryness
indicator. It grows on a variety of bog plants.
Spores curved, (7-)10-13(-14) µm long, with two transverse
septa, constricted at the septa. Apical cell (4-)6-7(-8) µm
wide, thick-walled, dark brown, with a sub-apical germ pore about
0.7 µm wide. Central cell brown; basal cell hyaline and
thin-walled.
- Spores of Meliola niessleana
(Type 14). The fungus is a parasite on Calluna vulgaris.
Spores 41-55 x 14-18 µm, three-septate, inequilateral (one
side almost straight), slightly constricted at the septa. Septa
thickened around the ca 1.5 µm wide pore.
- Spores of Neurospora
(Type 55C) indicate local bog fires.
Spores ellipsoidal, non-septate, brown, 22-28 x 15-18 µm,
with two protruding apical pores, about 1 µm wide; with
about 16 fine, longitudinal grooves.
Some algal spores:
- The hyaline spores of Mougeotia, Spirogyra
and Zygnema-type are produced by filamentous green
algae, inhabiting shallow, stagnant, oxygen-rich freshwater pools.
- Spores of Mougeotia are square, laterally straight to
concave; retuse angles often with depressions. Surface smooth
or with small pits.
- Spores of Spirogyra are ellipsoidal. Walls are smooth
or reticulate; spores show a longitudinal furrow which often encircles
almost the whole spore.
- Spores of Zygnema-type are spheroidal and flattened,
with pits all over the surface.
Testate Amoebae in pollen slides:
- The thecae of Amphitrema flavum and Assulina
indicate local relatively wet conditions. Many species of
Testate Amoebae do not 'survive' the pollen preparation method.
See Charman et al. (2000) for illustrations and ecological information
and a complete analysis of Testates.
Counting of microfossils should be continued until at least 400
pollen grains of taxa included in the pollen-sum are recorded.
Pollen-sum taxa are: trees, shrubs and upland herbs. Aquatic plants,
local bog plants (like Cyperaceae and Ericales) and spores are
excluded from the pollen-sum. However, their percentages will
be expressed on the pollen-sum.
Some spores (like Types 10 and 12) can be so frequent that counting
them until the pollen-sum is reached is too time-consuming. Therefore
counting of these highly frequently occurring spores can be stopped
when 50 pollen-sum taxa (or a certain number of the added Lycopodium
spores) are recorded. Before entering the data in the TILIA program
(for drawing diagrams) the number of spores should be 'extrapolated'
first, so that (rough) percentages can be calculated.
Please note that Bas van Geel (IBED-FNWI, Kruislaan 318, 1098 SM Amsterdam, Netherlands; e-mail: vangeel@science.uva.nl) is always willing to help in case of doubts about identification of non-pollen palynomorphs. If necessary samples can be photographed and sent as electronic attachments (.jpg files with compression so that the files are less than 1Mb).
Charman, D.J.,
Hendon, D. and Woodland, W.A. 2000. The identification
of testate amoebae (Protozoa) in peats. QRA Technical Guide
No. 9, Quaternary Research Association, London. 147 pp.
Transeau, E.N. 1951. The Zygnemataceae. Columbus
Graduate School Monographs, Contributions in Botany, 1. Columbus,
Ohio, 327 pp.
van Geel, B. 1978. A palaeoecological study of Holocene
peat bog sections in Germany and the Netherlands. Rev. Palaeobot.
Palynol. 25, 1-120.
van Geel, B. 1986. Application of fungal and algal remains
and other microfossils in palynological analyses. In Berglund,
B.E. (ed) Handbook of Holocene Palaeoecology and Palaeohydrology.
Wiley, Chichester. p. 497-505.
van Geel, B., Pals J.P., van Reenen G.B.A. and van
Huissteden J. 1995. The indicator value of fossil fungal
remains, illustrated by a palaeoecological record of a Late Eemian/Early
Weichselian deposit in the Netherlands. In Herngreen, G.F.W.
& L. van der Valk (eds) Neogene and Quaternary geology of
North-West Europe. Meded. Rijks Geol. Dienst 52: 297-315.
van Geel, B. and Grenfell H.R. 1996. Spores of
Zygnemataceae. In Jansonius, J. & D.C. McGregor (eds)
Palynology: principles and applications, Am. Ass. Strat. Palynol.
Found., Vol. 1: 173- 179.
van Geel, B. 2001. Non-pollen palynomorphs. In:
J.P. Smol, H.J.B. Birks and W.M. Last (eds.) Tracking environmental
change using lake sediments.; Volume 3: Terrestrial, algal and
silicaceous indicators. Kluwer, Dordrecht, p. 99-119.
For those who are interested to see more
NPP's from various sediment types:
Ask Bas van Geel for a copy of a xerox-copy book showing hundreds
of NPP.