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The determination and elimination of local elements in pollen spectra from different sediments
Review of Palaeobotany and Palynology Elsevier Publishing Company, Amsterdam - Printed in The Netherlands
THE D E T E R M I N A T I O N AND ELIMINATION OF LOCAL ELEMENTS IN POLLEN SPECTRA FROM D I F F E R E N T SEDIMENTS
ELI~KA RYBNiQKOV,/~ ANt) KAMIL RYBNI~EK
Botanical Institute of the Czechoslovak Academy of Sciences, Brno (Czechoslovakia)
(Received May 13, 1970)
SUMMARY
The present study is an attempt to determine local elements in pollen spectra obtained from analyses of various types of Postglacial organogenic sediments in Czechoslovakia. A survey of the local elements in algal gyttja (nekron mud), coarse detritus gyttja, brown moss peat, Carex peat, Phragmites peat, fen peat, Alnus carr (wood) peat, Sphagnum-Eriophorum peat, and Pinus carr peat is given in Table I. A short characterisation of the above-mentioned genetic types of sediments is also appended (pp. 166-167). From different types of sediments, several examples have been chosen to show the degree of possible error in quantitative ratios between the individual elements of pollen spectra. It is suggested that these errors may, in many cases, be corrected by eliminating local elements from the basic sum; but this elimination has to be differentiated according to the approximate floristic composition of the original peat-forming community, and it has to be performed separately for the different layers of the profile. INTRODUCTION It is well known that pollen spectra can be significantly influenced by over-representation of local elements (cf. FAEGRI and IVERSEN, 1964; JANSSEN, 1959, 1966). Palynologists, aware of this difficulty, try to avoid it by choosing for analytical investigation material in which the influence of local elements appears to be not too significant (cf. FAEGRIand IVERSEN, 1964, pp.52, 53). However, in some regions (for example, in the lower vegetational belts of Central Europe) it is almost impossible to find a suitable locality. In these regions palynologists have no option but to analyse material which is at their disposal, such as various types of fen peat, Alnus peat, etc. if they wish to produce at least an outline picture of the vegetational history of the area. In such cases, the obstacles encountered include, among other things, the over-representation of local pollen elements. The authors are convinced that, in Rev. Palaeobotan.PalynoL, 11 (1971) 165-176
165
many cases at least, it is impossible to use the usual method of eliminating the local element in the pollen flora by removing such elements uniformly from the whole profile. In this case, some of the dividing lines between periods, based on abrupt decreases or increases in the curves do not always separate climatic and vegetational periods; they may denote only the boundary between two genetically different layers of a profile. This means that the elimination of the local elements will be different in different parts of the profile and will be determined by the nature of the sediments. The results of pollen analyses should be compared with those of macroscopic remains and with the knowledge of the phytocenotic structure of corresponding peat-forming communities. Only then can the local elements in pollen spectra be specified and eliminated with sufficient precision. For some areas, especially northwestern Germany, the necessary studies have already been conducted (GRosSE-BRAUCKMANN, 1962, 1967; MENKE, 1968). In order to arrive at better evaluation of the pollenana[ytic results of Czechoslovak Postglacial organogenic sediments, an attempt is made to answer the following questions in the present paper: (1) Which elements of the pollen spectra can be considered as local and which as partly local in various genetic types of organogenic sediments? (2) To what degree does the origin of various types of sediments affect the decomposition of pollen spectra and the ratios between their members? MATERIAL In order to answer the first question, the authors selected groups of pollen spectra from different pollen diagrams constructed in their institute representing more or less typical layers of the following types of sediment: algal gyttja, coarse detritus gyttja, brown moss peat, Carex peat, Phragmites peat, fen peat, Alnus carr peat, Sphagnum-Eriophorum vaginatum peat, and the continental or subcontinental form of the latter type--Pinus carr peat. As no uniform classification of sediments has so far been attempted, their concise characterisation, a list of their main macroscopic remains and their probable phytocenotical origin (phytocenological nomenclature according to the Central-European classification system) is introduced here:
CG
Algal gyttja: fine-grained organic limnic sediment formed mostly by deposition of planktonic algae under meso- or eutrophic conditions, highly elastic, finely stratified, usually of olive-green shades. With the exception of sporadic remains of roots coming from higher layers, it does not usually contain ~laacroscopicplant remains. Coarse detritus gyttja: organic limnic sediment of high grade of humification, formed under plant communities of the class Potametea TOXENet PREISING, 1942. It is characterized by low elasticity, imperceptible stratification and dark brown to black colour. Most important macroscopic remains : Potamogeton, Ceratophyllum demersum, Nymphaea, Nuphar, Najas, Menyanthes trifoliata, Batrachium. It corresponds to Potamioni peat sensu TOLPA et al. (1967).
166
Rev. Palaeobotan. Palynol., 11 (1971) 165-176
AG
BM
CP
PP
FP
AP
SE
LP
Brown moss peat: telmatic sediment formed from primitive plant communities of the order Tofieldietalia PREISING apud OBERDORFER, 1949. It is characterized by the prevalence of slightly decomposed brown mosses, by fairly good stratification and by elasticity varying according to the degree of decomposition. The sediment is of yellow, yellow-brown, brown, or rust-brown eolour. Most important macroscopic remains: Drepanocladus intermedius, D. revolvens, D. sendtneri, Seorpidium scorpioides, Calliergon trifarium. In comparison with mosses, remains of vascular plants are represented only sporadically (Carex). It corresponds more or less to Bryaleti peat sensu TOLPA et al. (1967). Carex peat: telmatic sediment formed by plant communities similar to present communities of the order Magnocaricetalia PICNATTI, 1953 or of the alliance Eriophorion gracilis PREISINC apud OBERDORVER, 1957. Physical properties are highly variable. Most important macroscopic remains: Carex rostrata, C. gracilis, C. elata, C. pseudocyperus, C. aquatilis, C. diandra, C. lasiocarpa, Lyeopus europaeus, Seutellaria galerieulata. Mosses may be absent, or (under mesotrophic conditions) Sphagna sect. subseeunda as well as some S. sect. euspidata and (under eutrophic conditions) Calliergon giganteum, Meesia triquetra, etc. can be found. It corresponds more or less to Magnocaricioni peat sensu Toer, h et al. (1967) Phragmites peat: telmatic sediment formed by plant communities of the order Phragmitetalia W. KOCH, 1926 emend. PIGNATTI, 1953. Physical properties of the sediment are highly variable. The most important macroscopic remnant is: Phragmites communis. Mosses are usually absent; if present, their representation is conditioned by trophic sit uation similarly to the case of Carex peat (see this page). Phragmites peat forms frequent transitions to Carex 0eat, Alnus carr peat and Betula carr peat. It corresponds to kimno-Phragmitionipeat sensu TOLPA et al. (1967). Fen peat: some telmatic sediments, genetically heterogeneous to a certain degree, are denoted as fen peat in this study. They have approximately the same physical properties and structure. These peats are formed by the communities which can belong to the alliances Caricion eaneseentis fuscae NORDH., 1937 (under oligotrophic conditions--O), Rhynchosporion albae W. Koc~f, 1926 (under mesotrophic conditions--M) and the order Tofieldieta~a PREISING apud OaERDORFER, 1949 (under eutrophic conditions E). Most important macroscopic remains are: Carexfusca (OME), C. limosa (OME), C. chordorrhiza (OME), C. lasioearpa (OME). C. rostrata (OME), C. echinata (OME), Comarum pahtstre (OME), Menyanthes trifoliata (OME), Carex canescens (OM), Rhynehospora alba (OM), Carex davalliana (E), C. dioiea (E), Sphagna sect. cuspidata (OM), Bryum pseudotriquetrum (ME), Sphagna sect. subseeunda (M), Meesia triquetra (M). Drepanocladus intermedius et revolvens (E) D. sendtneri (E), Chrysohypnum stellatum (E). It forms frequent transitions to brown moss peat and Carex peat. It corresponds more or less to Cariceto-Bryaleti and Sphagno-Cariceti peats sensu TOLPA et al. (1967). Altars cart peat: more or less terrestric, exclusively telmatic sediment formed by plant communities of the class Alnetea glutinosae BRAUN-BLANQUET et TOXEN, 1943. It is characterized by the prevalence of remains of Alnus with Frangula, Salix, Betula, or even Pieea (this especially in the Carpathian Mountains). Due to considerable decomposition of the material it is usually difficult to ascertain the elements but Carex elongata, Ca#ha palustris, Rubus, Ribes occur sporadically. It corresponds to Alnioni peat sensu TOLPA et al. (1967). Sphagnum-Eriophorum vaginatum peat: terrestric sediment formed by dystrophic plant communities of the class Oxycocco-Sphagnetea BRAUN-BLANQUET et TOXEN, 1943. Its physical properties and structure are highly heterogeneous. The most frequent macroscopic remains are: Eriophorum vaginatum, Sphagna sect. euspidata, S. sect. acutifolia, S. sect. cymbifolia. It corresponds to Ombro-Sphagnioni peat sensu TOLeA et al. (1967). Pinus cart peat: formed by plant communities of the alliance Pino-Ledion T0XEr% 1955 on subcontinental and continental raised bogs. It is usually characterized by a high degree of decomposition with corresponding physical properties. The most frequent macroscopic remains are: Pinus, sometimes Ledum palustre. Otherwise vide the preceding type. It corresponds to Ledo-Pinioni peat sensu TO~PA et al. (1967).
Rev. Palaeobotan. Palynol., I1 (1971) 165-176
167
RESULTS The evaluation of the origin of pollen grains and spores in the spectra, obtained from the above-mentioned sediments, is based mainly on analyses of macroscopic plant remains in the sediments and on a detailed description of the layers. Only in some doubtful cases the present ftoristic composition of water and mire communities, probably analogous to those which originally formed the sediment, has also been taken into account. The results of this evaluation are given in Table I. The asterisk appended to the names of pollen types in the table denotes types whose origin in the spectra is not exclusively local, though in some cases most of the pollen grains are definitely of local origin. These pollen types comprise not only the pollen grains of woody plants (Alnus, Betula, Pinus, Salix), but also of some herb types, such as Daucaceae, which can be produced both by various mire or water species (Peucedanum palustre, Oenanthe aquatica, etc.) and by numerous dry-land species. A similar situation can be found in Poaceae (local Phragmites, Glyceria, Alopecurus geniculatus and A. aequalis, Molinia, etc.), in Silenaceae, etc. In order to ascertain the degree to which the local elements influence the pollen spectra of different origin, the percentage values of the members ot the spectra were calculated in two ways: first, as usual, from the total sum AP + N A P equal to 1 0 0 ~ (black curves in Fig.l-3) and, secondly, by eliminating from this total sum all the elements in the sediment which were found to be of local or predominantly local origin (white curves in Fig.l-3). The absolute values for these local woody plants and herbs eliminated in this way were then calculated independently of the first "dry-land" group. The sum of local AP + NAP was considered to be equal to 100%. In neither case were the spores of bryophytes and algae included in the total sum. The results of these conversions are recorded in abbreviated partial diagrams (Fig.l-3). The smallest quantitative differences between the two types of curve appear in diagrams recording spectra from limnic sediments (algal gyttja, coarse detritus gyttja) from brown-moss peat, and--which is especially interesting--in some cases also from Sphagnum-Eriophorum vaginatum peat (Fig.l). In spite of usually high pollen production of Eriophorum vaginatum in corresponding peat-forming communities, pollen grains of Cyperaceae (namely Cyperaceae type Eriophorum) Explanation of symbols in Table I: * Pollen grains produced by both local and dry-land plants. Where marked the prevalence of grains of local origin is presumed. + Regular occurrence, (+) Irregular occurrence with lower representation. ÷ ! Occurs in great quantities. M Under mesotrophic conditions. E Under eutrophic conditions. [] Characteristic pollen and spores combinations. For explanation of sediment abbreviations (AG, CG, etc.) see p.166-167. 168
Rev. Palaeobotan.Palynol., 11 (1971) 165-176
TABLE
I
LOCAL POLLEN GRAINS AND SPORES IN VARIOUS ORGANOGENIC SEDIMENTS IN CZECHOSLOVAKIA
Sediment
*
Cyperaceae
AG
CG
(+)
(+) (+)
* Poaceae
Potentilla-Comarum t. (+) Menyanthes trifoliata Typha latifolia (+) Equisetum (+) Galium t. R a n u n c u l a c e a e t. Ranunculus -Potamogeton (+) Myriophyllum cf. verticillatum Myriophyllum cf. spicatum + Alisma Nuphar Nymphaea Utricularia Ranunculus t. Batrachium Lythrum Polygonum t. amphibium Pedicularis * B r a s s i c a c e a e t. Cardamine prat. - R a n u n c u l a c e a e t. Caltha * A s t e r a c e a e t. Cirsium Lycopus-Mentha t.
BP
CP
PP
FP
AP
SE
+
+~ (+)
(+) +~
+~ (+)
(+) (+)
+ (+)
+ +
+ (+)
(+) (+)
--
-
(+) + (+) (+) (+)
+
+
+ -~ ~ +
(+) + + + +
+ ~ (+) (+) (+) (+)
--
+
(+) (+) (+)
(+) (+) (+)
--
(+)
(+)
(+1 ---
-(+) (+)
(+)
--
--
+
(+)
--
+
--
+ + +
+ + +
----
-+ + + + +
(+)
(÷)l -( +j) 1
(+)
----
* Daucaceae
Scutellaria-Lamium t. Rumex cf. maritimus Sparganium-Typha angustifolia t. Epilobium A s t e r a c e a e t. Bidens Elatine
(+) + + + (+)
LP
4
* Silenaceae
_
__
(~)
Parnassiapalustris Viola palustris Valeriana t. dioiea Orchidaceae
--
(+)
--
--
(+)
--
Drosera
--
(+)
--
Lysimachia vulgaris t. * Filipendula Chrysosplenium * Urtica dioica
(+) (+) + (+) + + + + (+) + + + (+) +
I+
+
+ + 4+ +
(+)
±
(+)
(+)
+
--
+ + + (+) (~) (+)
---+ + +
--
(+) (+)
(+1
(+)
--
* Polypodiaceae
* Humulus-Cannabis t. Solanum clttlcamara Valeriana t. officinalis * Alnus * Salix * Betula * Frangula alnus * Vaccinium Oxycoccas * Calluna vulgaris * Melampyrum * Pinus Ledum palustre Sphagnum Bryales Algae
--
--
--
(+)
(+)
--
(+)
(+)
(+)
--
(+) ~ 4-
I
~
(+) (+)
+
+
(+) (+) (+)
+~ + +
(+)
--
+ +
+ +
--
+
+
--
_
(+)
(+)
+M
(+)
(+)
+E
(-t-)
(+1
--
(~)
--
(+)
9Ll-g91(IL6l) ll"lOU@nd'uDjoqoownd'aO~
OLI
r~
~q R i
/o°~ I IJ _~
1
!
.,~-~t~ ~ "=
i
I
'-
~ I
~g
1
~7 ~2 t6"
15
20
NAP l
-)i
\',,
-- i~.l. loce/ plen/s .--exc/. local planl~
4P
Fig.1. Partial diagrams showing quantitative differences obtained from two different methods of "alculation of the same pollen spectra. Algal gyttja (a), coarse detritus gyttja (b), Sphagnum~riophorurn vaginatum peat (c), brown moss peat (d). TZ including local plants--black curves: FE excluding local plants--white curves.
30
f/
I0
25
t3
05"
SO
I
)#
I
LOCAL V E G E T A l I O N
380-425cm
Youn9er Drye~
Z,E R V E N E BLAFO J C - 3 - A
CO
"-
L
Io
QO
t
~0
)S
rO
"0
'&
0
I
t
LOC4L V E G E T A T/ON
NAP
;o
~0
so
ao
- - Jr,el, l o c a l ~1~,~t~ ,-- excI, local Dlanl~
lP
Younger Al/an//c
7V-5-D #O-90cm
P) ~ ",.
i
~
~.'~. ~ ,,I
t o~
~~
i
i,,
Ji-IjII
,, ~',,i
t
vn~s/n03 ~ ~ • ~
wY3.133
y--
3Y33V~Y3dA3 [-'-- XI7V$
gnNTv ~-
d~'d3.L33 ~ 3~Od,(70d YISIN3JcYF
"3VIQOd~70d P'I~-JrY33 ~ 3P'3OYOd ~-
~I7V3¢Y..T3~
Fig.2. Partial diagrams showing quantitative differences obtained from two different methods of calculation of the same pollen spectra. Carex peat (a), Phragmites peat (b), fen peat--mesotrophic form (c). TN including local plants--black curves; TN excluding local plants--white curves.
172
Rev. Palaeobotan. Palynol., 11 (1971) 165-176
need not reach high values in sediments Coming from the lower vegetational belts of Czechoslovakia. Another situation sometimes arises from analyses of mountainous raised bogs or ombrogenous raised bogs of humid areas in Europe, where the local elements may exert considerable influence (cf. RYBNi(zKOVX, 1966), but their delimitation and elimination do not usually raise any difficulties (see Table I, column SE). As shown by this example, even the mires of the type SphagnumEriophorum vaginatum can be highly suitable objects for pollen analysis. Another group of diagrams records the results of the two methods of calculation in the spectra obtained from Carex peat, Phragmites peat, and fen peat (Fig.2). They are characterized by an almost uniform and more or less regular distribution of local pollen grains in the spectra. This means that the two curves are approximately parallel although the quantitative differences between the two calculations can be considerable. When these sediments are succeeded in the profile by, for example, lake sediments (gyttja), the quantitative relations (when all AP + NAP = 100°J~,) of the two types of spectra are very difficult to compare in one curve. If local elements are not eliminated from the pollen spectra of that type, then false conclusion of a more general character may result. The great quantitative difference in the ratio AP/NAP from Carex peat (Fig.2a) can be given as an example here. This example is taken from the Younger Dryas period. The curve obtained from the usual total count suggests that there were no closed forests in the area, or that trees appeared there only sporadically. If, however, the local pollen types are excluded, the curve shows that at the end of the Late Glacial period the area was covered with forests or trees to a much greater degree. This hypothesis has also been supported by other pollen diagrams from the same region (cf. RYBNi(~KOV/,, 1969). The elimination of local elements in these cases appears to be very useful, especially for total counts. It is not so important if standard counting (AP = 100 ~ ) is used. The last group consists of spectra coming usually from wood peat (Fig.3). In the examples presented, the results of both calculations reveal not only considerable quantitative differences, but also differences in the two curves, probably due to the influence of the irregular distribution of pollen grains of local trees in the spectra. The exclusion of local elements from this group of spectra is, in most cases, almost a necessity if we wish to reconstruct more than just local tree cover. Similar situations can be found in sediments formed by communities with Betula, Picea, etc. in the cases in which one pollen type is highly over-represented, it is useful to take this fact into consideration during the microscopic examination. lf, for example, we do not eliminate predominantly local pine from the spectra obtained from the analysis ofPinus carr peat in southern Bohemia (Fig.3b, Borkovice), the curve of the ratio AP/NAP suggests that the analyses come from a region covered to a considerable degree by forest and with little farming activity. This, however, is at great variance with reality. Only after the local elements have
Rev. Palaeobotan. PalynoL, 11 (1971) 165-176
173
T
I
I ca
$
ca
~
#IDNOWH~S
HDNOVth:~
d WN + d~
'lr~V ~'cY31_73
dVN ~qAl 3 ~
~V33~-~AO
,gDNId d t r N +d i e
"NL-
~"/
SDN79" d V N Vd3.133 VI 7 V..TcY33
3V3OVOW
I
SANlddlttD 3 ~'_,-70VOd
S31OV SDOV.Y IY3,gld
SDTA,:YO0 ~ tv7D.l..4-O ~
SDN7V MO ~D7AcYO,9 ~. Xl7¢S
SDN/et
[
L_I_
E
Fig.3. Partial diagrams showing quantitative differences obtained from two different methods of calculation of the same pollen spectra. Alnus carr peat (a), Pintts carr peat (b). TZ including local plants--black curves; TZ excluding local plants--white curves.
174
Rev. Palaeobotan. Palynol., I1 (1971) 165-176
been eliminated, will the curve plotted from our calculations depict the actual state of the country. CONCLUSION
A more reliable interpretation of pollen diagrams can often be achieved if the ecological point of view and the origin of the organogenic sediments being analysed are taken into account. It is not suggested here that the method of separate counts in genetically different layers can be used for the construction of complete pollen diagrams which represent a profile consisting of several different sediments. Some pollen types which must be eliminated in one case must be added to the sum of dry-land vegetation in other cases (cf. p.168). It is, however, always possible to construct auxiliary partial diagrams. They greatly assist in the interpretation of the basic diagram, as they often clarify points otherwise explained only with considerable difficulty. On the other hand, these auxiliary diagrams cannot eliminate the difficulties in evaluation, resultirg from biological heterogeneity of pollen production, from the differential dispersion of pollen grains, from historical differences in vegetational composition and from other than local phytocenotic factors. It is also necessary to point out that numerous transitions between the various types of sediments discussed here can be found, so that the examples presented cannot represent all the types of organogenic sediments in Czechoslovakia. This means that each type of sediment should be treated separately. Nevertheless, it is hoped that the examples chosen are sufficient to draw attention to the advantages derived from the method of interpretation of pollen diagrams suggested here. ACKNOWLEDGEMENTS
This paper was read in Section III in the Eighth INQUA Congress in Paris (1969) under the title: The evaluation of pollen spectra from the ecological (phytosociological) point of view. In elaborating some types of sediments the authors were also able to profit from unpublished pollen analyses by Dr. V. JANKOVSK~ (brown moss peat and Pinus carr peat) and Dr. A. KONETOPSKY (A]nus peat). The authors would like to record their heartiest thanks. They are also indebted to Dr. D. D. BARTLE¥ from the University of Leeds (England) for the linguistic revision of this paper. REFERENCES FAEGRI, K. and [VERSEN, J., 1964. Textbook of Pollen Analysis. Munksgaard, Copenhagen, 2nd ed., 237 pp.
Rev. Palaeobotan. Palynol., 11 (1971) 165-176
175
GROSSE-BRAUCKMANN,G., 1962. Moorstratigraphische Untersuchungen im Niederwesergebiet. (I]-ber Moorbildungen am Geestrand und ihre Torfe.) VerOff. Geobotan. Inst. E.T.H., Ziirich, 37: 100-119. GROSSE-BRAUCKMANN, G., 1967. Ober die Artenzusammensetzung einiger nordwestdeutsche Torfe. In: Pflanzensoziologie und Palynologie. Ber. Intern. Syrup. Stolzenau/Weser, 1962, pp. 160-I 80. JANSSEN, C. R., 1959. Alnus as a disturbing factor in pollen diagrams. Acta Botan. Necrl., 8: 55-58. JANSSEN, C. R., 1966. Recent pollen spectra from the deciduous and coniferous-deciduous forest of northeastern Minnesota: a study in pollen dispersal. Ecology, 47(5): 804--825. MENKE, B., 1968. Ein Beitrag zur pflanzensoziologischen Auswertung yon Pollendiagrammen, zur Kenntnis friiher Pflanzengesellschaften in den Marschenrandgebieten der schleswigholsteinischen Westkiiste und zur Anwendung auf die Frage der Kiistenentwicklung. Mitt. Flor. Soz. Arbeitsgem., N.F., 13: 195-224. RYBNi(~KOV~, E., 1966. Pollen-analytical reconstruction of vegetation in the upper regions of the Orlick6 hory Mountains, Czechoslovakia. Folia Geobotan. Phytotaxon. Bohemoslov., 1(4): 289-310. RYBNi(~KOV,~, E., 1969. Die Entwicklungsgeschichte der W~ilder aufder B6hmisch-M~hrischen H6he im Sp~it- und Postglazial. Mitt. Ostalp.-dinar. Sekt. Intern. Verein. Vegetationskunde, 10(2): 64-69. To~,I,A, S., JASNOWSKI,M. und PALCZV~SKLA., 1967. System der genetischen Klassifizierung der Torfe Mitteleuropas. Zesz. Problem. Post~p. Nauk Rolniez., 76: 9-99.
176
Rev. Palaeobotan. Palynol., 11 (1971) 165-176
THE D E T E R M I N A T I O N AND ELIMINATION OF LOCAL ELEMENTS IN POLLEN SPECTRA FROM D I F F E R E N T SEDIMENTS
ELI~KA RYBNiQKOV,/~ ANt) KAMIL RYBNI~EK
Botanical Institute of the Czechoslovak Academy of Sciences, Brno (Czechoslovakia)
(Received May 13, 1970)
SUMMARY
The present study is an attempt to determine local elements in pollen spectra obtained from analyses of various types of Postglacial organogenic sediments in Czechoslovakia. A survey of the local elements in algal gyttja (nekron mud), coarse detritus gyttja, brown moss peat, Carex peat, Phragmites peat, fen peat, Alnus carr (wood) peat, Sphagnum-Eriophorum peat, and Pinus carr peat is given in Table I. A short characterisation of the above-mentioned genetic types of sediments is also appended (pp. 166-167). From different types of sediments, several examples have been chosen to show the degree of possible error in quantitative ratios between the individual elements of pollen spectra. It is suggested that these errors may, in many cases, be corrected by eliminating local elements from the basic sum; but this elimination has to be differentiated according to the approximate floristic composition of the original peat-forming community, and it has to be performed separately for the different layers of the profile. INTRODUCTION It is well known that pollen spectra can be significantly influenced by over-representation of local elements (cf. FAEGRI and IVERSEN, 1964; JANSSEN, 1959, 1966). Palynologists, aware of this difficulty, try to avoid it by choosing for analytical investigation material in which the influence of local elements appears to be not too significant (cf. FAEGRIand IVERSEN, 1964, pp.52, 53). However, in some regions (for example, in the lower vegetational belts of Central Europe) it is almost impossible to find a suitable locality. In these regions palynologists have no option but to analyse material which is at their disposal, such as various types of fen peat, Alnus peat, etc. if they wish to produce at least an outline picture of the vegetational history of the area. In such cases, the obstacles encountered include, among other things, the over-representation of local pollen elements. The authors are convinced that, in Rev. Palaeobotan.PalynoL, 11 (1971) 165-176
165
many cases at least, it is impossible to use the usual method of eliminating the local element in the pollen flora by removing such elements uniformly from the whole profile. In this case, some of the dividing lines between periods, based on abrupt decreases or increases in the curves do not always separate climatic and vegetational periods; they may denote only the boundary between two genetically different layers of a profile. This means that the elimination of the local elements will be different in different parts of the profile and will be determined by the nature of the sediments. The results of pollen analyses should be compared with those of macroscopic remains and with the knowledge of the phytocenotic structure of corresponding peat-forming communities. Only then can the local elements in pollen spectra be specified and eliminated with sufficient precision. For some areas, especially northwestern Germany, the necessary studies have already been conducted (GRosSE-BRAUCKMANN, 1962, 1967; MENKE, 1968). In order to arrive at better evaluation of the pollenana[ytic results of Czechoslovak Postglacial organogenic sediments, an attempt is made to answer the following questions in the present paper: (1) Which elements of the pollen spectra can be considered as local and which as partly local in various genetic types of organogenic sediments? (2) To what degree does the origin of various types of sediments affect the decomposition of pollen spectra and the ratios between their members? MATERIAL In order to answer the first question, the authors selected groups of pollen spectra from different pollen diagrams constructed in their institute representing more or less typical layers of the following types of sediment: algal gyttja, coarse detritus gyttja, brown moss peat, Carex peat, Phragmites peat, fen peat, Alnus carr peat, Sphagnum-Eriophorum vaginatum peat, and the continental or subcontinental form of the latter type--Pinus carr peat. As no uniform classification of sediments has so far been attempted, their concise characterisation, a list of their main macroscopic remains and their probable phytocenotical origin (phytocenological nomenclature according to the Central-European classification system) is introduced here:
CG
Algal gyttja: fine-grained organic limnic sediment formed mostly by deposition of planktonic algae under meso- or eutrophic conditions, highly elastic, finely stratified, usually of olive-green shades. With the exception of sporadic remains of roots coming from higher layers, it does not usually contain ~laacroscopicplant remains. Coarse detritus gyttja: organic limnic sediment of high grade of humification, formed under plant communities of the class Potametea TOXENet PREISING, 1942. It is characterized by low elasticity, imperceptible stratification and dark brown to black colour. Most important macroscopic remains : Potamogeton, Ceratophyllum demersum, Nymphaea, Nuphar, Najas, Menyanthes trifoliata, Batrachium. It corresponds to Potamioni peat sensu TOLPA et al. (1967).
166
Rev. Palaeobotan. Palynol., 11 (1971) 165-176
AG
BM
CP
PP
FP
AP
SE
LP
Brown moss peat: telmatic sediment formed from primitive plant communities of the order Tofieldietalia PREISING apud OBERDORFER, 1949. It is characterized by the prevalence of slightly decomposed brown mosses, by fairly good stratification and by elasticity varying according to the degree of decomposition. The sediment is of yellow, yellow-brown, brown, or rust-brown eolour. Most important macroscopic remains: Drepanocladus intermedius, D. revolvens, D. sendtneri, Seorpidium scorpioides, Calliergon trifarium. In comparison with mosses, remains of vascular plants are represented only sporadically (Carex). It corresponds more or less to Bryaleti peat sensu TOLPA et al. (1967). Carex peat: telmatic sediment formed by plant communities similar to present communities of the order Magnocaricetalia PICNATTI, 1953 or of the alliance Eriophorion gracilis PREISINC apud OBERDORVER, 1957. Physical properties are highly variable. Most important macroscopic remains: Carex rostrata, C. gracilis, C. elata, C. pseudocyperus, C. aquatilis, C. diandra, C. lasiocarpa, Lyeopus europaeus, Seutellaria galerieulata. Mosses may be absent, or (under mesotrophic conditions) Sphagna sect. subseeunda as well as some S. sect. euspidata and (under eutrophic conditions) Calliergon giganteum, Meesia triquetra, etc. can be found. It corresponds more or less to Magnocaricioni peat sensu Toer, h et al. (1967) Phragmites peat: telmatic sediment formed by plant communities of the order Phragmitetalia W. KOCH, 1926 emend. PIGNATTI, 1953. Physical properties of the sediment are highly variable. The most important macroscopic remnant is: Phragmites communis. Mosses are usually absent; if present, their representation is conditioned by trophic sit uation similarly to the case of Carex peat (see this page). Phragmites peat forms frequent transitions to Carex 0eat, Alnus carr peat and Betula carr peat. It corresponds to kimno-Phragmitionipeat sensu TOLPA et al. (1967). Fen peat: some telmatic sediments, genetically heterogeneous to a certain degree, are denoted as fen peat in this study. They have approximately the same physical properties and structure. These peats are formed by the communities which can belong to the alliances Caricion eaneseentis fuscae NORDH., 1937 (under oligotrophic conditions--O), Rhynchosporion albae W. Koc~f, 1926 (under mesotrophic conditions--M) and the order Tofieldieta~a PREISING apud OaERDORFER, 1949 (under eutrophic conditions E). Most important macroscopic remains are: Carexfusca (OME), C. limosa (OME), C. chordorrhiza (OME), C. lasioearpa (OME). C. rostrata (OME), C. echinata (OME), Comarum pahtstre (OME), Menyanthes trifoliata (OME), Carex canescens (OM), Rhynehospora alba (OM), Carex davalliana (E), C. dioiea (E), Sphagna sect. cuspidata (OM), Bryum pseudotriquetrum (ME), Sphagna sect. subseeunda (M), Meesia triquetra (M). Drepanocladus intermedius et revolvens (E) D. sendtneri (E), Chrysohypnum stellatum (E). It forms frequent transitions to brown moss peat and Carex peat. It corresponds more or less to Cariceto-Bryaleti and Sphagno-Cariceti peats sensu TOLPA et al. (1967). Altars cart peat: more or less terrestric, exclusively telmatic sediment formed by plant communities of the class Alnetea glutinosae BRAUN-BLANQUET et TOXEN, 1943. It is characterized by the prevalence of remains of Alnus with Frangula, Salix, Betula, or even Pieea (this especially in the Carpathian Mountains). Due to considerable decomposition of the material it is usually difficult to ascertain the elements but Carex elongata, Ca#ha palustris, Rubus, Ribes occur sporadically. It corresponds to Alnioni peat sensu TOLPA et al. (1967). Sphagnum-Eriophorum vaginatum peat: terrestric sediment formed by dystrophic plant communities of the class Oxycocco-Sphagnetea BRAUN-BLANQUET et TOXEN, 1943. Its physical properties and structure are highly heterogeneous. The most frequent macroscopic remains are: Eriophorum vaginatum, Sphagna sect. euspidata, S. sect. acutifolia, S. sect. cymbifolia. It corresponds to Ombro-Sphagnioni peat sensu TOLeA et al. (1967). Pinus cart peat: formed by plant communities of the alliance Pino-Ledion T0XEr% 1955 on subcontinental and continental raised bogs. It is usually characterized by a high degree of decomposition with corresponding physical properties. The most frequent macroscopic remains are: Pinus, sometimes Ledum palustre. Otherwise vide the preceding type. It corresponds to Ledo-Pinioni peat sensu TO~PA et al. (1967).
Rev. Palaeobotan. Palynol., I1 (1971) 165-176
167
RESULTS The evaluation of the origin of pollen grains and spores in the spectra, obtained from the above-mentioned sediments, is based mainly on analyses of macroscopic plant remains in the sediments and on a detailed description of the layers. Only in some doubtful cases the present ftoristic composition of water and mire communities, probably analogous to those which originally formed the sediment, has also been taken into account. The results of this evaluation are given in Table I. The asterisk appended to the names of pollen types in the table denotes types whose origin in the spectra is not exclusively local, though in some cases most of the pollen grains are definitely of local origin. These pollen types comprise not only the pollen grains of woody plants (Alnus, Betula, Pinus, Salix), but also of some herb types, such as Daucaceae, which can be produced both by various mire or water species (Peucedanum palustre, Oenanthe aquatica, etc.) and by numerous dry-land species. A similar situation can be found in Poaceae (local Phragmites, Glyceria, Alopecurus geniculatus and A. aequalis, Molinia, etc.), in Silenaceae, etc. In order to ascertain the degree to which the local elements influence the pollen spectra of different origin, the percentage values of the members ot the spectra were calculated in two ways: first, as usual, from the total sum AP + N A P equal to 1 0 0 ~ (black curves in Fig.l-3) and, secondly, by eliminating from this total sum all the elements in the sediment which were found to be of local or predominantly local origin (white curves in Fig.l-3). The absolute values for these local woody plants and herbs eliminated in this way were then calculated independently of the first "dry-land" group. The sum of local AP + NAP was considered to be equal to 100%. In neither case were the spores of bryophytes and algae included in the total sum. The results of these conversions are recorded in abbreviated partial diagrams (Fig.l-3). The smallest quantitative differences between the two types of curve appear in diagrams recording spectra from limnic sediments (algal gyttja, coarse detritus gyttja) from brown-moss peat, and--which is especially interesting--in some cases also from Sphagnum-Eriophorum vaginatum peat (Fig.l). In spite of usually high pollen production of Eriophorum vaginatum in corresponding peat-forming communities, pollen grains of Cyperaceae (namely Cyperaceae type Eriophorum) Explanation of symbols in Table I: * Pollen grains produced by both local and dry-land plants. Where marked the prevalence of grains of local origin is presumed. + Regular occurrence, (+) Irregular occurrence with lower representation. ÷ ! Occurs in great quantities. M Under mesotrophic conditions. E Under eutrophic conditions. [] Characteristic pollen and spores combinations. For explanation of sediment abbreviations (AG, CG, etc.) see p.166-167. 168
Rev. Palaeobotan.Palynol., 11 (1971) 165-176
TABLE
I
LOCAL POLLEN GRAINS AND SPORES IN VARIOUS ORGANOGENIC SEDIMENTS IN CZECHOSLOVAKIA
Sediment
*
Cyperaceae
AG
CG
(+)
(+) (+)
* Poaceae
Potentilla-Comarum t. (+) Menyanthes trifoliata Typha latifolia (+) Equisetum (+) Galium t. R a n u n c u l a c e a e t. Ranunculus -Potamogeton (+) Myriophyllum cf. verticillatum Myriophyllum cf. spicatum + Alisma Nuphar Nymphaea Utricularia Ranunculus t. Batrachium Lythrum Polygonum t. amphibium Pedicularis * B r a s s i c a c e a e t. Cardamine prat. - R a n u n c u l a c e a e t. Caltha * A s t e r a c e a e t. Cirsium Lycopus-Mentha t.
BP
CP
PP
FP
AP
SE
+
+~ (+)
(+) +~
+~ (+)
(+) (+)
+ (+)
+ +
+ (+)
(+) (+)
--
-
(+) + (+) (+) (+)
+
+
+ -~ ~ +
(+) + + + +
+ ~ (+) (+) (+) (+)
--
+
(+) (+) (+)
(+) (+) (+)
--
(+)
(+)
(+1 ---
-(+) (+)
(+)
--
--
+
(+)
--
+
--
+ + +
+ + +
----
-+ + + + +
(+)
(÷)l -( +j) 1
(+)
----
* Daucaceae
Scutellaria-Lamium t. Rumex cf. maritimus Sparganium-Typha angustifolia t. Epilobium A s t e r a c e a e t. Bidens Elatine
(+) + + + (+)
LP
4
* Silenaceae
_
__
(~)
Parnassiapalustris Viola palustris Valeriana t. dioiea Orchidaceae
--
(+)
--
--
(+)
--
Drosera
--
(+)
--
Lysimachia vulgaris t. * Filipendula Chrysosplenium * Urtica dioica
(+) (+) + (+) + + + + (+) + + + (+) +
I+
+
+ + 4+ +
(+)
±
(+)
(+)
+
--
+ + + (+) (~) (+)
---+ + +
--
(+) (+)
(+1
(+)
--
* Polypodiaceae
* Humulus-Cannabis t. Solanum clttlcamara Valeriana t. officinalis * Alnus * Salix * Betula * Frangula alnus * Vaccinium Oxycoccas * Calluna vulgaris * Melampyrum * Pinus Ledum palustre Sphagnum Bryales Algae
--
--
--
(+)
(+)
--
(+)
(+)
(+)
--
(+) ~ 4-
I
~
(+) (+)
+
+
(+) (+) (+)
+~ + +
(+)
--
+ +
+ +
--
+
+
--
_
(+)
(+)
+M
(+)
(+)
+E
(-t-)
(+1
--
(~)
--
(+)
9Ll-g91(IL6l) ll"lOU@nd'uDjoqoownd'aO~
OLI
r~
~q R i
/o°~ I IJ _~
1
!
.,~-~t~ ~ "=
i
I
'-
~ I
~g
1
~7 ~2 t6"
15
20
NAP l
-)i
\',,
-- i~.l. loce/ plen/s .--exc/. local planl~
4P
Fig.1. Partial diagrams showing quantitative differences obtained from two different methods of "alculation of the same pollen spectra. Algal gyttja (a), coarse detritus gyttja (b), Sphagnum~riophorurn vaginatum peat (c), brown moss peat (d). TZ including local plants--black curves: FE excluding local plants--white curves.
30
f/
I0
25
t3
05"
SO
I
)#
I
LOCAL V E G E T A l I O N
380-425cm
Youn9er Drye~
Z,E R V E N E BLAFO J C - 3 - A
CO
"-
L
Io
QO
t
~0
)S
rO
"0
'&
0
I
t
LOC4L V E G E T A T/ON
NAP
;o
~0
so
ao
- - Jr,el, l o c a l ~1~,~t~ ,-- excI, local Dlanl~
lP
Younger Al/an//c
7V-5-D #O-90cm
P) ~ ",.
i
~
~.'~. ~ ,,I
t o~
~~
i
i,,
Ji-IjII
,, ~',,i
t
vn~s/n03 ~ ~ • ~
wY3.133
y--
3Y33V~Y3dA3 [-'-- XI7V$
gnNTv ~-
d~'d3.L33 ~ 3~Od,(70d YISIN3JcYF
"3VIQOd~70d P'I~-JrY33 ~ 3P'3OYOd ~-
~I7V3¢Y..T3~
Fig.2. Partial diagrams showing quantitative differences obtained from two different methods of calculation of the same pollen spectra. Carex peat (a), Phragmites peat (b), fen peat--mesotrophic form (c). TN including local plants--black curves; TN excluding local plants--white curves.
172
Rev. Palaeobotan. Palynol., 11 (1971) 165-176
need not reach high values in sediments Coming from the lower vegetational belts of Czechoslovakia. Another situation sometimes arises from analyses of mountainous raised bogs or ombrogenous raised bogs of humid areas in Europe, where the local elements may exert considerable influence (cf. RYBNi(zKOVX, 1966), but their delimitation and elimination do not usually raise any difficulties (see Table I, column SE). As shown by this example, even the mires of the type SphagnumEriophorum vaginatum can be highly suitable objects for pollen analysis. Another group of diagrams records the results of the two methods of calculation in the spectra obtained from Carex peat, Phragmites peat, and fen peat (Fig.2). They are characterized by an almost uniform and more or less regular distribution of local pollen grains in the spectra. This means that the two curves are approximately parallel although the quantitative differences between the two calculations can be considerable. When these sediments are succeeded in the profile by, for example, lake sediments (gyttja), the quantitative relations (when all AP + NAP = 100°J~,) of the two types of spectra are very difficult to compare in one curve. If local elements are not eliminated from the pollen spectra of that type, then false conclusion of a more general character may result. The great quantitative difference in the ratio AP/NAP from Carex peat (Fig.2a) can be given as an example here. This example is taken from the Younger Dryas period. The curve obtained from the usual total count suggests that there were no closed forests in the area, or that trees appeared there only sporadically. If, however, the local pollen types are excluded, the curve shows that at the end of the Late Glacial period the area was covered with forests or trees to a much greater degree. This hypothesis has also been supported by other pollen diagrams from the same region (cf. RYBNi(~KOV/,, 1969). The elimination of local elements in these cases appears to be very useful, especially for total counts. It is not so important if standard counting (AP = 100 ~ ) is used. The last group consists of spectra coming usually from wood peat (Fig.3). In the examples presented, the results of both calculations reveal not only considerable quantitative differences, but also differences in the two curves, probably due to the influence of the irregular distribution of pollen grains of local trees in the spectra. The exclusion of local elements from this group of spectra is, in most cases, almost a necessity if we wish to reconstruct more than just local tree cover. Similar situations can be found in sediments formed by communities with Betula, Picea, etc. in the cases in which one pollen type is highly over-represented, it is useful to take this fact into consideration during the microscopic examination. lf, for example, we do not eliminate predominantly local pine from the spectra obtained from the analysis ofPinus carr peat in southern Bohemia (Fig.3b, Borkovice), the curve of the ratio AP/NAP suggests that the analyses come from a region covered to a considerable degree by forest and with little farming activity. This, however, is at great variance with reality. Only after the local elements have
Rev. Palaeobotan. PalynoL, 11 (1971) 165-176
173
T
I
I ca
$
ca
~
#IDNOWH~S
HDNOVth:~
d WN + d~
'lr~V ~'cY31_73
dVN ~qAl 3 ~
~V33~-~AO
,gDNId d t r N +d i e
"NL-
~"/
SDN79" d V N Vd3.133 VI 7 V..TcY33
3V3OVOW
I
SANlddlttD 3 ~'_,-70VOd
S31OV SDOV.Y IY3,gld
SDTA,:YO0 ~ tv7D.l..4-O ~
SDN7V MO ~D7AcYO,9 ~. Xl7¢S
SDN/et
[
L_I_
E
Fig.3. Partial diagrams showing quantitative differences obtained from two different methods of calculation of the same pollen spectra. Alnus carr peat (a), Pintts carr peat (b). TZ including local plants--black curves; TZ excluding local plants--white curves.
174
Rev. Palaeobotan. Palynol., I1 (1971) 165-176
been eliminated, will the curve plotted from our calculations depict the actual state of the country. CONCLUSION
A more reliable interpretation of pollen diagrams can often be achieved if the ecological point of view and the origin of the organogenic sediments being analysed are taken into account. It is not suggested here that the method of separate counts in genetically different layers can be used for the construction of complete pollen diagrams which represent a profile consisting of several different sediments. Some pollen types which must be eliminated in one case must be added to the sum of dry-land vegetation in other cases (cf. p.168). It is, however, always possible to construct auxiliary partial diagrams. They greatly assist in the interpretation of the basic diagram, as they often clarify points otherwise explained only with considerable difficulty. On the other hand, these auxiliary diagrams cannot eliminate the difficulties in evaluation, resultirg from biological heterogeneity of pollen production, from the differential dispersion of pollen grains, from historical differences in vegetational composition and from other than local phytocenotic factors. It is also necessary to point out that numerous transitions between the various types of sediments discussed here can be found, so that the examples presented cannot represent all the types of organogenic sediments in Czechoslovakia. This means that each type of sediment should be treated separately. Nevertheless, it is hoped that the examples chosen are sufficient to draw attention to the advantages derived from the method of interpretation of pollen diagrams suggested here. ACKNOWLEDGEMENTS
This paper was read in Section III in the Eighth INQUA Congress in Paris (1969) under the title: The evaluation of pollen spectra from the ecological (phytosociological) point of view. In elaborating some types of sediments the authors were also able to profit from unpublished pollen analyses by Dr. V. JANKOVSK~ (brown moss peat and Pinus carr peat) and Dr. A. KONETOPSKY (A]nus peat). The authors would like to record their heartiest thanks. They are also indebted to Dr. D. D. BARTLE¥ from the University of Leeds (England) for the linguistic revision of this paper. REFERENCES FAEGRI, K. and [VERSEN, J., 1964. Textbook of Pollen Analysis. Munksgaard, Copenhagen, 2nd ed., 237 pp.
Rev. Palaeobotan. Palynol., 11 (1971) 165-176
175
GROSSE-BRAUCKMANN,G., 1962. Moorstratigraphische Untersuchungen im Niederwesergebiet. (I]-ber Moorbildungen am Geestrand und ihre Torfe.) VerOff. Geobotan. Inst. E.T.H., Ziirich, 37: 100-119. GROSSE-BRAUCKMANN, G., 1967. Ober die Artenzusammensetzung einiger nordwestdeutsche Torfe. In: Pflanzensoziologie und Palynologie. Ber. Intern. Syrup. Stolzenau/Weser, 1962, pp. 160-I 80. JANSSEN, C. R., 1959. Alnus as a disturbing factor in pollen diagrams. Acta Botan. Necrl., 8: 55-58. JANSSEN, C. R., 1966. Recent pollen spectra from the deciduous and coniferous-deciduous forest of northeastern Minnesota: a study in pollen dispersal. Ecology, 47(5): 804--825. MENKE, B., 1968. Ein Beitrag zur pflanzensoziologischen Auswertung yon Pollendiagrammen, zur Kenntnis friiher Pflanzengesellschaften in den Marschenrandgebieten der schleswigholsteinischen Westkiiste und zur Anwendung auf die Frage der Kiistenentwicklung. Mitt. Flor. Soz. Arbeitsgem., N.F., 13: 195-224. RYBNi(~KOV~, E., 1966. Pollen-analytical reconstruction of vegetation in the upper regions of the Orlick6 hory Mountains, Czechoslovakia. Folia Geobotan. Phytotaxon. Bohemoslov., 1(4): 289-310. RYBNi(~KOV,~, E., 1969. Die Entwicklungsgeschichte der W~ilder aufder B6hmisch-M~hrischen H6he im Sp~it- und Postglazial. Mitt. Ostalp.-dinar. Sekt. Intern. Verein. Vegetationskunde, 10(2): 64-69. To~,I,A, S., JASNOWSKI,M. und PALCZV~SKLA., 1967. System der genetischen Klassifizierung der Torfe Mitteleuropas. Zesz. Problem. Post~p. Nauk Rolniez., 76: 9-99.
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Rev. Palaeobotan. Palynol., 11 (1971) 165-176