University of Groningen
An ecological characterization of plant macro-remains of Heveskesklooster (the
Netherlands)
Cappers, Reinier
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Publication date:
1994
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Citation for published version (APA):
Cappers, R. T. J. (1994). An ecological characterization of plant macro-remains of Heveskesklooster (the
Netherlands): A methodological approach Groningen: s.n.
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Summary
This thesisdealswith the archaeobotanical
analysisof soil samplesof the Heveskesklooster
terp
(provinceof Groningen,the Netherlands).It is characterizedby a methodologicalapproach,in
which additional studieswere done that are helpful for the ecologicalinterpretation of the
records.
When interpreting subfbssilplant remains from soil samples,several processesthat affect
the ultimatecompositionof the subfossilrecordshaveto be taken into account.Theseprocesses.
together with the structuresthat are influenced, are incorporated in a palaeoecologicalmodel.
Centralstructuralconceptsin this model are: ( I ) vegetationand accompanying
environment.(2)
soil flora, (3) subfossilassemblage
and (4) subfossilrecords.This approachhasbeen elaborated
in chapter 1.
An ecologicalcharacterizationof the Dutch Holocene palaeobotanicalrecordshas been
performed and compared with the recent Dutch flora present in c. 1850,to determine the
representativeness
of subfossilrecordsas to various ecologicalvariables.A total of over one
third of the recent Dutch flora is representedby subfossil macro-remains,excluding records
basedon pollen or wood only. If eachspeciesis assignedto only one ecologicalgroup,it appears
that in particular plants indicative of ruderal places,arable fields, dry underwood, fresh water
and banks are well representedin the subfossilrecords.Speciesgrowing in woods, dry grasslands
and on walls are underrepresented.It provesthat the type of preservationmakes little difference
to the representationon this level of analysis.A more detailedanalysisof representativeness
is
obtained if ecologicalranges in indicator values are taken into account. It shows that the
distribution of speciesas to both abiotic environmentalcharacteristicsand the structureof
vegetation and successionis determined by the type of preservation,feature type and species
frequency.
In additionto indicatorvalues,a number of selectindicatorspeciescan also be usedin the
ecological characterizationof a flora. Groups of indicator plants have been compiled for the
(1) salinity,(2) moistureregime,(3) nutrient availabilityand
following (a)bioticcharacteristics:
(a) the structureof vegetationand the stage of succession.
Selectioncriteria are adaptedto
palaeobotanicalresearch.Taxon weights are assignedto indicator plants and expressthe
possibility of recovery in an archaeologicalcontext. These weights are based on sample
frequencyin the Dutch palaeobotanicalrecords and are calculatedaccordingto the type of
preservation.
The analysisof drift litter collectedon river beachesand the North Seacoastrevealedthat
flowing water is an import dispersalagent of plant remains.Seedsof waterplantsespecially
adapted to water dispersalmake up only a minor part of the total assemblage,
due to the
submergedcondition in which most of the plant remainsare transported.Speciesin the drilt
litter show that they originate from a wide variety of habitats.Running water is therefore
consideredto be a vital link in long-distancedispersal.The botanicalcompositionof samples
from the west coast is mainly determinedby rivers that flow into the North Sea, in which
transportof sewageplays an important role. On the other hand,plantsfrom local salt marshes
and high tidal flats are well representedin drift litter along the northern part of the coast.
In addition to wild plant species,cultivatedplants are representedin drift litter as well.
Remains of these speciespartly originate from refuse and sewage and partly from standing
vegetation. Subfossiland fossil plant remains are also found in drift litter and originate from
older sedimentsdissectedby flowing water.
Therefore, in the interpretation of seed records from sediments that may have been in
contactwith flowing water, long-distance
dispersalby water has to be taken into account.This
183
also appliesto lcrps. that werc in contactwith watcr cluringstorm surgesuntil late medieval
timcs.Drift litter clepositcdon the slopesol tcrps will alsclincludeplant rcmainswashedaway
from the inundatedsoil.
are frequentlyI'oundand would
Subfossilendocarpsof mernbersof thc Potarnogetonaceae
be a major contributiontowardsan ccologicalintcrprctation.To improve futurc idcntifications
of these remains that arc difïicult to detcrminc. a morphologicalanalysiswas pcrformed on
cndocarpsfrom recentclriit litter and on a WcichsclianPleniglacialdeposit.A total of scvcnteen
specieswere establishcdancl are documcntcdby SEM photographsand descriptionsof their
characteristic
fcaturcs.
The frequent prcscnccof subfossilendocarpsol Potumogelo,gavc rcasonsto re-examine
thc cndocarpsof Dutch dwelling mounds.Onc cnclocarpof P. filiformis was lirund iimong the
unidentiÍledendocarpsof the Ouddorp terp (provinceof Zeeland).This cviclencc inclicatcsthe
possibilitythat in thc past drift litter was depositcclon the slopesof terps.
The habitation oÍ' thc Hcveskeskloosterterp. which was called 'Oostcrwicrum' until the
n i n e t e c n t hc e n t u r y .i s s u b c l i v i d eidn f o u r p e r i o c l s(:l ) c . 5 0 B C - c . 4 0 0 A D . ( 2 ) c . 8 ( X )- c . 1 3 0 0 .
( 3 ) c . 1 3 0 0- 1 6 1 0a n c l( z l ) l 6 l 0 - 1 9 1 5 T
. h e p r c s c n c co f a s m a l lt e r p f r o m t h c v c r v b c g i n n i n go f
habitationand scclirncrrtarv
recordsindicatemoist conclitions.Written sourcesrcport floodings
which frcquentlyaffectcdthc areauntil the enclol'thc thirclhabitationperiod. Farmhouseswere
presenton the terp cluringthe first. secondand last pcriod. Archaeologicalcxcavationshowed
for the first time the prcscnccof agriculturalland on thc terp proper, calleclvalg(c).During the
at Hcvcskcsklooster.
third habitationpcrioclzrcommanderyof the Johannitcrordcr wasfounclecl
yiclded many botanicalremains.With thc exceptionof
The samplesof Heveskesklooster
one sample.most rcmainswerc preservedby watcrlogging.As to the vascularplants,species
compositionwas mairrly dcterminedby age (pcriocl).feature type ancl depth. Environmental
could be demonstratcdfor the
changes.rellectcclby a shilt in speciescompositionoÍ'thc sarnplcs,
transitionof: (1) thc sccondand third periodsancl(2) thc third and last periocls.though there
were a limited nurnber of samplesof the last pcriod. Thcrc was no clear inclicationof the
presenceof drilt littcr nraterialin the cxaminedsarrrples.
However.spccicscompositionof the
samplesdo indicatea mix of speciesof differcnt origins.includingthe supply I'r'ombeyond the
terp.
During all iour perioclsol habitation,both halophytic and glycophyticspccicsarc well
There is a slight decreaseoï halophytcsin favour of glycophytcsin the courseof
representecl.
time. Salt-marshvcgctationsof the first pcrioclhavc been treated in detail. PlantsindicativeoI
moist and wet conditior.rs
dominatein all lour habitationperiods,but the thircland fclurthperiods
show a clear increascin the number of plants indicative of dry condilions.As to nutrient
availability.all four pcriodsarc representedby specicsindicatingpoor. moderatcand rich soils.
and there is cvidcncc ol' an increaseof taxa indicatingmoderate soils from thc first period
and pionecr vegetation.This
onwards.Dominant vcgctationtypesfor all pcriodsare grasslands
picture fits in quitc well with the characterization
ol'other terps along thc Dutch and German
coasts.Heveskeskloostcr
standsout by indicator taxa lor salineconditions.Classcso[ moisture
regimcsand nutrient availabilityare also relativelywcll rcpresented.
The ecologicalcharacterizationof the habitation periods partly overlap at the level of
individual szunplcs.Some diÍferentiationis possibleby classifyingsamplcsas 1o location and
featuretype.
Important agriculturalplantscultivatedby tl.rcterp dwellersare:Hortlcttm vulgore(in the
third period alsossp.distir'ltun),Avena sativu.Linttm usitutissimtrm.
Camelitrusutivu.Viciu.faba
var.ntínor and probablyalso Brnssicarapa and Cuttttubissí?1i
vd. Thesecropsarc alsornentioned
i n c o n n e c t i o nw i t h o t h e r D u t c h t e r p s .S z r m p l cosl ' t h e t h i r d h a b i t a t i o np c r i o c l s h o wt h e h i s h e s t
diversity.
184
The
inferred
ntelegu
cxceptl
econom
tcrps.is
Inz
The exa
belon-q
Pltruem
o[ thetc
San
common
nowada
m o s s c s(
grow on
for the p
tvt{ilus 5\'
Asi
are indic
characte
MOSSCS C
clcarly d
p l a n t so Í
plants oÍ
vascula
Ínosses
Heveske
nutricnt
s u p p l v .v
vascular
low nutri
plantso1
grasslan
Compari
selectio
lesuntil late medieval
remainswashedawaY
entlyfound and would
e future identifications
lsiswasperformed on
it. A totalof seventeen
of their
d descriptions
to re-examine
reasons
i wasfound among the
indicatesthe
r evidence
s.
losterwierum'
until the
\D. (2) c. 800- c. 1300,
n the verybeginningof
ourcesreportfloodings
:riod.Farmhouseswere
licalexcavationshowed
lledvalg(e).During the
ed at Heveskesklooster.
. With the exceptionof
vascularplants,species
I depth.Environmental
for the
bedemonstrated
;t periods.thoughthere
clear indication of the
:ciescompositionof the
;upplyfrom beyond the
rphyticspeciesare well
rphytesin the course of
tail.Plantsindicativeof
third andfourth periods
rditions.As to nutrient
moderateand rich soils.
ls from the first Pcriod
pioneervegetation.This
t h e D u t c ha n d G e r m a n
of moisture
ons.Classes
The presenceof the Johanniterorder in Heveskesklooster
during the third period is also
inferred from the increase of other economically important plants, of which Aframomum
meleguetashould be mentioned. Of other plants of this category,Isatis tinctoria constitutes an
exception, for it was found only in samples of the first habitation period. The diversity of
economicallyimportant plants in Heveskesklooster
is high and, compared with other Dutch
terps,is equalledby the Leeuwardenterps only.
In addition to the analysisof macro-remains,also palynologicalresearchwas performed.
The examined section comprisesthe upper part of the basal peat (BP) and the clay layers
belonging to Dunkerque I (D1-B 1a,c) and Dunkerque ll (Dll), intercalated by a
Phragmites/Scirpus
horizon (Dl-B 1b) and two vegetationhorizons (VH-1,2), and the lower part
of the terp belongingto the secondhabitationperiod.
yielded43 differenttaxa of mosses.It is shown that the more
Samplesof Heveskesklooster
commonspeciesare still presentin the area,whereasthe lessfrequentlyencounteredspeciesare
nowadaysrare or lacking in the north-easternpart of the Netherlands.In contrastwith recent
mossesof Heveskesklooster
and its near surroundings,subfossilmossesof this site that do not
grow on soil are scarceas a category.The analysisof seeds,fruits and leavesprovidesevidence
for the presenceof the following trees:Benila spp.,Salir viminalis,Queruts sp.,Sambucusnigra.
Malus sylvestrisand Prttnus domestica.Usually, these trees have a poor epiphytic moss flora.
As far as the mossesof Heveskesklooster
with a smallecologicalrangeare concerned,they
are indicative of fresh water, moist and poor soils and pioneer vegetation.Generally, this
characterizationcorrespondswith subfossilmossesof other terps. The ecological spectrum of
mossesof Heveskeskloosterdiffers only slightly from recent mossesin the Netherlands, but is
clearly distinguishable
from subfossilvascularplants of Heveskesklooster
and recent vascular
plants of the Netherlands.Halophytic mossesare rare, whereassubfossilhalophytic vascular
plants of Heveskeskloosterare well representedin comparisonwith the spectrum of recent
vascular plants. A similar shift is shown in waterplants.This category is rarely represented in
mosses,whereas they are relatively well representedin the subfossilvascular plants of
Heveskesklooster.
A noticeablediÍferencebetween mossesand vascularplants is shown rn
nutrient availability. Both subfossil and recent mossesare mostly indicative of low nutrient
supply, whereas vascularplants are not. This is strengthenedby the spectrum of subfossil
vascularplants,showingclearly that high nutrient supplyis overrepresented
at the expenseof
low nutrient supply.As to structureof vegetationand succession,
subfossilmossesand vascular
plants of Heveskesklooster are quite similar, for they both are indicative of particularly
grasslands
and pioneervegetation.Despitethis similarity,vascularplant representmore classes.
Comparing thesefour groups,it is manifestthat the ecologicalinterpretation is influenced by the
selectionof plants and the information derived from groups used as a frame of reference.
overlapat the level of
rplesas to location and
Tordeumvulgare(in the
'melinasutivn.Viciu .fuhu
: r o p sa r ea l s om e n t i o n e d
reriodsshow the highest
185