D71IJ Seed dispersal by cattle
The importance of endozoochory by cattle for the establishment of
heathiand and oligotrophic grassland species.
Student report P.G. Vos
Supervisors: Drs. H.M.C. Verhagen Drs. A.M. Mouissie Prof. dr. J.P.
Bakker
Lab. v. Plantenoecologie RUG, Haren, 2001
Pijksijniversitejt Grorqcr Bibliotheek Biologisch Cenr'ji Kerklaan
30 — Poshus 1 4
9750 AA HAPEN Photo front page: Scottish Highland cattle, resting
under oak trees. © A.M. Mouissie
1
This report discusses the endozoochorous seed dispersal by cattle
(Scottish Highland cattle) in
two study sites. The study sites consist of oligotrophic grassland,
heathiand and former arable
fields. EndozoochorOUs seed dispersal may play an important role in
the development of
oligotrophic grassland and heath on these former arable
fields.
The study sites have been divided in different area parts. In each
area part plots of 20 by 20 m
were created. In these plots vegetation was recorded, seed supply
was determined and the
number of dung pats was counted. Seed that survived the passage
through the cattle was
determined in the greenhouse. Also germination on field dung pats
was determined.
Target species form a small part of the seed supply in both study
sites. Selectivity of cattle in
terrain use determined the seed intake. The species dominant in
seed intake could be
determined by hand clipping in the grazing area. High number of
dung pats was found on the
mesotrophic grassland in both study sites and on the heathland in
Delleburen. Cattle avoided
the oligotrophic grassland in Delleburen. In Hullenzand the
Molinia-stands and the heathland
were avoided.
Many species of heathland and oligotrophic grassland are dispersed
by cattle dung. The
species dispersed most are Poa trivialis, P. annua, P. pratensis,
CerastiumfontaflUm and
Juncus species. In the field less seedlings germinated than in the
greenhouse. A number of
target species germinated on field dung pats. Most species
appearing on a field dung pat were
locally new.
Sterilising by heating of cattle dung killed almost all seeds but
also altered the structure of the
dung. Sterilised dung pats were used to examine the amount of seeds
blown in by the wind.
With sterilised dung pats it was shown that Rumex acetosella was
blown in.
EndozoochorouS dispersal by cattle is of little importance for the
dispersal of plant species of
heathland and oligotrophic grassland communities. It is discussed
that germination conditions
are very important in determining the importance of endozoochorous
dispersal for
establishment.
2
I
Contents
Endozoochorous seed dispersal 4
Methods 8
Terrain use of cattle and distribution of cattle dung 10
Potential seed intake 11
Blow in control 11
Colonisation of dung pats in the field 15
Blow in control 18
Discussion 22
Germination 23
3 Vegetation relevés September Delleburen 35
4 Mean number of seeds per inflorescence 37
5 Mean number of inflorescences 37
6 Number of seeds in the hand clippings 40
7 Mean number of seeds per liter dung 41
8 Mean number of dung pats per count date 42
3
Introduction
Dispersal of plant seeds Seed plants are sessile, and have a
limited ability for self-ppulsion. Successful colonisation of new
sites is therefor dependent upon arrival of seeds. There are
significant advantages for plants bearing traits that increase the
probability of successful dispersal. Seeds falling beneath the
parent plant are faced with competition for resources with their
parent, such as higher levels of density dependent seed predation
or higher densities of competing siblings with the associated
epidemiological problems associated with high densities such as
fungal or viral transmission among individuals (Stiles 1992). Seed
dispersal is the movement of seeds away from the parent plant. The
number of seeds dispersed is first determined by the seed output of
a plant species (Nathan & Muller Landau 2000). Dispersal is a
spatial process, but survival of seeds in a soil seed bank can be
entitled as dispersal in time (Willson 1992).
The spatial distribution of seeds around their source is called a
'seed shadow' (Janzen 1971). The term is most commonly used in
reference to the post-dispersal distribution of seeds around the
maternal parent, but it can also be used to refer to the
distribution of seeds around a source composed of multiple parents.
The unit of dispersal may be technically a fruit or a group of
fruits and the generic label should therefore be diaspore or
propagule (Willson 1992). The term of seed shadow may also be used
to include all diaspores of any morphological and genetic
derivation (Willson 1992) and it is also entitled as a seed-
dispersion pattern (Nathan & Muller-Landau 2000).
Plant seeds can be dispersed in many ways. Wind dispersal occurs in
almost all species. Water, man, machines and animals are dispersal
agents too (Bakker et al. 1996). For many plant species, animals
provide the means for the critical mobile stage in the plant's life
history (Stiles 1992). Specific feeding habits, territorial and
migration habits as well as the possibility of epi-, endo and
dysozoochory complicate the possible seed-dispersion patterns by
zoochory (Harper 1977). Exo- or epizoochory means animals transport
seeds in their fur or hoofs. Diaspores can also be constituent of
the diet and they are dispersed endo-or dysozoochorically.
Dysozoochory means that seeds are transported to particular places
to be eaten or to be stored (Bonn & Poschlod 1998).
Endozoochory means that seeds are taken in with the food and
excreted with the faeces. In most cases animals are predators and
dispersers at the same time. Losses of seed and germination ability
should be seen as the price for endo- and dysozoochory (Janzen
1971). Janzen (1984) postulated the Foliage-as-Fruit-hypothesis:
seed dispersal through consumption of the seeds by large herbivores
while they are eating the foliage of the parents plants is a normal
and selected dispersal mode for a number of species of small-seeded
herbaceous plants. This means that this group of plant species has
been adapted to seed dispersal by large herbivores.
Endozoochorous seed dispersal This study focuses on endozoochorous
seed dispersal. The potential range of spreading is determined by
the seed supply, the feeding habits of the animal species and the
survival of seeds through the gut. Also dispersal distance depends
on retention time and range of action of a particular animal
species (Bonn & Poschlod 1998). Malo & Suárez (1995b)
studied endozoochory over a whole season. They found that
endozoochory seems to be mainly determined by seed production of
the plant community. It was not dependent on herbivore species.
This may be true for the whole season, while much variation is
levelled out. But selectivity of cattle in seed intake may be
expected from their specific feeding habits. Plant communities
differ in structure and species composition and plant palatability
and may therefore differ in attractiveness to herbivores. Wallis De
Vries (1994) found that cattle discriminate between and within
different plant communities. Cattle preferred riverine grassland
above heathland. Within plant communities cattle preferred short
and leafy patches above tall and stemmy patches. Moreover cattle
took more bites at leafy patches than patches with much heath. Van
Rees (1984) found that cattle were highly selective in their
dietary
4
preferences and concentrated on a relatively small number of
species. Diet selection in grassland and heathiand communities was
very similar (WallisDe Vries 1994).
Photo 1. Cattle resting in a Molinia stand in the shadow of trees.
© Drs. H.M.C. Verhagen, and also the remaining photos.
Behaviour is not only determined by the presence of food. It is
also strongly influenced by the time of the day. Numerous studies
have shown an intensive grazing period starting around sunrise,
followed by a resting period around noon, followed by another
intensive grazing period at late afternoon, which lasts till just
after sunset. Cattle can graze during night when they have consumed
little food during daytime (Van Rees 1984).
The potential range of seed dispersal by endozoochory is also
determined by the resistance of particular species against the
process of chewing and gut passage (Russi et a!. 1992, Gardener et
a!. 1993). The influence that a particular animal species may have
on this process is by means of for example the chewing habits, the
way of digestion and the retention time. Some diaspore
characteristics are related with endozoochory, for example size and
hardness of the seed coat. Survival of legume seeds, both in the
digestive tract and outside in the dung was largely dependent on
the fraction of hard or impermeable seed in the sample (Gardener
eta!. 1993). Gardener eta!. (1993) showed that soft seeds swelled
on imbibition, the seed coat ruptured, and seeds became fragmented
especially after 70 h in the digestive tract. Legume seeds survive
passage through the digestive tract better than grass seeds
(Gardener eta!. 1993). However digestion by animals may also have a
positive effect by enhancing germination by scarifying seeds in the
gut (Howe & Smallwood 1982). Ingestion reduced hardseededness,
so that a greater proportion of the seeds was capable of
germinating after ingestion (Russi eta!. 1992). Gut passage is a
selective process because species differ for the properties
mentioned above.
An important aspect of endozoochorous seed dispersal, influencing
post-dispersal processes may be the gap formation by dung
deposition. A 350 kg cow voids ca 34 kg of faeces (5-6 kg dry
weight) and covers ca 0.75 m2 of ground each day (MacLusky, 1960 in
Harper 1977). A large faecal dropping represents a disaster for the
plants beneath and around it. The effects are at least fourfold:
(1) smothering and exclusion of light from the plants; (2) a local
disturbance of the nutrient relations of the pasture which may
extend beyond the faecal pat; (3) changes in the pattern of grazing
around the pat which animals tend to avoid; and (4) the creation of
an island for colonisation (Harper 1977) (Photo 2-5). Dung pat gaps
must be recolonised from propagules already present in the soil, in
the manure, or from propagules that arrive subsequently. The
success of plants and seeds situated underneath the dung is related
to their resistance to toxic effects from the fresh faeces and the
ability to penetrate the pats (Welch 1985). Weeda (1967 in Van Rees
1984) found in his study site that formation of
5
a hard crust on the cow pat, and consistency of the dung influenced
the rate of disappearance of cow pats. The relatively fibrous
nature of alpine vegetation ensures that cattle faeces are
deposited as solid masses, which because of the thy atmosphere,
rapidly dry out with the formation of a thick hard crust (Van Rees
1984). On the salt marsh of Schiermonnikoog decaying of dung pats
varied from 3 weeks to more than 30 weeks (De Boer 1974). The
photos 2-5 show different stadia from the decay of cattle dung pats
in Hullenzand.
Dispersed seeds defecated in a viable state by the herbivore can
play an important role in the recolonisation of these gaps, since
they are closer to the surface in the manure than seeds in the soil
seed bank (Malo & Suárez 1995a). Pakeman eta!. (1999) found
that three of the four most common species in rabbit pellets
established better under field circumstances than most other
species that were found in the pellets.
6
Photo 2. Freshly deposited cattle dung.
Photo 3. A. Cattle dung pat with many holes made by little dung
beetles or other insects. B. Cattle dung pat with a hard crust and
tracks of dung beetle activities on the right.
Photo 4 A, B, C. Old, trampled, dried out dung pats.
The importance of endozoochory Nowadays many agricultural soils
become available for nature development. In many of these sites
topsoil is removed to create the appropriate abiotic conditions for
restoration of heathland and species-rich grassland. However with
topsoil removal, the vegetation is removed and also a large part of
the seeds in the soil are often removed too. This means that these
sites must be colonised by seed dispersal. The impact of wind is
probably small. Windtunnel experiments with 22 species of pasture
and heath made clear that wind dispersal occurs on a scale of a few
meters (Zijlstra 1992). Strykstra eta!. (1998) showed this with a
windtunnel experiment in particular for the rare wind-dispersed
Arnica montana. Klooker et a!. (1999) found with seed traps that
90% of the seeds originated from within 2 meters of the seed trap.
Therefore it has been hypothesised that invasion of target species
can be stimulated by fencing the nature development site together
with source sites and graze them by different types of herbivores
(Klooker eta!. 1999). De Smidt & Heil (2000) showed in a
comparison of grazed with ungrazed sites a positive effect of
grazing by cattle on spread and establishment of characteristic
heathland species. These species were mostly mosses and epizoochory
may be responsible for this.
Dispersal is a very important process for the colonisation of
nature development sites. Cattle ingest numerous seeds and many of
these seeds survive the digestive tract. Hansen (1911, in Harper
1977) recorded that a cow grazing on a weedy field consumed in one
day 89.000 seeds of Planrago spp. and 564.000 seeds of Matricaria
chamomilla of which 85.000 and 198.000 respectively were voided at
58% and 27% germination capacity. In many nature conservation and
restoration sites grazing is used as a management tool. Cattle can
therefor act as dispersal agents in a nature development site when
this site is fenced in with source sites. Selectivity in terrain
use, feeding habits and survival of plant seeds in the digestive
tract affect the success of dispersal by cattle for nature
development.
In the present study the importance of endozoochory by cattle for
the establishment of plant species of heathland and oligotrophic
grassland plant communities is investigated. Therefore (1) a
comparison has been made between the potential intake of seeds and
the potential dispersal. The potential intake is measured as the
number of seeds that is present in the area. The potential
dispersal is the number of seeds that survive the digestive tract.
Therefor dung has been sampled from cattle, horses and sheep and
brought in a greenhouse. (2) Terrain use of cattle has been
determined by measuring the number of dung pats in different area
parts. (3) Colonisation of dung pats by vegetative shoots and
seedlings in the field has been recorded. Special attention has
been paid to the dispersal and establishment of characteristic
species of heathland and oligotrophic grassland vegetation on the
nature development sites, further referred to as target species
(Appendix 1).
7
Photo 5 A, B. Old dung pats, probably under moister conditions,
become vegetated.
Methods
Study sites The study is carried out in two sites, Delleburen and
Hullenzand. Delleburen and Hullenzand have been selected because
part of the sites is nature development site, part harbours
oligotrophic and mesotrophic plant communities and the sites are
both grazed by cattle.
Delleburen The Dellebuursterheide (200 ha) is situated in
east-Friesland (20 km east of Heerenveen) (Amersfoort coordinates
205/206, 552/553), and is a remnant of extensive heathlands along
the Tjonger. The study site consists of the Delleboeren (heathland,
bog and forest), the Hoorn (river dunes), former arable field of
which topsoil is removed (25 ha) and several pastures (Klooker
eta!. 1999). Almost the whole site (180 ha) is grazed year-round
since 1979 by livestock. Numbers fluctuate (Jager 1999). During the
study period the site was grazed by 13 Scottish Highland cattle, 18
Exmoor pony's and about 30 Drentse-Heide-sheep (this number became
about 60 in November).
Fig. 1. The study site Delleburen. The left part is the
oligotrophic grassland (0), the middle part is the heathiand and on
the right lies the nature development site (N). Further F= forest,
M= mesotrophic grassland, W= water. The north is at the top of the
chart.
8
Hullenzand Hullenzand (80 ha) is situated in south Drenthe (10 km
south east of Beilen) (Amersfoort coordinates 235, 533). It is a
remnant of extensive heathlands. It harbours dry and wet heathiand
communities with some oligotrophic grassland and drift sand
communities and agricultural fields that lie fallow from which 1.5
ha topsoil is removed (Klooker eta!. 1999). Ten (7 adults, 3
calves) Scottish Highlander cattle graze the site year-round. The
site has been enlarged with a large (60-70 ha) former agricultural
field from which topsoil is removed in 1998 and 1999. This part has
almost no vegetation cover. Cattle were sometimes seen resting
there.
Selection of area parts Each site is classified in different area
parts. The following criteria were used to select the area parts:
the proportion of the total site, relevance for nature development,
difference in structure and plant composition, and not too many
diverse area parts. Table I shows the classification for Delleburen
and Hullenzand. These figures are used as base for further
calculation in this study. In some area parts no dung plots were
placed. In the Molinia stands of Delleburen for example no plots
were established, as these parts are not easily accessible because
of the many tussocks and therefor also not attractive to cattle.
Further dung could not be counted in this area part because of
shallow water.
9
Fig. 2. The study site Hullenzand. The left and top part of the
chart are former arable field (X). Further Z=sanddunes,
C=Calluna-vegetation, K=Empetrum-vegetation, M=Molinia-stand,
D=Deschampsia- vegetation, O=young trees, B=Wood, T=deforested
sanddunes, W=water. The north is at the top of the chart.
Tabel 1. Surface area in hectares and the number of dung plots per
area part, for Delleburen (A) and Hullenzand (B). A) Delleburen
Area part Area (ha) N plots
Nature development site (1) 25* 10
Molinia/bog community 20** 0
Mesotrophic grassland Hoorn (2) 36** 0
Other mesotrophic grassland 9** 5
Heathland (3) 20** 10
*Klookeretaj 1999 ** Computed from chart Jager 1999
Jager 1999
Grassland (2) 7.5 7
Forest 6* 0 Fen community (1) 1.5** I
Molinia stand (5) 7* 7
Heathland (3) 2.5* 7
Sand dunes / heath 25.5* 0
Total site 80** 29 * Computed from chart Natuurmonumenten 1994 * *
Klooker et al. 1999, also derived from Wolters-Noordhoff
Atlasprodukties (1987) Grote
topografische atlas van Nederland deel 2 Groningen
Terrain use and distribution of cattle dung The distribution of
cattle in the study site's was determined in two ways: by direct
observation and indirect by counting dung pats in the different
area parts. The indirect method means that distribution of dung was
measured using 20 by 20 m. plots, further referred to as dung
plots. These dung plots were laid out at random in each area part.
Bamboo sticks in every edge defined a plot. In Delleburen 36 plots
were established and in Hullenzand 29 plots. Counting occurred once
every three to four weeks. Dung pats were counted 7 times in
Delleburen and 6 times in Hullenzand from July till December.
Double counting was prevented with paint-marking. At different
count dates different colours of paint were used, so dung pats of
different ages could be identified later. Results of the first
count date are not used for calculation, because densities may be
biased by different decay rates. These are for example greater in
pasture than in heathiand (Bakker et al. 1983). Direct observations
were done mainly when the site was visited. Direct observation
means that location and activity of the cattle in the site was
noted when fieldwork was done. This occurred 2 to 3 times on a
field day. These observations were done to control/correct the
results of the indirect method. Additional information could be
obtained from the position of fresh dung, tracks etc. Two days
before sampling of cattle dung, cattle were observed to know the
foraging site to make it possible to relate this knowledge to the
seed content of the dung. These observations have only taken place
for Hullenzand in July, for the other sample dates this was not
possible.
10
Potential seed intake Seed supply was measured once in July and
once in October. Seed supply was determined in plots of 0.25 m2 of
patches that differed in structure and plant composition. All stems
bearing seeds were counted within these plots. Three of these
relevés were done per dung plot (a plot of 20 by 20 m, see under
terrain use. For almost all species with seed, seed content of the
stems was determined. This was done once in July and once in
October in both study sites. From these data the absolute seed
supply of the dung plots could be computed.
Vegetation relevés were made in July per dung plot to correct for
species that were not found with the seed supply estimation. With
this method it was noted if a species was dominant (d), if it had
seed (z) and if it was flowering (b). In September, for all species
abundancy was noted according to the Tansley scale (Tansley 1946) :
D= dominant A= abundant F= frequent 0= occasional R= rare.
The absolute seed supply may be no good estimator for seed intake
by cattle. When bites are simulated this may be a better estimator
for the seed intake by cattle. Therefor seed intake per bite was
estimated by plucking vegetation low to the ground by hand,
according to the method described by Wallis De Vries (1994). 25
bites were simulated for each area part (five sample plots with
five bites per sample plot). This was only done two days before
dung collection. In July it was done only once in the Hullenzand
study site and in October it was done once in Delleburen. In
combination with direct observations this may be a good estimation
of seed intake.
Potential dispersal To detect which species can be dispersed by
endozoochory, seed content of dung can be measured. Seeds that have
been swallowed and survived the chewing and gut passage can be
determined by germinating them in the greenhouse. Twelve to fifteen
freshly deposited cattle dung samples (total 10 1.) from different
dung pats was collected once in July and once in October in each
study site. After collection dung was stratified two weeks at four
degrees Celsius. After stratification dung was homogenised by
washing on a sieve and spread on trays with sterile sand and soil.
Seedlings occurring in the dung were identified and alter that
removed. Plants becoming so large as to obscure or prevent
germination of other seeds were removed; if not positively
identified they were grown separately until identification was
possible. July dung was determined till 10 January 2001 (five
months). Only July dung samples and seed supply is used in the
analyses presented in this report, because data of cattle dung
collected in October are presently incomplete.
Colonisation of cattle dung A number of fresh dung pats in the
Delleburen area were marked in July (14-07-00). They were marked
with flags in the nature development site (n=8) and in the
mesotrophic grassland (n=7). These dung pats were examined in
August and December. Dung pats that were marked with paint when
counting dung (from the first three count dates) were examined in
Delleburen in September. Observed dung pats were located in the
nature development site (n=17), heathland (n=16) and oligotrophic
grassland (n=5). The age of these dung pats ranged from 1 to 3.5
months after dung voiding. The number of colonisers (germination
and vegetative in growth) and amount of bare dung were noted on
these dung pats.
Blow in control Seedlings that germinate on cattle dung do not
necessarily originate from that cattle dung. They may be blown in
by wind or otherwise have been dispersed to the dung pat. To
determine if seedlings are originating from the dung two methods
were used. The first method assumes that only seeds of the
surrounding vegetation blow in. Most seeds fall within 30 cm from
the parent plants (Klooker eta!. 1999). Species than can be assumed
to be dispersed from elsewhere through cattle, if they are found on
the dung and not in the vegetation 30 cm around the dung pat.
Therefor vegetation in a circle of 30 cm around the dung pats was
determined.
11
The second method is more direct. When seedless dung pats are put
next to normal dung pats seed blow in can be determined directly
and distinguished from dispersal by cattle dung. The biggest
problem with making dung seedless is to prevent loss of dung
structure. Freezing till 80 degrees is effective in killing seeds,
but the structure of cattle dung is lost and pats decompose faster
in the field (pers. comm. J.P. Bakker). In the present study
heating dung till 80 degrees was used to kill the seeds
inside.
An extra sample of fresh cattle dung (ill) was collected for
sterilisation of dung in Delleburen in July (14-07-00). This dung
from different dung pats was diluted to 12 liters, mixed and
homogenised. Mixing was done by hand in a bucket. 3 x 1 liter dung
were stratified for two weeks, washed and then spread on sterile
soil in the greenhouse to determine seed content. 6 liters of dung
were sterilised by drying at 80 °C for three days. 3 x 1 liter of
sterilised dung was spread on soil in the greenhouse to determine
the effectiveness of killing seeds by drying. 3 x 1 liter of
sterilised dung and 3 x 1 liter that were neither sterilised nor
stratified were spread within a 15.1-cm diameter PVC ring on the
nature development site in Delleburen. This resulted in a pat that
had the same shape and thickness as natural dung pats.
Table 2: Overview of the blow in control experiment. Eleven liters
dung were sampled and mixed. To enable mixing, the dung was diluted
with water to twelve liters. The mixed dung was divided in twelve
portions of 1 liter. Three portions were stratified, three portions
were stored, and six portions were sterilised. three sterilised
portions were brought to the field, and 3 sterilised Dortions in
the greenhouse.
Sampling Mixing 21-7 Treatment Purpose 14-7 Dung -Dung mixed, 3 x 1
I. stratified 25-7 till 14-8, to Determine seed content sampled
-diluted to 12
liters, -divided in 12 portions
greenhouse 3 x 11. stored till 1-8, to field
6 x 1 I. sterilised 3 x 1 I. 1-8, to 29-7 till 31-7 field
3 x I I. cooled till 14/8, to greenhouse
Determine germination in the field Determine blow in of seed in the
field Control for sterilisation success
Data analyses The potential intake of seeds has been compared with
potential seed dispersal in two ways. Seed supply in July was
compared with seed germination in the greenhouse dung of July by
means of a Spearman's rank correlation. Because seed supply and
seed germination in the greenhouse were not identical samples, data
could not be tested for species separately. Data for species are
shown qualitatively. Direct observations in combination with hand
clippings were compared with greenhouse germination with a
Spearman's rank correlation, also.
Terrain use of cattle was tested for randomness with correction for
the different sizes of the area parts with a Chi-square test.
Actual numbers of dung per dung plot over the whole season were
tested against an equal number of dung pats per dung plot. With a
Tukey HSD test differences between area parts were tested.
Germination of seedlings in the greenhouse and in the field was
compared with a Spearman's rank correlation. Germination on cattle
dung was compared between dung pats of different ages with a
Spearman's rank correlation. Blow in of seeds was not tested but
shown qualitatively. With a T-test was tested if displacing of dung
within the sterilisation experiment had an effect in comparison
with untreated field dung. Differences between species were tested
with a Kruskall-Wallis-Test. All analyses were carried out with the
package SPSS 9.0
12
Results
Seed supply In Table 3 the percentages of different species in
cattle dung and in the field are shown. The seed presence (seed
supply) in the field and germination from dung pats in the
greenhouse are not correlated. This means that the species
producing the highest number of seeds in the field are not the
dominant species germinating in the dung in the greenhouse. For
Delleburen seeds in the cattle dung are mainly of Poa trivialis,
Alopecurus genicularus, Cerastiumfontanum, Juncus bulbosus,
Ranunculus repens (Table 3A). In the field seed supply is dominated
by Erica tetralix, Agrostis capillaris, Juncus articulatus, Juncus
effusus (Table 3A). For Hullenzand seeds in cattle dung are mainly
of Juncus bufonius, Juncus effusus, Poa trivialis,
Cerastiumfontanum, Juncus bulbosus (Table 3B). In the field seed
supply is dominated by Rumex acetosella, Holcus lanatus, Gnaphalium
uliginosum and Erica tetralix (Table 3B).
Table 3: Percentage of dung seed content in the greenhouse and seed
supply in the field of different plant species. Target species are
bold. No value means a percentage <1. Betula sp. has probably
blown in in the cattle dung.
Dung (green- house)
Cerastiumfontanum vulgare 5
Juncus bulbosus 5
Ranunculus repens 3
Lolium perenne Sagina procunzbens 1
Leontodon autumnalis 1
Rumex acetosella 2
Erica tetralir 10
Agrostis capillaris 11
Juncus articulatus 21
Dung (green- house)
Festuca ovina 2
Gnaphalium uliginosum 5
For Delleburen it is unknown where the cattle were foraging two
days before sampling. Therefore no comparison can be made between
the seed intake of and germination in the greenhouse. For
Hullenzand some observations of grazing cattle have been done and
some hand clippings have been done in this vegetation, but on
different places then where the cattle have grazed. Table 4 shows
the mean number of seedlings per liter dung and the number of seeds
simulated by means of the hand clipping. For Spearman's rank
correlation all sample places got an equal weight because the exact
grazing time on these places was not known. There is a significant
correlation between the seed content of the dung pats in the
greenhouse and the seed supply found by means of hand clippings
(p<O.O5) if all species in the hand clippings and/or in the
cattle dung are included in the analysis. For the species that are
present in both hand clippings and cattle dung there is no
correlation when the other species are
A) Delleburen. B) Hullenzand.
(
omitted. This means that the species found most in the dung in the
greenhouse had the highest number of seeds found by the hand
clippings. Species in the hand clippings are the dominant species
in the dung in the greenhouse (Table 4), except for Juncus
bufonius. This species was not found by means of hand
clipping.
Photo 6. It was not possible to observe the grazing behaviour of
cattle of Hullenzand in high vegetation from a distance, because
they were shy.
Table 4: Mean number of seedlings per liter dung in the greenhouse
and the number of seeds/40 bites simulated by means of the hand
clipping. The second column is the sum of the last four columns and
is used for the test for correlation. The last four columns show
the four sample plots where cattle have been grazing and are shown
to indicate variation among the samples. N is the number of
samples. The Poa sp. is Poa pratensis or Poa trivia us. Target
species are bold.
seeds/I - seeds! 40 bites
N 15 4 5 3 2 1
Juncus bufonius 50
Holcus lanatus 19 8.3 8.3
Trifolium repens 10 33 33
Rumexacetosella 6.3 99 51 48
Epilobium palustre 5.7
Betula sp 2.7
Lolium perenne 1.2 1.1 1.1
Geranium sp. 0.8 Veronica ari'ensis 0.7 Veronica serpyllifolia 0.6
Plantago lanceolaza 0.3 Chamerion angustifolium 0.2 Plantago major
0.2 Sonchus asper 0.2 Cardamine pratensis 0.1
Carexnigra 0.1
14
Distribution of cattle and dung Distribution of dung differs from
randomness for different plots (x2 test, p<O.OO2). Table 5 shows
the numbers of dung pats in different area parts in Delleburen and
Hullenzand. In Delleburen dung density in oligotrophic grassland is
significantly smaller than the dung density in the heathland and
mesotrophic grassland. In Hullenzand the dung density in the
Molinia stand and in the heathland is significantly smaller than in
the deforested sand dunes (Table 5).
Table 5: Mean numbers of dung pats per count date in different area
parts in Delleburen (A) and Hullenzand (B). These results have been
obtained with a Tukey HSD (a0.05) for the number of dung pats in
different area parts over all data. Different letters indicate
significant differences. A) Delleburen
Area part N Mean ± SE
Oligotrophic grassland 77 0.91 ± 0.40 a
Nature development site 70 1.53 ± 0.42 ab Heath 70 2.77 ± 0.42 b
Mesotrophic grassland 35 2.80 ± 0.60 b
B) Hullenzand Area part N Mean ± SE
Molinia vegetation 35 0.17 ± 1.61 a Heath 35 2.34 ± 0.61 a
Mesotrophic grassland 35 2.97 ± 0.61 ab Fen 5 3.40± 0.61 ab
Deforested sanddunes 35 6.00 ±0.61 b
Colonisation of dung pats in the field The identified seedlings on
dung pats in the field have been divided into monocotyles and
dicotyles. The proportion of monocotyles: dicotyles is 7:3 for all
ages of field dung pats. The mean number of seedlings does not
significantly differ between dung pats of different ages
(Kruskall-Wallis). Table 6 shows the species composition for dung
pats of three different ages. Poa annua, P. trivialis and Agrostis
capillaris are the most frequent species germinating on the cattle
dung in the field.
15
Table 6: Mean number of seedlings found on dung pats per species in
Delleburen, September 2000. Percentages are given between brackets.
The colour of the paint that was used with counting and marking of
counted dung could be used to determine roughly the age of the
cattle dung pats. The first two categories do overlap because
marking was done on two days the first time with about a week in
between. Examining dune Dats in Sentember was done in a one-week
period. Target species are bold. age >9 wks 7-11 wks 3-7 wks N
13 14 11
Poa annua 4.3 (32) 1.3 (10) 0.73 (8) Poa trivialis 3.0(22) 4.0 (31)
1.9 (21) Agrostis capilaris 1.4 (10) 3.0 (23) 0.55 (6) Rumex
acetosella 0.68 (5) 0.52 (4) 0.46(5) Ranunculus repens 0.41 (3)
2.34 (18) 0.55 (6) Gnaphalium uliginosum 0.27 (2) 0.13 (1) 0.27 (3)
Cerastiumfontanum 0.14(1) 0.26 (2) 0.27 (3) Molinia caerulea 0.14
(1) 0.52 (4) Stellaria palustris 1.5 (11)
Hypochaeris radicata 0.68 (5) Agrostis stolonifera 0.54 (4)
Agrostis canina 0.14 (1) Deschampsia flexuosa 0.14 (1) Lysimachia
vulgaris 0.14 (1) Taraxacum sp. 0.27 (2) 0.09(1) Alopecurus
geniculatus 0.14 (1) 0.09 (1) Plantago lanceolata 0.78 (6) 0.36 (4)
Holcus lanatus 0.26 (2) 0.36 (4) Lolium perenne 0.27 (3) Festuca
pratensis 0.27 (1) Luzulasp. 0.27(1) Scirpus cespitosa 0.27 (1)
Steliaria media 0.27 (1) unidentified monocotyledons 2.0 (22)
unidentified dicotyledons 0.82 (9) Mean number of seedlings per
dung pat 13.5 13 9.1
There is only one significant correlation between dung of 7- 11 and
3-7 weeks old (Table 7). The species composition and abundance is
partly similar on these dung pats. No significant correlation is
found with dung of more than 9 weeks old (Table 7), although this
partly overlaps with 7-11 weeks.
Table 7: Comparison of the number of seedlings per plant species
compared for field dung of different ages. The correlation
coefficients (Spearman's rho) are shown. N=23.
7-11 wks 3-7wks >9 wks ns ns 7-llwks
** Correlation is significant at the .01 0.776**
level (2-tailed).
Determination of the species occuring in a radius of 30 cm around
the dung pats shows that 60-90 % of the seedlings on a dung pat is
not found in a circle with a radius of 30 cm of the dung pat (Table
8). When unidentified species are omitted, then about 60% of the
seedlings in the nature development site is new on that pat, for
heathland and oligotrophic grassland it is even about 90%. The
nature development site is species rich compared to the other area
parts.
16
Table 8: Percentage of all seedlings germinating on cattle dung in
the field in three area parts. The first column shows the mean
number of seedlings, in the second column the number of seedlings
is corrected for potential seed blown in. For correction, relevés
have been made of the surrounding vegetation in a circle with a
radius of 30 cm. For species that were present within this circle
seedlings were considered as been blown in from the local
vegetation and omitted in the second column. . means this species
was also found in cattle dung in the greenhouse. Target species are
bold. Values in bold are values that differ between measured and
corrected values.
Heathland Nature development site
N 17 16 5
Rumexacetosella • 0.5 0.5 6.4 4.9 19 19
Poa trivialis • 30 30 25 15
Poaannua' 30 30 7.4 7.4
Agrostis capillaris • 14.9 6.8 14.2 5.9 9.4 0
Plantago lanceolata. 1.4 1.4 5.9 5.9
Cerastiumfontanum • 2.3 2.3 1.5 1.5
Alopecurus geniculatus • 0.5 0.5 0.5 0.5
Hypochaeris radicata 4.4 4.4
Agrostis canina 1 1
Festuca pratensis • 0.5 0.5
Stellaria palustris 9 9
Gnaphalium uliginosum • 3.6 3.6
Unidentified species 11 28
Newly introduced species as a % of total number of seedlings
90 56 63
17
Blow in control Sterilising by means of heating method killed
almost all seeds in dung (Table 9). Seedlings of Erica tetralix,
Asteraceae arid Sagina procumbens germinated on the sterilized
dung. Sonchus asper, Chamerion angustfo1ium, Epilobium palustre and
Betula sp. germinated on sterilized, stratified and control and
thus are probably blown in.
Table 9: sterilized dung compared with stratified dung in the
greenhouse. Seedlings in the control tray show blow in of seeds in
the greenhouse. For each species number of seedlings is given and
percentages are given between brackets. Target species are
bold.
sterilized Stratified - control Poa trivialis 99 (37.8) Juncus
bufonius 86 (32.8) Ranunculus repens 18 (6.7)
Carexovalis 11(4.3) Cerastiumfontanum 7.4 (2.8) Juncus bulbosus 6.6
(2.5) Juncus acutiflorus 6.6 (2.5) Alopecurus geniculatus 5.0 (1.9)
Juncus effusus 3.9 (1.5) Poa pratensis 2.9(1.1) Holcus lanatus 2.1
(0.8) Poa annua 1.6 (0.6) Veronica serpyllifolia 1.3 (0.5)
Trifolium repens 1.1(0.4) Epilobium ciliatum 0.3 (0.1) Gnaphalium
uliginosum 0.3 (0.1) Juncus spec 0.3 (0.1) Luzula sp. 0.3 (0.1)
Polygonum sp. 0.3 (0.1) Rumex acetosella 0.3 (0.1) Sonchus asper
0.3 (0.1) Glyceriafluitans 0.3 (0.1) Lolium perenne 0.3 (0.1) Erica
tetralix 0.33 (3.7) Sonchus asper 0.33 (3.7) Asteracea 0.33 (3.7)
Chamerion angustzfolium 0.67 (7.4) unidentified dicotyledons 0.67
(7.4) (0.1) Sagina procumbens 1.7 (18.5) (1.6) Epilobiuni palustre
1(11.1) (0.6) 0.34 (20) Betula sp 4 (44.4) (0.1) 1.36 (80) mean
number of seedlings/sample 9 263 1.7
Rumex acetosella and Lythrum portula are both found on sterilised
pats in the field, but not in the greenhouse dung (Table 10). These
species were also in the surrounding of the dung pat and had set
seed. The number of seedlings does not differ significantly between
displaced (not sterilised and stenlised field dung pats.
18
Table 10: The number of seedlings for different treatments of the
blow in control experiment (total 12 x II.). Results are shown for
Lythrum portula and Rumex acetosella, total mono- and dicotyledons
and total seedlings.
Greenhouse Field
sterilised
sample 1 2 3 1 2 3 1 1 2 3 4 1 2 3 1 2
Lythrum portula Rurnex acetosella 10 7 5
Total monocotyledons
2 23 27 5 12 7 5 10
Total seedlings: 11 10 6 358 180 251 5 31 2 2 10 5 22 22 5 12
There is no significant difference between field dung pats and dung
pats that have been stored for two weeks for the germination of
monocots, dicots or total number of seedlings (Figure 3). There is
however a significant difference for Cerastiumfontanum. Dicots
germinate later than monocots and in the stored samples there have
germinated almost no dicots on the first date, while on the
undisturbed field dung pats dicots have already germinated than. On
the second date (November) the difference has disappeared. A same
thing can be seen for the monocots: there are slightly more
seedlings on the undisturbed field dung pats than on the displaced
dung pats on the first date, while on the second date, most
monocots on the ondisturbed dung pats have died. Although the
differences are not significant, it suggests that there is a delay
in germination. Monocots and dicots may germinate later on
displaced dung pats. Monocots show a high mortality.
Figure 3: Delleburen: number of seedlings of monocots and dicots on
untreated dung pats and dung pats that were stored for two
weeks.
19
•Treated but unsterilized dung patches
Monocots Monocots 16-8-00 28-11-00
Dispersal of target species In Hullenzand 62% of the seed supply in
the area parts measured are seeds of target species (Fig 4). Almost
the whole seed supply from target species is seed from Rumex
acetosella, and if Rumex acetosella is omitted only 3% of the seed
supply is formed by target species (Table 11). In the greenhouse
dung the target species form only 14.3% of the seed supply. Rumex
acetosella is present in a much smaller proportion in the
greenhouse dung. In Delleburen target species form 13.7% of the
seed supply in the field and 5.5% of the species in the greenhouse
dung (Fig 4). The percentage of seedlings of target species on
field dung pats is almost equal with the percentage of target
species in the seed supply, but the species composition differs.
There is only small overlap in target species in the seed supply,
dung seed content and field germination. In Hullenzand seven out of
25 target species in the seed supply were found in the greenhouse
dung (Table 11). In Delleburen eleven out of 30 target species in
the seed supply were found in the greenhouse dung and additionally
five target species were found germinating on field dung
pats.
% 70
60
50
40
30
20
10
Hz seed supply
Figure 4: Percentage of target species in Hullenzand and Delleburen
in seed supply, dung samples and germination on dung patches in the
field.
20
Ob seed Db Db field greenhouse supply greenhouse germination
germination germination
Table 11: Overview of the percentage of target species in the seed
supply (per surface area), seedlings in the greenhouse and in the
field dung for Delleburen (A) and for Hullenzand (B). nm= not
measured. 0 means it was determined the species had no seed in
July, field germination was measured in September.
A) Delleburen:
Leontodon autumnalis 1 <1
Veronica scutellata <1 <1
Scirpus cespitosa nm <1
—Drosera intermedia nm
Drosera rotundifolia nm
Viola canina nm
—Viola palustris nm
seed supply
Carexnigra nm <1
Juncusacutiflorus nm <1
Agrostis canina nm Anthoxanthum odoratum nm Carexovalis nm Carex
panicea nm Carexpilulifera nm Drosera intermedia nm Drosera
rotundifolia nm Empetrum nigrum nm Gentiana pneumonanthe nm Galium
saxatile nm Juncus squarrosus nm
Leontodon autumnalis nm Nardus stricta nm Potentilla anserina nm
Potentilla erecta nm
Ranunculusflam,nula nm
Corynephorus canescens nm
Achillea millefolium 0 Calluna vulgaris 0 Festuca rubra 0 Molinia
caerulea 0 Calamagrostis epigejos 0
21
Discussion
Seed intake The method used for measuring seed supply was very time
consuming. Per area part density of inflorescences was estimated
and the number of seeds per inflorescence was determined per
species. It was assumed that all seeds in the inflorescences were
ripe. The seed supply was calculated by multiplying these numbers
with the areas. A number of species present in the field were not
found in the dung. However it is not known if this is due to the
fact that these species are not eaten, or do not survive the
digestive tract of the cattle. The seeds of Agrostis capillaris
were probably not ripe yet on the date of dung sampling. There are
some species that have been blown in such as Betula sp. that were
found in the control tray. Species that were not in the control
tray but have probably been blown in are Chamerion angustfo1ium and
Sonchus asper. Chamerion angustifolium was present in both study
sites but had no seed at the when dung was sampled and Sonchus
asper may be a good wind disperser like Sonchus oleracea that has a
terminal velocity of 0.27 rn/s (Bonn & Poschlod 1998).
When seed content of dung is compared with seed supply in the field
for different periods, it was found by Malo & Suarez (1995b)
that seed content of dung is correlated with seed supply in the
field. In the present study this could not be shown because there
was only one sample date. In the present study there was no
correlation found between seed content in the dung and seed supply
in the field. So seed supply is not the only important factor
determining the seed content of dung. Selectivity by cattle is
therefore also an important factor. The study sites in this
research are not homogeneous and are too large to graze as a whole
in a short time period. Herbivores have to decide where to graze.
Therefore at least in the short term seed intake is a selective
process. A method to deal with this problem in future research is
to take dung samples from different dates within a short period.
Grazing over the whole site may then be represented in the dung
samples. Then a better correlation between seed supply and seed
intake may be expected.
Another method to deal with this problem is to observe the cattle
two or three days before sampling as most small seeds are retained
in cattle for 2-3 days. The precise duration for gut passage is not
known (Squires 1981 in Gardener et al. 1993). In Hullenzand direct
observations have been done two days before sampling. The cattle
could only be observed from a large distance, because cattle were
very shy, probably due to the presence of calves. At four sites
where the cattle grazed, hand clippings have been taken. In the
analysis it was assumed that grazing on these sites was equal, to
make a comparison with dung seed content possible. A significant
correlation between dung seed content and seeds in the hand
clippings was found. Species in the hand clippings are the dominant
species in the greenhouse dung. The only exception is .1. bufonius.
Probably too few samples have been taken to detect this species
that may have a clustered distribution. Wallis De Vries (1994) also
used the method of hand clipping. Correlation between dung seed
content and hand clippings makes it likely that this is a good
method to measure seed intake.
Terrain use and distribution of dung It is useful to distinguish
between occupancy and foraging. Occupancy includes implications of
treading and of dunging and urinating. Foraging is used for grazing
denoting consumption (De Leeuw & Bakker 1986). Occupancy can
easily be measured from the amount and dispersion of voided dung
(Welch 1984a). A relationship between foraging intensity and
terrain use is sometimes found (Van den Bos & Bakker 1990) but
not always. Although the main activities of the animals are
foraging and resting, direct observation by De Leeuw & Bakker
(1986) revealed that these activities did not take place evenly
over their study site. Foraging patterns could therefore not be
quantified from occupancy patterns. Time spent resting and foraging
varies among plant communities (Bakker eta!. 1983). If the amount
of dung voided is a measure of foraging activities, the time spent
on foraging and resting should be proportional in various pats of
the vegetation. In their study site no resting was observed in
sections whereas foraging did take place. In other sections six
times more resting than
22
foraging was found to be the case. Hence, the amount of dung
provides information about the occupancy but not about foraging.
Thus the recording of the dung pats give good indication of
occupancy but not of grazing. The method of counting dung pats is
an accurate and direct way to determine the distribution of
endozoochorous dispersed seeds.
In both study sites cattle use all area parts but terrain use is
not random. Avoidance of oligotrophic grassland was found in
Delleburen and this may be caused by the presence of sheep that
mainly graze there. Avoidance of Molinia-stands and in heath was
found in Hullenzand. Bokdam & Gleichman (2000) found similar
results in a heathland site. In their study Deschampsia heath was
preferred. In Hullenzand, deforested sand dunes were preferred.
Also much Deschampsia was present in that area part.
Cattle have other preferences for plant communities when resting
than when grazing (Van Rees 1984). In Delleburen and Hullenzand
cattle often rest under trees or stand in or near water. Bokdam
& Gleichman (2000) found that forest was intensively used as a
shelter during the night. The high values of dung pats in heathland
in Delleburen could be explained with preference of cattle for that
area parts for resting. Sheep also prefer heathland to rest
(Bakkeretal. 1983).
Welch (1984) found that the factors most influencing occupancy were
nearness to improved grasslands or swards containing many
attractive graminoids, and the role of each moorland tract in the
management of the farm to which it belonged. Spatial arrangement
may play a role. The high values of dung pats in heathland in
Delleburen could also be explained with spatial arrangement,
because in Delleburen, heathland is situated in the center of the
site and may be visited therefor frequently. In Hullenzand,
nearness of wood may play a role for the shy cattle to hide and
could therefore influence terrain use.
It is assumed that dung plots represent the different area parts.
However the dung density measured can be influenced by different
factors. First, differential search abilities can make a recovery
of dung to be not equally easy in all communities (De Leeuw &
Bakker 1986). In our sites this is not the case because in all dung
plots dung pats could be easily counted. Second spatial arrangement
and edge effects may play a role. Edge effects may influence the
value for mesotrophic grassland, because all dung plots in that
type were situated at the east side of the study site in
Delleburen, while a large part of mesotrophic grassland was
situated at the south side. Finally in October large parts of
nature development site and mesotrophic grassland became flooded.
It must be assumed that also here dung plots represent the area
part well. To correct for the inaccuracies of the indirect method,
direct observations have been done. Results are not shown because
the number of observations was small. An indirect observation
represents a 3- to 4-week period, a direct observation only one
day. To determine the distribution over different area parts many
more observations should be done, because observation on one day
usually gives information of just that particular day.
Germination Many seeds germinated from dung in the greenhouse.
Species present in dung have been eaten by cattle, have survived
chewing and gut passage followed by germination. The proportions of
plant species in dung are affected by differences in intake,
survival and germination. In the field significant less seedlings
were found on the dung pats than in the greenhouse. There are many
possible explanations for that. Germination in the field was
recorded in September but greenhouse seedlings were counted until
January. Surface site/ volume ratio in the greenhouse is larger
than in the field. Estimation of surface site and volume of field
dung is very difficult. When field dung was compared with
greenhouse dung this was done with and without correction for the
estimated volume. The correction gave no difference in the outcome
of the statistical tests. Vegetation cover, growth rate of the
vegetation and height and wetness of the soil on may influence
colonisation of dung pats. Malo & Suárez (l995a) found in a
Mediterranean pasture that cattle dung pats are mainly colonised by
seeds transported within the faeces, in contrast to the
predominance of vegetative colonisation of dung pats in Scottish
heathland (Welch 1985). These factors were not measured in the
present study.
23
In many studies the same species or genera of species are found to
be transported by dung. In many studies Poa species were found the
main species dispersed by dung (Van Rees 1984, Welch 1985, Malo
& Suárez 1996, Bokdam & Gleichman 2000, Mitlacher 2000). In
the present study Poa trivialis was the most dispersed species and
Poa annua and Poa pratensis were found to be dispersed very well by
dung. Cerastium species are also often found (Bokdam &
Gleichman 2000, Welch 1985) as in the present study. Also Juncus
species are often present in the dung. In the present study they
were not found on dung pats in the field, but Welch (1985) found
that 13% of the seedlings in the field were Juncus species. Bokdam
& Gleichman (2000) related germination on field dung to
Ellenberg values: species on dung pats have an nitrogen value IN?
6. Nitrophilous species may have an advantage by endozoochorous
dispersal since they can germinate under eutrophic conditions in
the dung.
Dung deposition and decomposition have impact on the distribution
of plant species. Welch (1985) states that with cattle dung several
transmitted species attained greater cover than in the previously
existing vegetation. Malo & Suarez (1995) concluded that
endozoochorous seeds were the main source of recovery in gaps
generated by dung pats. A small scale spatial pattern in which gaps
were dominated by endozoochorous species was the result. The impact
of dung deposition and decomposition on the formation of pats of
plant species could proceed in three ways (Dai 2000). One way of
dung impact is by influencing the deposition of seeds in the dung.
This is described in the present study. A second way is by changing
the relative abundance of species in the soil seed bank under dung.
Seeds that are viable in soil for <1 year (transient) vanish
from the soil during decomposition of dung. On the long term when
dung composes soil seed bank is altered in this way. A third way is
the intensification of the growth of some species through nutrient
release. Seed arrival is no guarantee for establishment.
Post-dispersal processes have to be considered to understand the
importance of dispersal (Nathan & Muller-Landau 2000). Dung
deposition and decomposing determine an important part of the
success of dispersed seeds. Dung pats can function as open gaps in
the vegetation. Seeds that germinate in dung may not only result
from endozoochorous dispersal, but germination can also result from
seeds that are blown in by the wind or are otherwise dispersed.
When is assumed that only seeds of species within a circle with a
radius of 30 cm are blown in, than most species germinating on
cattle dung appear to be locally new and are probably transported
by cattle dung. The time scale of this research is too small to
conclude that the species can establish in a new gap. For the long
term further research has to reveal the role of germination of
seeds on dung pats for recovery of the gaps created by dung
deposition and establishment of dung-dispersed species in the
vegetation.
The mortality of the monocots in the field shows that differences
between species in the breaking of dormancy are important for
survival. Dormancy appeared to be important in preventing losses in
the faeces (Gardener et al. 1993). Dormancy is a delaying
mechanism, which prevents germination under conditions, which might
prove to be unsuitable for establishment. The breaking of dormancy
does not in itself trigger germination, but is a necessary
prerequisite of it. Thus a seed may need to experience some
environmental conditions which act as trigger for germination, but
which would be quite unsuitable for germination as such (Fenner
1985). Dormancy can be broken by passage through the digestive
tract and defecated or regurgitated seeds germinate to higher
percentages than those that have not been ingested (Baskin &
Baskin 1998). The way in which a digestive system breaks physical
dormancy is unknown, but it is assumed to be via acid and/or
mechanical scarification. In evaluating germination data of seeds
with physical dormancy separated from faecal or regurgitated
material, attention should be paid to the amount of time between
deposition of the material and the retrieval of seeds. Fermentation
of faecal material could increase temperature; consequently, seeds
would receive a wet-heat treatment after they are deposited. Also,
because waste materials are dropped on the soil surface, seeds are
exposed to the extremes of daily temperature fluctuations that
occur in the habitat. These daily temperature changes may be high
enough to break physical dormancy (Baskin & Baskin 1998).
24
Blow in control experiment Heating of dung was very effective in
killing seeds. There was some germination of species probably blown
in. Only for Erica tetralix and Sagina procumbens this is not true
and they have probably survived sterilisation. Heating affects the
structure and composition of the dung. After sterilisation it was
not possible to saturate the dung with water. Dung has a strong
coherence but when broken it does not adhere. The brownish colour
is lost and dung is as black as soil. This may affect germination
conditions. Specific compounds that hinder germination of Erica
tetralLr may be rinsed out by sterilisation. Such processes may
bias detecting species by germinating seeds in herbivore dung in
the greenhouse. To handle the problem of altered structure and
composition in the future an autoclave may be used because water
content of dung is not affected during sterilisation. Sterilised
dung used in the present study detected the blow in of Rumex
acetosella on field dung pats. Improving this method may provide
more insight in the colonisation of dung pats in the field.
When dung pats are stored, there is a delay in germination of those
dung pats. There is no significant difference for the germination
of monocots, dicots or total seedlings but there is a significant
difference for Cerastiumfontanum. It is unlikely that this is a
difference in seed content of dung for C. fontanum because
unsterilised dung in the greenhouse also contained C. fontanum. The
time of deposition does not influence the time and order of
germination after deposition. Many seedlings of monocots germinated
first, dicots germinated somewhat later. The dominance of monocots
in the greenhouse dung may be of no importance for other species
under field conditions. The difference in the number of monocots in
the present study in August and December signifies a big mortality.
Gardener et a!. (1993) found also a big mortality and explained
this with the drying out of the dung pats.
Target species Target species form a small part of the seed supply
in both study sites. Erica tetralix was most abundant in
Delleburen, but was not found in the dung samples. It germinated
once on horse dung in Delleburen (in one sample 7 seedlings) and
once in sterilized dung (1 seedling). The cattle may not have eaten
heath or only small amounts. Germination in dung might also be a
constraint. Rumex acetosella formed 59% of the seed supply in
Hullenzand but formed only 2% of the seedlings in the greenhouse.
Two days before dung collection cattle were observed grazing on the
deforested sand dunes where this species was very dominant.
Explanations for the relative low amount of Rumex acetosella in the
greenhouse dung are that cattle may avoid Rumex acetosella or that
its large seeds may not survive chewing very well. Seed supply of
Juncus bulbosus was not measured in the dung plots because the
abundancy of this species was low. However Juncus bulbosus may be
found on paths and near drinking places. The fact of a small seed
supply of target species may determine the effect of dispersal by
cattle. In Hullenzand seed supply of target species is small when
Rumex acetosella is omitted. In Delleburen there are more target
species and seed supply is greater (with omission of R.
acetosella). As a group target species have no advantage of
endozoochorous dispersal, as this selection was based on other
criteria than the dispersal mechanism, but individual species may
profit from endozoochoiy.
Preferences of cattle for certain plant species or area parts may
determine an important part of the success of dispersal of target
species. Cattle spent much time in the mesotrophic grassland and
deforested sand dunes in Hullenzand and heathland in Delleburen.
The heathland is probably used as a resting site. During the
growing season cattle prefer grass for grazing (Welch 1984, Bokdam
& Gleichman, 2000). Cattle graze little on resting sites. Seed
intake in resting sites is low, but dung deposition is probably not
smaller than in grazing sites. So resting sites function as a sink
for plant seeds. Seed intake in grazing areas is higher and grazing
areas function as a seed source. In summer mesotrophic grassland
may function as a seed source, while the heathland functions as a
sink for seeds in summer. During the winter the heath may become an
important seed source. Calluna is added to theirgrass diet between
November and March, and it can reach a maximum of 50% of all bites
in January (Welch 1984, Bokdam & Gleichman, 2000). The success
of dispersal from target species is dependent on the area part in
which they occur. In mesotrophic grassland the seed supply of
25
target species is small. In summer the grazing intensity in the
heathiand is low and therefor the intake and dispersal of these
seeds will be small. In winter cattle prefer heathiand for grazing.
It is the question how many seeds of target species are available
then for dispersal. Determining seed supply in winter and
collection of winter dung should be done to answer this
question.
Target species can be dispersed and/or can germinate in cattle
dung. On the short term conditions may be not favourable for
species of heathiand and oligotrophic grassland communities.
Abiotic germination conditions and competition with other seedlings
and vegetative shoots may affect establishment. On the longer term,
dispersal may be important for target species. The nutrients in the
dung will leach out and the conditions may become more favourable
for target species. Another disturbance on the same spot after
decaying of the dung may initiate germination of the target
species. Target species may disperse over larger distances in
contrast with wind dispersal and they are distributed over a larger
area. The different area parts and the abundance of target species
in a particular site are probably determining the selectivity of
the cattle and the endozoochorous dispersal for the target
species.
Conclusion Many plant species are dispersed by cattle dung. The
species most dispersed were Poa species like P. trivialis, P. annua
and P. pratensis, Cerastiumfontanum and Juncus species. In the
field much less seedlings germinated than in the greenhouse. Target
species germinated on field dung pats. Most species appearing on a
field dung pat were locally new. With sterilised dung pats it was
shown that Rumex acetosella was blown in. Sterilisation by heating
of cattle dung killed almost all seeds but altered also the
structure of the dung.
Target species form a small part of the seed supply in both study
sites. Selectivity of cattle in terrain use determined the seed
intake. The dominant species in seed intake could be determined by
hand clipping in the grazing area. Avoidance of oligotrophic
grassland was found in Delleburen and avoidance of Molinia-stands
and in the heathland was found in Hullenzand. Preference in
occupancy was found for mesotrophic grassland in both study sites
and in heathland in Delleburen.
Endozoochorous dispersal by cattle is of little importance for the
dispersal of target species. The number of seeds of target species
is very small compared to the number dispersed seeds of non-target
species. Many target species that are present in our study sites
were not dispersed at all. Preferences for area parts by cattle
determine an important part of the success of dispersal of target
species. However some target species may profit from endozoochory
like Rumex acetosella that was found in the greenhouse and on the
dung in the field. Establishment is also restricted by germination
conditions. Further research should focus on germination
conditions.
26
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29
.1
Appendix 1. All target species found within the dung plots or
germinating on cattle dung from the two study sites (Klooker eta!.
1999).
Found in both study sites Achillea millefolium Agrostis can ma
Anthoxanthum odoratum Calluna vulgaris Carex nigra Carex ova us
Carex pan icea Carex pilulifera Drosera intermedia Drosera
rotundifolia Empetrum nigrum Erica rerralix Festuca ovina Fesruca
rubra Gentiana pneurnonanrhe Galium saxa tile Hypochaeris radicata
Juncus acuriflorus Juncus bulbosus Juncus squarrosus Leontodon
autumnalis Luzula campestris/multiflora Molinia caerulea Nardus
stricta Potentilla anserina Potentilla erecta Ranunculusfiammula
Rumex acetosella
30
only found in Delleburen Hieracium umbellatum Hydrocotyle vulgaris
Jun cus con glomeratus Lythrum portula Myrica gale Rhynchospora
alba Scirpus cespitosa Spergularia rubra Stellaria palustris
Veronica scurellara Viola canina Viola palustris
Appendix 2 Vegetation relevs July 2000
A) Delleburen. Pres = fraction of dung plots in which a species is
present, b= species flowering, z= species with seed and d= species
dominant in the majority of the plots. Calamagrostis canescens in
this table might be identified wrong, than it may be Arrhenaterum
elatius.
Oligotrophic grassland Mesotrophic grassland Nature development
Heathland Path
n=ll n=5 n=l0 n=10
pres bzd pres bzd pres bzd pres bzd
Achillea miIi(folium 0.09 0.20 b 0.00 0.10
Agrostis caninae 0.00 0.00 0.10 0.00
Agrostis capiliaris 1.00 dz 1.00 z 1.00 dz 0.50 z i Alnussp. 0.00
0.00 0.10 0.00
Antlwxanthum odoratum 0.27 z 0.00 0.00 0.10 z
Betula sp. 0.00 0.00 0.70 0.80
Bromus .cp. 0.18 z 0.00 0.00 0.00
Calamagrostis canescens 0.09 0.00 0.00 0.00
Calluna vulgaris 0.00 0.00 0.70 b 1.00 db
Cardarnine prazensis 0.00 0.80 0.00 0.00
Carexnigra 0.91 z 0.00 0.10 0.00
Carexovalis 0.27 z 0.00 0.10 z 0.00
Carexpanicea 0.00 0.00 0.20 z 0.10 z
Carexpilulifera 0.00 0.00 0.00 0.50 bz
Cerastiumfontanum vuigare 0.64 bz 0.60 bz 0.50 bz 0.50 bz a
Ceratocapws cia viculata 0.36 b 0.00 0.00 0.00
Cirsiu,n arvense 0.18 bz 0.20 0.10 b 0.00
C:r.czumpalustre 0.18 0.00 0.20 0.00
Deschainpsiaflexuosa 0.18 z 0.00 0.00 0.20 z
Drosera ,ntermedia 0.00 0.00 0.20 bz 0.10 bz
Drocera rotundifolia 0.00 0.00 0.10 z 0.00
Enpc'irun nz'ru,n 0.00 0.00 0.00 0.40 z
EjnIo/,iun palustre 0.00 0.20 bz 0.80 bz 0.00
Erua tetralix 0.00 0.00 0.70 bz 1.00 dbz
Festuca ovina 0.91 dz 0.00 0.00 0.10 z
Fe.ctuca rubra 0.36 a 0.00 0.00 0.00
Galeopsis speciosa 0.00 0.00 0.00 0.00
Ga1iunpa1ustre 0.27 z 0.20 0.70 bz 0.00
Galium saxatile 0.91 a 0.00 0.00 0.00
Gentianapneunwnanthe 0.00 0.00 0.10 b 0.00
Glyceriafluituns 0.09 a 0.20 0.00 0.00
Gnaphaiium uliginosum 0.00 0.00 0.20 z 0.00
Hoicus lanatus 0.55 bz 1.00 dbz 0.80 z 0.60 z z
II. irocotv1e vulgaris 0.00 0.00 0.10 0.00 !'ueri.c radicata 0.09 b
0.00 0.30 bz 0.00
Is,; ;s s,, utifiorus 0.09 z 0.00 0.20 z 0.00
/,ss;s ss ,sticulatus 0.00 0.00 0.30 a 0.00
Jun us Isulbosus 0.00 0.00 0.50 z 0.10 a
Jun ac ssnglomsrazus 0.09 a 0.00 0.20 z 0.00
lunsiss elfusus 0.82 z 0.80 z = 1.00 dz 0.10 z
Janus .cquarrosus 0.45 z 0.00 0.60 z 0.40 z
Iu'ssntssdon autuninalis 0.18 bz 1.00 bz — 1.00 bz 0.00
Lsslissmperenne 0.00 0.60 z 0.00 0.00 z
Lotus uliginosum 0.18 b 0.00 0.80 bz 000 Luzula mult4flora 0.09 z
0.00 0.00 0 00
Lycopus europaeu.s 0.00 0.00 0.60 b 0 0>)
Lysimachia vulgaris 0.00 0.00 0.60 bz 0 00
Lythrumportuia 0.00 0.00 (>20 000 Mentha aquazica 0.09 b 0.00 0
00 0.00
31
pres bzd pres bzd pres bzd pres hid
Molinia caerulea 0.45 b 0.00 0.50 b I 00 h
Myrica gale 0.00 0.00 0.00 0.10
Nardus stricta 0.82 0.00 0.00 0 30
Osmunda regalis 0.00 0.00 0.20 0.03
Persicaria amp/tibia 0.00 0.40 b 0.40 bz 0.! 0 z
Persicuria hydropiper 0.00 0.00 0.00 0.00 h
Phleumprutensis 0.00 0.00 0.10 0.00
Phragmizes oust ru/is 0.00 0.00 0.20 0.00
,:nussp. 0.00 0.00 0.00 0.20
Pla,zfago lanceolata 0.09 0.20 z 0.00 0.10 b
.'lantago major 0.00 0.60 z 0.60 z 0.10 b
Poa annua 0.00 0.00 0.00 0.00 bz
Poa pratensis 0.00 0.00 0.00 0.10
Po/vt,'o,,unz aviculure 0.00 0.20 b 0.00 0.00
Potenti/la anserinu 0.27 bz 0.00 0.00 0.00
Potcnttlla erecta 0.36 bz 0.00 0.00 0.30
Prunuspadus 0.00 0.00 0.50 0.50
Quercus .cp. 0.00 0.00 0.00 0.80
Ranunculus ocr/s 0.00 0.00 0.00 0.10 bz
Ran unculuc flanznwla 0.27 bz 0.00 0.70 bz 0.00
Rwiunculus repens 0.45 bz 1.00 bz 0.30 bz 0.60
Rorippa amphibia 0.09 z 0.00 0.10 0.00 I
Rubusfruzicosus 0.00 0.00 0.00 0.10
Rumex aceto.co 0.36 z 1.00 z 0.20 0.00
Rumex ace to.cella 1.00 bz 0.20 bz 0.50 bz 0.50 bz
Ru,nex crispus 0.00 0.00 0.10 z 0.00
Rvnclzosporu alba 0.00 0.00 0.00 0.10 b
So/tx aurzta 0.00 0.00 0.70 0.00
So/tx repens 0.00 0.00 0.10 0.00 .
Scirpu.c ce.cpiwsa 0.00 0.00 0.00 0.20
Scutellaria galericulata 0.09 b 0.00 0.00 0.00
Senecio vulgare 0.45 bz 0.00 0.00 0.00 I
Sorbusaucuparia 0.00 0.00 0.00 0.10
Stellar/a gram/flea 1.00 bz 0.00 0.00 0.00
bStellar/a media 0.09 bz 0.20 bz 0.00 0.10 bz
Turaxacumsp. 0.09 0.20 0.30 0.00
Thelypterispalustris 0.00 0.00 0.20 0.10
Trifolium repens 0.27 bz 1.00 z 0.70 bz 0.40 bz a
Viola can/na 0.09 z 0.00 0.00 0.00 .
Viola palustris 0.09 z 0.00 000 0.00
32
B) Hullenzand. Pres = fraction of dung plots in which a species is
present, b= species flowering, z= species with seed and d= species
dominant in the majority of the plots. One tree species in the
Molinia stand was not determined
Grassland Deforested sanddunes
Ac/zillea nüllefoliu,n 0.43 bz 0.00 0.00 0.00
Agrostis caninae 0.00 0.00 0.00 0.00 z
Agro.ctis capt/loris 1.00 z 0.71 z 1.00 z 0.00 z
Betulasp. 0.00 1.00 0.86 0.14 a a
Brionus sp. 0.43 z 0.00 0.00 0.00
Cal/usia ulgaris 0.00 0.71 b 1.00 db 0.71 b b b
Cares panicea 0.00 0.00 0.29 0.00
Carexpiluhfera 0.00 0.29 0.71 0.14 z a
Carex sp. 0.00 . 0.57 bz 0.14 z 0.00
Cerastiumfontwzu,n 0.14 bz 0.71 bz 0.86 bz 0.14 z bz a
Ceratocapnos claviculata 0.00 0.29 bz 0.00 0.14 b
Chanierwn angustfiu1ium 0.00 0.14 bz 0.00 0.14 bz bz
Cirsiumarvense 0.14 bz 0.00 0.00 0.00 a
Cirsiumpalustre 0.14 z 0.00 0.00 0.00 a
Crepis capillaris 0.57 bz 0.00 0.00 0.00 bz
Deschampsiaflexuosa 0.00 1.00 z 0.86 z 0.57 z z z
Drosera intermedia 0.00 0.00 0.14 b 0.00
Drvopteris carthusiana 0.00 0.86 0.00 0.29
Enipetrunt nigrum 0.00 0.00 0.00 0.14
Epilobiumpalustre 0.14 bz 0.71 bz 0.29 bz 0.14 z z
Erica let ralix 0.00 0.00 1.00 bz 0.57 bz b
Erigeron canadensis 0.14 b 0.29 bz 0.00 0.14 b hi
Festucaovina 0.29 0.14 z 1.00 z 0.00
Fesguca rubra 0.00 0.00 0.14 z 0.00
Galeop.cis specio.sa 0.00 0.14 b 0.00 0.00
Galiu,nsaxatile 0.00 1.00 bz 0.00 0.14
Gentianapneunwnanzhe 0.00 0.00 0.00 0.43 b
Geumsp 0.00 0.00 0.00 0.00 a
Gnaphaliumuliginosum 0.14 z 0.00 0.00 0.00 bz
FIokuslantitus 0.14 dbz 1.00 bz 0.86 z 0.14 z bz
Hrpochaeris radicata 0.14 dbz 0.57 bz 0.14 b 0.00 b
Juncus bulbosus 0.00 0.00 0.29 z 0.00 a z
Juncuseffu.cu.c 0.00 0.43 bz 0.71 bz 0.00 bz z z
Juncus.rquarrosus 0.00 0.14 bz 1.00 z 0.00 z
Leontodon autumnali.c 0.14 dbz 0.14 bz 0.00 0.00 b bz
Loliusnperenne 0.14 z 0.00 0.00 0.00 z
Lotus sp 0.00 0.00 0.00 0.00 b
Matricaria recutia 0.00 0.29 b 0.00 0.00 b bz
.hcli,zia caerulea 0.00 0.71 bz 1.00 db 1.00 bd b
Vc,rdus strata 0.00 0.00 0.57 0.00 a
.1(1 circa asnp/ccbca 0.00
Pluntago major 0.14 0.14 z 0.71 b 0.00 z
Poaannua 0.00 0.14 z 0.14 b 0.14 z bz
Polygonum aviculare 0.00 0.00 0.00 0.00 b
Pozentilla erecta 0.00 0.00 0.14 bz 0.00
Prunuspadus 0.00 0.29 0.14 0.14
Quercus Np. 0.00 0.86 0.43 0.57
Ranunculusrepens 0.14 0.14 0.00 0.00 b
Rubusfruticosus 0.00 1.00 bz 0.29 0.00
Ru,,iex acetosa 0.29 z 0.00 0.00 0.00
Rumexacetosella 0.14 bz 1.00 bz 1.00 bz 0.43 bz z a
Salix aurita 0.00 0.00 0.00 0.00 a a
Salix repens 0.00 0.00 0.14 0.00
Seneciojacobeia 0.14 z 0.57 bz 0.00 0.00 z
Seneciovulgare 0.14 bz 0.29 bz 0.00 0.00
Sorbus aucuparia 0.00 0.71 0.00 0.00 a
Stellaria media 0.00 0.14 z 0.00 0.00
Tanacetum vulgare 0.14 0.00 0.00 0.00
Taraxacum Np. 0.14 0.00 0.00 0.00
Trifolium repens 0.29 z 0.29 z 0.71 bz 0.00 a z
Vicia/LLuhyrus sp. 0.29 0.00 0.00 0.00
34
Appendix 3. Abundancy of species in the dung squares (20*20 m) in
Delleburen (between 13 and 20 September). S= oligotrophic
grassland, N= nature development area, H= heathiand. b: plant is
flowering, z: plant has seed. Abundancy noted by means of the
Tansley scale: D=dominant; A=abundant; F=frequent; O=occasional;
R=rare (Tansley 1946). Pinus sp. = often Pinus sylvestris, Betula
sp. = often Betula pubescens, Quercus sp. = often Quercus
robur.
SI S2 S5 S6 S9 NI N2 N3 N6 Ni N8 H8 H9 HIO
Agrostis can ma R
Agrostis capillaris Dz Fz Dz Dz Dz Dz Dz A Dz Dz Dz R
Agrostis stolomfera 0 Alnussp. R
Anthoxanthum odoratum Rz R R
Betulasp. R R 0 0 0 0 A 0 Calamagrostis epigejos R
Calluna vulgaris — — — — — Rb Rbz Fbz Obz Obz Fz Dbz Obz Ab
Cardanune pratensis A
Carex ovalis Rz Rz Oz Rz
Carex panicea R R
Cirsium arvense R F
Cirsiumpalustre Rb R R
Drosera rozundifolia R
Empetrum nigrum 0 F Fz Az
Epilobium palustre Rz Oz
Erica tetralix Rz Rz Dz Ob Oz F Az Dz Dbz
Eupatoriuin cannabinum R
Festuca pratensis R
Galiu,n palustre R () F
Gentiana pneunuman the R
Hieracium umbellatum Rz
Hokus lanatus 0 R Fz I) A A Az Dz A 0 R
Holcus flWlliS 0 Hydrocotyle vulgaris 0 R
Hvpochaeris radicata 0 0 F
— —Juncus acutijiorus Rz Fz
Juncus articulazus Oz Oz
Juncusbufonius Rb 0 Juncus effusus Rz Fz Oz D Dz Fz Dz Dz Az
Juncus squarrosus Oz Oz Rz Oz Oz Fz Fz 0z
Leon todon auzumnalis Fz F. Fbz Fbz Az Fz
Lotus uliginosus Fz Oz Ri Abz Az
Luzukaniultifiora Rz R
Lvcopus europaeus Rz Fz 0 Lysiniachia vulgaris Rz R Fz Oz Oz
Lythrum portula R—
Appendix 3 continued
SI S2 S5 S6 S9 NI N2 N3 N6 N7 N H IF) III()
Menthu arvensis Rz
Molinia caeruleu Oz Fz Fz Az Dz Fz Fi I), I), I),
Myrica gale ()
Osmundu regalis 0 R
Ploatago lanceolata Oz 0 R R
antago niJjor 0 0 R
(JflPIUU }
Pt ti/Itt S[) R
icr it sp 0 R R R R
Rut, u/us ilanunala Fbz 0
Run in ii lu.c repen.c D A F F F 0 R
R/twui.cJrun'ula ()
Runiex at cairo R A F 0 R R
Rui,u'x atetosella R Oz Az Abz Fz 0 0 0 Fz
ricptic/obtusiJtilius? Rz
i- pint R
I s/it in I
0
36
Appendix 4) Numbers of seeds per inflorescence for Delleburen and
Hullenzand in July and October 2000 Delleburen: Hullenzand:
July October Agrostis capillaris 80 6
Bromus sp. 11 0
Calluna vu/garis 42.9 Carex nigra 96 Carex ova/is 16.7 28 Cerastium
fontanum 15 8.2 Cirsium arvense 13
Deschampsia flexuosa 4.5 Epiobium palustre 80 Erica tetralix 121.1
25 Festuca ovina 1.0 0.6 Festuca rubra 11
Gallum saxatile 5.3 Holcuslanatus 13.6 2
Hypochaeris radicata 15.1 20 Juncus acutiflorus 160 Juncus
articu/atus 730.2 100
Juncus effusus 1000 420 Juncus squarrosus 43.7 50 Leontodon
autumna/is 56.5 24
Lolium perenne 4.8 0.8 Lotus uliginosus 5.5 47 Lycopus europaeus
200 Lysimachia vu/garis 100 140
Mo/inia caeruiea 60 Nardus stricta 0 Persicaria amphibium 4.4
Phleum pratensis 4 P/a ntago major 70 Poa annua 4.8 1
Potentilla erecta 14.5 1.4 Ranuncu/us f/ammula 16.3 Ranunculus
repens 15.9 Rumex acetosa 150 160 Rumex acetosella 150 8
Ste/lana graminae 3.3 Taraxacum sp 7 36.5 Tnifolium repens 14
21
July October Achillea mi/Iefo/ium 50 Agrostis canina 0.6 Agrostis
capillanis 1.8 5 Bromus sp. 0 Ca/ama grostis epigejos 15 Calluna
vu/ganis 50 Cerastium fontanum 35 22 Ceratocapnos clavicu/ata 6
Cirsium arvense 13 Crepis capi/lanis 2.1 18 Deschampsia flexuosa
7.5 2.2 Epiobium palustre 150 7 Enica tetra/ix 50 Erigeron
canadensis 50 85 Festuca ovina 0.1 Festuca rubra 2 Gnaphalium
Iuteo-album 55 Gnaphallum uliginosum 400 0 Holcus lanatus 45 0.3
Hypochaeris radicata 18 14 Juncus bulbosus 35 Juncus effusus 15
2
Juncus squarrosus 14
Molinia caerulea 3 Nardus stnicta 0.1
Phleum pratensis 40 Plantago major 90 Poa annua 5.5 Rumex
acetose//a 102.5 4.8 Senecio jacobaea 140 Senecio palustris 10
Taraxacumsp. 36.5 Tnifolium repens 21
Vicia/Lathyrus sp. 1.6
Appendix 5A: Mean number of inflorescences per species per m2 in
different area parts, for the Delleburen site in July and October
2000. Appendix 5B. Number of inflorescences from different plant
species per m2 per vegetation type, for the Hullenzand site in July
and October 2000. G= mesotrophic grassland (N=7), H= heathiand
(N=7), K= deforested sand dunes (N=7), M= Molinia stand, (N=7) and
V= bare soil. (N=1)
37
0. 00
.
0. 1
0. 1
0. 1
2. 67
0. 00
0. 0c
1 .0
0. 00
0. oc
1. 1€
0. 00
0. 00
0. 00
0. 00
0. 0c
0. 0c
0. 00
0. 01
0. 00
0. 00
0. 00
0. 00
0. 00
0. 00
0. 00
0. 00
0. 00
0. 00
0. 00
Appendix 6: Number of seeds in the hand clippings
A) Number of seeds per 10 bites in hand clippings in Hullenzand
from 4 sample plots in July and from 2 sample plots in October.
Each sample consisted of 25 hand clippings. These 25 hand clippings
consisted of five bites per patch. Place 2: a transition from
deforested sand dunes to a Molinia-fen vegetation; 3: path through
Juncus effisus-vegetation; 4: path with much Holcus lanatus in
young forest; 5: open place in forest which is very similar to the
vegetation of the deforested sanddunes. Meso= mesotrophic grassland
and defo= deforested sanddunes. Poa sp. In the table is not Poa
annua, but probably Poa pratensis or Poa trivialis.
July October
Juncus bulbosus 62 39 368
Rumex acetosella 51 48 1 29
Holcus lanatus 8.2 0.33 2.5
Loliuni perenne 1 0.33
Juncus effusus 160
Poa sp. 28
B: Number of seeds in samples of 10 hand clippings of vegetation of
two area parts in Delleburen collected between 20 and 26
October.
Trees Mesotrophic Nature development Oligotrophic Molinia Heathi
grassland site grassland stand and
N 1 10 4 3 2 2
Agrostis capillaris 4 21 7.7
Holcus lanatus 0.2
40
— I
Appendix 7: Mean number of seeds per liter dung germinated in all
dung samples in the greenhouse per herbivore type and the mean
number of seedlings per species expressed as a percentage of the
total number of seeds. Three groups of samples are from Delleburen,
the last group from Hullenzand, all sampled in July. Target species
are bold.
Delleburen - Hullenzand pony sheep cattle cattle
10 11 12 15
151 171 1197 249
geniculatus 8 4 7
2 4 5 13
1 2 3 1
5
3
I
1
1
3
41
Cl)
0 (Cl 0. 0) C •0 0 0 .0 E C
8
Cuc.5
1
0
Appendix 8. Mean number of dung pats in the area parts per count
date in Delleburen (A) and Hullenzand (B).
A. Delleburen: Area parts: Oli= oligotrophic grassland, Meso=
mesotrophic grassland, Nat= nature development site and Heath=
Heathland.
•OIi DMeso DNat •Heath
count date
B. Hullenzand: Area parts: defo= deforested sand dunes, meso=
mesotrophic grassland, Mol= Molinia-stand, Heath= Heathland and
bare= bare soil. The values of the first count date are not
represented, but values are: defo: 11.7; meso: 6.7; mol: 2.0;
Heath: 49.0; bare: 41.0
9
8
7
6
5
4
3
2
0
D M 01 D H e a t
2 3 4 5 6
count date
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