Biologia 64/4: 694—704, 2009
Section Botany
DOI: 10.2478/s11756-009-0067-x
Soil nutrient heterogeneity and competitive ability
of three grass species (Festuca ovina, Arrhenatherum elatius
and Calamagrostis epigejos) in experimental conditions
Ivan Tůma, Petr Holub & Karel Fiala
Institute of Botany, Department of Ecology, Academy of Sciences of the Czech Republic, Poříčí 3b, CZ-60300 Brno, Czech
Republic; e-mail: [email protected]
Abstract: We studied the effects of differences in root growth and nutrient pool on the competitive ability of Festuca ovina
(short grass), Arrhenatherum elatius and Calamagrostis epigejos (tall grasses) grown in monocultures and in mixtures of
homogeneous and heterogeneous environments during two growing seasons. Analysis of variance revealed a significant effect
of plant species on nutrient concentrations in above-ground biomass and of substrate type on contents of N, K, Ca, Mg
in biomass. The ANOVA also confirmed the significant effect of competitive environment on the concentration of N, K
in above-ground biomass. In heterogeneous environments, both tall grasses (in competition with F. ovina) were able to
produce more roots in the nutrient-rich patches and to accumulate more nitrogen in plant tissues, which was associated
with higher yield of their above-ground biomass. Thus, the relative competitive ability for nutrients of both tall grasses was
higher than that of F. ovina. This competitive ability of A. elatius to C. epigejos increased in heterogeneous treatments.
Key words: nutrient concentration; nutrient pool; relative yield; root biomass; root proliferation
Introduction
The availability of essential resources for plant growth
is spatially and temporally patchy in natural environments (e.g., Gupta & Rorison 1975; Lechowicz &
Bell 1991; Jackson & Caldwell 1993; Farley & Fitter 1999). Plant roots have developed foraging mechanisms that help them to enhance root nutrient uptake in patches of high nutrient concentration and to
acquire adequate amounts of nutrients (Fransen & de
Kroon 2001). Fransen et al. (2001) summarise results
of several authors and mention that plants acquire nutrients in proportion to their biomass in homogeneous
environments and that the competition for nutrients
is relatively size symmetric. In heterogeneous environments, nutrient rich-patches may be reached by larger
plants relatively easily so that they take up nutrients
earlier than is possible for smaller plants. Such a disproportional advantage in nutrient acquisition results
in asymmetric competition. Thus, asymmetric competition is associated with increasing size differences among
competing plants and accelerated competitive exclusion. However, the situation can change if the root foraging abilities of species are very different, e.g., if the
smaller species is a better forager (see Fransen et al.
2001).
Most of the competition experiments have been
carried out under homogeneous conditions and some
studies have shown that smaller plants (individuals)
have a competitive advantage when compared with
c 2009 Institute of Botany, Slovak Academy of Sciences
their larger neighbour (e.g., Newberry & Newman 1978;
Weiner et al. 1997). The results published by Fransen et
al. (2001) indicate that heterogeneity alone, without a
change in the overall nutrient availability of the soil, can
change the relative competitive ability of two perennial
plant species. This shift is consistent with expectations
based on differences in root foraging ability between the
species observed in experiments with isolated plants.
Wijesinghe et al. (2005) concluded that spatial and temporal pattern of nutrient supply strongly affects some
important facets of plant community structure, but has
less influence on others. Therefore further understanding of community responses to the pattern of nutrient
supply will require experiments testing the responses
of individual species to heterogeneity with and without
competitors present.
Grasslands in the Podyjí National Park (South
Moravia, the Czech Republic) are a highly diverse community with many characteristic species (see Fiala et
al. 2004). A great part of the area was covered with a
dry acidophilous short grass vegetation represented by
the plant community Potentilo arenariae-Agrostidetum
vienalis (dominated by F. ovina L.). Since 1995, however, a large increase of tall grasses Arrhenatherum
elatius (L.) J. Presl et C. Presl and Calamagrostis
epigejos (L.) Roth has been observed in these communities. Great areas of original short grass communities have been already replaced by nearly monospecific stands of these tall grasses. Both mentioned tall
grasses represent plant species of global importance due
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Soil nutrient heterogeneity and competitive ability of three grass species
HOMOGENEOUS
HETEROGENEOUS
Fig. 1. The planting pattern and the two soil treatments used in
the experiment. The nutrient-rich patches in the heterogeneous
treatments are indicated by darker areas. The planting locations
are indicated by O. The plants considered either 100% of each
species in the monocultures or 50% of each species in the mixtures. In mixtures, the planting positions of the two species were
alternated.
to their intensive expansion of various ecosystems and
to recent spread in large areas in Europe and North
America (e.g., ten Harkel & van der Meulen 1996; Rebele & Lehman 2001; Sedláková & Fiala 2001; Wilson &
Clark 2001). C. epigejos, a rhizomatous perennial grass,
tolerates most often dry sites on soils with a very low
content of organic matter and low to very low contents
of nitrogen; however both the growth and reproduction
are enhanced under open, moist and nutrient (especially
N) rich conditions (Jańczyk-Weglarska 1996; Rebele &
Lehmann 2001; Fiala et al. 2003). Dolečková & Osbornová (1990) described the mechanisms of successful
expansion of C. epigejos involving, besides others, extensive and very efficient system of rhizomes, vegetative
spreading of the guerrilla type, and high production of
above-ground biomass that turns into a thick layer of
undecomposed litter. A. elatius, a tuft forming perennial grass (phalanx type of growth), is commonly found
on well-aerated, moderately deep neutral or nearly neutral soils of high to moderate fertility (Pfitzenmeyer
1962). F. ovina is a tuft forming perennial grass (phalanx type of growth). The plant is tolerant of dry and
poor sandy soils. A. elatius is characterized by fast potential growth rate and large nitrogen losses whereas F.
ovina has slow growth rate and small nitrogen losses
(Tůma et al. 2005).
Above mentioned results inspired us to set up an
experiment to study root foraging ability and its consequences for the nutrient acquisition of the same expansive grass species. The purpose of this study was to
examine whether a higher foraging ability under patchy
resource distribution confers a competitive advantage in
695
heterogeneous environments. In our experiment, we examined the effect of differences in root foraging ability
on the nutrient pool, biomass production and the competitive ability of F. ovina, A. elatius and C. epigejos
growing in monocultures and mixtures of two species
in both homogeneous and heterogeneous soil environments during two growing seasons.
The following hypotheses were tested:
i) The selective root placement in response to soil
nutrient heterogeneity will be greater in the tall grasses
A. elatius and C. epigejos compared to the short grass
F. ovina.
ii) This will lead to increased competitive ability of
tall grasses in a heterogeneous environment compared
to a homogeneous environment since larger plants reach
and take up nutrients more easily than is possible for
smaller plants.
iii) The selective root placement in response to nutrient heterogeneity will be greater in C. epigejos compared to A. elatius due to an extensive system of belowground organs and its ability to use rhizomes in the selective placement of ramets into high resource patches.
iv) In C. epigejos and A. elatius competition, soil
nutrient heterogeneity will favour C. epigejos.
Methods
The study was carried out as a outdoor experiment. The
experimental garden is located in SW part of Brno (49◦ 12
N, 16◦ 34 E) at 190 m above sea level. Mean annual temperature at Brno, is 9.4 ◦C and long-term mean annual precipitation is 595 mm. In May 2002, large containers (650
× 480 × 240 mm) were filled either with a homogeneous
or heterogeneous soil artificially prepared. In order to facilitate drainage a 30 mm layer of gravel-sand was placed in
the bottom of each container. A PVC frame consisting of
100 × 100 mm cells (25 cm tall) was placed in each container before filling. The PVC frames were removed after
filling. Individual treatments were represented by different
mixtures of nutrient-rich soil and sand. In the homogeneous
treatment, all cells of the PVC frame were filled with a 1:1
soil mixture of nutrient-rich soil and sand (pH 6.1, organic
matter 8.58%, mineral N = 4.2 mg 100 g−1 , P = 8.0 mg 100
g−1 , K = 17.0 mg 100 g−1 , CaO = 180.0 mg 100 g−1 , MgO
= 43.0 mg 100 g−1 ). In the heterogeneous treatment half of
the cells, every other cell, were filled with the nutrient-rich
soil (pH 5.5, organic matter 86.1%, mineral N = 61.5 mg
100 g−1 , P = 52.9 mg 100 g−1 , K = 90.0 mg 100 g−1 , CaO
= 895.0 mg 100 g−1 , MgO = 339.0 mg 100 g−1 ) and half
of the cells were filed with the nutrient poor sand (pH 7.2,
organic matter 1.19%, mineral N = 1.7 mg 100 g−1 , P =
3.0 mg 100 g−1 , K = 12.0 mg 100 g−1 , CaO = 50.0 mg 100
g−1 , MgO = 39.0 mg 100 g−1 ). Hence, the overall nutrient
availability was identical in both treatments (Fig. 1).
Containers were planted to contain 30 individuals
(139 plants per m2 ). Individual tillers of each species were
planted in a regular pattern in a standard replacement design either as a monoculture of one of the three species or
in a 1:1 ratio of potentially competing species. Each combination was replicated 3 times. Plants used in this study
were propagated vegetatively from the field material. Original plants, i.e., tufts (genets) of A. elatius and F. ovina of
the medium size and soil blocks of C. epigejos were dig out
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I. Tůma et al.
696
1.8
Homogeneous
Below-ground biomass [g dm-3]
1.6
c
bc
1.4
bc
1.2
b
1
0.8
a
a
0.6
0.4
0.2
0
F. ovina
F. ovina x A.
elatius
A. elatius
F. ovina
F. ovina x C.
epigejos
C. epigejos
Plant species
Fig. 2. Below-ground dry mass (in g dm−3 ) recorded in monocultures and mixtures of short grass Festuca ovina and tall grasses
Arrhenatherum elatius and Calamagrostis epigejos in homogeneous soils. Data are means ± SE. Different letters denote significantly
different values (LSD test, P < 0.05).
in grass stands in the Podyjí National Park and transported
to the experimental garden. Randomly selected young tillers
(ramets) of similar size (with 3–4 leaves of A. elatius and
C. epigejos or 3–5 tillers of F. ovina) were used in the experiment. Tillers were planted at the corners of the cells
and their roots had immediate access to two rich and two
poor patches. The soil moisture content in each container
was kept at 11% by volume using irrigation wicks. On extremely dry summer days of 2003, the soil in each container
was also watered daily.
At the end of experiment (September 2003), plants
were clipped at the soil surface and separated into vegetative
and flowering shoots if present. At the end of experiment, 6
soil cores (96 mm in diameter, 220 mm in depth) were taken
from the monocultures in both homogeneous and heterogeneous treatments in order to determine the degree of selective root placement of the species. In heterogeneous treatments soil cores were taken separately from nutrient-rich
and poor patches. Soil cores were also taken in the mixtures
in each treatment, but the roots of the two species could not
be distinguished. Root samples were washed free of soil over
a 0.5 mm mesh sieve. Both above- and below-ground plant
material was dried at 70 ◦C and weighed. Root density (dry
mass of below-ground biomass per unit soil volume, i.e., in
g dm−3 ) was calculated. To analyze the effects of interspecific competition, the biomass of two respective species in
mixed culture was expressed by their relative yields, which
were defined by the biomass of each species in mixed culture relative to its biomass in the monoculture (100%) (see
Silvertown 1982). An increase in the relative yield (values higher than 50%) implies that the respective species
wins in competition with the second species, whereas a decrease implies that the particular species loses. The plant
biomass analyses were performed from an extract obtained
by wet combustion of dried plant material; nitrogen by the
micro-Kjeldahl technique; phosphorus colorimetrically, with
ammonium vanadate; potassium by flame photometry; Ca
and Mg by atom absorption photometry. The analyses were
made at the chemical laboratory of the AGROLAB company in Troubsko, CZ. Uptake of nutrients was calculated
by multiplying the dry mass of biomass by nutrient concentrations recorded at the end of the second year (2003).
Obtained data were evaluated by means of the multifactorial analysis of variance, using the statistical package
STATISTICA 6.0. Three-way ANOVA analysis was used to
test the effect of grass species, soil heterogeneity and competitive interactions as independent variables on the dependent variable, content of nutrients in plant biomass. Data
on nutrient uptake, below-ground biomass and relative yield
of above-ground biomass were also subjected to analysis of
variance (ANOVA) and the significant differences among
means were tested using LSD test (P < 0.05). Different letters (a, b, c, etc.) were used to denote significantly different
values.
Results
Selective root placement and competitive ability of the
tall grasses Arrhenatherum elatius and Calamagrostis
epigejos compared to the short grass Festuca ovina
At the end of the two-year experiment, root densities
in the monocultures of A. elatius in homogeneous environments tended to be higher (1.52 ± 0.25 g dm−3 ,
mean value ± standard error) than those in the monocultures of C. epigejos (1.40 ± 0.19 g dm−3 ) and particularly of short grass F. ovina (0.63 ± 0.19 g dm−3 ,
statistically significant difference at P < 0.05) (Fig. 2).
In the heterogenous treatment neither tall species was
able to produce significantly more root biomass in the
nutrient-rich patches than in the nutrient-poor patches.
However, in both the mixtures F. ovina with either
A. elatius or C. epigejos, the richer patches contained
higher root densities by 26% and 22%, respectively,
than the nutrient-poor soil (Fig. 3).
The analysis of variance of data from all treatments
showed that nutrient concentrations in above-ground
biomass (vegetative shoots) were significantly affected
by species and contents of N, K, Ca, Mg in biomass
by type of substrate (Table 1). The effect of different
substrates on nutrient concentration in above-ground
biomass was reflected in significantly lower contents of
nutrients, above all of nitrogen concentration, in grasses
growing in monocultures in a heterogeneous environment, i.e. in soil where nutrients were not equally distributed (A. elatius has 1.46% and F. ovina 1.35% of
N), than those growing in homogeneous environment
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Soil nutrient heterogeneity and competitive ability of three grass species
697
3
Below-ground biomass [g dm-3]
Heterogeneous
2.5
h
2
g
fg
efg
1.5
def
cde
bcd
1
abc
ab
ab
a
a
0.5
0
F. ovina
F. ovina x A.
elatius
A. elatius
F. ovina
F. ovina x C.
epigejos
C. epigejos
Plant species
Fig. 3. Below-ground dry mass (in g dm−3 ) recorded the nutrient-rich (black columns) and nutrient-poor (white columns) patches
of the species in monocultures and mixtures of short grass Festuca ovina and tall grasses Arrhenatherum elatius and Calamagrostis
epigejos in heterogeneous soils. Data are means ± SE. Different letters denote significantly different values (LSD test, P < 0.05).
Table 1. The effect of plant species, substrate heterogeneity and competitive environment on nutrient concentration in vegetative
above-ground shoots (NS non significant, * P < 0.05, ** P < 0.01, *** P < 0.001).
Effects
Effects
%N
%P
F
Species (S)
Substrate (H)
Competition (C)
S×H
H×C
S×C
S×H×C
%K
% Ca
% Mg
df
2
1
1
2
1
2
2
16.8
7.5
12.7
0.19
4.08
0.07
0.76
F
***
**
***
NS
*
NS
NS
76.3
3.9
0.17
0.06
1.31
2.35
0.40
F
***
NS
NS
NS
NS
NS
NS
(A. elatius 1.73%, F. ovina 1.66% of N, Table 2). Competitive environments resulted mostly in higher concentrations of N and K in above-ground biomass of tall
grasses growing with F. ovina than in that of monocultures. Thus, the ANOVA revealed significant effects
of competition on the concentration of N and K while
the effects on other nutrients were not significant. In
heterogeneous soil environment these differences were
greater but mostly not significant.
The amount of above-ground dry mass and nutrients bound in the biomass of grasses (biomass of vegetative and flowering shoots) growing in monocultures
were mostly lower in heterogeneous environments (Tables 3, 4 and 5). The greatest differences (decreases
down to nearly 50% of the amount recorded in homogeneous treatments) were recorded in short grass F. ovina,
whereas the differences in tall grasses were the least,
particularly in C. epigejos. On the contrary, on heterogeneous compared to homogeneous soils, nutrient pool
in tall grasses growing with F. ovina increased, conspicuously in C. epigejos, while the accumulation of nutrients by F. ovina decreased. The highest mean values of
N uptake were in the homogeneous treatment and the
lowest differences, with comparatively lower uptake, in
heterogeneous treatment in monocultures of C. epigejos
(N uptake lower by 18%). The greatest differences were
162.0
8.2
15.6
3.25
5.03
5.29
0.13
F
***
**
***
*
*
**
NS
35.4
37.1
0.18
2.67
0.003
0.68
0.64
F
***
***
NS
NS
NS
NS
NS
23.3
12.9
0.10
0.35
0.04
0.32
0.39
***
***
NS
NS
NS
NS
NS
in F. ovina (decrease by 48%). Significantly higher N
uptake by tall grasses (A. elatius 6.85 ± 1.52 g N m−2 ,
C. epigejos 8.62 ± 0.21 g N m−2 ) than that by F. ovina (0.83–0.87 g N m−2 ) was assessed in heterogeneous
treatments in mixtures of A. elatius or C. epigejos with
F. ovina.
At the end of the 2-yr cultivation, tall grasses
A. elatius and C. epigejos were outcompeting Festuca
in mixed cultures (Fig. 4). Relative yield values of
the grasses examined here demonstrated that both tall
grasses had significantly greater biomass accumulation
than did the small grass F. ovina in heterogeneous than
they did in homogeneous treatments (Fig. 4). The values for F. ovina varied about 30% in both substrate
types whereas relative yield of A. elatius and C. epigejos reached 72.6% and 56.1% and even 115.8% and
91.2% in homogeneous and heterogeneous treatments,
respectively.
Comparison of selective root placement and competitive ability of tall grasses Arrhenatherum elatius and
Calamagrostis epigejos
Although not significant, root density in the monocultures of A. elatius in homogeneous environments was
higher than that in the monocultures of C. epigejos
(Fig. 5). However, this tendency was not noticeable in
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Table 2. Nutrient concentrations (in %) in above-ground vegetative shoots of Festuca ovina (Fo), Arrhenatherum elatius (Ae) a
Calamagrostis epigejos (Ce) growing in homogeneous and heterogeneous environments. Different letters denote significantly different
values between different species and treatments for individual mineral elements (LSD test (P < 0.05) after ANOVA).
Treatment
Homogeneous
Species monoculture
Fo
N
P
K
Ca
Mg
1.66
0.25
1.47
0.62
0.19
±
±
±
±
±
Ae
0.08 defg
0.02 cde
0.06 ab
0.02abcd
0.02abcd
1.73
0.3
2.74
0.70
0.27
Treatment
Fo
N
P
K
Ca
Mg
1.36
0.20
1.69
0.57
0.21
±
±
±
±
±
1.35
0.22
1.32
0.81
0.15
±
±
±
±
±
Ae
0.05 abc
0.01bc
0.05a
0.07ghi
0.01ab
1.46
0.28
2.25
0.90
0.23
Treatment
0.82 abc
0.01ab
0.14bc
0.04abc
0.01bcde
±
±
±
±
±
Ce
0.10 abcd
0.17ef
0.22d
0.02hi
0.02cdef
1.27
0.19
1.46
0.61
0.18
±
±
±
±
±
0.16 ab
0.02ab
0.14ab
0.06abcd
0.001abc
Homogeneous
Fo × Ae
Mixture
Species
Fo × Ce
Fo
1.76
0.25
1.70
0.68
0.18
±
±
±
±
±
Ae
0.06fghi
0.01cde
0.10bc
0.05bcdefg
0.03abc
1.79
0.29
2.91
0.75
0.28
±
±
±
±
±
Ae × Ce
Fo
0.18ghi
0.02f
0.23f
0.04defg
0.05f
1.92
0.25
1.83
0.65
0.17
±
±
±
±
±
Ce
0.15hi
0.02cde
0.03c
0.03bcde
0.03abc
Treatment
1.21
0.18
1.45
0.55
0.19
±
±
±
±
±
Ae
0.16a
0.02a
0.11ab
0.001ab
0.02abcd
1.73
0.27
2.85
0.73
0.29
±
±
±
±
±
Ce
0.12efghi
0.01def
0.31f
0.04defg
0.03f
1.52
0.18
1.55
0.49
0.22
±
±
±
±
±
0.08cdef
0.02a
0.18ab
0.05a
0.03cde
Heterogeneous
Fo × Ae
Mixture
Species
N
P
K
Ca
Mg
0.10 efghi
0.02f
0.04ef
0.07cdefg
0.04ef
Heterogeneous
Species monoculture
N
P
K
Ca
Mg
±
±
±
±
±
Ce
Fo × Ce
Fo
1.68
0.25
1.81
0.77
0.14
±
±
±
±
±
Ae
0.02defgh
0.01cde
0.04c
0.02efgh
0.01a
1.69
0.26
2.76
0.98
0.20
±
±
±
±
±
Ae × Ce
Fo
0.10defg
0.02def
0.08ef
0.18j
0.04abcd
1.95
0.24
1.82
0.80
0.14
±
±
±
±
±
Ce
0.05i
0.01cd
0.15c
0.01fghi
0.01a
1.51
0.19
1.55
0.66
0.18
±
±
±
±
±
Ae
0.01bcde
0.01ab
0.03abc
0.04bcde
0.01abc
1.53
0.26
2.50
0.93
0.25
±
±
±
±
±
0.05cdef
0.02def
0.11de
0.12ij
0.06def
Ce
1.38
0.19
1.64
0.58
0.19
±
±
±
±
±
0.13abc
0.01ab
0.12bc
0.01abc
0.01abcd
140
Heterogeneous
Homogeneous
d
120
Relative yield [%]
100
c
80
cd
bc
60
40
a
a
a
a
20
F. ovina
4
C. epigejos
Plant species
3
A. elatius
F. ovina
C. epigejos
2
F. ovina
1
A. elatius
F. ovina
0
Fig. 4. Relative yields of above-ground biomass (in %) in mixtures of short grass Festuca ovina and tall grasses Arrhenatherum elatius
and Festuca ovina and tall grass Calamagrostis epigejos in homogeneous and heterogeneous soils. Data are means ± SE. Different
letters denote significantly different values (LSD test, P < 0.05).
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Soil nutrient heterogeneity and competitive ability of three grass species
699
Table 3. Dry mass (in g m−2 ) of above-ground biomass of Festuca ovina (Fo), Arrhenatherum elatius (Ae) a Calamagrostis epigejos
(Ce) competing in homogeneous and heterogeneous environments. Data are means ± SE.
Treatment
Homogeneous
Species monoculture
Fo
Ae
Ce
Shoots
Vegetative
Flowering
Total
240 ± 62
79 ± 16
319 ± 70
332 ± 56
293 ± 73
625 ± 118
546 ± 91
325 ± 9
871 ± 93
Treatment
Heteregeneous
Species monoculture
Fo
Ae
Ce
Shoots
Vegetative
Flowering
Total
151 ± 25
44 ± 8
195 ± 17
248 ± 83
136 ± 75
384 ± 158
386 ± 108
294 ± 36
680 ± 138
Treatment
Homogeneous
Fo × Ae
Fo × Ce
Ae × Ce
Mixture
Species
Fo
Ae
Fo
Ce
Ae
Ce
Shoots
Vegetative
Flowering
Total
58 ± 3
40 ± 16
98 ± 20
279 ± 59
155 ± 55
434 ± 29
66 ± 13
24 ± 6
90 ± 12
385 ± 193
206 ± 64
591 ± 257
149 ± 19
94 ± 14
243 ± 33
196 ± 46
186 ± 7
382 ± 41
Treatment
Heterogeneous
Fo × Ae
Fo × Ce
Ae × Ce
Mixture
Species
Fo
Ae
Fo
Ce
Ae
Ce
Shoots
Vegetative
Flowering
Total
47 ± 8
10 ± 5
57 ± 8
375 ± 97
313 ± 62
688 ± 144
52 ± 26
7±2
59 ± 28
516 ± 76
281 ± 83
797 ± 145
116 ± 63
106 ± 64
222 ± 126
136 ± 8
164 ± 58
300 ± 61
Table 4. Nutrient pool (in g m−2 ) in total above-ground biomass of Festuca ovina, Arrhenatherum elatius a Calamagrostis epigejos
growing in monoculture in homogeneous and heterogeneous environments. Percentage differences between homogeneous (100%) and
heterogeneous treatments are also given. Letters denote significantly different values between species and treatments for individual
mineral elements (LSD test (P < 0.05) after ANOVA).
Homogeneous
Species monoculture
N
P
K
Ca
Mg
F. ovina
4.12
0.65
3.59
1.90
0.88
±
±
±
±
±
A. elatius
0.96ab
0.14ab
0.82a
0.39a
0.17b
7.82
1.25
11.80
4.02
1.51
±
±
±
±
±
2.25bc
0.35c
2.17b
1.03b
0.38c
C. epigejos
9.26
1.31
11.10
4.43
1.62
±
±
±
±
±
1.88c
0.12c
1.35b
0.59b
0.17c
Heterogeneous
Species monoculture
N
P
K
Ca
Mg
F. ovina
2.15
0.37
2.04
1.51
0.25
±
±
±
±
±
0.25a
0.06a
0.26a
0.24a
0.03a
(52.2%)
(56.9%)
(56.8%)
(79.5%)
(28.4%)
those grasses growing in monocultures in the heterogeneous soil. Data on tall grasses growing in monocultures in the heterogeneous treatments indicate that the
A. elatius
5.38
1.12
8.10
4.01
0.95
±
±
±
±
±
1.38ab (68.8%)
0.34bc (89.6%)
2.35b (68.6%)
0.96b (99.7%)
0.18b (62.9%)
C. epigejos
7.63
1.19
9.25
4.27
1.20
±
±
±
±
±
1.35bc (82.4%)
0.09bc (91.5%)
1.71b (83.3%)
0.61b (96.4%)
0.15bc (74.1%)
nutrient-poor patches may contain higher root densities
than the nutrient-rich soil (statistically significant only
in C. epigejos). The lower, but not significant, root denUnauthenticated
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I. Tůma et al.
700
2
Homogeneous
Below-ground biomass [g dm -3]
1.8
1.6
Heterogeneous
e
de
cde
1.4
bcd
bc
1.2
ab
ab
ab
1
a
0.8
0.6
0.4
0.2
0
A. elatius
A. elatius x C.
epigejos
C. epigejos
A. elatius
A. elatius x C.
epigejos
C. epigejos
Plant species
Fig. 5. Below-ground dry mass (in g dm−3 ) recorded in monocultures and mixtures of tall grasses Arrhenatherum elatius and Calamagrostis epigejos in homogeneous and heterogeneous soils (black columns – the nutrient-rich patches, white columns – nutrient- poor
patches). Data are means ± SE. Different letters denote significantly different values (LSD test, P < 0.05).
Table 5. Nutrient pool (in g m−2 ) in total above-ground biomass of Festuca ovina (Fo), Arrhenatherum elatius (Ae) a Calamagrostis
epigejos (Ce) competing in homogeneous and heterogeneous environments. Percentage differences between homogeneous (100%) and
heterogeneous treatments are also given. Different letters denote significantly different values between different species and treatments
for individual mineral elements (LSD test (P < 0.05) after ANOVA).
Homogeneous
Fo × Ae
Mixture
Species
N
P
K
Ca
Mg
Fo
1.34
0.17
1.05
0.58
0.13
±
±
±
±
±
Fo × Ce
Ae
0.28ab
0.02a
0.09a
0.12a
0.03a
6.06
1.04
9.60
3.07
1.11
±
±
±
±
±
1.12de
0.14c
0.66c
0.35c
0.18ef
Ae × Ce
Fo
0.95
0.18
1.23
0.54
0.13
±
±
±
±
±
Ce
0.16a
0.04a
0.23a
0.05a
0.04a
4.31
0.68
5.12
2.55
0.85
±
±
±
±
±
1.12cd
0.07b
1.05b
0.63c
0.22d
Ae
3.14
0.50
4.97
1.74
0.66
±
±
±
±
±
Ce
0.39c
0.03b
0.75b
0.26b
0.07bcd
4.55
0.58
4.83
1.66
0.74
±
±
±
±
±
1.07cd
0.12b
1.08b
0.25b
0.14cd
Heterogeneous
Fo × Ae
Mixture
Species
N
P
K
Ca
Mg
Fo
0.87±0.17a
0.13±0.02a
0.87±0.15a
0.43±0.04a
0.07±0.01a
Fo × Ce
Ae
Fo
(65%) 6.85±1.52ef (113%) 0.83±0.39a
(76%) 1.09±0.15c (105%) 0.13±0.07a
(83%) 10.83±1.79c (113%) 1.00±0.59a
(74%) 4.67±0.49d (152%) 0.46±0.22a
(54%) 0.88±0.04de (79%) 0.08±0.04a
sities in the richer patches characterized the mixtures
of both tall grasses A. elatius and C. epigejos (Fig. 5).
Data indicate, that selective root placement in response
to nutrient heterogeneity does not differ between the
two tall grass species, i.e. they had not produced more
root biomass in the nutrient-rich patches than in the
nutrient-poor patches.
In comparison with C. epigejos, higher concentration of nutrients was found mostly in above-ground
biomass of the vegetative shoots of A. elatius growing in
monoculture in both substrates (Table 2). Similarly, in
competitive environments, concentrations of nutrients
(P, K, Ca, Mg) were significantly higher in A. elatius
(87%)
(72%)
(81%)
(85%)
(61%)
Ae × Ce
Ce
Ae
Ce
8.62±0.21f (187%)
1.13±0.05c (191%)
8.98±0.19c (175%)
4.45±0.15d (174%)
1.18±0.06f (138%)
3.39±0.92c (108%)
0.64±0.18b (128%)
4.97±1.11b (100%)
2.54±0.43c (146%)
0.56±0.04bc (85%)
3.01±0.19bc (66%)
0.47±0.09b (81%)
3.54±0.42b (73%)
1.51±0.19b (91%)
0.46±0.07b (62%)
and lower in C. epigejos than that of Festuca in both homogeneous or heterogeneous soils. Concentrations of N
and K in above-ground biomass of tall grasses growing
in competition with one another ranged between 1.53–
1.73% of N and 2.50–2.85% of K in A. elatius whereas
N and K concentrations in C. epigejos ranged from 1.38
to 1.52% and 1.55 to 1.64% respectively (Table 2).
Although not significant, the amounts of nutrients
bound in the biomass of C. epigejos growing in monoculture were mostly higher than those recorded in A.
elatius in both homogeneous and heterogeneous treatments (Table 4 and 5). However, when A. elatius was
grown in competition with C. epigejos, nutrient pool
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Soil nutrient heterogeneity and competitive ability of three grass species
80
Homogeneous
70
Hetrogeneous
b
Relative yield [%]
60
50
a
a
a
40
30
20
Plant species
2
C. epigejos
A. elatius
1
C. epigejos
0
A. elatius
10
Fig. 6. Relative yields of above-ground biomass (in %) in mixtures
of tall grasses Arrhenatherum elatius and Calamagrostis epigejos
in homogeneous and heterogeneous soils. Data are means ± SE.
Different letters denote significantly different values (LSD test,
P < 0.05).
of N, P and K was higher on heterogeneous soils in A.
elatius and all nutrients were lower in C. epigejos on
heterogeneous soils (Table 5). When in competition a
lower amount of N was accumulated in C. epigejos on
heterogeneous (3.01 ± 0.19 g N m−2 ) than on homogeneous (4.55 ± 1.07 g N m−2 ) substrates. In contrast,
3.39 ± 0.92 g N m−2 and 3.14 ± 0.39 g N m−2 was
accumulated in A. elatius in heterogeneous and homogeneous environments, respectively.
Although, at the end of the two-year experiment,
relative yields of both tall grasses growing in mixtures
in homogeneous treatments were similar (42.1% – A.
elatius and 43.9% – C. epigejos) while the yield of A.
elatius in the heterogeneous treatment was 67.2% while
that of C. epigejos was only 39.7%. These differences
were statistically significant (Fig. 6). Thus the heterogeneous environment contributed to the competitive
advantage of A. elatius when in competition with C.
epigejos.
Discussion
Competitive ability of the tall grasses Arrhenatherum
elatius and Calamagrostis epigejos compared with that
of the short grass Festuca ovina
There were mostly statistically insignificant differences
between below-ground plant parts produced by plants
in nutrient-poor patches compared to those in nutrientrich soil in both the monoculture and heterogeneous
environments. Thus, the first of our predictions, i.e.,
that selective root placement in response to nutrient
heterogeneity would be greater in the tall grasses (C.
epigejos, A. elatius) than in the short grass (F. ovina)
was not fully confirmed.
However, C. epigejos produced about twice and A.
elatius about three times more root biomass than did
701
F. ovina, indicating that tall grasses have denser and
more extensive root systems. Nevertheless, several authors reported that roots can respond to the nutrient
heterogeneity by proliferation within the nutrient-rich
patches (e.g., Gross et al. 1993; Wijesinghe & Hutchins
1997; Fransen et al. 1998, 2001; Farley & Fitter 1999;
Šmilauerová 2001). If asymmetric competition exists
its most likely mechanism would be increased root
density in nutrient-rich patches. However, such pronounced effect of nutrients on root biomass grown in
nutrient-rich patches was not always found (e.g., Einsmann et al. 1999; Blair 2001; Fransen & de Kroon
2001). After 2 years, for example, root biomass per
unit soil volume was higher for Holcus lanatus (plant
of nutrient-rich habitats) in rich than in poor soils, but
no selective root placement was detectable for Nardus
stricta (plant of nutrient-poor habitats) by Fransen &
de Kroon (2001). In our experiment, density of root
systems increased in mixtures of both tall grasses in
competition with Festuca, particularly, in nutrient rich
environments. The morphological root plasticity may
be altered when plants are grown in competition, since
root behaviour may have differed in mixtures from that
in monocultures (Mahall & Callaway 1992; Jastrow
& Miller 1993; Krannitz & Caldwell 1995). At higher
neighbour root abundances, below-ground competitive
intensity increased rapidly (Cahill & Casper 2000).
Our results are mostly in agreement with data obtained by Wijesinghe et al. (2001) that indicated that
species with large root systems are less selective in placing their roots in nutrient rich patches than species
with smaller root systems. They found a significant
negative correlation between the mean root biomass
of each species and its precision of root placement in
nutrient-rich patches. A. elatius was the least precise
forager in their experiment. However, precision in some
larger-rooted species can be responsive to pattern of
nutrient supply. Therefore we agree with the aforementioned authors that the relationship between the
scale of species’ root systems and their precision in placing roots in high quality patches of soil is still open to
question.
The analysis of variance and comparison of all data
have shown that concentration and uptake of nutrients
of three studied grass species were mostly affected by
different substrates and were reflected in both differences in relative yield and competitive ability of grasses.
The effectiveness of root proliferation was estimated by
quantifying the amount of nutrients accumulated by
plants over the course of the experiment. The amount
of N taken up by above-ground biomass of individual plants differed significantly by species as well as
by treatments. A substantially higher nutrient uptake
given by the below-ground competition may increase
plant growth and this fact may explain the higher competitive ability of both tall grasses relative to F. ovina. Lower amounts of nutrients were concentrated in
the studied grasses growing in heterogeneous than in
homogeneous environments. These results are in agreement with conclusions formulated by Jackson & CaldUnauthenticated
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702
well (1996) and Ryel & Caldwell (1998) showing that
plants that do not alter their root morphology or physiology in response to local nutrient enrichment acquire
fewer nutrients in heterogeneous than in homogeneous
environments, even if the total amounts available are
the same. Similarly, as in our experiment, Ryel & Caldwell (1998) also found that uptake of both N and P was
highest in soils with the nutrients distributed uniformly
and the decline was greater for N than for P in heterogeneous environments. In the mixtures of grass species
on homogeneous soils, denser root systems of both tall
grasses were associated with significantly larger concentration of nutrients by above-ground biomass than
in the F. ovina. Similarly, the significantly higher values of N uptake by the tall grasses (A. elatius and C.
epigejos) when in competition of with F. ovina in heterogeneous environments and the greater above-ground
biomass produced by the tall grasses were associated
with a significant increase in their relative yield. These
increases resulted from a greater ability of both tall
grasses to acquire nutrients in heterogeneous than in the
homogeneous environments when competing with Festuca. Thus, in contrast to the homogeneous treatment,
the competitive ability of both tall grasses, particularly
of A. elatius, substantially increased in heterogeneous
environments relative to that of F. ovina. These results
confirmed our second assumption that tall grasses A.
elatius and C. epigejos are able to suppress F. ovina
more markedly in heterogeneous environments, since
larger plants may reach and take up nutrients more
easily than is possible for smaller plants.
Comparison of competitive ability of the tall grasses Arrhenatherum elatius and Calamagrostis epigejos
We assumed that C. epigejos, a guerilla grass, is the
species with a greater ability to acquire nutrients from
heterogeneous soils since this plant is characterized by
an extensive system of below-ground organs and is able
to use rhizomes in the selective placement of ramets
into high resource patches (see de Kroon & Hutchings
1995). Similarly, Humphrey & Pyke (1998) reported
that guerrilla grass (Elymus lanceolatus ssp. lanceolatus) exploited resources more quickly in the first year
by faster growth and greater ramet production. But
in our experiment, no differences were found between
the density of root systems of tall grasses studied at
the end of the second year of the experiment, nor between their relative yields recorded in mixtures in homogeneous environments, reaching 42.1% in A. elatius
and 43.9% in C. epigejos. In addition, the competitive
ability of C. epigejos relative to A. elatius declined in
the heterogeneous environment when compared to homogeneous treatments. Thus our results show that the
opposite of what was expected in our fourth assumption. Nutrient heterogeneity enhanced the competitive
ability of A. elatius relative to C. epigejos. Similarly,
Warren et al. (2002) reported that although Arrhenatherum elatius and Holcus lanatus produced similar
amounts of above-ground biomass in monoculture, A.
elatius was the superior competitor when the species
I. Tůma et al.
were grown together in pots. Similarly, Fraser & Grime
(1998) characterized A. elatius as a fast-growing, earlysuccessional species whose biomass responds dramatically to a high soil fertility treatment (see also Berendse
& Elberse 1989). The greatest significant increases in
relative yield of A. elatius growing in mixtures with C.
epigejos for one year occurred in both unfertilized and
fertilized unclipped treatments (Tůma et al. 2005). Individual plants that reach the nutrient-richer areas first
can potentially dominate them by increasing their nutrient uptake. Thus, in early-successional phases, heterogeneous soil environments may enhance competitive
ability of tuft forming A. elatius, i.e., a plant species
with the phalanx type of growth. Grasses of this growth
type are among the most successful plants and, in addition, their success is probably also associated with their
ability to store carbohydrate in tiller bases of young
tufts and results in both rapid regrowth in spring and
after damage pressures (see also Cheplick & Chui 2001).
The benefits of foraging are usually defined in
terms of nutrient uptake or short-term growth, but
the long-term growth of perennial plants depends on
the balance between nutrient uptake and losses due
to turnover of plants (Berendse 1994). Species from
nutrient-rich habitats, as A. elatius, display more root
proliferation than those from nutrient-poor habitats
(see Fransen et al. 1998). However, plant species from
nutrient-poor habitats, like C. epigejos, have an advantage by being better able to retain captured nutrients due to a longer life span of tissues (Berendse
et al. 1987; Aerts 1989; Diemer et al. 1992; Schläpfer
& Ryser 1996). On the contrary, fast growing species,
such as A. elatius, may lose their initial advantage of
fast growth because of the nutrient losses due to a short
organ life span (Schläpfer & Ryser 1996). C. epigejos
expanding into alluvial meadows and acid dry grasslands displays lower N losses in fresh litter, or higher
N productivity, both resulting in a higher nitrogen use
efficiency than was assessed in intact grasslands (Holub
2003; Fiala et al. 2004). Thus the utilization of N by
old C. epigejos stands appears to be very efficient. According to Fransen & de Kroon (2001), no studies have
been carried out at the appropriate time-scale to investigate how root proliferation and below-ground plant
part longevity interact with the ability to capture nutrients and to grow in patchy environments. The morphologically more plastic Festuca rubra achieved a higher
relative shoot biomass in heterogeneous soils in the first
growing season, but subsequently lost its advantage to
the physiologically more plastic Anthoxanthum odoratum (Fransen et al. 2001). Results of a 5-year cultivation experiment indicate that the competitive superiority of C. epigejos was evident on the most productive
substrate in the long run (Rebele 2000). Similarly our
field observations suggest that C. epigejos is able to
spread into stands formed by A. elatius tufts and replace A. elatius (Fiala et al. 2004). Competitive ability
of C. epigejos can obviously increase with time, i.e.,
with the formation of large below-ground plant part
systems, rhizomes in particular. Therefore C. epigejos
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Soil nutrient heterogeneity and competitive ability of three grass species
can not be superior in heterogeneous soils due to its still
insufficiently formed young, 2-year old rhizome systems
corresponding to only 14% of above-ground biomass,
reaching 802 g m−2 (average value) in our experiment in
comparison with 44–62% of above-ground parts (719–
741 g m−2 ) found in old stands (Fiala 2001; Fiala et al.
2003). The mechanisms of successful expansion of C.
epigejos involves an extensive and very efficient system
of rhizomes and vegetative spreading of the guerrilla
type, among others. Species like C. epigejos, capable of
the guerrilla type growth are often more successful later
in succession than those of phalanx type growth like A.
elatius (Prach & Pyšek 1994). These conclusions are
in contradiction with findings published by Humphrey
& Pyke (1998). They found that biomass, ramet numbers and rhizome growth of guerrilla grass were reduced
in the second year, as was its advantage. According to
them, the phalanx grass species had slower growth, produce more ramets in later years, appeared adapted to
more stressful conditions and were able to exploit resources more effectively. In the case of C. epigejos, however, the guerrilla growth strategy, effective N utilization, and interference competition through dense cover
of above-ground biomass and litter could further cause
competitive exclusion of A. elatius. However, C. epigejos is not able to spread if the stress factors nutrient
deficiency and drought are combined (Süss et al. 2004).
The size of the nutrient patch, speed of root growth
and the lag period before a competitor discovers the resource will determine how much resource is available or
depleted by the first plant. Thus several variables such
as the patch size of the soil resource and plant’s root
foraging ability may affect the competition for nutrient
resources. Our results obtained in both cultivation experiments (Tůma et al. 2005, present paper) and field
studies (Fiala et al. 2003, 2004) can contribute to the
elucidation of differences in the behaviour of both expanding tall grasses in succession processes. They also
support the conclusion of Fransen & de Kroon (2001)
that short and long-term effects of root foraging and
root competition may be qualitatively different. Therefore further studies focussed on the effects of soil heterogeneity at temporal and spatial scales under field
conditions are still needed.
Acknowledgements
The authors are greatly indebted to Prof. F. Seischab for
linguistic assistance. The study was supported by grant No.
206/02/0581 from the Grant Agency of the Czech Republic
and the project No. AV076005908.
References
Aerts R. 1989. The effect of increased nutrient availability on
leaf turnover and aboveground productivity of two evergreen
ericaceous shrubs. Oecologia 78: 115–120.
Berendse F. 1994. Competition between plant populations at low
and high nutrient supplies. Oikos 71: 253–260.
Berendse F., Oudhof H. & Bol J. 1987. A comparative study
on nutrient cycling in wet heathland ecosystems. I. Litter
703
production and nutrient losses from the plant. Oecologia 74:
174–184.
Berendse F. & Elberse W.T. 1989. Competition and nutrient
losses from the plant, pp. 269–284. In: Lambers H. et al.
(eds), Causes and consequences of variation in growth rate
and productivity of higher plants, The Hague.
Blair B. 2001. Effect of soil nutrient heterogeneity on the symmetry of belowground competition. Plant Ecol. 156: 199–203.
Cahill J.F. & Casper B.B. 2000. Investigating the relationship between neighbour root biomass and belowground competition:
field evidence for symmetric competition belowground. Oikos
90: 311–320.
Cheplick G.P. & Chui T. 2001. Effect of competitive stress on
vegetative growth, storage, and regrowth after defoliation in
Phleum pratense. Oikos 95: 291–299.
de Kroon H. & Hutchings M.J. 1995. Morphological plasticity in
clonal plants: the foraging concept recognisered. J. Ecol. 83:
143–152.
Diemer M., Körner C. & Prock S. 1992. Leaf life spans in wild
perennial herbaceous plants: a survey and attempts at a functional interpretation. Oecologia 89: 10–16.
Dolečková H. & Osbornová J. 1990. Competition aability and
plasticity of Calamagrostis epigejos. Zpr. Čs. Bot. Společ. 25:
35–38.
Einsmann J.C., Jones R.H., Pu M. & Mitchell R.J. 1999. Nutrient
foraging traits in 10 co-occurring plant species of contrasting
life forms. J. Ecol. 87: 609–619.
Farley R.A. & Fitter A.H. 1999. The response of 7 co-occurring
herbaceous perennials to localized nutrient-rich patches. J.
Ecol. 87: 849–859.
Fiala K. 2001. The role of root system of Calamagrostis epigejos in its successful expansion in alluvial meadows. Ekológia,
Bratislava, 20: 292–300.
Fiala K., Holub P., Sedláková I., Tůma I., Záhora J. & Tesařová
M. 2003. Reasons and consequences of expansion of Calamagrostis epigejos in alluvial meadows of landscape affected by
water control measures – A multidisciplinary research. Ekológia, Bratislava, 22(Suppl. 2): 242–252.
Fiala K., Záhora J., Tůma I. & Holub P. 2004. Importance of
plant matter accumulation, nitrogen uptake and utilization
in expansion of tall grasses (Calamagrostis epigejos and Arrhenatherum elatius into acidophilous dry grassland. Ekológia, Bratislava, 23: 225–240.
Fransen B. & de Kroon H. 2001. Long-term disadvantages of
selective root placement: root proliferation and shoot biomass
of two perennial grass species in a 2–year experiment. J. Ecol.
89: 711–722.
Fransen B., de Kroon H. & Berendse F. 1998. Root morphological
plasticity and nutrient acquisition of perennial grass species
from habitats of different nutrient availability. Oecologia 115:
351–358.
Fransen B., de Kroon H. & Berendse F. 2001. Soil nutrient heterogeneity alters competition between two perennial grass
species. Ecology 82: 2534–2548.
Fraser L.H. & Grime J.P. 1998. Top-down control and its effect on
the biomass and composition of three grasses at high and low
soil fertility in outdoor microcosms. Oecologia 113: 239–246.
Gross K.L., Peters A. & Pregitzer K.S. 1993. Fine root growth
and demographic responses to nutrient patches in four oldfield plant species. Oecologia 95: 61–64.
Gupta P.L. & Rorison I.H. 1975. Seasonal differences in the availability of nutrients down a podzolic profile. J. Ecol. 63: 521–
534.
Holub P. 2003. Nitrogen use efficiency and dominance of Calamagrostis epigejos in floodplain meadows. Ekológia, Bratislava,
21(Suppl.): 268–274.
Humphrey L.D. & Pyke D.A. 1998. Demographic and growth
responses of guerrilla and a phalanx perennial grass in competitive mixtures. J. Ecol. 86: 854–865.
Jackson R.B. & Caldwell M.M. 1993. The scale of nutrient heterogeneity around individual plants and its quantification with
geostatistics. Ecology 74: 612–614.
Jackson R.B. & Caldwell M.M. 1996. Integrating resource heterogeneity and plant plasticity: modelling nitrate and phosphate
uptake in a patchy soil environment. J. Ecol. 84: 891–903.
Unauthenticated
Download Date | 6/15/17 9:49 AM
704
Jańczyk-Weglarska J. 1996. The strategy of Calamagrostis epigejos (L.)Roth individual development under ecological conditions of the valley ravine of the river Warta near Poznań.
Seria Biologia 56, Universytet A. Mickiewicza, Poznań.
Jastrow J.D. & Miller R.M. 1993. Neighbour influences on root
morphology and mycorrhizal fungus colonization in tallgrass
prairie plants. Ecology 74: 561–569.
Krannitz P.G. & Caldwell M.M. 1995. Root growth responses
of three Great Basin perennials to intra- and interspecific
contact with other roots. Flora 190: 161–166.
Lechowicz M.J. & Bel L.G. 1991. The ecology and genetics of
fitness in forest plants. II. Microspatial heterogeneity of the
edaphic environment. J. Ecol. 79: 687–696.
Mahall B.E. & Callaway R.M. 1992. Root communication mechanisms and intracommunity distributions of two Mojave
Desert shrubs. Ecology 73: 2145–2151.
Newberry D. & Newman E. 1978. Competition between grassland
plants of different size. Oecologia 33: 361–380.
Pfitzenmeyer C.D. 1962. Arrhenatherum elatius (L.) J. & C.
Presl. J. Ecol. 50: 235–245.
Prach K. & Pyšek P. 1994. Clonal plants – what is their role in
succession? Folia Geobot. Phytotax. 29: 307–320.
Rebele F. 2000. Competition and coexistence of rhizomatous
perennial plants along a nutrient gradient. Plant Ecol. 147:
77–94,
Rebele F. & Lehmann C. 2001: Biological flora of Central Europe:
Calamagrostis epigejos (L.)Roth. Flora 196: 325–34
Ryel R.J. & Caldwell M.M. 1998. Nutrient acquisition from soils
with patchy nutrient distribution assessed with simulation
models. Ecology 79: 2735–2744.
Schläpfer B. & Ryser P. 1996. Leaf and root turnover of three
ecologically contrasting grass species in relation to their performance along a productivity gradient. Oikos 75: 398–406.
Sedláková I. & Fiala K. 2001. Ecological problems of degradation
of alluvial meadows due to expanding Calamagrostis epigejos.
Ekológia, Bratislava, 20(Suppl. 3): 226–233.
Silvertown J.W. 1982. Introduction to plant population ecology.
London and New York, 209 pp.
I. Tůma et al.
Šmilauerová M. 2001. Plant root response to heterogeneity of
soil resources: effects of nutrient patches, AM symbiosis, and
species composition. Folia Geobot. 36: 337–351.
Süss K., Storm C., Zehm A. & Schwabe A. 2004. Succession in
inland sand ecosystems: Which factors determine the occurrence of the tall grass species Calamagrostis epigejos (L.)
Roth and Stipa capillata L. Plant Biol. 6: 465–476.
ten Harkel M.J. & van der Meulen F. 1996. Impact of grazing
and atmospheric nitrogen deposition on the vegetation of dry
coastal dune grasslands. J. Veg. Sci. 7: 445–452
Tůma I., Holub P. & Fiala K. 2005. Competitive balance and
nitrogen losses from three grass species (Arrhenatherum
elatius, Calamagrostis epigejos, Festuca ovina). Biológia 60:
1–6.
Warren J., Wilson F. & Diaz A. 2002. Competitive relationships
in a fertile grassland community – does size matter? Oecologia
132: 125–130.
Weiner J., Wright D. & Castro S. 1997. Symmetry of belowground
competition between Kochia scoparis individuals. Oikos 79:
85–91.
Wijesinghe D. & Hutchings M. 1997. The effects of spatial scale
of environmental heterogeneity on the growth of clonal plant:
an experimental study with Glechoma hederacea. J. Ecol. 85:
17–28.
Wijesinghe D.K., John E.A., Beurskens S. & Hutchings M.J.
2001. Root system size and precision in nutrient foraging:
responses to spatial pattern of nutrient supply in six herbaceous species. J. Ecol. 89: 972–983.
Wijesinghe D.K., John E.A. & Hutchings M.J. 2005. Does pattern of soil resource heterogeneity determine plant community structure? An experimental investigation. J. Ecol. 93:
99–112.
Wilson M.V. & Clark D.L. 2001. Controlling invasive Arrhenatherum elatius and promoting native prairie grasses through
mowing. Appl. Veg. Sci. 4: 129–138.
Received January 25, 2008
Accepted July 29, 2008
Unauthenticated
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