Effect of different N, P, K fertilisation on plant species
composition and species richness in an alluvial meadow
Pavlů L.1, Poetsch E.M.2, Pavlů V.1,3, Hejcman M.1, Hujerová1 R. and Gaisler J.3
1Department of Ecology, Czech University of Life Sciences Prague, 165 21, Czech Republic; 2Federal Research
and Education Centre Raumberg-Gumpenstein, 8952 Irdning-Donnersbachtal, Austria; 3Department of
Weeds and Vegetation of Agroecosystems, Crop Research Institute, 460 01, Czech Republic; [email protected]
Abstract
A fertilisation experiment in Admont (Austria) was set up in an alluvial wet meadow in 1946. Since then,
23 fertiliser treatments with various dose of N (nitrogen 80 kg ha-1 year-1), P (phosphorus 35 kg ha-1
year-1), K (potassium 100 kg ha-1 year-1) and a non-fertilised control (Co) have been applied. In 2015 a
botanical survey was conducted in selected treatments: (1) Co, (2) P, (3) K, (4) N, (5) KN, (6) PN, (7)
PK and (8) NPK fertilisation. The highest number of plant species was revealed in P treatment, the lowest
in Co treatment. Four groups of treatments with similar plant species composition were recognised on an
ordination diagram based on RDA analysis: Co, P, K, and PK treatments form the first group, PN and
KN treatments make up the second group, N treatment comprises the third group and NPK treatment
constitutes the fourth group. Legumes Trifolium repens and Trifolium pratense had the highest abundance
in the first group, Agrostis capillaris and Plantago lanceolata were supported by N, KN and PN treatments,
Trisetum flavescens was positively affected by NPK fertilisation. N fertilisation supported short growing
species, especially short grasses, P and K fertilisation supported legumes and other forbs.
Keywords: grassland, nutrients, cutting, biomass, diversity
Introduction
Alluvial meadows are grasslands that were formed in the flood plains of river valleys. As they were developed
on mineral rich soils, their management was very intensive and in case of nutrient impoverishment they
were fertilised (Hrevušová et al., 2014). Applied management of alluvial meadows should provide not
only sufficient forage as well as other natures of ecosystem services (e.g. species diversity). Long-term
grassland experiments are an indispensable tool for understanding production and ecosystems services
functions. The Admont Grassland Experiment (AGE) belongs to the oldest still-running grassland
fertiliser experiments in the Central Europe. In 2015 we carried out a botanical survey in the AGE to
specify in more details the effect of chosen applied nutrients and their combinations on the vegetation.
Materials and methods
The long-term field fertilisation experiment was established in 1946 in Admont, province of Styria
(Austria) (47°34`52``N and 14°27`04``E, 635 m a.s.l.). The average annual precipitation at this site
is 1,227 mm with a long-term mean annual air temperature of 6.8 °C. The parent material of the site
is alluvium, the soil type is a gleyic, brown alluvial soil. The dominant species are Agrostis capillaris,
Anthoxanthum odoratum, Trisetum flavescens, Leontodon hispidus, Plantago lanceolata and Trifolium
pratense. According to Austria flora (Fischer et al., 2008) the species were a priory categorized to short
and tall grasses, short and tall forbs. Species with a mean height ≥0.5 m were classified as tall whereas
those below this threshold were classified as short.
In 2015 eight out of 23 different fertiliser treatments with various dose of N (nitrogen 80 kg ha-1 year-1),
P (phosphorus 35 kg ha-1 year-1), K (potassium 100 kg ha-1 year-1) and a non-fertilised control (Co) were
selected for comprehensive botanical survey: (1) unfertilised control (Co), (2) P, (3) K, (4) N, (5) KN,
(6) PN, (7) KP and (8) NPK fertilisation.
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639
AGE was established in four permanent, randomized blocks, using rectangular plots with a size of 2.9×7.1
m each. All treatments are cut regularly three times a year (around 25 May, 20 June and 30 September,
depending on the particular weather and growing conditions). In May 2015 just before the first cutting
date, the cover of all vascular plant species was recorded using the percentage scale of the whole plots.
Redundancy analysis (RDA) in the CANOCO 5.0 program (Ter Braak and Šmilauer, 2012) was used
to evaluate multivariate vegetation data in the year 2014. The blocks were treated as covariables to restrict
permutations into blocks. A mixed linear model (one way ANOVA) with block as random factor was used
for evaluation of number of vascular plant species, cover of short and tall grasses, cover short and tall forbs.
Results and discussion
The mean number of all vascular plant species ranged from 37.8 (P) to 28.3 (Co) per plot (Table 1).
However, in P treatment on average 19.5 species showed a cover less than 0.5%. The low number of
vascular plant species in the control treatment was probably caused by long-term cutting management
with remarkable biomass removal. A lot of nutrients were depleted with removing biomass during the
previous 69 years with tree time defoliation a year, resulting in an unexpected decrease in number of
plant species. Besides that in Co treatment a large mean cover of mosses (26.2%) occurred. The highest
species richness revealed in P treatment is not in accordance with the results of Janssens et al. (1998) that
associate high level of plant available P with low plant species richness. Probably one-sided fertilisation of
phosphorus in P treatment in our experiment is responsible for low productivity of above ground biomass
which is usually connected with a negative relationship with species richness.
The results of RDA from the year 2015 showed significant (P<0.001) effects of treatments for the
first ordination axis and all ordination axes in plant species composition. The percentage of explained
variability by the first axis and all ordination axes was 26.7 and 55.6 respectively. Four groups of
treatments with similar plant species composition were recognised on an ordination diagram based on
RDA analysis (Figure 1): (1) the unfertilised control, P, K, and PK treatments form the first group; (2)
PN and KN treatments make up the second group; (3) N treatment comprises the third group and; (4)
NPK treatment constitutes the fourth group. For example legumes Trifolium repens and T. pratense had
the highest abundance in the first group, A. capillaris and P. lanceolata were supported by N, KN and PN
treatments, tall grass T. flavescens was positively affected by NPK fertilisation.
As frequent defoliation generally supports short plant species because of lower competition and better
light conditions, the fixed cutting frequency of three times a year was probably responsible for higher
cover of short species (Table 1) in our experiment. The highest cover of short plant species was observed
in N treatment (100.7%) together with the highest cover of short grasses (66.8%). On the other hand
Table 1. Mean proportions (%) of tall grasses, short grasses, tall forbs, short forbs and mosses and mean number of all plant species in the
studied treatments. Numbers represent average of four replicates ± standard error of the mean; P = probability value.
Treatment
Co
P
K
N
KN
PN
PK
NPK
P-value
640
Tall grasses
4.3±1.6
24.8±6.5
2.1±0.6
4.6±1.0
6.8±0.9
24.4±2.9
16.4±2.8
31.7±4.7
<0.001
Short grasses
25.0±5.9
21.0±1.1
24.9±3.1
66.8±3.2
43.3±7.9
35.7±3.5
23.7±4.3
14.7±2.8
<0.001
Tall forbs
21.0±4.7
34.3±4.8
29.0±2.4
8.8±1.8
20.9±2.7
12.2±2.4
41.9±0.6
24.8±3.9
<0.001
Short forbs
33.0±10.4
33.4±3.4
45.1±5.6
33.9±6.0
44.7±10.1
45.5±7.0
34.9±1.6
52.7±7.3
<0.001
Mosses
26.2±6.8
–
4.8±4.2
–
–
–
–
–
<0.001
Number of all plant species
28.3±1.4
37.8±1.1
29.5±1.3
31.8±2.3
33.3±0.9
33.3±1.1
35.0±1.5
33.3±1.2
0.003
Grassland Science in Europe, Vol. 21 – The multiple roles of grassland in the European bioeconomy
Figure 1. Ordination diagram showing the results of a redundancy analysis of vegetation data. For treatment abbreviations see materials and
methods section. Species abbreviations are based on first four letters from genus and four letters of species name.
tall species were mostly supported by P treatment (59.1%) as well as by the other treatments with P
application – PK treatment (58.3%) and NPK (56.5%). In all these treatments the cover of grasses was
lower than the cover of forbs. The lowest covers of grasses were recorded in K (27.0%) and in the control
(29.3%) treatments. Support of legumes cover by P (30.1%), K (27.8%) and PK (40.2%) application
in our experiment is in agreement with results of Hrevušová et al. (2014). As N fertilisation supported
grasses and P, K fertilisation supported forbs the combined application of N, P, K fertilisation showed
intermediate influence on plant species composition.
Conclusions
The results from AGE showed that both plant species richness and plant species composition were
affected by applied fertilisation. The highest number of plant species occurred in the P treatment, whereas
the lowest came up in the unfertilised control. Long-term N fertilisation supported short plant species,
especially short grasses, whilst P and K fertilisation supported legumes and other forbs.
Acknowledgements
The long term experiment is maintained by AREC Raumberg-Gumpenstein. Botanical survey and paper
preparation was supported by MACR (RO0415) and by the Faculty of Environmental Sciences of the
Czech University of Life Sciences in Prague.
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