Analele ştiinţifice ale Universităţii “Al. I. Cuza” Iaşi
Tomul LII, s. II a. Biologie vegetală, 2006
THE DIVERSITY OF THE PALUDAL VEGETATION FROM THE LEFT
SIDE OF IZVORUL MUNTELUI – BICAZ ACCUMULATION LAKE
OANA ZAMFIRESCU, Ş. R. ZAMFIRESCU 
Abstract: Diversity is an important indicator of a community status. The paludal vegetation from the
south-western part of the Stânişoara Mountains consists of plant communities of two associations:
Typhetum latifoliae Soó 1927 and Typhetum schuttleworthii Soó 1927. The diversity analysis was
carried out by taking into account the species index and the Shannon index. Both associations displayed
low values of the species richness (approximately 11 species per relevé) and and of the relative
diversity (6 – 14 %). The average values of the species richness and the relative diversity do not differ
significantly from each other. These results are consistent with the ecological characteristics of the
investigated associations.
Keywords: paludal communities, species richness, evenness, diversity.
Introduction
The aim of this study is to present the diversity two paludal plant associations
from the natural ecosystems from the left side of the Izvoru Muntelui-Bicaz reservoir. The
studied area is located on the south-western slopes of the Stânişoara Mountains. The
identified associations – Typhetum latifoliae Soó 1927 and Typhetum schuttleworthii Soó
1927 – appertain to the alliance Phragmition australis W. Koch 1926, order Phragmitetalia
australis W. Koch 1926, class Phragmitio-Magnocaricetea Klika et Klika et Novac
1941[9]. The diversity of these plant communities is important for their productivity. In
addition, diverse communities are generally more resilient to habitat disturbance [11].
Material and methods
The study of the vegetation from these natural ecosystems comprised
phytosociological methods recommended by The Central European Phytosociological
School, according to the principles and methodology developed by J. Braun-Blanquet and
J. Pavillard (1926)[1] and adapted by A. Borza (1934). The names of the associations were
selected after The Phytosociological Nomenclature Code developed by J. J. Barkman, J.

“Al. I. Cuza” University, Faculty of Biology, B-dul Carol I no.11, 700506 - Iassy, Romania
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Moraveç and Rauschert in 1986. The descriptions of the associations were made
considering the characteristic, dominant and differential species, and led to the construction
of the phytosociological tables The classification of the associations was made with
reference to synthetic works regarding the vegetation of Romania [3]. The chosen sample
areas were related with the vegetation types. Thus, for hygrophilous vegetation, the
sampled areas were 10 – 25m2. The relevés resulted from the investigation of the zones
considered characteristic for each association.
Specific quantitative contributions were rendered by the abundance-dominance
index, in conformity with the system of J. Braun-Blaquet and J. Pavillard. Abundancedominance scores were transformed in average percentages (+, 1, 2, 3, 4, 5 became 0.1%,
5%, 17.5%, 37.5%, 62.5%, and 87.5% respectively) [4].
Diversity was represented through species richness (S), Shannon Index (H) and
relative diversity (Hrel). The Shannon index formula is H=-Σ pi ln(pi) where pi – decimal
fraction of the i species individuals [5]. Using the value of H one can calculate the species
abundance equitability, or evenness, which reveals how different is the studied community,
compared to an ideal equitable community. The evenness formula is Hrel=H/Hmax (Hrel
value is between 0 – 1) where Hmax =ln(S) or the value of H calculated with the same
number of species, but equal pi values [5]. Another way to assess diversity was by
performing the SHE analysis (S = species richness, H = Shannon index diversity, E =
evenness). This technique [2, 7] allows the independent and yet simultaneous evaluation of
the species richness and evenness contributions to the community diversity. The diversity
measures used in SHE analysis are the above-mentioned S and H together with Buzas and
Gibson’s evenness (E) which was calculated with the equation E = e H/S where e is the
natural logarithm base. The advantage of this formula is that H can be decomposed as the
sum of ln(S)+ln(E) (eH=SE so H=ln(S)+ln(E)). Further more, because E≤1, ln(E) will be a
negative number. Therefore, H diversity equals its maximum value, ln(S), less the amount
of evenness, ln(E) [8, 10].
For the diversity measures statistical description we calculated the measures of the
central tendency, variability, and the confidence interval of the mean with 95% probability.
The significance of the differences between the diversities of the association was checked
with the Mann-Whithney U test [6].
Results and discussion
The plant communities of the association Typhetum latifoliae occur in shallow
ponds, 0.2 m deep, and on the edge of eutrophic ponds, on hydromorphic and rich in
nutrients soils. The differential and dominant species are Typha latifolia, Typha
angustifolia, and Alisma plantago-aquatica. They are accompanied by many hygrophilous
and meadow species.
The investigated communities were identified in the following locations: Varniţa
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forest road (Hangu village) and Potoci.
The diversity measures (Table 1., Figure 1.) show that relevé 1 was the most
divers, the richest in species (13 species) and had the highest relative diversity (11.7% of
the maximum diversity for the same number of species). Relevé 4 was more diverse then
relevé 2, although the latter was richer in species (12 species), because its evenness was
greater. Relevés 4 and 3 had the same species richness. However, the diversity of relevé 3
is decreased by its low evenness. Even though it had the highest evenness, relevé 5 was the
least diverse of all for the reason that it contained only 8 species.
The average density estimates revealed that the association Typhetum latifoliae
had a relative diversity of 6.5±4.1% and a species richness of 11±2.323 species.
Table 1 - Diversity measures of Ass. Typhetum latifoliae (H – Sahnnon index, Hrel –
relative diversity, E –evenness, S – species richness)
Relevé
1
2
3
4
5
Average
Confidence Level (95%)
H
0.3
0.129
0.117
0.18
0.062
0.158
0.112
Hrel
0.117
0.052
0.049
0.075
0.03
0.065
0.041
E
0.103
0.094
0.102
0.108
0.132
0.109
0.018
S
13
12
11
11
8
11.0
2.323
ln(E)
-2.264
-2.355
-2.281
-2.218
-2.017
-2.227
0.158
ln(S)
2.566
2.485
2.398
2.398
2.079
2.385
0.229
3
2
1
ln(S)
H
ln(E)
0
-1
-2
-3
5
3
2
4
1
Relevé
Figure 1 - SHE analysis of Ass. Typhetum latifoliae (1 – 5 – relevés in H ascending order,
H – Sahnnon index, Hrel – relative diversity, E –evenness, S – species richness)
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The association Typhetum schuttleworthii is less frequent than the previous one.
The plant communities of this association occur in depressions that become temporarily
flooded in spring [12]. The characteristic species is Typha schuttleworthiiI, which is
accompanied by many meadow plants with broad tolerance to hydrological conditions.
During our investigations, the communities were identified from the following
locations: Buhalniţa –Piciorul Vânăt forest road (marsh), Hangu, and Buhalniţa.
Table 2 - Diversity measures of Ass. Typhetum schuttleworthii (H – Sahnnon index, Hrel –
relative diversity, E –evenness, S – species richness)
Relevé
1
2
3
4
5
Average
Confidence Level (95%)
H
0.725
0.097
0.097
0.73
0.07
0.344
0.435
Hrel
0.302
0.039
0.039
0.294
0.032
0.141
0.178
E
0.188
0.092
0.092
0.173
0.119
0.133
0.056
S
11
12
12
12
9
11.20
1.619
ln(E)
-1.673
-2.388
-2.388
-1.755
-2.127
-2.066
0.422
ln(S)
2.398
2.485
2.485
2.485
2.197
2.410
0.155
3
2
1
ln(S)
H
ln(E)
0
-1
-2
-3
5
2
3
1
4
Relevé
Figure 2 - SHE analysis of Ass. Typhetum schuttleworthii (1 – 5 – relevés in H ascending
order, H – Sahnnon index, Hrel – relative diversity, E –evenness, S – species richness)
The SHE analysis (Table 2., Figure 2.) revealed that relevé 4 was the most diverse,
although it contains the same number of species (12 species) as relevés 2 and 4, because its
evenness is greater. Relevé 1 is almost as diverse as relevé 4, despite its lower species
richness (11 species), for the fact that it has the highest evenness. The low evenness is also
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responsible for the difference with regard to diversity between relevés 2 and 4. Relevé 5
has the lowest diversity because of its reduced species richness (9 species).
For the association, the average diversity estimates revealed that a relative
diversity of 14.1±17.8% and a species richness of 11.2±1.62 species.
The comparison of the diversity estimates of the investigated associations revealed
that the values were somewhat grater in Typhetum schuttleworthii than in Typhetum
latifoliae (Figure 3.). However, this difference proved not to be statistically significant
(U=12.0, p=0.917 for Shanonn index and relative diversity, U=11.0, p=0.753 for evenness,
and U=11.5, p=0.827 for species richness).
Figure 3 - Comparison of associations’ diversity estimates (H – Sahnnon index, Hrel –
relative diversity, E –evenness, S – species richness, tyf_lat – Ass. Typhetum latifoliae,
tyf_sch – Ass. Typhetum schuttleworthii).
These results are also supported by the ecological characteristics of the
investigated associations: Both of them contain mainly mesohygrophytes,
mesotermophytes and euryionic species [12].
The low diversity may be explained by the dominance of the characteristic species
whereas the other species are less abundant. This situation may be due to the hydrological
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conditions of the habitats in which they occur with alternatively flood and drought periods.
Conclusions
The diversity of the paludal plant communities from the left side of the Izvoru
Muntelui-Bicaz reservoir is relatively low, representing 6 – 14 % of the potential diversity.
Similarly, the species richness has relatively small values – around 11 species.
Some plant communities had unexpected diversities because of the relation
between the species richness and the evenness. Generally, that means that low evenness
values decreased high species richness values, and vice-versa.
The associations are not significantly different in regard to their diversity
estimates. Consequently, the diversity resemblance of the investigated associations is
consistent with their ecological characteristics.
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