BIOLOGY ORIGINAL ARTICLE
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35
Aspects of vegetation and soil relationshipsaround athalassohaline lakes of Wadi El-Natrun,
Western Desert, Egypt
Monier Abd El Ghani, Rim Hamdy*, Azza Hamed
The Herbarium, Faculty of Science, Cairo University, Giza 12613, Egypt
ABSTRACT
The relationship between soil parameters and vegetation around the inland saline lakes of Wadi El-
Natrun in the Western D esert of Egypt was studied. Twenty-five species in 22 stands constituted the
floristic composition included one tree, 3 annuals and 21 perennial herbs. The saline feature of
this habitat enabled some salt tolerant species to grow and flourish. Four species (Juncus acutus L. ,
J. rigidus Desf. , Cyperus laevigatus L. var. laevigatus and Phragmites australis (Cav.) Trin. ex Steud.
subsp. australis) were constantly recorded around the 7 studied lakes which exhibited wide ecologicaland sociological ranges, while 8 species were confined to only one lake (narrowest sociological range).
Based on their frequency values, classification of the recorded resulted in 5 vegetation groups. Each of
these groups was linked to one or more of the soil factors which determines its distribution. Application
of Redundancy Analysis (RDA) indicated that CaCO3, Ca+2, SO4
-2, NO3-, K+ and Cl- were the most
important soil variables affected the vegetation around the studied lakes. I t is recommended that
conservation measures should be taken to protect the remaining populations of Typha elephantinathroughout Wadi El-Natrun which represents its type locality from extinction.
Key words: Egypt; halophytes; Inland salt marshes; Redundancy analysis; Saline lakes; Salinity; Soil-
environment relations.
J Biol Earth Sci 201 4; 4(1 ): B21 -B35
Original Submission: 1 1 November 201 3; Revised Submission: 1 0 January 201 4; Accepted: 1 4 January 201 4
Copyright © 201 4 Author(s). Journal of Biology and Earth Sciences © 201 4 Tomasz M. Karpiński. This is an open-access article
distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction
in any medium, provided the original work is properly cited.
http: //www.journals. tmkarpinski.com/index.php/jbes or http: //jbes.strefa.pl
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B21
Journal of Biologyand Earth Sciences
TMKARPIŃSKIPUBLISHER
ISSN: 2084-3577
* Corresponding author:
Rim Hamdy
E-mail : [email protected]
INTRODUCTION
Athalassohaline lakes are inland saline aquatic
environments with ionic proportions quite different
from the dissolved salts in seawater. They are tem-
porary bodies of water with sal inities >3gl-1 and lac-
king any connection to the marine environment [1 ].
Salt lakes are confined to dry regions of the world
where evaporation exceeds precipitation and where
they are often more abundant than fresh waters.
Saline lands are widely distributed globally and
make up about 1 0% of the Earth’s terrestrial surface
[2]. Inland saline lakes have received increased at-
tention in recent years due to their sensitivity to cl i-
matic change. Climatic conditions must reach a
certain degree of aridity effectively to remove water
by evaporation or freeze drying and so produce
progressively concentrated brine. Geochemical and
hydrological features are largely responsible for
control l ing the concentration and composition of the
resulting brine [3, 4]. Changes in evaporation and
precipitation can affect the physical and chemical
conditions in such lakes [5-9].
In Egypt, certain areas are lower than the sea
level and constitute depressions in the desert west
of Nile Delta. They include some water bodies cha-
racterized by high salinity and considered as a va-
luable economic resource that can be developed for
better exploitation. One of these depressions is
Wadi El-Natrun (23 m below sea level) which consi-
dered among the important depressions in the We-
stern Desert for land reclamation and uti l ization.
The presence of irrigation water as underground
water of suitable quality, the existence of natural
fresh water springs and the availabi l ity of some mo-
isture contained in the sandy layers above the shal-
low water table southwest of the depression are the
main reasons for the importance of Wadi El-Natrun
region [1 0].
The inland saltmarshes of the Western Desert of
Egypt are found in the form of Sabkhas around the
lakes, springs and wells of the oases, e.g. Siwa,
Dakhla, Kurkur, Dungul, etc. and the depressions,
e.g. Qattara, Wadi El-Natrun, El-Fayum, etc. Being
lower in level than the surrounding territories, the
inland saltmarshes are characterized by a shallow
underground water table. In certain instances, the
underground water is exposed forming lakes of
brackish or saline water [11 ]. The formation of this
sal ine is due to the uncontrol led spil l ing of water
and flooding of the plains, or to the water table
El Ghani et al. Vegetation and soil relationships around athalassohaline lakes of Wadi El-Natrun, Egypt
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35 B22
which is being close to the ground [1 2]. The vege-
tation around these lakes has a patchy structure:
different patches contain different species (or so-
metimes one species) and even different growth
forms [1 3].
Wadi El-Natrun is characterized by small di-
sconnected lakes in its bottom, al igned with its ge-
neral axis in the north-west direction except Lake
Al-Gaar [1 4]. These lakes receive a limited supply
of groundwater which seeps into the depression.
Since the evaporation rate is high and the lakes l ie
in closed basins without outlet, the water in the la-
kes has a high salt concentration and are suscepti-
ble to marked fluctuations in level and salinity.
Although different colourations due to microbial po-
pulations are indicated by some of the lakes names
(Hamra = red, Khadra = green, Bida = white), the
colouration of the lakes is not constant, but is sub-
ject to seasonal changes. There is a discrepancy
regarding the number of lakes in Wadi El-Natrun,
which ranged between two to sixteen [1 5]. Yet, Za-
hran and Wil l is [1 4] reported the presence of 8 prin-
cipal lakes for a distance of about 30 km; perma-
nent water in al l or some of their parts; from south
to north: Fasida, Um Risha, Al-Razoniya, Abu-Gu-
bara, Hamra, El-Zugm, Al-Bida, Khadra and Al-
Gaar, noting that Abu Gubara and Hamra form one
lake in the summer. The Natrun occurs in solution in
the lakes, forms a crust around the edges of the la-
kes and in deposits on their bottom. Natrun deposits
have long been known and were used by the an-
cient Egyptians in the manufacture of glass, rem-
nants of which are sti l l found in the southern part of
the depression.
Compared to studies of coastal marshes, l ittle
attention has been paid to inland saline landscapes
[1 6, 1 7]. The earl iest account of the vegetation of
the salines in Wadi El-Natrun was that of Stocker
[1 8]. The plant growth was studied around some re-
presentative lakes, providing the actual distribution
of plants around the lakes using aerial photos of two
lakes [1 9]. The phytosociology of the wetland vege-
tation revealed the presence of three distinct com-
munities in addition to two species of common
occurrence with no sociological affi l iation (Cyperuslaevigatus and Juncus acutus) [20]. Some studies
were undertaken; focused on the vegetation around
the inland saline lakes of Wadi El-Natrun [21 , 22]
Typha elephantina Roxb. and Cyperus papyrus at
the shore of Um Risha Lake associated with some
water loving plants has been reported [23, 24]. The
human impact revealed that Wadi El-Natrun repre-
sents a raw grazing ecosystem and ecological ly
fragile with unique features and resources [1 0]. In
addition some studies recorded natural and cultiva-
ted land cover types in the area between 1 997 and
2000, as well environmental indices from DEM, cl i-
mate atlas data, land-use observation and soil
sampling were recorded [25, 26].
In a previous work [27], the spatial distribution of
the flora of Wadi El-Natrun within its various habi-
tats, and its changes throughout the last 7 decades
was investigated. This study aims to recognize and
analyze the floristic diversity and variations in the
vegetation around the inland saline lakes of Wadi
El-Natrun, and to assess the environmental factors
that affect their species distribution.
The study area
Wadi El-Natrun is a narrow depression located in
the west of the Nile Delta, approximately 11 0 km
northwest of Cairo between longitudes 30° 80' 20"
and 30° 82' 90"E and latitudes 30° 81 ' 60" and 30°
83' 20"N (Figure 1 ). The total area of Wadi El-Na-
trun is approximately 281 .7 km2, extending in a
NW–SE direction. The origin of the underground
water in Wadi El-Natrun is seepage from the Nile
El Ghani et al. Vegetation and soil relationships around athalassohaline lakes of Wadi El-Natrun, Egypt
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35 B23
stream, because of its proximity and low level. A
series of isolated saline lakes occupy the axis of the
depression. The water level in the lakes fluctuates
seasonally along the year rising up in winter and
fal l ing down in summer but never get dry, and ran-
ges from 1 6 m in Zagig Lake to 23 m in Al-Gaar and
Fasida Lakes (Figure 1 ). Wadi El-Natrun area is re-
garded as an extremely arid region where mean
annual rainfal l , evaporation, and temperature are
41 .4 mm, 11 4.3 mm, and 21 °C, respectively (Egyp-
tian Meteorological Authority, 2006).
The water enters the lakes in two ways, as
springs in some of the lakes and as very small stre-
ams or trickles found on the sloping edges of the
lakes which find their way directly to the lakes. The
origin of the water entering the depression has been
discussed [28-31 ].
Also the geology of Wadi El Natrun has been
studied by many authors [29, 32, 33]. In general,
the area is covered by Quaternary lake deposits
and old al luvial deposits of sand and gravel laid
when the sea encroach the area and the Nile flowed
through it. The lake deposits and alluvium are un-
derlain by l imestone of Miocene, Oligocene and
Pliocene ages.
The dominating land-use practice is grazing and
Fig. 1. Schematic map ofWadi El-Natrun, showing the position of the studied lakes.
El Ghani et al. Vegetation and soil relationships around athalassohaline lakes of Wadi El-Natrun, Egypt
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35 B24
using the electric conductivity. Sulphates were de-
termined gravimetrical ly and the soluble sulfates
precipitated as barium sulphate. Sodium and po-
tassium ions were determined using a flame photo-
meter. Calcium and magnesium ions were deter-
mined by titration with EDTA. The estimation of
chlorides in the soil extract was carried out by titra-
tion methods against si lver nitrate (AgNO3) using
potassium chromate (K2Cr2O7) as an indicator. So-
luble nitrogen including ammonia and nitrate in soil
was determined using Kjeldahl method.
Data analysis
A floristic data matrix (25 species × 22 stands)
was subjected to classification by cluster analysis of
the computer program CAP (Community Analysis
Package) version 1 .2 [40] using the minimum va-
riance as an algorithm, and a dendrogram had been
presented. The vegetation groups produced from
cluster analysis was then subjected to ANOVA
(One-Way Analysis of Variance) based on soil va-
riables to find out significant variations among gro-
ups. The default option of the computer program
CANOCO software version 4.5 for window was
used for al l ordinations [41 ].
Indirect gradient analysis was performed using
Principal Components Analysis (PCA), and the di-
rect gradient analysis by Redundancy Analysis
(RDA). Seventeen environmental variables were in-
cluded in RDA: pH, electric conductivity (EC), nitra-
tes (NO3-), calcium carbonate (CaCO3), sodium
(Na+), potassium (K+), calcium (Ca+2), magnesium
(Mg+2) , chloride (Cl-), sulphates (SO4-2), ammonium
(NH4+), bicarbonates (HCO3
-), organic matter (OM),
fine sand, coarse sand, si lt and clay. Due to high in-
flation factors, electric conductivity, fine sand, si lt
and clay were excluded from the analysis. Al l data
variables were assessed for normality (SPSS for
windows version 1 7.0) prior to the RDA analysis,
and appropriate transformations were performed
when necessary to improve normality according to
Zar [42]. The relationships between vegetation gra-
dients and the studied environmental variables can
be indicated on the ordination diagram produced by
RDA biplot. The exploratory RDA was evaluated
using interest correlations and RDA axes were eva-
luated statistical ly by means of a Monte Carlo per-
mutation test (499 permutations) [43].
Mapping the vegetation changes around some
selected saline lakes (wet pastures) were based on
the estimation of distances between different belts
cutting. Wadi El-Natrun is a good source of forage,
based on the palatable salt marsh vegetation cover
(77%), and these resources are currently used su-
stainable by the local inhabitants. However, areas of
natural forage that serve as rangelands are subjec-
ted to several types of degradation, overgrazing,
removal for agriculture and fragmentation by roads
network and urban sprawl [1 0]. The wadi can be
best described as a raw grazing ecosystem for ra-
ising l ivestock (such as: goats, sheep, cows and
camels) noting that each type of l ivestock has a
grazing behaviour different from the other. Expan-
ding human demand and economic activities are
putting constantly increasing pressure on land and
other particular natural resources in the area cre-
ating suboptimal use and even destruction.
MATERIALS AND METHODS
Data collection
Between 2008 and 2011 , 22 randomly chosen
stands, with certain degree of homogeneity, were
permanently visited to study the vegetation and flo-
ristic composition around the studied 7 lakes (Figu-
re 1 ). The number of studied stands around each
lake varies and depends on the vegetation hetero-
geneity and species dominance. Due to inaccessi-
bi l ity to Lake Fasida, 2 stands were available.
Within each stand, species present were recorded,
and its frequency (F%) was calculated. Taxonomic
nomenclature fol lows Täckholm and updated by
Boulos [34-38].
Soil samples were collected from each stand at
three depths: 0-1 0, 1 0-25 and 25-50 cm. The sam-
ples were pooled together forming one composite
sample, spread over sheets of paper and left to dry
in the air. Dried soils were passed through 2 mm
sieve to remove gravel and debris, and then packed
in paper bags for physical and chemical analysis.
Soil textural analysis was determined by the hydro-
meter analysis method, and the results were used
to calculate the percentages of sand, si lt and clay).
Organic matter was determined by drying and igni-
tion at 600°C for 3 hours, and CaCO3 content was
determined volumetrical ly using Coll in's calcimeter
apparatus. Soluble bicarbonates were determined
[39]. Soil extracts were prepared and then used in
order to determine chemical analysis. Soil reaction
(pH) was measured in soil water extract (1 :2.5)
using a Beckman pH meter. The electrical conducti-
vity (EC) was measured in soil water extract (1 :5)
El Ghani et al. Vegetation and soil relationships around athalassohaline lakes of Wadi El-Natrun, Egypt
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35 B25
(zones) by using a meter tape and walking.
RESULTS
Floristic variations
Table 1 demonstrated the floristic analysis of the
25 species of vascular plants from 22 stands asso-
ciated with the studied seven lakes in the study
area, and distributed as fol lows: one tree, 3 annuals
and 21 perennial herbs. The latter included Juncusacutus, J. rigidus and Cyperus laevigatus var. laevigatus as the common species. I t is obvious that thedesert outskirt surrounding the lakes favor the
growth of some perennials such as Phragmites australis, Imperata cylindrica (L.) Rauesch. , Alhagigraecorum Boiss. and Desmostachya bipinnata (L.)
Stapf. Furthermore, the saline feature of this habitat
enabled some salt tolerant species to grow and flo-
urish such as Typha domingensis (Pers.) Poier. ex
Steud. , Typha elephantina and Spergularia marina(L.) Bessler. Among the less common species Sonchus maritimus, Panicum turgidum Forssk. and Cynodon dactylon L. were noticed. Six species were
occasionally recorded (recorded in one stand)
and/or very modestly represented. These included
xerophytic species such as Sporobolus spicatus(Vahl) Kunth and Centropodia forskaolii (Vahl) Copeand water loving species such as Zannichellia palustris L. , Berula erecta (Koch ex Rchb.) Rchb.f. and
Samolus valerandi L.The performance of species within the different
lakes revealed that four species (Juncus acutus, J.
rigidus, Cyperus laevigatus var. laevigatus and
Phragmites australis subsp. australis) were con-
stantly recorded around the 7 lakes which exhibited
wide ecological and sociological ranges. On the
other hand, 8 species were confined to only one
lake (narrowest sociological range) where Panicumturgidum and Centropodia forskaolii were confinedto Al-Gaar Lake, Samolus valerandi and Berulaerecta to Hamra Lake, Sporobolus spicatus and Digitaria sanguinalis (L.) Scop. to Um Risha Lake,
Solanum elaeagnifolium to El-zagig Lake, and the
water-loving plant Zannichellia palustris to Al-Bida
Lake (Table 1 ).
Classification of the vegetation and soil charac-
teristics around studied lakes
Based on their frequency values, classification of
the recorded 25 species from 22 stands around the
7 lakes resulted in 5 vegetation groups (A-E), and
named after the dominant and highly frequent spe-
cies. Based on the cluster analysis outcome, the
dendrogram in Figure 2 was elaborated, and the
characteristic species of each group was displayed
in Table 2. Clearly, pH (p = 0.006), percentages of
coarse sand (p = 0.020), and silt (p = 0.045), sho-
wed significant differences between the identified
vegetation groups (Table 3).
Group A: Juncus rigidusDesmostachya bipinnataTypha elephantinaArundo donax L. group
It is characterized by the dominance of Juncusrigidus and Desmostachya bipinnata together with
Fig. 2. Cluster analysis of the 22 stands around the studied 7 lakes of Wadi El-Natrun. (A – E) are the
5 separated vegetation groups.
El Ghani et al. Vegetation and soil relationships around athalassohaline lakes of Wadi El-Natrun, Egypt
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35 B26
Table 1. Floristic composition of the selected 22 stands of the lakes habitat; + = presence; - = absence.
El Ghani et al. Vegetation and soil relationships around athalassohaline lakes of Wadi El-Natrun, Egypt
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35 B27
Table 2. Overall composition and distribution of the associated species
within the five vegetation groups in Lakes habitat of Wadi El-Natrun.
Figures in bold are the leading dominant species with higher presence
percentages (P%).
Typha elephantina and Arundo donax in stands 11 5and 11 6 which located in Al-Gaar and Al-Bida La-
kes. Among the associated species; Tamarix nilotica, Alhagi graecorum, Panicum turgidum, Cyperuslaevigatus var. laevigatus and Imperata cylindricacan be enumerated. Centropodia forskaolii showeda certain degree of fidel ity to this group. Organic
matter, fine sand, coarse sand, pH and bicarbonate
attained their highest values in this group (Table 3).
Group B: Typha domingensis groupThis group (1 2 species) characterized the three
stands (111 , 1 1 8 and 1 20) from Um Risha, El–Ra-
zoniya and El-Zagig Lakes with high soil contents of
sulphates, Ca+2, Mg+2, Na+, K+ and Cl- ions. Typhadomingensis was the characteristic species, while
the common associated species included Alhagigraecorum, Juncus rigidus, Juncus acutus, Cyperuslaevigatus var. laevigatus, Phragmites australis
El Ghani et al. Vegetation and soil relationships around athalassohaline lakes of Wadi El-Natrun, Egypt
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35 B28
Table 3. Mean values, standard deviations (±SD) and ANOVA F values of the soil variables, species richness (SR)
and Shannon's index (H’) in the stands representing the five vegetation groups obtained by cluster analysis in the lakes
(* = P ≤ 0.05 and **= P ≤ 0.01 ). CS = Coarse Sand; EC = Electric Conductivity; FS = Fine Sand; OM = Organic Matter.
subsp. australis, Desmostachya bipinnata, Arundodonax and Cynodon dactylon were recorded. Digitaria sanguinalis and Senecio glaucus L. subsp. coronopifolius (Maire) C. Alexander were confined to
this group. I t is interested to note the complete ab-
sence of Typha elephantina.Group C: Juncus acutusCyperus laevigatus var.
laevigatus group
This group characterized by Juncus acutus andCyperus laevigatus var. laevigatus in 7 stands fromfive lakes (Al-Bida, El–Razoniya, Al-Gaar, Fasida
and Um Risha) with soil rich in NH4+ and clay con-
tents (Table 3). Juncus rigidus and Alhagi graecorum were the co-dominant species of this group
(F=85.7% and 71 .4%, respectively). Among the as-
sociated species; Tamarix nilotica, Phragmites australis subsp. australis and Aeluropus littoralis
(Gouan) Parl. were recorded. The complete absen-
ce of Typha elephantina, Arundo donax, Panicumturgidum, Imperata cylindrica, Centropodia forskaolii, Cynodon dactylon, Senecio glaucus subsp. coronopifolius and Digitaria sanguinalis can also be
noticed.
Group D: Juncus acutusImperata cylindrica group
This is the most diversified (1 5 species) among
the recognized groups. I t is characterized by the
dominance of Juncus acutus and Imperata cylindrica in 4 stands (1 03, 1 1 7, 1 1 0 and 1 22) on soil rich inNO3
- content (49.73 ± 3.08). The dominant species
showed their highest abundance in this group, to-
gether with Cyperus laevigatus var. laevigatus and
Phragmites australis subsp. australis. Sporadic
species were Typha domingensis, Desmostachyabipinnata, Sonchus maritimus and Cynodon dacty
El Ghani et al. Vegetation and soil relationships around athalassohaline lakes of Wadi El-Natrun, Egypt
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35 B29
Fig. 3. Principal Component Analysis (PCA) scatter plotfor the 22 stands around the lakes habitat in Wadi El-
Natrun along the first two axes, with the vegetation
groups (A-E) superimposed.
lon. Five species showed a degree of consistency tothis group: Zannichellia palustris, Sporobolus spicatus, Samolus valerandi, Berula erecta and Solanumeleagnifolium Cav.
Group E: Juncus rigidusJuncus acutus groupThis group comprised 1 3 species from 6 stands
inhabiting soil rich in CaCO3 and silt content (Table
3), where Juncus rigidus and J. acutus were the do-minant species (Table 2). Typha domingensis was
the most common species. Associated species inc-
luded Imperata cylindrica and Typha elephantina.Occasionally recorded species (present in only one
stand; P=1 6.6%) was Aeluropus littoralis. Notably,Arundo donax, Centropodia forskaolii, Desmostachya bipinnata, Tamarix nilotica (Ehrenb.) Bunge,
Alhagi graecorum, Cynodon dactylon, Senecio glaucus subsp. coronopifolius, Digitaria sanguinalis,Zannichellia palustris, Sporobolus spicatus, Samolusvalerandi, Berula erecta and Solanum eleagnifolium.Ordination of stands
Principal Components Analysis (PCA) scatter plot
showed the segregation of the 5 groups along the
first 2 axes (Figure 3). Stands of group (A) occupied
the highest position in the ordination plan. This gro-
up was dominated with Juncus rigidus, Desmostachya bipinnata, Typha elephantina and Arundodonax. Stands of the vegetation groups (D) and (E)which dominated with Juncus acutus, J. rigidus andImperata cylindrica occupied the positive side of
axis 1 , while stands of the vegetation groups (B)
and (C) that dominated with Typha domingensis,Juncus acutus and Cyperus laevigatus var. laevigatus occupied the other negative end.
Soil-vegetation relationships
The relationships between the results of vegeta-
tion and soil analyses using Redundancy Analysis
(RDA) with the 5 vegetation groups (A-E) were
shown in Figure 4. During this analysis, five varia-
bles showed high inflation values (Ec, Na+, fine
sand, si lt and clay), so they are discarded from the
analysis. I t can be noted that stands of group C
were affected by ammonia; stands of groups D and
E were correlated with pH and CaCO3 while those
of group B were affected by SO4-2 and Ca+2. Two
stands of group A exhibited high correlation to or-
ganic matter and coarse sand. In addition to other
stands of groups C and E were correlated with
HCO3-.
The successive decrease of eigenvalues of the
Fig. 4. The RDA ordination biplot of the first 2 axes
showing the distribution of 22 stands around the lakes,
with the examined soil variables.
El Ghani et al. Vegetation and soil relationships around athalassohaline lakes of Wadi El-Natrun, Egypt
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35 B30
four RDA axes (0.1 40, 0.1 1 5, 0.090 and 0.077 for
axes 1 , 2, 3 and 4, respectively) that i l lustrated in
Table 4 suggesting a well structured data set. The
species-environment correlations were high for the
four axes, explaining 67.5% of the cumulative va-
riance. These results suggested an association be-
tween vegetation and the measured soil variables
presented in the biplot. The inter-set correlations
resulted from RDA of the examined soil variables
were shown in Table 4. Axis 1 was positively corre-
lated with CaCO3, while negatively correlated with
Ca+2, SO4-2 and NO3
-. The RDA axis 1 can be inter-
preted as CaCO3-NO3- gradient. Axis 2 was positi-
vely correlated with coarse sand, and negatively
correlated with CaCO3, Ca+2, K+, Cl-, SO4
-2, and
NO3-. The RDA axis 2 can be interpreted as coarse
sand-Cl- gradient. A test for significance with an
unrestricted Monte Carlo permutation test found the
F-ratio for the eigenvalue of RDA axis 1 and the
trace statistics to be significant (p=0.03), indicating
that the observed patterns did not arise by chance.
The ordination biplot diagram (Figure 4) was similar
to the pattern of ordination obtained from the flori-
stic PCA (Figure 3), with most of the sites remaining
in their respective cluster group.
Mapping of vegetation around lakes
Figures 5 and 6 are sketch drawings exemplify
zonation of vegetation around two saline lakes (wet
Table 4. Redundancy analysis results showing the inter-set correlations of the soilvariables, together with eigenvalues and species-environment correlation of the
studied lakes. For abbreviations and units, see Table 2. *= P ≤ 0.05.
Fig. 6. Vegetation mapping around El-Hamara Lake
showing the distribution of the dominant species.
Fig. 5. Vegetation mapping around El-Hamara Lake
showing the distribution of the dominant species.
El Ghani et al. Vegetation and soil relationships around athalassohaline lakes of Wadi El-Natrun, Egypt
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35 B31
ties. This difference may be related to the method of
vegetation analysis that fol lowed in each study. The
significant role of abiotic factors that control l ing the
distribution of halophytes in sal ine habitats was stu-
died [47-49]. Redundancy analysis (RDA) of the
present data set demonstrated the effect of edaphic
factors on the spatial distribution of plant communi-
ties around the lakes. CaCO3, Ca+2, K+, SO4
-2, NO3-
and coarse sand were of significant variations
(p<0.05) among the 5 vegetation groups (communi-
ties). RDA axis 1 can be inferred as CaCO3-NO3-
gradient, while RDA axis 2 showed a gradient of
coarse sand and Cl- gradient. These results were in
consistent with those of El-Sawaf and Emad El-
Deen [20]. On the contrary, around the inland sali-
ne lakes in Dakhla and Siwa Oases of the western
Desert [50], 1 2 halophytic plant communities l inked
to two main habitats (wet-moist and dry-mesic)
were identified, with few communities were in com-
mon with Wadi El-Natrun salines. Alhagi graecorum,Tamarix nilotica, Cressa cretica, Juncus rigidus andPhragmites australis were the most common in thetwo oases. Whereas communities of Cyperus laevigatus, Suaeda aegyptiaca, Suaeda vermiculata,Typha domingensis and Aeluropus lagopoides wererecorded from Dakhla Oasis, Cladium mariscus andArthrocnemum macrostachyum communities were
recorded from Siwa Oasis. The most important
edaphic variables affecting the distribution and
structure of the plant communities were: sal inity,
moisture content and fine fractions, yet CaCO3 con-
tent seem to be more effective in the Dakhla Oasis.
When studying the saltmarsh communities of the
western Mediterranean coastal desert [51 ], they
pointed out that sal inity; concentration of different
ions and the periodical variation in the water table
determine the distribution of species and the diffe-
rences between communities. They also conclude
that the saltmarsh vegetation in this part of the co-
untry represents a transition from the western com-
munities in North Africa and those characteristic of
the Eastern Mediterranean region.
From a phytosociological point of view, the pure
community of Typha elephantina existed under the
conditions of deep fresh water (total soluble salts c.
2000 ppm) around Al-Gaar Lake. Typha domingensis replaced T. elephantina when the total soluble
salts reached 4000 ppm coupled with basin eleva-
tion. More accumulation of sand on the bank enco-
uraged Phragmites australis to grow [21 ]. Simpson
stated that Typha domingensis is more sensitive to
pastures); El-Hamra for the former and Um Risha
for the latter. These are the most common among
the lakes of Wadi El-Natrun.
ElHamra LakeA wide bare zone of barren soil devoid of vege-
tation surrounds the southern shore of this lake.
Thickets of Cyperus laevigatus var. laevigatus coverthe ground of the distant zone far away from the
shore. The latter zone was always wet, and the
plants were browed by goats and animals. A narrow
belt of Juncus acutus surrounds the outer l imits of
this zone. Along the eastern side, a pure zone of
Juncus acutus vertical ly traverses these two zones.Um Risha Lake
Apparently, the grass Desmostachya bipinnatalargely contributes to the vegetation zones around
this lake, with the absence of the sedge Cyperuslaevigatus var. laevigatus. Along the western side ofthe shore, Juncus actus zone was represented,
otherwise Alhagi graecorum zone were recognized.
A zone of barren soil separates the outer zone of
Juncus acutus from the inner Desmostachya bipinnata zone.
DISCUSSION
In total, 25 species were recorded, and repre-
sented the species composition around the inland
saline lakes in this study. The fewer number of spe-
cies (mostly salt-tolerant) may be attributed to the
high soil sal inity around the lakes. Such salinity
stress on floristic diversity in the study area and re-
lated areas was documented [44-46]. Application of
multivariate analysis techniques (classification and
ordination) to the floristic composition and soil fe-
atures around the lakes yielded five vegetation gro-
ups (communities):
(A) Juncus rigidusDesmostachya bipinnataTyphaelephantinaArundo donax,(B) Typha domingensis,(C) Juncus acutusCyperus laevigatus var. laevigatus,(D) Juncus acutusImperata cylindrica, and(E) Juncus rigidusJuncus acutus.
None of the obtained vegetation groups has
analogues in other former studies. Despite the dif-
ference in their dominating species, these commu-
nities are undoubtedly having the same floristic
composition of the previously recorded communi-
El Ghani et al. Vegetation and soil relationships around athalassohaline lakes of Wadi El-Natrun, Egypt
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35 B32
salt than Phragmites australis as the latter forms
well into Lake Mariut while Typha is present only
where the Lake receives fresh water from Mahmu-
diya canal [52]. El-Sawaf and Emad El-Deen reco-
gnized the disappearance of Typha species from
Hamra Lake where Phragmites australis was scat-
tered among the Juncus acutus plants as well as
higher elevations, near the road [20]. They also re-
cognized 3 distinct communities around the lakes:
(A) Juncus rigidusTamarix nilotica community, in-
habited soil with relatively high contents of Cl-, Na+,
SO4-2, pH and EC with high silt content and low
sand, related to the fairly sal ine habitats.
(B) Phragmites australisTypha elephantina com-
munity inhabiting swampy lands (border of the la-
kes) where there is a rich and continuous feed of
fresh brackish water. Soils showed low content of
Cl-, Na+, SO4-2, relatively high organic matter and
silt and low values of EC and sand.
(C) Nitraria retusaSporobolus spicatus community,
inhabited soil with low content of Cl-, Na+, SO4-2, re-
latively high organic matter and silt and low values
of EC and sand.
Boulos et al [21 ] reported that Juncus acutuscommunities were scattered among Cyperus laevigatus were they distributed as contour l ines paral lelto the lake bank, and both species decreased in
number and vigour by increasing the ground surfa-
ce unti l they disappeared. In the present study, Typha elephantina was represented in vegetation
group (A), with fewer individuals. I t is recommended
that conservation measures should be taken to pro-
tect and secure the remaining populations thro-
ughout Wadi El-Natrun which represents its type
locality from extinction [53].
Two species; Zygophyllum album and Nitraria
retusa deserve special comments. In Egypt, Zygo-
phyllum album is a species of wide ecological am-
plitude. I t was recognized by several habitats of the
country, such as in the l ittoral salt marshs [54], in
the inland desert, in the wadis of the l imestone ha-
bitat [55], in the sand dunes of the oases of the
Western Desert of Egypt [56]. Zygophyllum albumcommunity abounds in the sand formations west of
the lakes (e.g. Hamra and El-Rhazonia Lakes) fur-
ther than area occupied by Sporobolus spicatuscommunity and in water runnels l ined with sand de-
posits and dissecting the gravel deposits where the
salinity is lower [57]. El-Sawaf and Emad El-Deen
[20] recorded Zygophyllum album just as associated
species to community of Nitraria retusaSporobolus
spicatus. Nitraria retusa forms one of the main
scrubland types along the northern part of the Red
Sea littoral of Egypt, and is also common in the wa-
dis of the l imestone desert east of the Nile. Nitrariaretusa was recorded in some of the principal wadis
to the west of Hamra Lake and on terraces east of
El-Khadra and Al-Gaar lakes [58]. Boulos [21 ] re-
ported that Nitraria retusa dominated with increasedsalinity on the surface soil layer, where the under-
ground water table was deep. In this study, it is a
point of importance to recognize the disappearance
of Zygophyllum album and Nitraria retusa around
the studied lakes.
The zonation of saltmarsh vegetation is a uni-
versal phenomenon [1 7, 59, 60]. Concentric zona-
tion of halophytic communities around small lakes
and saltmarshes of the Egyptian oases and the
ring-shaped vegetation formations in NW-Egypt re-
sulting from different habitat gradients were descri-
bed [61 , 62]. The vegetation and flora of Qara Oasis
demonstrated four concentric zones of plant com-
munities bounding the oasis [63]. The zonation pat-
terns of the l ittoral salt marsh vegetation are mainly
influenced by the tidal phenomena, seven salt
marsh zones of plant communities around middle
lakes (Hamra, Zugm, Zagig, Al-Bida and El-Khadra)
of Wadi El-Natrun were observed [54, 57]: Swamps
of Typha elephantina and Phragmites australis, Cyperus laevigatus and Juncus acutus complex (wet
salt marsh), Sporobolus spicatus community, Desmostachya bipinnata community, Zygophyllum album community, Nitraria retusa community and a
community of Tamarix sp. , where the last five com-munity revealed as the dry salt marsh. He also re-
cognized the mosaic pattern of the vegetation which
means that the plant l ife is affected by several inte-
racting factors with no single dominant factor. In
Wadi El-Natrun, the lakes occupy the central part of
this depression, and bordered by saline which may
harbour different plant communities [1 9]. While the
conditions though different, yet vegetation zonation
is control led by seasonal fluctuations of water level
in the lakes and hence that of water table: shal low
in wet season and deeper in dry season. Under the
prevalent arid cl imate, evaporation causes the ac-
cumulation of salts at the ground surface forming
crusts. The other important factor is rel ief [64]. The
soil physical and chemical characteristics are appa-
rently one of the main factors influencing the plant
cover, distribution and also the zonal pattern of the
vegetation types [65].
1 0.
1 1 .
1 2.
1 3.
1 4.
1 5.
1 6.
1 7.
1 8.
1 9.
20.
21 .
22.
23.
24.
25.
El Ghani et al. Vegetation and soil relationships around athalassohaline lakes of Wadi El-Natrun, Egypt
Journal of Biology and Earth Sciences, 201 4, Vol 4, Issue 1 , B21 -B35 B33
1 .
2.
3.
4.
5.
6.
7.
8.
9.
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TRANSPARENCY DECLARATION
The authors declare no confl icts of interest.
AUTHORS' CONTRIBUTION
MAEG: Conception and design; MAEG and RH:
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