Soil Determinants for Distribution of Halocnemum
strobilaceum Bieb. (Chenopodiaceae) Around Lake Tuz, Turkey
Tug Gul Nilhan,
Yaprak Ahmet Emre
In this study we aimed to reveal the ranges and effectiveness
of soil parameters on the distribution of H. strobilaceum. Halocnemum
strobilaceum Bieb. is a widespread species in saline habitats and
the distribution pattern of this halophytic species around Lake Tuz in
Central Anatolia was examined according to the soil characteristics. pH,
electrical conductivity, soil humidity, salt percentage, soluble Ca2+,
Mg2+, Na+, K+, CO32–,
HCO3–, Cl– and SO42–
values, total cations, cation exchange capacity, sodium adsorption ratio,
exchangeable Na+, K+, Ca2+ and Mg2+
values were the examined soil properties. The most effective soil parameters
for flowering period were found as Na, SO4, total cations,
SAR and EC and for seed bearing period as EC, Mg, total cations, Cl, Na,
SO4 and salt (%) content of the soil.
In Turkey, 2-2.5 ha of the soils is saline or salt effected
(Munsuz et al., 2001) but the ecological studies on saline soils
and halophytes are limited. For the utilization of saline ecosystems,
their soil, vegetation and floristic characteristics and also the relationships
between them should be understood in detail. The changes in each components
of a natural ecosystem, especially plants and soil, lead to changes in
whole system gradually. For these reasons, the importance of separation
and classification of plant communities in the ecosystems, their limitations
as well as their relations with other components of ecosystem become more
clear (Jafariet al., 2003).
Saline habitats exhibit moisture and soil salinity fluctuations
throughout the year, this is one of the factors determining the distribution
of plants. The most important factors determining the plant distribution
in saline habitats are soil salinity, water availability and competition
(Ungar, 1987; Pujol et al., 2000). There is a zonation among halophytic
communities in coastal and inland salt marshes (Chapman, 1974). Around
Lake Tuz, there is an obvious plant zonation according to the changes
in soil salt content and type. H. strobilaceum occupies in almost
pure stands in the coastal and inland salt steppes and marshes and occasionally
occur with other species (Pujol, 2000; Danin, 1981). It is a monotypic
perennial species, very frequent from South Europe through Asia to Mongolia
and North Africa between 0-1000 m (Jalas and Suominen, 1980; Freitag,
Different studies have revealed that although competition
influences the growth and distribution of the plants, soil characteristics
are of high importance in distribution of halophytic plants (Jafari et
al., 2003). Although it was known that the H. strobilaceum is
a halophytic species it can spread at the areas with relatively low saline
soils around Lake Tuz. With this study it was aimed to find out the soil
parameters and their ranges that were effective on the distribution of
Lake Tuz is the second largest lake in Turkey and is situated
at 38°25`-39°10` N and 35°5`-33°48` E and at the altitude of c.910 m.
It was declared as a Specially Protected Area in 2000 because of its high
biodiversity and the endemism ratio. Lake Tuz is on the route of migrating
birds and provides nesting and breeding area for them. Lake Tuz is a closed
saline lake of hypersaline-alkaline with the depth of 1 m. It is fed almost
entirely by ground water inflows and rain flows in winter and more than
half of the lake area dried out in summer season. The salinity of the
lake was measured as 83% at the eastern part of the lake in 1991 (Kashima,
MATERIALS AND METHODS
Brief description of the study area: The study area is under the
influence of semi-arid very cold Mediterranean climate (Emberger, 1932).
The annual total precipitation of the area changes between 326 and 387
mm. The ranges of mean, mean minimum and maximum temperatures are as follows
respectively; 10.2-12.1, -6- -3.8, 29.8-30.7°C. The precipitation regime
of the area is SpWFSu and belongs to the East Mediterranean precipitation
regime type 2.
The localities where the H. strobilaceum specimens
collected are as follows; Kulu N 38° 56.247` E 033° 18. 943` (1st zone),
Cihanbeyli N 38° 45.112` E 033° 04.566` (1st and 2nd zone), Sereflikochisar
N 38° 52.441` E 033° 25.547` (1st, 2nd and 3rd zone), Aksaray N 38° 39.069`
E 033° 41.083 (1st and 2nd zone). The geological units of the surrounding
area of the lake are mainly composed of paleozoic metamorphic schists,
Mesozoic limestone and ophiolite, neogene sedimentary rock and tertiary
and quaternary volcanic sediments from mountains Erciyes, Hasan and other
volcanoes (Ketin, 1963). Hydrologically it is a closed basin, except for
some karstic sinkholes.
Field studies and soil analysis: The soil samples and plant specimens
were collected and the distribution of H. strobilaceum around Lake
Tuz was defined between 2003 and 2004. During the winter period because
of frost and snow cover soil samples were omitted. The flowering and seed
bearing periods of H. strobilaceum were determined. The distribution
pattern of plants around Lake Tuz is very homogeneous therefore the selected
regions represent its ecology. During the selection of the localities,
the authors tried to find the most isolated parts with less anthropogenic
influences on the distribution of H. strobilaceum. For this reason,
8 localities were selected for soil sampling where H. strobilaceum
was spread. Although Lake Tuz is a specially protected area, human impact
on the ecosystem is very clear. This area is one of the most important
salt works of Turkey, there is also agricultural and cattle breeding activities.
According to the field surveys 3 zones were determined, the closest one
was named as 1st zone and then 2nd and 3rd. Four of the localities were
from the 1st zone, 3 of them from the 2nd and 1 of them from the 3rd zone.
The cover abundance scale of H. strobilaceum around
Lake Tuz were determined according to Braun-Blanquet (1932).
Soil samples were taken from 0-20 cm depth, air dried and
passed through 2 mm sieve before laboratory analysis. The analysis conducted
to determine the soil characteristics were; saturation with water, electrical
conductivity (EC), pH of saturated paste and saturation extract, soluble
anions and cations (Na+, K+, Ca2+, Mg2+,
Cl–, HCO3–, CO32–
and SO42–), exchangeable anions and cations (Na+,
K+, Ca2+, Mg2+), cation exchange capacity
(CEC) and humidity.
Saturation paste was prepared from 200 g 2 mm sieved soils.
Soil moisture was determined by weighing of 4 g soil before and after
overnight waiting in oven. The saturation paste extracted under partial
vacuum at 2-4 atm pressure used for the determination of dissolved salts
and soil pH. Electrical Conductivity (EC) and pH were determined by using
Electrical Conductivity meter and pH meter, respectively (Richards, 1954).
The soluble sodium and potassium by flame photometer soluble calcium and
magnesium amounts were also determined. Carbonate and bicarbonate contents
of the soil samples were determined by titration with H2SO4.
For the determination of chloride soil samples were titrated with AgNO3.
The sulphate amounts of the soil samples were determined mathematically
by subtraction of total anions from total cations. The exchangeable sodium,
potassium, calcium, magnesium amount were determined according to Richards
(1954). The boron content of the soil samples was determined spectrophotometrically
(indicate the instrument). The cation exchange capacity was determined
according to the sodium acetate method (Bower et al., 1952). All
the soil analysis and measurements were triplicated and the average values
were used in the statistical analysis.
Statistical analysis: The soil analysis results were evaluated
with SPSS 13 and the Principal Component Analysis was used to determine
the most effective factors at flowering and seed bearing periods.
RESULTS AND DISCUSSION
During the field surveys, 3 zones were observed around the
Lake Tuz according to the salt concentration of the soil. Within these
zones H. strobilaceum is the dominant plant species at the first
zone which is the closest one to the lake. At the first zone H. strobilaceum
is either the only species or present together with Salicornia europaea
L. sl. At the second and third zones, the population density of H.
strobilaceum decreased. According to the vegetation analysis the abundance-cover
ratios of H. strobilaceum at these 8 locations can be show from
The ranges of soil parameters examined at the areas where
H. strobilaceum is distributed are presented in Table
2. The maximum, minimum and mean values of the soil parameters of
9 months from the localities where
||Abundance-cover values of H. strobilaceum
||Monthly ranges of soil parameters
H. strobilaceum spread were used to define the ranges
of these parameters. According to Table 2 it can be understood that H.
strobilaceum has a wide range of ecological tolerance for the mentioned
According to the field studies the flowering and seed bearing
periods range from August to October. The soil parameters of these months
were used in statistical analysis for the determination of the most effective
factors on development and distribution of H. strobilaceum. The
values of flowering and seed bearing periods were evaluated with SPSS
13 by using Principal Component Analysis. For the flowering period as
a result of PCA, it was found that 96.85% of the variance was explained
by 5 factors which were meaningful according to eigenvalues (Table
3). The first factor explained 22.078% of the total variance. The
first and second factors defined 42.815% of total variance and first,
second and third factors explained 61.815% of the total variance. The
soil determinants effective on the first factor were found as soluble
Na+ and SO42–, total cations, SAR and
EC. The ones that were effective on the second factor were exchangeable
Ca2+ and K+, exchangeable Mg2+ and Na+,
soluble Ca2+ and saturation with water. For the third factor
effective on the soil variables were CEC and B (Table 4).
According to the PCA results for seed bearing period, the first factor
explained 45.165% of the cumulative variance. The statistically meaningful
4 factors according to their eigenvalues explained 95.658% of cumulative
variance (Table 5). First and second factors explained
60.254% of total variance. The soil variables related with first factor
were EC, total cations, salt percentage and soluble Mg2+, Cl–,
Na+, Ca2+ and SO42–. Cation
Exchange Capacity (CEC), exchangeable K+, humidity, saturation
with water and pHmud were related with the second factor. In
the view of these results, it can be stated that the first factor that
was effective on distribution of H. strobilaceum are EC, Mg2+,
total cations, Cl–, Na+, Ca2+, SO42–
and salt percentage. The second factor is related with CEC, Kexc,
humidity, saturation with water and Mgexc (Table
H. strobilaceum is a halophytic plant which can grow
under highly saline conditions and is a weak competitor as the other halophytes.
Competition is one of the limiting factors determining the distribution
of halophytes at the soils where salinity is low (Bertness, 1991b; Pennings
et al., 2004; Ungar, 1998). The presence of H. strobilaceum
depends on soil parameters and competition. The population density of
H. strobilaceum decreases with decreasing salinity and increasing
competition. Our findings and observations support the results of Danin`s
(1981) on the H. strobilaceum
Variance (%) of each axis.
Flowering (Extraction method: Principal Component Analysis)
|Extraction method: Principal Component Analysis
Loading values of variations
explaining each of the components for flowering period
Extraction Method: Principal
Component Analysis. Rotation Method: Varimax with Kaiser Normalization.
a Rotation converged in 11 iterations
Variance (%) of each axis.
Seed bearing (Extraction method: Principal Component Analysis)
|Extraction method: Principal Component Analysis
individuals occupying around the small cavities where the
salt accumulation exists and prevents the germination and development
of other species.
It was found that there were no significant differences
between the recovery rate of germination and germination rate in distilled
water for H. strobilaceum (Pujol et al., 2000) which support
the results of our soil analysis used to define the ranges of soil parameters.
According to our results, the appropriate soil conditions for the growth
of H. strobilaceum differ extensively,
Loading values of variations
explaining each of the components for seed bearing period
Principal Component Analysis. Rotation Method: Varimax with
Kaiser Normalization. a Rotation converged in 6 iterations
which is in agreement with the germination results of Pujol
et al. (2000). Although the soil parameters are effective on the
distribution of H. strobilaceum, it can spread into the less salty
steppes around Lake Tuz if there was not a harsh competition.
The common factors effective on flowering and seed bearing
periods were found as EC, Na+, SO4– and
amount of total cations. These factors reflect soil salinity and its forming
components, respectively, are very effective on plant growth and adaptation,
under saline conditions.
Even though there are many studies on the zonation patterns
in saline habitats (Snow and Vince, 1984; Bertness and Ellison, 1987;
Bertness 1991a, b; Pennings and Callaway, 1992), the forces that mediate
these zonation patterns are still paradigm. As a result of these experimental
studies, it was found that there is an inverse relationship between competition
ability and stress tolerance, the more competitive plants occupy the least
saline habitats and the more salt tolerant species occupy the most saline
areas (Bertness, 1992; Pennings and Callaway, 1992; Pennings et al.,
2004). Plant composition and the distribution of species along the salt
gradient in saline habitats depend on multivariate factors like edaphic,
biotic and also the individual resistance of the plants (Pennings and
Callaway, 1992; Snow and Vince, 1984; Alvarez Rogel et al., 2001).
The distribution of H. strobilaceum depends on soil salinity and
competition; if the situation is not very competitive it can spread on
the soils where the salinity is relatively low. The population density
of H. strobilaceum decreases with decreasing soil salinity for
the determination of the factors causes this decrease there should be
some studies conducted on the interspecific competition. To find out the
importance of edaphic factors in plant zonation and pattern, transplant
experiments should be carried out.
This study was supported by Ankara University Scientific
Research Project 2003-07-05-079. The authors also thankful to Teoman Kankilic
for his kind help.
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