Rend. Fis. Acc. Lincei DOI 10.1007/s12210-017-0624-0

Relationships between soil and plant communities distribution throughout primary succession in deltaic plains of Go¨lyazi Natural Reserved Area (Terme/Samsun, Turkey) Hasan Korkmaz1 • Cebrail Yildirim2 • Erkan Yalc¸in1

Received: 21 December 2016 / Accepted: 20 May 2017 Ó Accademia Nazionale dei Lincei 2017

Abstract This study has been carried out to examine the driving forces of succession and the vegetation and pedological factors relationships, throughout primary successional processes in deltaic plain areas in Go¨lyazi Natural Reserved Area (Black Sea coast of Turkey). Determined to process and mechanisms of primary succession patterns, we analyzed cover-abundance of plant species and soil data in plots using multivariate classification (TWINSPAN) and ordination (DCA and CCA) techniques. The results of TWINSPAN indicated that the sample plots could be classified into six plant communities which belong to different succession stages and representing three successional main phase. It was identified that two communities belong to early mean phase, three communities belong to intermediate phase, and one community belongs to late main phase. We also measured 16 variables of soil in each community to examine the driving forces of succession and the vegetation and pedological factors relationships. The findings obtained from DCA and CCA analysis suggested that the most important environmental factors are affecting the process of succession are local microtopography, water table depth, EC, organic matter (%), CaCO3 (%), sNa and silt (%) of soil. Keywords Floodplain  Primary succession  Multivariate analysis

& Hasan Korkmaz [email protected] 1

Department of Biology, Faculty of Arts-Sciences, University of Ondokuz Mayis, 55139 Samsun, Turkey

2

Ministry of National Education, Atakum Cumhuriyet Anatolian College, Samsun, Turkey

1 Introduction Succession is universal process of formation development which is an orderly unidirectional process of community change in which communities replace each other sequentially until a stable (selfreproducing) community is reached (Clements 1916; Johnson and Miyanishi 2007) and it is one of the most important aspects of vegetation ecology (Liu et al. 2011). The floodplain areas such as Go¨lyazi Natural Reserved Area are defined as low lying land that are subject to inundation by lateral overflow water from rivers or lakes with which they are associated (Tockner and Stanford 2002). For many centuries, these forested areas in river valleys had been intensely occupied and used by humans. The evidence is obvious in active physiographic areas, dunes, strands, lakes, floodplains, bad lands, and etc., in areas disturbed by man. Most of them were transformed into agricultural lands or settlement zones (Leyer 2005). The hydrologic regimes of floodplain wetlands depend to varying degrees on flow in the main channel, making the wetlands particularly vulnerable to hydrologic changes resulting from flow regulation (Reid and Quinn 2004). These changes have caused fragmentation and the loss of 90% of floodplain forests in Europe. Today, floodplain forests are considered rare over most of the continent (Kopec´ et al. 2014). The floodplain forests along the great rivers, specifically alluvial forests are defined as important and protected under the Habitat Directive of the European Union (EU Council Directive 92/43/EEC of 21 May 1992 on the Conservation of Natural Habitats and of Wild Fauna and Flora, Annex I). According to the Bern Convention, the floodplain forests ecosystems are threatened (Kavgacı et al. 2016).

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2 Materials and methods

groundwater and a lot of drainage canals between October and April. Forest communities developed on raised and temporarily flooded portions, while the lowest portions of the study area were covered with shallow lagoons and drainage canals which were dominated by emergent herbaceous wetland communities. The study area is influenced by the rainy and cool Mediterranean climate and precipitation quotient (Q) is found to be 121.3 and belonging to marine first type of oceanic precipitation regime (August, Winter, Summer, Spring) (Akman 1990). The annual mean temperature is 13.8 °C (minimum 2.1 °C January; maximum 27.7 °C July), annual mean rainfall amount to about 922.1 mm. Almost all natural vegetation in the Yes¸ ilırmak Delta Plain has been destroyed or fragmented, because a large part of the Delta Plain is being used for agricultural purposes and human settlements. Moreover, large forestlands are degraded into grasslands and agricultural area because of intensive logging and poor management. The rest of the area is forested with Populus 9 canadensis, Fraxinus angustifolia in some sections and Pinus pinaster on the coastal sand dunes by Ministry of Forestry (Korkmaz et al. 2011). Whereas, natural properties of vegetation in the Go¨lyazi (Terme/Samsun) Natural Protected Area that formed eastern part of Yes¸ ilırmak Delta Plain was able to protect, because it was first declared as ‘‘natural protected area’’ in 1975, and then declared as ‘‘wildlife development area’’ in 2005 and ‘‘nature park’’ in 2016 by the Ministry of Forestry and Water Management. The study area was preferred owing to the fact that objective data could be collected about primary progressive successional process since it is a deltaic plain under special protection and it can represent the whole of the Yes¸ ilırmak Delta plain.

2.1 Study area

2.2 Data collection

Go¨lyazi natural protected area is constitute eastern part of the Yes¸ ilırmak Delta Plain which it largest delta plain in the Black Sea Region of Turkey (41°120 4700 –41°200 320 N; 36°490 1800 –37°010 1900 E). It is a Quaternarian deltaic plain and formed with alluvial materials carried by Yes¸ ilırmak River and Terme stream (Akkan 1970; Erkal 1993). The study area covers approximately 3306 ha area, a large part of which has hydromorphic and alluvial soils, and the part bordering the Black Sea is covered with coastal dunes approximately with a width of 150 m. Large proportions of the delta plain with an elevation between 0 and 10 m is seasonally inundated with different duration periods according to the localities as a result of the overflow waters from Akgo¨l and Simenit lagoons fed by rainfall,

For each plant community belonging to all successional stages in the study area ten sample plots were synchronously taken and randomly selected from floristically and structurally homogeneous places according to the minimal area concept (Westhoff and van der Maarel 1978). A vegetation quadrat was established for each of these sample plot, and the sizes of sample plots were selected as 5 m2 for Cladium mariscus (initial stage of primary hydroseral succession); 50 m2 for Sparganium erectum subsp. neglectum (second stage of early main phase) and Juncus acutus (first stage of intermediate main phase); 250 m2 for Alnus glutinosa subsp. barbata (second stage of intermediate main phase) and F. angustifolia subsp. oxycarpa flooded forests (third stage of intermediate main

However, deltaic plains of big rivers belong to the most variable and least predictable environments on earth. The complicated development of vegetation in river deltas reflects the unstable character of these landscapes (Rejma´nek et al. 1987). This is surprising considering riparian areas are diverse dynamic portions of the landscape that contribute to both terrestrial and aquatic ecosystems (Fierke and Kauffman 2006). Because of that, understanding their ecological and biological richness is important not only for their sustainable management but also to restore and rehabilitate lost or degraded fields (Kavgacı et al. 2016). River deltaic plains offer an excellent opportunity to study processes of primary succession (Odland and del Moral 2002; Zhang et al. 2007). Thus, floodplains are also unique among terrestrial ecosystem types to experience recurrent primary succession over time scales relevant to development and succession of plant communities. For many unaltered rivers, especially in piedmont areas, channel migration rates are sufficient to maintain large areas in relatively immature stages of development (Bechtold and Naiman 2009). Primary successional process of the Go¨lyazi Natural Reserved Area had not been studied previously and the only existing studies were descriptive ones by Tu¨fekc¸iog˘lu (2005), Korkmaz et al. (2011, 2012). The aims of this study are: (1) What are the early, middle and late succession stages of plant communities in Go¨lyazi Natural Reserved Area? (2) Which hydrological and pedological factors are play the most important roles to determine the vegetation composition and structure in succession, respectively.

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phase) and 500 m2 for Carpinus betulus forest (subclimax stage of primary hydroseral succession) (van der Maarel 2005). Cover-abundance data for all vascular plants were recorded on the basis of weekly periods for each sample plot using the Braun-Blanquet (1964) scale, between February and November, in 2014 and 2015. Taxonomic nomenclature has followed that of Davis 1965–1985), Davis et al. (1988), Gu¨ner et al. (2000) and Gu¨ner (2012). From each plant community, three soil samples were taken at a depth of 30 cm from the topsoil in the midgrowing season (July). Throughout the study, a total of 18 soil samples were taken and, a total of 72 analysis were done by four iterative. They were then air dried and sieved through a 2 mm mesh prior to analysis. Soil organic matter (%) was determined using the Walkley and Black method (Nelson and Sommers 1982). The CaCO3 (%) concentrations were determined using a Scheibler calcimeter (Soil Survey Staff 1993). Soil texture was determined using the Bouyoucus hydrometer method, and the clay content was expressed as % (Demiralay 1993). HCO3 and Cl by Ayyıldız (1990); in saturation mud pH and EC (soil electrical conductivity) by Richards (1954); available P and Fe by AB-DTPA (1 M NH4HCO3 ? 0.005 M DTPA, PH = 7.6) in A.A.S. (atomic absorption spectrophotometer) by Soltanpour and Schwab (1977) and Sag˘lam (1997); and water soluble K, Mg and Na analyzed by Sag˘lam (1997). The depth to the water table for each plant community was measured in vertical boreholes on the basis of monthly periods through one year as the water table depth below the ground surface (cm), and it was calculated as the annual mean water table depth. Negative values refer to situations where the water table depth is above the soil surface, while positive values refer to situations where it is below the soil surface. 2.3 Numerical analysis Plant communities were separated using TWINSPAN (two-way indicator species analysis) procedure. To determine what environmental factors were significant we also treated our data with detrended correspondence analysis (DCA) and canonical corresponding analysis (CCA). Data set was classified by TWINSPAN using the ‘‘Community Analysis Package 4.1.3 version’’ software (Seaby and Henderson 2007a). The pseudospecies cut levels and maximum number of indicators per division were set as 0, 2, 5, 10, 20 and 5, respectively. This calculation was based on the cover–abundance data of species corresponding to the transformations of the Braun-Blanquet scale as proposed by van der Maarel (1979). Detrended correspondence analysis (DCA) is an indirect gradient analysis technique (ter Braak 1986) employed for

data ordination. To establish the relationships between plant composition topography and soil factors DCA was performed, using Community Analysis Package 1.50 version (Seaby and Henderson 2007a), which enabled sites to be plotted based on species composition and abundance. Hierarchical clustering method was used in DCA (ter Braak 1994). To detect gradients in species composition and speciesenvironment relations, canonical correspondence analysis (CCA) was performed using the ECOM 2.1.3.137 version (Seaby and Henderson 2007b) software programmes.

3 Results 3.1 TWINSPAN classification of succession stages In the study area, successional stages which belong to hygrocolous series take Akgo¨l and Simenit lagoons as axel, and expands to periphery. Based on TWINSPAN analysis, 60 plots and 151 species were classified into 6 succession stages groups, representing 3 successional main phase (Fig. 1). Shallow lake and terrestrial main groups of plots were determined at first level of TWINSPAN dendrogram. Shallow lake main group was divided into aquatic and semi-aquatic plots cluster formed at second level. Aquatic plots distributions on the lowest portions of study area which are permanently covered with water where monospesific C. mariscus (S1), a tall bulrush community, which is the initial stage of primary hydroseral succession, were formed. Semi-aquatic plots distributions on shallow coast of lagoons and in drainage channels in the study area, where only 3 months (July, August and September) drawdown occurs (Table 1) and monodominant Sparganium erectum subsp. neglectum (S2), a tall bulrush community formed, which is the second stage of early main phase. Terrestrial main group was divided into two groups, as herbaceous and woody clusters at level 2 of TWINSPAN dendrogram. Herbaceous cluster formed plots on the low portions and of the study area, where drawdown occurs for five months (July, August, September, October, November) (Table 1) and monodominant Juncus acutus community (S3) was formed, which is the first stage of intermediate phase. Woody plot group was divided as flooded forest and not flooded forest clusters at level 3 of dendrogram. Flooded forest plots, which take place in middle elevation position of the local microtopographic gradient of the study area were divided into two clusters at level 4 of TWINSPAN. Monodominant A. glutinosa subsp. barbata forest (S4), which is the second stage of intermediate phase, was formed on flooded portion between December and April

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While three species were only shared between the shallow lake communities (S1 and S2), the common species are much more in the terrestrial communities (S3, S4, S5 and S6). 3.2 Ordination analysis of successional stages (DCA and CCA)

Fig. 1 TWINSPAN clusters of sample plots in the study area. S1, Cladium mariscus; S2, Sparganium erectum subsp. neglectum, S3, Juncus acutus, S4, Alnus glutinosa subsp. barbata, S5, Fraxinus angustifolia subsp. oxycarpa, S6, Carpinus betulus

(5 months) (Table 1), while F. angustifolia subsp. oxycarpa forest (S5), which is the third stage of intermediate phase, was formed on flooded portion between December and February (3 months) (Table 1). On the not flooded and well drained soils on higher elevation portions of the local microtopographic gradient of the study area C. betulus forest developed (S6), which constitute to climax stage of primary hydroseral successional processes in the study area. We also created a comparison table that contained taxa had the presence above 33% in communities (Table 2).

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Eigenvalues were calculated as 0.90 and 0.54 for the first and second axes at DCA, respectively. Plot groups were distributed according to local microtopographic position and pH gradient along axis 1 and axis 2 of DCA ordination, respectively. In this case, it is obtained that there is negative corelation between microtopographic gradient and axis 1, while there is positive corelation between pH and axis 2 in DCA ordination. The plots that belong to S1 community (C. mariscus), which are initial stage of hydrosere, take place on the lowest portions of the study area covered with water permanently and aggregate on the positive end of axis 1, while the plots that belong to S6 community (C. betulus), which is the climax stage of hydrosere, takes place on highest and not flooded portions of the study area, and aggregate on the negative end. The plot groups belonging to other communities (S2: Sparganium erectum subsp. neglectum, S3: Juncus acutus, S4; A. glutinosa subsp. barbata and S5: F. angustifolia subsp. oxycarpa) aggregate along axis 1 according to local microtopographic gradient of study area (Fig. 2). On the second axis, plots were mainly distributed according to pH gradient (Table 3). Thus, the plots belonging to S6 community aggregate toward the negative end of axis 2, while the plot groups belonging to S3 community distributed toward positive end axis 2, in line with the increase of soil pH (Fig. 2). The first two axes CCA were significant (p \ 0.001) according to Monte-Carlo permutation test. Eigenvalue of axis 1 is 0.77 and explain 26.01% of total variance, while eigenvalue of axis 2 is 0.51 and explain 17.34% of total variance. Most significant soil parameters were EC and soluble sodium (sNa) according to intraset correlation coefficient (Table 4). The first axis of CCA showed positive correlation with organic matter, CaCO3, EC, sNa and silt while water table depth showed negative correlation with first and second axis (Fig. 4). As can be seen in the CCA ordination, the forest dominated by C. betulus grow on the portions that have deepest water table depth levels and lower organic matter, CaCO3, EC and sNa, while Fraxinus angustifolius subsp. oxycarpa and monospesific dominant A. glutinosa subsp. barbata forests grew on the portions with similar soil conditions which has lower water table compared to C. betulus community (Figs. 3, 4). By contrast, C. mariscus, Sparganium erectum subsp.

Rend. Fis. Acc. Lincei Table 1 The variation of monthly and annual mean water table depths (cm) of the TWINSPAN groups in the study area Communities of stages

Jan.

Feb.

Mar.

Apr.

May

Jun.

Jul.

Aug.

Sept.

Oct.

S1

-68

-69

-69

-58

-42

-20

S2

-41

-40

-22

-20

-11

-4

S3

-25

-22

-20

-18

-12

Nov.

Dec.

Annual mean

-11

4

4

-24

-34

-63

-37.50

5

10

7

-8

-10

-23

-13.30

-8

10

20

30

20

10

-15

-3.00

S4

-15

-15

-9

0

66

90

114

116

114

110

70

-15

52.00

S5

-11

-10

35

30

85

120

131

146

144

140

120

-5

77.00

S6

120

100

75

62

105

154

200

240

235

220

190

150

154.00

neglectum and Juncus acutus communities grew on the portions which permanently and more long term flooded and which have mainly with higher organic matter, CaCO3, EC, sNa and silt, respectively (Fig. 3; Table 4).

4 Discussion Hydrologic regime, topographic position, and sediment composition, strongly influence both the vegetation zonation and the succession process (Kandus and Malva´rez 2004) and their biologic sustainability is strictly connected with the natural flooding regime (Kopec´ et al. 2014). Besides, this type of topography-controlled water table most likely occurs in relatively low-permeable and anisotropic aquifers subjected to unusually high (in view of the low permeability) areal recharge rates or in nearly flat terrain (Haitjema and Mitchell-Bruker 2005). Rosenberry and Winter (1997) reported that seepage from topographically higher wetlands can flow via groundwater to discharge into wetlands at lower elevation. Sample plots were grouped on CCA ordination throughout primary hydroseral successional process according to the gradients of water table depths, organic matter (%), EC, CaCO3 (%), soluble Na and silt (%). The natural development of vegetation is slow and its course depends on many factors: soil conditions, etc. (Cojzer et al. 2014). CaCO3 is an important edaphic factor that influence soil pH, texture and organic matter contents (Jafari et al. 2003). As in this study, it was stated by several authors (de Kovel et al. 2000; Ha¨rdtle et al. 2005) that organic matter content of soil is an important factor in the distribution of communities and the floristic composition. Besides electrical conductivity (EC) is thought that an indicator of soil salt content provide an index to soil salt content. High salt concentrations can inhibit plant growth by reducing osmotic soil moisture uptake, and excessive salts can be toxic to the plants (Noon 1996). It was reported in a study about this subject that the level of salt (EC) and redox potential of soil water have a key role in the zonation of vegetation (Sanchez et al. 1998). Because, hydrologic

setting is a significant and sometimes paramount factor in controlling of the chemical and biological conditions of a wetland (Rosenberry and Winter 1997). Another important point to touch on is that age of the habitat (de Kovel et al. 2000) and inundation regime (Zeilhofer and Schessl 1999) are the main agents used to determine physical and chemical properties of soil in different portions of delta plains. For instance, redox conditions in wetland soils are strongly influenced by water table depth fluctuations. Spatial and temporal changes in the occurrence of oxic and anoxic conditions have drastic effects on the rates of ammonification, nitrification and denitrification. Furthermore, under natural conditions the hydrological regime of riparian wetlands often entails large seasonal fluctuations in water table elevation (Hefting et al. 2004). A water table depth gradient was formed based on the local topographic change determine distribution model communities belonging to hydroseral stages by effecting physical and chemical properties of the soil. Because of this reason, the primary succession of forest types in floodplain locations is associated with a range of soil series that reflect the alluvial nature of the environment and drainage conditions (van Cleve et al. 1996). Shallow lake communities are permanently flooded almost throughout the year, while terrestrial habitats have developed as a result of temporarily inundation period and annual mean water table depths in the study area. Because fluviodynamics lead to different successional stages by creating different habitats such as wetland, riverin and semiaquatic (Ward et al. 1999). All plant species in shallow lake areas are distributed according to the duration of inundation period and the degree of tolerance to saturation (Weiher and Keddy 1995). Following units can be distinguished. Aquatic C. mariscus community, which constitute the initial stage of early mean phase of primary hydroseral succession, occur in many parts of the lagoons which inundated throughout the whole year. Sparganium erectum subsp. neglectum community that included in Phragmito-Magnocaricetea according to Zu¨rich-Montpellier phytosociological system (Korkmaz et al.

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Rend. Fis. Acc. Lincei Table 2 The most presence taxa ([33.0%) of the TWINSPAN groups were shared among communities S1 S1 S2

S3

– Hydrocotyle vulgaris Rumex hydrolapathum Salvinia natans –

S4

–

S5

–

123

S2

S3

S4

S5

–

– –

– –

– –

Alisma plantago-aquatica Butomus umbellatus Alisma plantago-aquatica Apium graveolens Clinopodium vulgare subsp. vulgare

Clinopodium vulgare subsp. vulgare

– Alisma plantago-aquatica Bellis perennis Calystegia silvatica Carex nigra subsp. nigra Euphorbia helioscopia Euphorbia palustris Galium palustre Hypericum perforatum Periploca graeca var. graeca Plantago major subsp. major Poa trivialis Polygonum salicifolium Primula vulgaris Ranunculus constantinopolitanus Rubus canescens var. glabratus Rubus sanctus Rumex tuberosus Samolus valerandi Bellis perennis Carex nigra subsp. nigra Centaurium erythraea subsp. erythraea Euphorbia helioscopia Euphorbia palustris Galium palustre Lotus corniculatus var. corniculatus Oenanthe silaifolia Periploca graeca var. graeca Poa trivialis Primula vulgaris Ranunculus constantinopolitanus Rubus canescens var. glabratus Rubus sanctus Rumex tuberosus

– –

–

Ajuga reptans Arum euxinum Bellis perennis Cardamine hirsuta Cardamine tenera Carex nigra subsp. nigra Carex remota Carex riparia Clinopodium vulgare subsp. vulgare Cornus sanguinea subsp. australis Crataegus curvisepala Equisetium arvense Euphorbia helioscopia Euphorbia palustris Euphorbia stricta Ficus carica subsp. carica Frangula alnus subsp. alnus Fraxinus angustifolia subsp. oxycarpa Galium aparine Galium palustre Geum urbanum

–

Rend. Fis. Acc. Lincei Table 2 continued S1 S5

–

S2

S3

S4

S5

Glechoma hederacea Hedera helix Humulus lupulus Lapsana communis subsp. intermedia Leucojum aestivum Lysimachia verticillaris Myosoton aquaticum Oenanthe pimpinelloides Orchis papilionacea var. papilionacea Periploca graeca var. graeca Poa trivialis Potentilla reptans Primula vulgaris Quercus hartwissiana Ranunculus constantinopolitanus Rosa canina Rubus canescens var. glabratus Rubus sanctus Rumex tuberosus Ruscus aculeatus var. angustifolius Sambucus ebulus Smilax excelsa Sonchus asper Stachys sylvatica Stellaria media subsp. media Tamus communis subsp. communis Trifolium hybridum var. hybridum Urtica dioica

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Rend. Fis. Acc. Lincei Table 2 continued

S6

S1

S2

S3

S4

S5

–

Clinopodium vulgare subsp. vulgare

Calystegia silvatica Carex nigra subsp. nigra Euphorbia helioscopia Hordeum murinum subsp. glaucum Hypericum perforatum Poa trivialis Primula vulgaris Ranunculus constantinopolitanus Rubus canescens var. glabratus Rubus sanctus Rumex tuberosus Trifolium repens var. repens

Ajuga reptans Arum euxinum Calystegia sepium subsp. sepium Calystegia silvatica Cardamine hirsuta Cardamine tenera Carex nigra subsp. nigra Carex remota Carex riparia Clinopodium vulgare subsp. vulgare Cornus sanguinea subsp. australis Crataegus curvisepala Equisetium arvense Euphorbia helioscopia Euphorbia stricta Ficus carica subsp. carica Frangula alnus subsp. alnus Fraxinus angustifolia subsp. oxycarpa Galium aparine Geum urbanum Glechoma hederacea Hedera helix Hypericum perforatum Lapsana communis subsp. intermedia Leucojum aestivum Myosoton aquaticum Oenanthe pimpinelloides Poa trivialis Potentilla reptans Primula vulgaris Quercus hartwissiana Ranunculus constantinopolitanus Rosa canina Rubus canescens var. glabratus Rubus sanctus Rumex tuberosus Ruscus aculeatus var. angustifolius Sambucus ebulus Smilax excelsa Sonchus asper Stachys sylvatica Stellaria media subsp. media Tamus communis subsp. communis Trifolium hybridum var. hybridum Urtica dioica Vicia sativa

Acer campestre subsp. campestre Ajuga reptans Arum euxinum Arum maculatum Bromus sterilis Cardamine hirsuta Cardamine tenera Carex nigra subsp. nigra Carex remota Carex riparia Clinopodium vulgare subsp. vulgare Conyza canadensis Cornus sanguinea subsp. australis Crataegus curvisepala Equisetium arvense Euonymus latifolius Euphorbia helioscopia Euphorbia stricta Ficus carica subsp. carica Frangula alnus subsp. alnus Fraxinus angustifolia subsp. oxycarpa Galium aparine Geum urbanum Glechoma hederacea Hedera colchica Hedera helix Lapsana communis subsp. intermedia Leucojum aestivum Ligustrum vulgare Myosoton aquaticum Oenanthe pimpinelloides Poa trivialis Potentilla reptans Primula vulgaris Quercus hartwissiana Ranunculus constantinopolitanus Rosa canina Rubus canescens var. glabratus Rubus sanctus Rumex tuberosus Ruscus aculeatus var. angustifolius Sambucus ebulus Smilax excelsa Sonchus asper Stachys sylvatica Stellaria media subsp. media Tamus communis subsp. communis Trifolium hybridum var. hybridum Urtica dioica

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Fig. 2 DCA ordination diagram of the TWINSPAN groups in the study area Table 3 Physical and chemical soil properties of the TWINSPAN groups in the study area S2

S1

S3

S4

S5

S6

OM, %

7.76 ± 0.39

2.91 ± 0.07

0.56 ± 0.15

1.59 ± 0.19

2.76 ± 0.23

1.27 ± 0.20

CaCO3, %

0.03 ± 1.05

0.08 ± 0.08

0.38 ± 1.53

0.33 ± 0.08

0.05 ± 0.05

0.21 ± 0.09

50.82 ± 1.36

67.11 ± 0.78

61.46 ± 12.20

35.27 ± 5.07

20.41 ± 4.42

40.33 ± 7.87

Sand, % Silt, %

32.48 ± 1.52

14.00 ± 0.44

6.19 ± 1.70

12.67 ± 0.91

20.41 ± 2.21

30.19 ± 3.95

Clay, % Cl, ppm

16.71 ± 0.71 995.05 ± 120.80

18.79 ± 0.54 162.71 ± 13.53

32.90 ± 11.72 124.84 ± 56.59

51.98 ± 4.75 375.05 ± 35.00

60.08 ± 3.85 263.29 ± 61.21

29.63 ± 12.25 272.17 ± 68.33

HCO3, ppm

291.00 ± 16.83

225.00 ± 10.88

281.30 ± 19.62

263.00 ± 32.59

337.00 ± 17.52

202.40 ± 18.12

pH

7.38 ± 0.04

6.81 ± 0.07

8.50 ± 0.19

7.74 ± 0.11

6.76 ± 0.06

6.51 ± 0.18

EC, mS cm-1

4.26 ± 0.29

0.39 ± 0.07

0.50 ± 0.12

0.40 ± 0.07

0.30 ± 0.03

0.14 ± 0.03

s.Na, ppm

105.66 ± 14.44

18.48 ± 1.49

9.46 ± 2.82

5.35 ± 0.69

6.37 ± 1.60

1.67 ± 0.20

e.K, ppm

11.25 ± 0.41

9.74 ± 0.33

17.75 ± 2.75

12.35 ± 2.03

25.29 ± 0.82

14.50 ± 1.22 16.00 ± 3.60

e.Na, ppm

4.71 ± 0.19

6.75 ± 0.53

17.29 ± 6.68

10.01 ± 0.65

25.37 ± 3.08

e.Mg, ppm

16.15 ± 1.50

21.99 ± 0.75

9.56 ± 1.07

9.97 ± 2.42

11.97 ± 2.19

3.80 ± 0.51

Fe, ppm

80.29 ± 25.63

73.31 ± 3.10

22.85 ± 4.36

56.46 ± 16.82

90.83 ± 25.32

64.05 ± 8.74

P, ppm WTD (cm)

6.54 ± 2.09

1.07 ± 0.22

0.50 ± 0.09

1.03 ± 0.14

2.98 ± 1.85

2.67 ± 0.91

-37.50 ± 1.48

-13.30 ± 1.01

-3.00 ± 1.01

52.00 ± 1.83

77.00 ± 0.65

154.00 ± 1.68

WTD annual mean water table depth; ± standart error; n = 12

2012), which constitute the second stage of early mean phase of primary hydroseral succession occured on shallow portions of lagoons and in many of drainage canals where drawdown occurs only for three months (July, August and September). Since hydrology is a major forcing factor in

wetlands, differences in hydrologic regime are shown to influence wetland plant communities through differences in primary production, species diversity, and the distribution of species within ecosystems (Pratolongo et al. 2007). Therefore, drawdown has been shown to have strong

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Rend. Fis. Acc. Lincei Table 4 Intraset correlation coefficient and eigenvalue of the first two axes for canonical correspondence analysis

Axis 1

Axis 2

OM

0.69

-0.29

CaCO3

0.70

0.01

Sand

0.01

0.35

Silt

-0.01

20.50

Clay

-0.24

-0.02

Cl

0.28

-0.38

HCO3

0.08

0.23

pH

0.07

0.14

EC

0.82

-0.22

s.Na

0.75

-0.11

e.K

-0.17

0.05

e.Na

-0.23

0.01

e.Mg

0.46

0.30

Fe

0.03

-0.15

-0.02 20.65

-0.26 20.73

P WTD Canonical Eigenvalue

0.77

0.51

% Variance explained

26.01

17.34

Cumulative % variance

26.01

43.35

0.74

0.81

Kendal rank correlation of species/environment scores Bold refers to highly significant OM organic matter, EC electrical conductivity, WTD water table depth

Fig. 3 CCA ordination diagram of the TWINSPAN groups related to environmental factors in the study area

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Fig. 4 Diagram of primary successional stages in Go¨lyazi Natural Protected Area. S1 Cladium mariscus, S2 Sparganium erectum subsp. neglectum, S3 Juncus acutus, S4 Alnus glutinosa subsp. barbata, S5 Fraxinus angustifolia subsp. oxycarpa, S6 Carpinus betulus

effects on the composition and abundance of aquatic vegetation (Wagner and Falter 2002). We observed that annual water regime determine aquatic communities and species distributions in the shallow lake. The distribution and species composition of wetland plant communities can be influenced by hydrology (Johnson et al. 1985). We can even say hydrological regime during the whole year is the single most important condition in determining the character and existence of wetlands. Different hydrologic conditions can have considerable influence on variability in site species composition, frequency, and dominance. A narrow range of the wetland hydrology gradient was selected to standardize hydrologic conditions across all sites, reduce the sampling area, and minimize affects on variability caused by the two most important factors in the hydrologic regime: moisture periodicity and depth of inundation (Noon 1996). Besides, the end products of nitrogen cycling available for plants in wetlands are controlled by soil moisture (Hefting et al. 2004). Herbaceous Juncus acutus community constitutes the first stage of intermediate main phase of hydroseral succession is included in Molinio-Arrhenatheretea according to Zu¨rich-Montpellier phytosociological system (Korkmaz et al. 2012), and it develops on the lower portions of the study area due to the fact that these portions have longer inundated period (8 months) compared to the area where

other flooded communities occur and where water table depth is lower, generally EC, CaCO3 (%) and sNa is comparatively high, but the organic matter (%) is low. Alnus glutinosa subsp. barbata and F. angustifolia subsp. oxycarpa forests occur in the portions of the study area which are comparatively elevated and have shorter inundated periods (3–4 months), and where the higher water table, and these forests constitute second and third stages of intermediate main phase of hydroseral succession, respectively, both of which are included in Salici purpureae-Populetea nigrae class syntaxonomically (Korkmaz et al. 2012). Climax C. betulus forests, which are included in Querco-Fagetea class syntaxonomically (Korkmaz et al. 2012), occur in the parts of the delta plain which have no inundation period, lowest water table and well drained soils and constitute late main phase of hydroseral successional processes. Because floodplain forests reflect different vegetation characteristics by depending on the flood regime (Kavgacı et al. 2011a). Some parts of the floodplain area that is the poorest in terms of nutrient and moisture are dominated by C. betulus forests are only inundated in winter (Kavgacı et al. 2011b, 2016). During succession there was a shift in the chemical nature of the soil organic matter towards more recalcitrant forms of organic carbon in soil under trees compared with grassland. Plant biomass production in the early stages of forest

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contains a large amount of lignin which remains in soil litter. In another way, vegetation composition can affect microbial community through the quantity and quality of the organic matter provided by different plant species (Chabrerie et al. 2003). Besides, woody plants with bacterial symbionts that fixes N often drive primary succession throughout N-accretion and enhanced soil development (Bellingham et al. 2005) and especially alder plays an important role in the nitrogen (N) economy of boreal forest because of its high capacity for atmospheric N fixation (Ruess et al. 2006). Therefore, since A. glutinosa subsp. barbata symbiosis with Frankia sp. which nitrogen fixes into root nodules, it can play an important role in primary successional process due to the fact that it grows in azonal soils in early successional habitats. (Akkermans et al. 1983; Swensen 1996). Besides, the most basic property in which black alder differs from other pioneer species is its hygrophilous character or, more specifically, tolerance to swamping (Obidzin´ski 2004). Thus, A. glutinosa subsp. barbata forests constituted first woody stage of hydroseral processes in the portions due to relatively longer inundation period in the lower terrestrial portions of the study area, while F. angustifolia subsp. oxycarpa forests constituted second woody stage of primary hydroseral processes in the portions with relatively shorter inundation period and lower water table. When these communities were also compared to each other in terms of soil organic matter, pH and soil clay content, it can be said that A. glutinosa subsp. barbata forests constituted first woody stage of hydroseral processes. Carpinus betulus forests are climax stage of the primary hydroseral processes in the delta plains. In late successional stage, C. betulus individuals prominently increase with other tree species under better drainage conditions (Kandus and Malva´rez 2004). Bernadzki et al. (1998) reported that, Tilia cordata and C. betulus individuals increased while the early successional Fraxinus excelsior and A. glutinosa decreased in the last period of succession. Obidzin´ski (2004) obtained that black alder may play the role of a pioneer species in the habitat of fresh oak-linden-hornbeam forest (Tilio-Carpinetum typicum). Burkart (1957) described that, the hydrosere of the delta islands as a replacement process from low diversity communities, with herbaceous pioneer species, to forests of complex structure and high species richness. In his words, the forest would represent ‘‘the regional subclimax.’’ The late-succession species C. betulus (Feurdean et al. 2013) that as climax forests develop in stands which are well drained and have a lowest annual mean water table because of not having any inundation period. In C. betulus community, the most frequent species were Sambucus nigra, Viola odorata, Diospyros lotus, Primula vulgaris subsp. sibthorpii and Geum urbanum. In this way, diaspors of dominant C. betulus as well as Quercus robur, Carex remota, Hedera helix and Ruscus

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aculeatus, etc. may immigrate from the surrounding forested area. Because, regarding soil humidity, the seedlings of C. betulus and Q. robur have a relatively wide ecological range and were found to be more abundant on intermediate or drier stands (Terwei et al. 2013). Carpinus betulus and Q. robur are also characterized by dyszoochorous and anemochorous modes of dispersal (Dzwonko and Loster 1992). Carpinus betulus is a successful coloniser of temperate deciduous forest (Kwiatkowska et al. 1997) and its seed dispersal distance up to 130 m have been observed (Coart et al. 2005). In the present study, it seems that soil heterogeneity derived from differences in sedimentation rate and hydrologic regime is a key factor influencing species colonization and persistence (Kandus and Malva´rez 2004). Thus, the sample plot groups were distributed by their microtopographical position along the first axis on DCA ordination diagram and water table depths also showed negative correlation with first axis while it was positively correlated with second axis of CCA ordination. It is necessary to understand the relationships between water availability, soil characteristics, and vegetation. A strong connection exists between water table depth, soil–water content, and the floodplain species. Water table depths that are influenced by microrelief in lowland delta plains caused to important differences in the physical and chemical features of soil. Community distribution and floristic composition were affected by the physical and chemical features of soil in floodplains (Kruger et al. 1983; Sabatier et al. 1997; Castelli et al. 2000; Tockner and Stanford 2002). The distribution of common species is directly related to the ecological and floristic nature in communities. It points to the ontogenic relationship at the successional stages. Because, the time period of flooding influenced on the floristic composition in communities (Van Geest et al. 2005). The plant biodiversity increased with the progressive successional processes that play major roles in the spatio-temporal heterogeneity on the floodplains (Ward et al. 1999). Plant community succession is becoming one of the important aspects of restoration ecology and is the subject of a large body of ecological research (Zhang 2005). Thus, the basics of successional theory are also being applied to the relatively new fields of restoration ecology and invasion biology (Young et al. 2005).

5 Conclusions A large part of the study area, is a fully deltaic flood plain with an elevation of 0–10 m from sea level. It consists of hydromorphic and alluvial soils which are regularly flooded due to the overflow of lagoons every year.

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Accordingly, water level fluctuations of lagoons regulate the spatial distribution patterns of the communities belonging to aquatic stages and are effective on that of the communities which belong to terrestrial stages. Sedimentation rate and hydrologic regime are key factors influencing species colonization and persistence on deltaic floodplain. Sediment accumulation is based on inundation from lagoons on Go¨lyazi Natural Protected Area. Therefore, groundwater resources should not be dried to continue the flooding and sediment accumulation by lagoons. At least water storages of drainage canals should be discharged directly to lagoons instead of in the Black Sea. In this way, primary hydroseral succession processes based on hydrological regime and groundwater depth may be sustainable. Acknowledgements The Project was financially supported by Research Council of Ondokuz Mayıs University (Project Number: PYO.FEN.1904.11.025). We wish to thank Ahmet Demirci (English lecturer) for his kind grammatical help. Compliance with ethical standards Conflict of interest The authors declare that they have no conflict of interest.

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