Wetlands (****) **:*** ***

DOI **.****/s*****-***-0035-9

ORIGINAL PAPER

Vegetation Response to Re-flooding

in the Mesopotamian Wetlands, Southern Iraq

M. A. Hamdan & T. Asada & F. M. Hassan &

B. G. Warner & A. Douabul & M. R. A. Al-Hilli &

A. A. Alwan

Received: 12 March 2009 / Accepted: 11 November 2009 / Published online: 16 March 2010

# Society of Wetland Scientists 2010

Abstract Wetlands in the Mesopotamian Plain in southern of chloride and bicarbonates in surface water and higher

Iraq were extensively drained in the 1990s. Re-flooding of percent organic matter in sediment than those prior to

drained areas commenced in 2003, and included parts of the drainage. Comparisons among the three study sites in the

Central marsh between the Euphrates and Tigris Rivers. re-flooded areas and those between pre-drainage and post-

New vegetation in the re-flooded areas of the Central marsh flooding sites suggests that differences in water quality,

was studied in 2006. Most of the wetland plant species and including more saline conditions in the re-flooded wetlands,

communities widely distributed prior to drainage have might be hindering the biomass recovery. The water source

reappeared, but there were some species and communities being limited to only the Euphrates River, a much more

that did not re-establish. Aboveground plant biomass is subdued seasonal fluctuation in the quantity of water input

recovering in some communities, but in most of the new and output, and inputs of contaminated waters appear to be

communities, biomass and diversity were low. Post- responsible for the delay in vegetation recovery in the

flooding sites were characterized by higher concentrations Central marsh.

Keywords Biomass . Marsh . Middle East . Phragmites

M. A. Hamdan : F. M. Hassan australis . Plant ecology . Typha domingensis

Department of Biology,

University of Baghdad College of Science for Women,

Baghdad, Iraq

Introduction

T. Asada : B. G. Warner : A. Douabul

Canada-Iraq Marshlands Initiative, University of Waterloo, The wetlands in southern Iraq represent extensive aquatic

Waterloo, ON N2L 3G1, Canada

habitat in a region where freshwater is scare. As a

T. Asada : B. G. Warner consequence, all forms of life, including humans, have

been drawn to and dependent upon the wetlands for at least

Department of Earth and Environmental Sciences,

University of Waterloo, the last 8,000 years (Heyvaert and Baeteman 2008). Thus,

Waterloo, ON N2L 3G1, Canada

the deliberate destruction undertaken by the government

e-mail: abpo1v@r.postjobfree.com

during the 1990s and the reduction to

wetland extent was an environmental disaster (Maltby

A. Douabul

Marine Sciences Centre, Faculty of Science, University of Basrah, 1994; Partow 2001). With the fall of the Iraqi Government

Basrah, Iraq

in the spring 2003, the wetland region in southern Iraq was

no longer off limits. Local residents, with no direction or

M. R. A. Al-Hilli

plan, took it upon themselves to release water from artificial

Department of Biotechnology, University of Baghdad,

Baghdad, Iraq canals and reservoirs back onto the former wetlands

(Richardson et al. 2005). As of December 2006, it was

A. A. Alwan

estimated that water once again covered 58% of the pre-

Department of Biology, College of Science, University of Basrah,

drainage wetland extent (UNEP 2008).

Basrah, Iraq

Wetlands (2010) 30:177 188

178

Post-re-flooding, among the most obvious changes in the (24 h average) at 34.5 C in July and the lowest at 12.2 C in

region was a re-occurrence of hydrophytic vegetation January (World Climate 2005). Temperatures can reach

(Richardson and Hussain 2006). New plant communities 50 C in summer and 0 C in winter. Mean annual precipitation

dominated by species that existed prior to drainage re- is about 100 mm on the northern edge of the wetlands and

established on the flooded lands (Hussain and Alwan about 150 mm to the south, with most precipitation falling

2008). However, questions remain as to the longer term from November through April, and little in summer. Annual

sustainability of these wetland ecosystems in southern Iraq evaporation is up to 3,000 mm (Rz ska 1980).

(Richardson et al. 2005; Richardson and Hussain 2006) The Mesopotamian wetlands can be divided into three

including: What are the ecological characteristics of these parts based on geographic position. Wetlands to the south

wetland communities at their early stages of succession of the Euphrates River are named Hammar marsh, those to

after re-flooding? Will they be able to persist? Finally, what the east of the Tigris River are named Huwaiza marsh, and

actions might be required to sustain wetland vegetation? those in the center between the rivers are named Central

Given that vegetation is the most obvious component of marsh (Fig. 1). Three study sites (Abu Subat, Abu Al-

wetlands and is shaped by the interplay of physical, Narssy, and Abu Chwelan) were established for detailed

biogeochemical, and hydrological processes in the ecosys- vegetation study in 2006 in a part of the Central marsh that

tem, hydrophytes can be useful bioindicators of site was re-flooded after 2003 (Fig. 1, Table 1). In the 1970s

conditions and ecosystem health (Batzer and Sharitz 2006; before the drainage period, plant surveys were also

van der Valk 2006). Our field sites in 2006 lie in what is conducted in the Central marsh (Al-Hilli et al. 2009).

referred to as the Central marsh. Here a similar vegetation Post-2003 re-flooding was restricted to the southern part of

study was performed in the mid-1970s, prior to widespread the Central marsh, so our field sites were selected in that

drainage (Al-Hilli et al. 2009). Thus an opportunity existed area and did not overlap with the field sites in the north that

to compare pre-drainage and post-re-flooding hydrophytic were sampled earlier (Sahain and Surayfa; Fig. 1). Howev-

communities. An understanding of the ecology of hydro- er, another previous study by Maulood et al. (1979)

phyte communities will be valuable for the development of conducted in the south Central marsh also during the

future restoration and management plans in the Mesopota- 1970s indicates that vegetation and water quality conditions

mian wetlands. in north and south Central marsh were similar. Thus, we

feel that the plant data in Al-Hilli et al. (2009) is a

Materials and Methods

Study Site

The Mesopotamian Plain lies wedged between the Iraq

portion of the Arabian Shield and the foothills of the Zagros

Mountains (Guest and al-Rawi 1966) in the East subregion

of the Saharo-Arabian vegetation zone (Zohary 1973).

Extensive wetlands lie on the southern area of the

Mesopotamian Plain at the confluence of the Tigris and

Euphrates Rivers (30.5 to 32.5 N, 44 to 48 E). The

wetlands exist as an island of primarily halo- and

hydrophytic vegetation surrounded by desert and savanna

vegetation (Guest and al-Rawi 1966; Zohary 1973). At least

15,000 km2 of wetlands, lakes, and rivers existed in the

mid-1970s in this region (Rz ska 1980; Al-Hilli et al.

2009). The wetlands cover a large, flat, gently sloping clay-

silt alluvial plain, occupying a large tectonic depression

between the gypsum deposits of the Jezirah and Western

Plateau of the Arabian Shield to the west, and the

conglomerates, sandstones and folded limestones of the

Fig. 1 Study sites shown on a satellite image taken by Aqua on June

Zagros Mountains to the east.

1, 2006 (MODIS Rapid Response System, 3 times) and bicarbonate (>30 times) were higher in re-

Abu Subat Abu Al-Narssy Abu Chwelan flooded areas than in the areas sampled in 1973. Although our

study sites in 2006 were further south than Sahain and Surayfa,

Fig. 2 Bi-plot of partial principal component analysis (partial PCA)

chemical data from southern marshes at Abu Subat in 1978

of monthly environmental parameters from January to December in

2006. The effect of seasonal variation of environmental parameters on (Maulood et al. 1979) suggest that chloride concentrations in

PCA was removed from the ordination by designating months as a

surface waters were quite similar prior to drainage (Abu

covariable. Samples were classified by sites. Environmental parame-

Subat: 147 282 mg L 1; Sahain and Surayfa: 121

ters whose fit into ordination space was >5% are included in the

216 mg L 1). Salts that accumulated on the sediment surface

diagram as vectors: WD: water depth; EC: electrical conductivity

(surface water); Ca: calcium (surface water); Mg: magnesium (surface during the decades of drying probably leached into the re-

water); Cl: chloride (surface water); PO4: phosphate (surface water);

flooded water and increased concentrations of chloride and

NO3: nitrate (surface water); Na: sodium (surface water); K: potassium

sodium; high evaporation rates and water stagnation would

(surface water). The percentage of the total variance explained by the

have contributed further to high saline conditions (Richardson

first and second axis was 37.4 and 12.1%

Wetlands (2010) 30:177 188 183

1.0

Development of Vegetation in the Re-flooded Wetlands

Cer dem

Mesopotamian wetlands were historically very productive.

Pot pec

Na

In 1973, summer aboveground biomass of the most

Pot cri

Typ dom

Myr spi

dominant species, Phragmites australis and Typha domi-

Phr aus Naj mar

AXIS 2

K

ngensis, was at the upper end of values for primary

Naj min

EC

SO4

Pot per production of the same or closely related species in the

Sch lit

Cl

world (Table 4). Productivity of post-flooding communities

has not attained values comparable to 1973. Among the

NO3 Sal nat Pot luc WD

three study sites, Abu Subat had the greatest aboveground

Pot nod

biomass of P. australis and T. domingensis, but values were

>1 kg m 2 lower than in Sahain in 1973. The lower salinity

PO4 Lem min

-0.8

in the most productive Abu Subat site in relation to the

AXIS 1

-1.0 1.0

other two sites suggests that the recovery in aboveground

Ceratophyllum demersum community

biomass of P. australis and T. domingensis was hindered by

Najas marina community

Potamogeton crispus community saline conditions. High salinity can also reduce species

Potamogeton lucens community

diversity in hydrophyte communities (Khedr 1997). High

Lemna minor community

concentrations of sulphate in re-flooded waters might

Salvinia natans community

Phragmites australis community

suggest that sulphate salts accumulated in surface sediments

Schoenoplectus litoralis community

during the period of drainage and then formed mono-

Typha domingensis community

sulphide minerals under intense reducing conditions caused

Fig. 3 Tri-plot of partial redundancy analysis (partial RDA) of plant by re-flooding (USAID 2006). Mono-sulphidic ooze could

cover and environmental parameters in January, March, and July

impair plant respiration and hinder biomass recovery

2006. The effect of seasonal variation on RDA was removed from the

(USAID 2006). The Schoenoplectus litoralis community

ordination by designating months as a covariable. Samples were

classified by communities. Environmental parameters whose absolute

t-values >2.1 are included in the diagram as vectors: WD: water depth;

1.2

EC: electrical conductivity (surface water); Cl: chloride (surface

WD

water); SO4: sulfate (surface water); PO4: phosphate (surface water);

NO3: nitrate (surface water); Na: sodium (surface water); K: potassium

(surface water). Cross symbols show species: Cer dem: Ceratophyllum

demersum; Lem min: Lemna minor; Myr spi: Myriophyllum spicatum;

Naj mar: Najas marina; Naj min: Najas minor; Phr aus: Phragmites

australis; Pot cri: Potamogeton crispus; Pot luc: Potamogeton lucens;

AXIS 2

Pot nod: Potamogeton nodosus; Pot pec: Potamogeton pectinatus; Pot

per: Potamogeton perfoliatus; Sal nat: Salvinia natans; Sch lit: pH

Schoenoplectus litoralis; Typ dom: Typha domingensis. The percent- Cl

OM-S

age of the total variance explained by the first and second axis was

HCO3

16.7 and 8.8%

et al. 2005). In addition to the release in salt compounds from

-0.8

sediments, the change in water source would also contribute to

high concentration of bicarbonates in re-flooded sites. Re- AXIS 1

-0.8 1.2

flooding occurred solely from the Euphrates River. While

April 1973 April 2006

Tigris River water contains less dissolved minerals because it

August 1973 August 2006

drains mountain forest and moist steppe vegetation, Euphrates

River water tends to be more saline and rich in calcium Fig. 4 Bi-plot of principal component analysis (PCA) of five

carbonate and gypsum because it drains desert and arid steppe. environmental parameters in 1973 and 2006. In August of 1973,

water chemistry parameters were not measured when the water table

Sediment organic matter accumulated more in the re-

was belowground (applies to most sampling plots of the tall emergent

flooded wetlands than at Sahain and Surayfa during the 1970s. communities), and such sampling plots were not included in PCA.

However, aboveground biomass was higher in Sahain and Salvinia natans and Lemna minor communities in 2006 were not

Surayfa during the 1970s than in our re-flooded sites. This included because the organic matter content in sediment was not

measured for those communities. Samples were classified by year and

could be explained by a decrease in re-suspension and

month. WD: water depth; pH: pH (surface water); Cl: chloride

removal of dead plant matter in re-flooded marshes because (surface water); HCO3: bicarbonates (surface water); OM-S: organic

water flows through the wetlands were greater prior to matter content (sediment). The percentage of the total variance

drainage. explained by the first and second axis was 62.9 and 19.9%

Wetlands (2010) 30:177 188

184

Table 4 Published aboveground primary productivity values for Phragmites and Typha species

Productivity (gm 2 yr 1)

Species Location Reference

Phragmites australis (P. communis) Egypt 4,400 Serag (1996)

1,140 2,500 Gorham and Pearsall (1956)a

Northern Britain

Hong Kong 2,198 Lee (1990)

Kv t (1971)a

Czechoslovakia 1,614

Christie (1981)b

South Africa 877

781 829 Andersen (1976)a

Denmark

428 2,252 Boyd and Hess (1970)a

Typha latifolia Southeastern USA

330 1,336 McNaughton (1966)a

Central and western USA

Pearsall and Gorham (1956)a

Northern England 400

Kv t (1971)a

T. angustifolia Czechoslovakia 2,592

Andersen (1976)a

Denmark 807

Polisini and Boyd (1972)a

T. australis South Carolina 1,483

Christie (1981)b

T. capensis South Africa 695

T. glauca Iowa 2,297 van der Valk and Davis (1978)

T. orientalis Australia 2,334 Roberts and Ganf (1986)

a

Data obtained from the summary table in Bradbury and Grace (1983)

b

Maximum standing crop

was the only community where aboveground biomass values Many species and communities responded well to re-

were higher in the re-flooded sites than in the sites before flooding, but some others that existed in the mid-1970s were

drainage, and this plant grows better in more saline conditions not encountered in 2006, including some previously wide-

than P. australis or T. domingensis (Al-Hilli 1977). Biomass spread species (Myriophyllum verticillatum, Polygonum

values were especially high at Abu Chwelan where water salicifolium, Nymphoides indica, Nymphoides peltata, and

levels were shallowest and nutrient concentrations highest Utricularia spp.). These species may be intolerant of

among the three study sites (Fig. 2, Table 3). degraded, saline, eutrophic conditions (Croft and Chow-

Lower overall productivity at our 2006 study sites Fraser 2007). There are some parallels in our findings to

those in the Agmon wetland in Israel s Hula valley. The

compared to 1973 sites could also be explained by differences

in geographical locations and related environmental condi- Agmon wetland was artificially re-flooded in the mid-1990s

tions. The water source in Sahain and Surayfa before drainage following drainage that occurred in the late 1950s (Ham-

was only the Tigris River, whereas the areas recently flooded bright and Zohary 1998). Many of the same species that

(Abu Subat, Abu Al-Narssy, and Abu Chwelan) were fed by failed to return to the Central marsh also did not to return to

the Euphrates River. The saline and calcium carbonate and the Agmon wetland, including Nymphaea alba, Utricularia

gypsum rich water of the Euphrates River might limit the australis, Butomus umbellatus, Marsilea sp., and Ludwigia

growth of hydrophytes. The loss of a hydrological pulse in sp. (Kaplan et al. 1998). Some of the species that

spring might have also led to a loss in nutrient loads upon disappeared at Agmon (e.g., N. alba, Ludwigia palustris,

which dominant plant communities depend (Partow 2001; and B. umbellatus) could survive if artificially re-introduced,

Naff and Hanna 2002). However, lower diversity in most of but the re-introduction failed to re-establish U. australis and

the communities in 2006 compared with 1973 might simply Marsilea minuta (Kaplan et al. 1998). These results suggest

develop because plant communities are still at early that specific environmental conditions for species survival

development stages and may still possess the potential to may affect which species reappear in re-flooded wetlands.

develop into communities with greater productivity and Emergence of new genera, such as Chara and Nitella, in

diversity. Lower diversity is typically observed in restored the re-flooded wetlands likely reflects a response to high

versus natural wetlands (Galatowitsch and van der Valk calcium (mostly in the form of bicarbonates) from the

1995). Alternatively, it is also possible that re-flooded Euphrates River. Hydrilla is another genus not recorded

wetlands have already stabilized and achieved maximum before drainage, but it was found to be abundant in other

production under the current environmental conditions. localities (Abu Zirig and Chebaysh) in the Central marsh

Much longer field monitoring is necessary to accurately after re-flooding. Its rapid growth and allelopathic ability

assess the successional development of wetland plant might become a concern because it might outcompete other

communities after re-flooding (Kellogg and Bridgham 2002). aquatic species (Alwan 2006).

Wetlands (2010) 30:177 188 185

In the mid-1970s, some plant communities occurred in fluctuation in water levels and inducing spring flood pulses

areas that were intermittently or seasonally flooded around might be important for some plant communities to re-

the margins of the main wetlands (Al-Hilli 1977). These establish (Middleton 1999). Inputs of contaminated waters

areas might have increased overall diversity. With the new from villages and agricultural fields must be monitored

more controlled hydrological regime, intermittently wet carefully and controlled. Species known to have existed in

areas have been greatly reduced in extent. With constant, the past but have not reappeared (species of Nymphaea,

controlled supplies of water flowing into the wetlands, Nymphoides, and Utricularia) could serve as indicators of

water levels remain aboveground year round, and a sharp restoration success.

boundary exists between wetland and terrestrial areas. Restoration of the wetland plant communities is

Inducing seasonal variation in water conditions could important not only ecologically, but also culturally and

promote numerous facultative and obligate wetland species. economically. The Mesopotamian wetlands have a long

history of human occupation, and vegetation has been

Implications for Wetland Restoration shaped in many ways by the people using the wetlands.

Polygonum salicifolium was a common species in the

Establishing clear goals is critical to wetland restoration wetlands before drainage and was an important food

(Middleton 1999; Batzer and Sharitz 2006; van der Valk source for water buffalo that are central to the traditional

2006). Although current re-flooding efforts in Iraq s Central livelihoods of local inhabitants. However, that plant has not

marsh began as uncoordinated releases of water, re- been found in re-flooded wetlands. Artificial introduction and

establishment of some plant communities occurred quickly. management of such species might be necessary to meet the

However, if the restoration goal is to restore the wetlands to needs of the local people. Our study underscores the value and

conditions as they were in the mid-1970s, more carefully necessity of ecological field studies to characterize the

planned efforts will also need to be included. In terms of conditions and processes influencing wetland development

vegetation, some species and communities known to exist and restoration. Future restoration success rests with a

previously have not returned in the re-flooded wetlands, management plan that is not only accepted and implemented

aboveground biomass of dominant P. australis and T. by all stakeholders, but also, one that is based on sound

domingensis communities are not yet as productive as wetland science.

before, and overall species diversity remains low. It appears

that changes in hydrology and geochemistry are responsi-

Acknowledgements This work is a contribution from the Canada-

ble. Careful regard must be paid to water releases from

Iraq Marshlands Initiative (CIMI). We gratefully acknowledge

upstream dams and reservoirs, to the nature of flood water financial support from the Iraq Ministry of Higher Education and

sources, and to outflow water patterns. Restoring seasonal Research and the Canadian International Development Agency.

Appendix 1

List of Wetland Plant Species Observed in the Central Marsh

Before drainage After re-flooding

197*-****-**** 2007

Year Historical 2006

recordsb

Source Al-Hilli Alwan (2006) Alwan (2006, This study

Contact this candidate