Vegetation Response to Re-flooding in the Mesopotamian Wetlands, Southern Iraq

Abstract

Wetlands in the Mesopotamian Plain in southern Iraq were extensively drained in the 1990s. Re-flooding of drained areas commenced in 2003, and included parts of the Central marsh between the Euphrates and Tigris Rivers. New vegetation in the re-flooded areas of the Central marsh was studied in 2006. Most of the wetland plant species and communities widely distributed prior to drainage have reappeared, but there were some species and communities that did not re-establish. Aboveground plant biomass is recovering in some communities, but in most of the new communities, biomass and diversity were low. Postflooding sites were characterized by higher concentrations of chloride and bicarbonates in surface water and higher percent organic matter in sediment than those prior to drainage. Comparisons among the three study sites in the re-flooded areas and those between pre-drainage and postflooding sites suggests that differences in water quality, including more saline conditions in the re-flooded wetlands, might be hindering the biomass recovery. The water source being limited to only the Euphrates River, a much more subdued seasonal fluctuation in the quantity of water input and output, and inputs of contaminated waters appear to be responsible for the delay in vegetation recovery in the Central marsh.

A Comparison of the Composition and Diversity of Tree Populations along a Hydrological Gradient in Floodplains (Southern Québec, Canada)

“…We can assume that the low recruitment rate in frequent flood zones is explained by the higher flood frequency, which prevents annual shoots from being maintained and causes a drop in the survival rate of the saplings in subsequent years [26,28,37]. As floods can occur once or twice a year (spring and fall), young shoots have a lesser chance of survival.…”

Impacts of Floods on Organic Carbon Concentrations in Alluvial Soils along Hydrological Gradients Using a Digital Elevation Model (DEM)

“…This loss of litter significantly reduces the contribution of organic carbon and over time causes soil depletion [26][27][28]. This can hinder the main soil-forming processes and biogeochemical cycles, in addition to having an impact on plant-soil interactions and riverside ecosystems [29,30].…”

Seasonal changes in zooplankton communities in the re-flooded Mesopotamian wetlands, Iraq

“…The salinity increased after re-flooding and chloride concentrations were found to be more than three times higher in 2006 than in 1970s in the re-flooded Central Marsh (Maulood et al 1979;Hamdan et al 2010). During the decades of drying periods, salts accumulated on the sediment surface and were probably flushed into the re-flooded water.…”

“…Brachionus plicatilis is one of the abundant rotifers in this study, which is common in alkaline and brackish waters because it tolerates high osmolarities (Wallace & Snell 1991). The high pH is probably related to both dissolution of salts on re-flooding and an increase in HCO 3 À concentration after re-flooding (more than 30 times in Central Marsh; Hamdan et al 2010). The buffering effect of atmospheric CO 2 , which usually occurs for rivers, would have been overpowered by the high HCO 3 À concentration.…”

“…In this sense, the study identified progress of ecosystem rehabilitation of the Mesopotamian wetlands after the re-flooding. Many macrophyte species and communities also responded well after the re-flooding (Hamdan et al 2010). Unfortunately, however, the wetlands continue to have reduced water supply since 2008 and large areas of the wetlands remain desiccated.…”