Vegetation-environment relationships along El-Salam Canal, Egypt

The bank and open water vegetation along El‐Salam Canal in north‐eastern Egypt were studied in relation to the prevailing environmental factors. The hypothesis that terresterial and aquatic species would show different downstream patterns of species richness was tested by sampling species composition and environmental variables along 80 km of the canal. Species richness was highest in the first 30 km of the canal. The downstream decrease in species richness exhibits interpretable downstream patterns. Total species richness increased with increasing organic matter in the soil and decreased with both increasing soil and water salinity along the gradient. The indicator species of TWINSPAN analysis are: Azolla filiculoides, Echinochloa stagnina, Eichhornia crassipes and Saccharum spontaneum (cluster I); Ceratophyllum demersum, Ludwigia stolonifera and Typha domingensis (cluster II); Potamogeton pectinatus and Phragmites australis (cluster III); Tamarix nilotica and Suaeda vera (cluster IV). The environmental factors influencing the vegetation clusters were analysed using canonical correspondence analysis ordination (CCA). The water salinity, total nitrogen and total phosphorus appeared to be the most important factors controlling the abundance of aquatic plant distribution along the canal. The shoreline vegetation is mainly controlled by salinity, K+ and organic carbon of the soil. Water analysis indicated that the salinity of the water increases southwards and the minimum salinity of the water (0.78 mS/cm) was recorded at the intake of the canal. The maximum value (7.5 mS/cm) of water salinity was recorded near the Suez Canal. Copyright © 2001 John Wiley & Sons, Ltd.