Analysis of vegetation assemblage in the salted plain of the lower Chelif, Algeria

Abstract

In order to establish the relationships between the plants communities and environmental gradients that prevail in the arid plain of the lower Cheliff, one of the largest salted alluvial plain in North Africa, we examined vegetation composition and the environmental variables, using 20 species sampled in 111 stands, followed by a direct gradient analysis. Classification of the vegetation using modified TWINSPAN classification resulted in the recognition of four vegetation units, each of these four units with a definite floristic composition, highly significantly different according to ANOSIM test, was linked to a specific habitat. Multivariate analyses including detrended correspondence analysis (DCA) and correspondence analysis (CCA) showed that vegetation distribution pattern was mainly related to conductivity and soil structure. CCA axis 1 (45.7% of variance explained) was mainly positively correlated to conductivity, Na+, clay and Ca++, with an exclusive appearance of halophilous species characteristic of the extreme salinity conditions. While it was negatively correlated mainly with soil structure and pH, these conditions were accompanied by the highest plant diversity in the study area, with the appearance of two vegetation units, adding up 13 species belonging to 8 families. CCA axis 2 (20.1% of variance explained) was positively correlated with soil structure and Na+, while it is negatively correlated mainly with Ca++, with the occurrence of three species indicating the worst soil structure conditions

Keywords

• Anosim, Conductivity, Correspondence analysis, Twinspan, Vegetation units

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