The present investigation aimed at focusing on the efficiency of Aristida plumosa Linn. as an ideal dune fixer at Balouza area, North Sinai, Egypt. Measurements of nebkha and canopy characteristics during different developmental stages in 2014 were accomplished, in addition, sand trapped mass, shoot and root biomass and sand aggregation adherent around roots were determined. The allelopathic effect of root and rhizosphere extracts of A. plumosa on seed germination percentage and early growth of Portulaca oleracea L.  and on its shoot and root development was studied. In addition, phenolic compounds in root tissue and rhizosphere, microorganisms density in rhizosphere and non-rhizosphere soil beneath A. plumosa were studied. Dune plant communities were also surveyed and analysed at the studied region.  Shoot elongation rate of A. plumosa exceed sand trapped rate, it recorded 2.67, 4.33 and 2.11 mm day^-1 from sand deposition. Shoot biomass reached 165.8 g m^-2, root biomass was 12.82 g m^-2 and sand aggregates around roots recorded 7.25 g m^-2.  The negative effects observed in P. oleracea root growth traits were higher from root extracts than soil rhizosphere extracts, whereas shoot length and germination of P. oleracea were most affected by rhizosphere extracts than root extracts. Phenol extracted by methanol subjected to HPLC/UV qualitative analysis and revealed that coumaric and resorcinal acids were found in both root and rhizosphere extracts, but in higher concentrations in former one. Bacterial count was significantly higher than number of fungi in the soil near A. plumosa grass. However, total microorganisms density was significantly higher in rhizosphere soils compared with non-rhizospheric samples.