INFLUENCE OF SOIL PROPERTIES ON PLANT SPECIES DISTRIBUTION AND DIVERSITY IN ANTHROPOGENIC HABITATS OF ARID NUBIAN DESERT CITIES, EGYPT

Abstract

    Home gardens (HG), public gardens (PG), road islands (RI), and vacant lots (VL) were the most common urban habitats in Kharga and Dakhla Oases that were analyzed in terms of species distribution patterns. In total, 39 geo-referenced sampling stands were surveyed and were distributed as follows among these habitats: 16 in home gardens (HG), 11 in public gardens (PG), 8 in road islands (RI), and 4 in vacant lots (VL). The total number of recorded species showed variation among habitats: 132 species in HG, followed by PG (112 species), RI (71 species), and VL (58 species). The vegetation structure of the home gardens was characterized by orchard trees, cultivated herbs and xerophytes, while that of public gardens was dominated by ornamentals and wetland plants. On the contrast, the road islands and vacant lots were largely composed of weeds and xerophytes. Eleven variables, including coarse sand (CS), fine sand (FS), clay, moisture content, electrical conductivity, soil reaction, organic matter, carbonates, sodium, sulphates, and phosphates, were used in the CCA analysis after soil variables with high inflation factors were eliminated. After applying cluster analysis to presence /absence dataset of 112 species × 39 sampling stands, 14 vegetation cluster groups were recognized, each was dominated by one or a number of species. Soil characteristics showed significant correlations with the separated cluster groups. The Shannon–Wiener index ranged from 1.93 to 3.27, and species richness ranged from 8 to 27.33 species per stand, with clear separation among vegetation groups along the DCA axes, indicating ecologically meaningful differences even without formal significance testing. Clearly, weeds and ruderal species were most abundant in disturbed habitats impacted by the effects of disturbances and the species invasion in urban habitats. Our results confirmed that managed habitats can act as biodiversity refuges in arid urban ecosystems, while disturbed sites require restoration to limit invasive spread and enhance native plant diversity.