Study of vegetation and diversity indices and surface soil properties affected by urban wastewater application in combating desertification projects (Case study: Segzi, Isfahan)

The effects of using urban wastewater on vegetation and plant diversity indices and surface soil properties were evaluated in combating desertification station of Segzi in east part of Isfahan. Six sites with respect to the planted species (Haloxylon persicum and Nitraria schoberi) and irrigation types (control or no irrigation, water-logged and furrow irrigation methods) were selected with 4 -12 replications. Forty seven surface soil samples were collected and soil texture, organic matter content, acidity, electrical conductivity, calcium and magnesium concentrations, and structure stability were measured. Cover percentage of the species was measured in 47 nested plots. The species richness, diversity and evenness in all replications were calculated by Margalef, Shannon and Simpson indices, respectively. Principal Component Analysis (PCA) and one-way ANOVA were used to interpret the relationships between soil and vegetation properties. Results showed that using urban wastewater significantly increased vegetation cover (about 24.81 to 31.3 %) but plant diversity was not statistically affected. Soil organic matter content and as a consequence of aggregate stability, were significantly increased by irrigating the sites with wastewater. Dispersible clay was decreased (i.e. soil structural stability was increased) as a result of irrigating with wastewater. Therefore, urban wastewater might be used as a source of water for range restoration projects to prevent desertification in natural ecosystems.