Grazing impact on vegetation cover and some soil factors (Case study: Houz-e-Soltan Lake, Qom)

Grazing effect on vegetation cover and soil factors in natural environments is inevitable. The present study was conducted to investigate the effect of grazing on soil factors and distribution of plant species in grazed and non-grazed areas in rangelands of western parts of Hoz-e-Soltan Lake, Qom. Systematic-randomized sampling method was used alongside of 4 transects. Adjacent to the transects 10 plots of 4 square meters were put within the exclosure and its outside. In each plot, soil samples from 0-30 cm depth were taken. The list of plants and their canopy cover were determined for each study site. Also, the properties of acidity, electrical conductivity, soil texture, lime, percentage of phosphorus, sodium, potassium, calcium, Magnesium, chlorine, carbonate, bicarbonate and nitrogen were measured. Using the CANOCO software, ordination of the plant communities was drawn according to the characteristics of the soil by conventional comparative analysis (DCA, CCA). The results showed that livestock grazing have impact on the relationship between vegetation and soil in this area. As the results showed, nitrogen in addition to salinity and sodium had a significant effect on vegetation changes in the grazed area. In fact, proper grazing management increases the amount of nitrogen in the grazed area. Which could be count on as a soil improvement tool in terms of nitrogen content increase. More nitrogen in its turn increases the presence of two important species namely Suaeda aegyptiaca and Artemisia sieberi. Results suggest that as livestock grazie from the shrubs, as the dominant plants of the area, the deterioration of other plants is prevented and the quality of forage production is increased. Therefore, by managing livestock grazing in the studied area and other similar steppe regions, improvement of vegetation composition gets possible and consequently soil properties improves in the long term.