STUDYING ENVIRONMENTAL FACTORS ON HALOPHYTE AND XEROPHYTE PLANTS ESTABLISHMENT IN DESERT REGION (CASE STUDY: SEMNAN, IRAN)

Abstract

It is necessary to investigate the relationship between the vegetation each area with the soil because with this method determines the relationship between the condition and different factors in nature with the area vegetation. Therefore, was investigated the relationship in Delazian, Semnan. To study the vegetation, we identified vegetation types by aerial photography and determination of work units and using field survey and GPS. Typing based on physical appearance, canopy cover percentage, density, and distribution range of dominant plant species was carried out by plot and transect. 5 vegetation types were diagnosed (respectively, from upland to the saline lake are including Tamarix Sp. (1), Seidlitzia rosmarinus (2), Nitraria Schubert (3), Salsola rigida (4) and Haloxylon persicum (5)). Then, the soil samples were taken from within the types. Physicalchemical soil factors such as salinity, Gypsum, soluble cations, and anions, organic matter, lime, etc. were taken from depths of 0-30 and 30-60 cm. In order to investigate the relationship between vegetation types and environmental factors (soil factors such as salinity, SAR, cations and anions and other environmental factors such as groundwater depth, rainfall, temperature, relative humidity, altitude) was used of software PC-ORD and principal component analysis (PCA). The results showed that soil factors are effective in the establishment and distribution of vegetative tape and factors affecting on the differentiation of plant communities are including salinity, SAR, cation exchange capacity, OM, clay, silt, sand, K+, Cl-, calcium, magnesium, sodium, gypsum and limestone, carbonate and bicarbonate, sulfate and water table level.