Introduction of Flora, life form and Chorotype of plants in the critical dust sources in South of Horalazim and south east of Ahvaz

The Middle East, Iran and Khuzestan are located in arid region of the world and the phenomenon of dust is one of the characteristics of these regions. There are 7 critical dust centers with an area of 350000 hectares in Khuzestan province. These areas are identifie in the 7 range and include: South of Horalazim, north of Khorramshahr, east of Ahvaz, south east of Ahvaz, Bandar Imam to Omidieh, Mahshahr to Hindijan and east of Hindijan. The purpose of this study is provide a floristic list of plant species, determination of life form and geographical distribution. The selection of these areas was due to planting, vinas and oil mulch projects implemented in these centers.

Plant samples were collected by using field survey method in the spring and summer of 2019 in natural habitats critical sources including number 1, 2 (Horalazim) and 4 (south east of Ahvaz) of Ahvaz. After determining the level of sample parts by Whitaker method, Systematic random sampling method with network dimensions of 200 × 150 meters was used.135 plots of 100 square meters were selected in each sample plot, in addition to the number and surface cover, the scientific names of plants were identified and recorded separately by genus and species. The samples were identified using botanical sources up to the species level. Then their Corotype and biological form were determined.

Results showed that there are 154 plant species belonging to 36 families in the study area. The largest families in the region were Chenopodiaceae (24 species) followed by Asteraceae (24 species) and Poceae (22 species). In terms of life forms of plant five life forms were found including therophytes (68 species), hemicryptophytes (44 species), phanrophytes (21 species), chamoephytes (15 species) and cryptophytes (6 species). It was found that annual species in the region were 60% and perennial species were 40%. Analysis of the geographical distribution of plants in the region showed that 54 species Irano- Turanian, 40 species Irano- Turanian, Sahara- Sidian, 18 species Sahara-Sidian, 13 species Irano-Turanian, Mediterranean Sahara-Sidian, 10 Irano-Turanian, Mediterranean, 5 species Sahra-Sidian, Mediterranean, 4 species Irano- Turanian, Euro- Siberian, Mediterranean, 4 species Irano- Turanian, Euro- Siberian, Sahra- Sidian, 2 species cosmopolite, 2 species pluri regional ans 2 species Irano- Turanian, Euro- Siberian.

The families of Chenopodiaceae, Asteraceae and Poaceae had a good distribution in the dust centers in Ahvaz. Therophyte and hemicryptophyte species are more abundant than other life forms, and these species were able to settle in the region in harsh climatic conditions. Therefore, these species can be used to control dust through biological control.