Floristic Composition, Life form and Biological Form of Plants in Relation to the Abandonment Time of Agricultural Land in Chaharmahal and Bakhtiari province (Case study: rangelands of Shirmard village)

In this study, the floristic composition was investigated in relation to the abandonment time of agricultural land in rangelands of Shirmard village . For this purpose, 96 old-fields in four time periods of abandonment less than 5, 5-15, 15-25 and more than 25 years were selected in two plant communites of shrubland and grassland. Thereafter, 24 key rangeland areas were chosen around the old-fields. In each of the selected old-fields and key rangeland areas, 10 plots of 4 m2 were established and in each plot all plant species were recorded. to investigate the effect of the abandonment time of agricultural land on the floristic composition of plants, firstly, the data of 600 plots sampled in each plant community were entered into Excel separately and arranged. secondly, the presence and non-presence of each plant species in each of the time periods of abandonment were investigated. The results showed that in periods of abandonment time less than 5, 5 to 15, 15 to 25, more than 25 years, and key rangeland areas around them, 101, 113, 135, 120, 138 species in shrubland and 100, 116, 124, 131, 128 species in grassland community were present respectively. Perennial forbs, hemicryptophyte, and Asteraceae, Fabaceae and Poaceae families had the highest number of species in both types of vegetation. Generally, the results of this study indicate that in the initial stages of agricultural land abandonment, annual plant species such as Aegilops triuncialis, Bromus tectorum, Heteranthelium piliferum, Echinops leiopolyceras, Secale cereale, Taeniatherum caput-medusae, Zoegea crinita, Carthamus oxyacanthus, Picnomon acarna and Turgenia latifolia accounted for more than half of the vegetation composition, which should be seriously considered in order to prevent the failure improvement ,restoration projects and the risk of fire.moreover, 37 valuable plant species such as Allium austroiranicum, Chaerophyllum macropodum, Ferula ovina, Astragalus fragiferus, A.kirrindicus, A.maassoumii, A.pseudoibicinus, A.piptocephalus, Onobrychis cornuta, Phlomis aucheri, Salvia multicaulis, Smyrnium cordifolium , Teucrium polium, Trigonella disperma and others have not been able to return to the abandoned agricultural lands through the natural regeneration after more than 25 years, which should be introduced into the vegetation by experts through seeding ,sowing projects and to be more protected and supported.