Identification and prioritization of plants for conservation and stabilization of marls (Case study: Tanghesorkh Watershed, Fars Province)

Marls as the most sensitive geological structure against erosion and weathering have a major role in sediment yield of watersheds. Due to the lack of vegetation or sparse pattern of vegetation cover in the Marl Formations; by identifying suitable plants and establishing and propagating them in these areas, the amount of erosion can be reduced. it is difficult to carry out the implementation of erosion control structures in Marl lands due to their mechanical properties; therefore, erosion control using biological measures is necessary and this requires accurate identification of species diversity. Due to the importance of this issue, suitable plants for the conservation of marls were identified in the Tanghesorkh Watershed of Fars Province.

Eleven points with dominance and the presence of marl outcrops were selected as sampling points. The sampling method for studying vegetation in these areas was based on physiognomic-floristic method and using transects and plot methods. Samples were collected in early autumn 2019, late winter 2019 and spring and summer 2020 and using valid scientific methods and plant species were identified. Also, biological form, longevity, vegetation form and chorology were determined. Then, different plant characteristics (density, frequency, canopy and root and rhizome status, amount of litter produced, generation method and longevity) and ranking of plants were studied in order to stabilize and protect the marl soils.

Around 108 plant species belonging to 29 families and 88 genera were identified. Asteraceae family with 18 species, Papilionaceae family with 17 species and Poaceae family with 13 species, are in the first to third ranks, respectively, and 16.67, 15.74 and 12.03% of the number of species to allocate them. In terms of longevity, 40 annual species (16 species of grass and 24 species of forb) and 68 species of perennials (8 species of grass, 30 species of forb, 18 bushes, 2 trees and 10 shrubs) were identified. A total of 37.04 and 62.96% of the total species accounted for plant. Life form included therophyte (36.12%), hemicryptophyte (24.07%), camphite (17.59%), geophyte (11.11%) and phanerophyte (11.11%). 55 species with a specific chorotype specific to the Iran-Turani vegetation zone had the highest frequency (50.93%). According to botanical characteristics, 30, 38, and 40 species in the first to third ranks for conservation of marl in this watershed were introduced.

Species such as Astragalus susianus, Astragalus faciculifolious, Astragalus gossypinus, Artemisia Aucheri, Convolvuvlus acathocladus, Convolvuvlus leiocalycinus, Amygdalus scoparia, Acantholimon asphodelinum, Stipa barbata and Glycyrrhiza glabra is recommended for the establishment and reproduction of in marl-covered areas in this watershed. Also, due to the irregular exploitation of these lands, it is necessary to protect these areas by controlling and managing livestock grazing. Therefore, this conservation provides opportunities for regeneration and survival of valuable plant species in this watershed.