التنوع الاحيائي للغطاء النباتي وعلاقته ببعض صفات التربة والصفات البيئية في منخفض بحر النجف -عراق

" Biodiversity of Vegetation and its related of some soil and environmental Characteristics in the Najaf sea Depression- Iraq

This study was conducted in the Najaf Sea Depression region to conduct a comprehensive survey of the terrestrial vegetation cover and identify its biodiversity and plant communities. The region was divided into five stations, and a number of quantitative and qualitative characteristics of the vegetation cover were studied at these stations. The vegetation survey was conducted through monthly field trips in the summer and autumn seasons, and weekly trips in the winter and spring seasons, to all study stations during the years 2022-2023, i.e., from January 2022 to October 2024. Some environmental factors were measured, such as weather characteristics provided by the Iraqi Meteorological and Meteorological Authority at the Shabaja station in Khan al-Rahba, near the Najaf Nature Reserve. Monthly reports were sent by the Meteorological Authority on the weather conditions for the years 2022-2023, including air temperature, solar radiation, relative humidity, rainfall, wind, and evaporation.
Some soil properties were also measured, such as soil reactivity, electrical conductivity, organic matter, mineral carbon, organic carbon, and gypsum concentrations, as well as the concentration of certain elements, positive and negative dissolved ions, cation exchange capacity, and soil texture.
Biotic factors were also studied, and several environmental parameters were calculated, such as frequency, density, coverage, the critical value index, and the Shannon index of plant biodiversity. The current study included a comprehensive survey of gymnosperms and angiosperms of dicotyledons and monocotyledons growing wild. 255 species were found belonging to (41) families, divided as follows: Dicotyledons (214) species belonging to (34) families, monocotyledonous species amounted to (40) species belonging to (6) families, and gymnosperms (1) species belonging to (1) family. They were scientifically classified and their local and common names, whether Iraqi or Arab, were mentioned, as well as their permanence and economic importance (medical, toxic, food, fodder, industrial, harmful, aromatic, ornamental plants, fuel, or other uses), in addition to their geographical distribution and seasonal changes in the vegetation cover.
Plant communities were also studied, and the most widespread plants in all study areas were the communities of wild jujube (Zisiphus nummulariae), tamarisk (Haloxylon salicornicum), tamarisk (Zygophyllum coccineum), tamarisk (Tamarix), jabbaj (Cornulaca leucocantha), jabbaj (Alhagi graecorum), shuwail (Cressa cretica), kitina (Bassia eriophora), and baker’s tamarisk (Malvus thuringiensis). A number of plant families dominated the study, including the Compositae family, which included 42 species, followed by the Legume family, Papilionaceae, which included 35 species, the Chenopodiaceae family, which included 30 species, the Poaceae family, which included 29 species, the Cruciferae family, which included 19 species, the Caryophylaceae family, ten species, the Euphorbiaceae family, nine species, the Plantaginaceae family, and six species each for the Tamarixaceae and Cyperaceae families. The dominant genera are Plantago and Euphorbia, with seven species each, followed by Launaea, Saueda, and Tamarix, with six species each, Salsola, with five species, and Astragalus, Medicago, Cyperus, and Bassia, with four species each.
The dominant genera were Plantago and Euphorbia, with seven species recorded for each, followed by Launaea, Saueda, and Tamarix, with six species each, Salsola, with five species, and Astragalus, Medicago, Cyperus, and Bassia, with four species each. The economic importance of plants was assessed, with the highest number of medicinal plants recorded at (185) species, followed by (152) fodder plants or human food, followed by (24) species of plants used as fuel, followed by (23) species of poisonous plants, (16) species of ornamental plants, and (9) species of aromatic plants, followed by (6) species of harmful plants. The number of species was calculated in terms of permanence. The statistics of the study results showed that the vast majority of the collected species are herbaceous plants, with their number reaching 147 wild species out of 255 wild species. As for the number of shrubby species, it is 34 wild species, perennial herbaceous plants (45) species, wild trees (7), biennial plants (7), and parasitic plants (3) species. The results showed differences between the growing seasons and study stations in Shannon-Wiener index values. The highest index values were recorded in the spring season at station four, reaching 3.744, followed by station one in the spring season, reaching 3.561, and station three, also in the spring season, reaching 3.320. Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS) to demonstrate the extent of the relationship between biodiversity and environmental and soil factors. Statistical analysis of the Pearson correlation coefficient between biodiversity and environmental factors showed a clear relationship between biodiversity and rainfall. However, none of the soil characteristics showed a significant relationship, except for soil components (silt), which were positively correlated with plant biodiversity.