Introduction Biodiversity as a key factor of sustainability of natural ecosystems have been largely used in studies on natural vegetations (e. g. rangelands) at different spatial scales. BAHARKISH pasture with area of 1035 hectare is situated in 60 km distance southern of the city Quchan in Khorasan Razavi province. The lowest and the highest altitudes of the pasture are 1740 and 2440 meters a. s. l., respectively. Long-term (25-year) mean annual precipitation and temperature of the region is 337 mm and 9. 4° C with 998. 2 mm evaporation. In this study, about 200 hectares of BAHARKISH pasture with moderate grazing pressure was chosen by the clipping and weighing method to study the effects of environmental factors of plant species richness and diversity. Materials and Methods In order to evaluate the effect of ecological factors on the biodiversity of plant species in Quchan BAHARKISH pasture, at first all topographic maps (1: 25, 000), geological maps (1: 100, 000), aerial photos (1: 20000) and satellite images of Quchan BAHARKISH were collected. Then, maps of altitude classes, slope, aspect and geological formations were prepared and merged by overlapping in ArcGIS 10. 2. The generated maps were coded and 13 homogenous working units and their maps were prepared for further studies, field visits and pasture vegetation measurements. Finally, four homogeneous vegetation types were determined for sampling based on the structure, distribution, and presence of dominant species. Hence, in each vegetation type 35 plots (2m2 each) were systematic-randomly selected and used for composite soil sampling (0-30 cm depth) and estimation of vegetation indices. The species number and percentage of canopy cover were estimated in each plot and the plot locations were recorded with GPS devices in U. T. M system. Plant species diversity per plot was estimated using Shannon-Wiener and Simpson diversity indices, richness index of Margalef and evenness index of Smith-Wilson in Ecological Methodology software. One-way ANOVA was used to examine the components of biodiversity and Tukey test was performed for multiple mean comparisons. Principal component analysis (PCA) was conducted to classify vegetation types and to determine the contribution of ecological factors on biodiversity of the studies pasture. Results and Discussion The results indicated that altitude had significant effect on species diversity, richness and evenness and the highest values of Simpson and Shannon indices were obtained at 1900-2200 m a. s. l. Indirect effect of soil formation and direct influence of temperature were led to variation in distribution of plant species and rangeland community structure. Amount and type of precipitation and consequently vegetation type was changed with altitude. Species richness and diversity was significantly affected by slope, and lower slopes (<15%) showed the highest values of richness and diversity index. However, evenness was higher in 15-45% slopes. Overall, northern slopes had significantly higher species diversity, suggesting that plant available water is drastically influenced by slope through infiltration rate and land index. Results of PCA indicated that the first PC containing soil organic carbon, sand content and slope had the highest effect on species diversity. Conclusion In general, it can be concluded that plant biodiversity in natural ecosystems was affected by topographic and edaphic factors particularly in high altitudes. The results of PCA showed that the PC1 including percentage of soil organic carbon, organic matter and clay and PC2 including electrical conductivity and elevation, percentage of soil moisture, silt, sand and slope had the greatest impact on species diversity. In addition, getting insight in to the relationship between diversity and ecological, topographic and edaphic factors can be proposed as an ecological approach for sustainable rangeland management.

Livestock grazing is one of the most influencing factors on the rangeland community structure and composition, which can also change the vegetation diversity. The main aim of this research was to survey the flora and plant biodiversity at three rangeland sites, being used under different grazing intensities, BAHARKISH, Quchan, Iran. Three sites were systematically selected along a spatial gradient of low, moderate and high grazing intensity, and 20 quadrates were randomly established within each site. Species composition, abundance and canopy cover were recorded within the quadrates. Simpson and Shannon diversity and Carmago and Smith & Wilson evenness indices were measured for each site. Floristic studies led to the identification of 156 plant species belonging to 34 families. The floristic composition of the area was strongly dominated by the Irano-Touranian elements. Shannon and Simpson diversity indices were significantly higher under the moderate than the low and heavy grazing intensity sites and the lowest diversity was significantly recorded for the heavy grazing site. Evenness indices did not significantly differ between the low and moderate grazing sites, but it was significantly lower under the high grazing site. In conclusion, proper livestock grazing is necessary for preservation of species diversity in the semiarid rangelands, Moderate grazing maintained the species diversity while light and sever grazing reduced or even eliminated some sensitive plant species.

Studying the interaction between range plants increase our knowledge on the ecosystem functions. The balance between competition and facilitation was studied between a semi-shrub (Artemisia Khorassanica Podl.) and a perennial grass (Bromus kopetdaghensis Drobov.) in BAHARKISH rangelands, Quchan, Iran. Sampling was carried out where both species were growing alone, or the perennial grass was growing under canopy of the perennial shrub. Measurements were conducted at the early growth, full vegetative or flowering stages of A. khorassanica. In the early growth season, higher soil moisture, and lower MDA and H2O2 were found for the understory than open space, indicating facilitative effects of shrub on the grass. The reverse results were found during summer times, which were interpreted as competitive interaction. The grass individuals also could affect soil moisture and physiological performances of the nurse shrub, with their effect being negative during both early and late growth season. In conclusion, results of this experiment suggest a tradeoff in the positive (facilitation) and negative (competition) interactions between A. khorassanica and B. kopetdaghensis. The type of relationship between the nurse shrub and its understory grass depends on the soil moisture availability during different times of a growth season.

Background and objectives: Spiny and cushion plant species are critical for protecting species diversity in pastures. This study investigates the facilitative role of Astragalus gossypinus and Acantholimon raddeanum in enhancing species diversity across three management sites: Exclosure, Exclosure + Drill seeding method, and heavy grazing in the summer rangelands of Bharkish Qochan, Razavi Khorasan. Methodology: Three sites-Exclosure, Exclosure + Drill seeding method, and heavy grazing (livestock feeding area)—were selected and sampled using three 100 m transects in each representative area in June 2023. At each site, 30 paired plots for each species were established under nurse species and adjacent open spaces. Structural characteristics (large crown diameter, small crown diameter, height), and number, frequency, and percentage of plant species cover were recorded. Shannon-Wiener diversity, Margalef richness, Camargo uniformity, and density indices were calculated for the nurse species canopy and adjacent open spaces. Diversity indices were measured using Ecological Methodology 7. 2 software, richness indices using Past 3. 06 software, and density by counting. SPSS22 software was used for data comparison via two-way ANOVA and Duncan's test. Results: Species richness and plant density indices were higher under the canopy of nurse species than in adjacent open spaces across all management sites. The highest indices were in the Exclosure + Drill seeding method site under A. gossypinus Fisch. (richness: 4. 5, density: 8. 3), while the lowest were in heavy grazing open spaces under A. raddeanum (richness: 0. 8, density: 1. 1). Significant differences in species diversity indices were found between under-canopy and open spaces, with higher values under the canopy, demonstrating the supportive role of the nurse species. A. gossypinus Fisch. showed higher species diversity indices compared to A. raddeanum due to its structural characteristics. Comparing the three sites, no significant difference in species diversity indices was found between Exclosure and Exclosure + Drill seeding method sites, but heavy grazing sites showed significantly lower indices. Exclosure + Drill seeding method with native species improved species diversity indices, benefiting from ecological conditions, topography, and high plant diversity in the rangeland. Conclusion: Nurse plants enhance plant growth and survival by providing favorable conditions for other species. To improve vegetation, the use of nurse species is recommended due to their ability to create microclimates and offer protective effects in pastures.

This research was conducted to compare plant functional types (PFT) and traits in an old-field (abandoned for 28 years) and a control site, in the BAHARKISH rangelands, Quchan, Iran. In the both sites, 40 randomized quadrates were established. Floristic list, frequency, canopy cover and 20 vegetative, phenological and morphological plant traits were measured for all plant species, within each quadrate. According to the Pearson correlation analysis, and by using R software, 9 plant traits including life form, plant canopy, reproduction mode, reserve organ, root type, leaf phenology, growth form, life cycle, and regeneration mode, were known as the major plant functional traits. Data classification and ordination were applied on a matrix of 9 traits ×112 species, by using CANOCO and TWINSPAN softwares. It led to identification of 5 plant functional types. Total canopy cover of two PFT was significantly (70%) reduced and that of three PFT’s were relatively (10-20%) increased in the abandoned field. In conclusions, plants being annual, therophyte, geophytes, and rhizomatus are tolerant, whereas those being perennial (phaneropyte, chemaphyte, hemicryptophyte), having tap root system, and wide canopy cover are known as sensitive to ploughing disturbance.

Spiny and aromatic species in rangelands can play important role in the conservation of plant species in rangelands; however, few studies have been done on the role of these plants under different levels of livestock grazing. In this research, the facilitation effects of spiny (Astragalus chrysostachys Boiss) and aromatic (Artemisia kopetdaghensis (Poljakov) Y. R. Ling) shrubs were studied on species diversity along a grazing gradient. In 2017, five sites were selected in BAHARKISH rangelands, Quchan, where the livestock grazing varied from low to very intense. In each site, 30 twin plots were established under a canopy of the nurse shrubs and their nearby open spaces. Density, frequency and canopy cover of all plants were measured within the plots. Species diversity were reduced by increasing the grazing intensity, but it was consistently higher under canopy. In the highest grazing intensities, species diversity was higher under the canopy of Artemisia than Astragalus; however, opposite results were found under the high grazing intensity. In conclusion, in the areas of high grazing (livestock rest points), the aromatic species (Artemisia) may not be protected against livestock grazing, and spiny shrubs (Astregalus and Acantholimon) may still maintain their nursing effects.

The type of plant-plant interaction has prominent influences on the structure and composition of the natural plant communities. Facilitation between shrubs and their understory plants leads to the positive spatial associations, and hereby enhances the survival rates of the understory plants. We studied the type and extent of spatial association between four rangeland shrubs (Astragalus mesedensis, Artemisia khorasanica, Acantholimon prostegium, and Acantholimon erinaceum) and two perennial forage grasses (Bromus kopetdaghensis, and Festuca alaica) in their natural habitats, BAHARKISH, Quchan, Iran. Results indicated positive association (facilitation effect) between shrubs and perennial grasses, with no negative association (competition effect) being found for any species pairs. Among the nurse species, A. mesedensis showed greater and Acantholimon species indicated smaller positive association, while A. khorasanica did not show any association with the grasses. Between the beneficiary species, greater association with the nurse shrubs was found for F. alaica than B. kopetdaghensis. Accordingly in this study, A. mesedensis and F. alaica are the best nurse and beneficiary species, respectively. Our findings indicate the important role of nurse shrubs in preserving forage range plants. These results can also be used in the rangeland restoration projects, especially for seeding forage plants under the canopy of nurse shrubs.

While producing medicinal plants is more economic in their natural habitat than in farms, their establishment problems and slow growth rate are the main constraints under the natural conditions. This study was conducted to investigate the possibility for seedling transplantation of thyme into the natural conditions, in order to investigate the effect of mycorrhiza inoculation on establishment of this species in Bahar Kish rangeland, Quchan. Seeds were planted in glasshouse in small trays for 45 days, after that, seedlings were inoculated with two mycorrhiza species, Glomus mosseae and Glomus intraradices. After one month growth, the inoculated seedlings were transplanted into the natural. A complete randomized Block design with 30 replication was used.The results showed that mycorrhiza colonization with G. mosseae was 92% and with G. intraradices was 68%.There was no significant effect of inoculation on seedling establishment at early season, but at the end of growth there was a negative effect by G. intraradices but a positive effect by G. mosseae. Symbiosis with G. mosseae increased dry matter of leaf, stem, total dry matter and height of the plants while with G. intraradices had reduced these traits or the effects were non-significant. In conclusion pot planting can be an efficient method for establishing T. vulgaris under natural habitats, G. mosseae can be a beneficial symbiant for establishment of T. vulgaris in BAHARKISH rangelands.

Artemisia is a widely distributed genus from Asteraceae. Some species of the genus despite having allelopathic effects, provide favorable microclimatic conditions for the establishment of range plants under its canopy. Therefor, study of nurse plant, s allelopathic effect such as Artemisia korassanica Krasch. on understory like Bromus kopetdaghensis Drobov. is necessary. In this research, sampling was carried out in a range site in BAHARKISH, Ghochan by systemic randomized method at four different stages of the growth and development of shoot and root of A. khorassanica. we studied effect of water extraction on level (3% W/ V) of shoot and root of A. khorassanica on dry weight, chlorophyll content and soluble carbohydrate content of the shoot and root in B. kopetdaghensis seedling, and also we studied the amount of phenolic compounds and their changes during the different stages of growth and development in A. khorassanica. Results indicated that shoot extract of Artemisia had stronger inhibitory effect than the root extract and caused significant decrease on thedry weight and growth of leaf and root in B. kopetdaghensis. Total phenolics content in shoot extract as well as its inhibitor effect decreased gradually from the beginning towards the end of growth season. According to the results of the present research, it seems that the most suitable time for planting of Bromus seeds under the Artemisia canopies is in October, when Artemisia plants are in the seed rippening stage.