Vegetation cover is one of the most important factors for ecosystem sustainability; thus, recognizing and understanding factors affecting the establishment and distribution of vegetation communities are necessary. This study was aimed to determine the relationship between vegetation and soil parameters of Ardestan rangelands, Isfahan Province. Primarily, the vegetation types were distinguished in the field using physiognomic method. Plot size was determined applying minimal area method. The number of plots was determined using statistical method. Systematic randomized sampling was used and performed along three transects of 100 m length. Ten plots of 6m2 were established along each transect at 10-meter intervals. Three soil profiles were dug in each area and soil samples were taken at a depth of 0-150 cm to study 21 soil factors. The results of factor ANALYSIS showed that among variables studied, 17 variables were the most effective factors on vegetation types of the study area. To determine the effect of environmental factors on the establishment of vegetation, CANONICAL CORRESPONDENCE ANALYSIS was used applying CANOCO software. Ordination results showed that environmental factors such as soil texture, lime, potassium and electrical conductivity had the most important role in the establishment and expansion of plant communities in the study area.

In order to identify the correlations and relationships between different traits in the bread wheat, 30 genotypes were investigated as sub-factors under the split plot experiment in the completely randomized design in greenhouse and the randomized complete block design in the field with three replications under the normal irrigation and post-anthesis water stress conditions. The results of the CANONICAL correlation ANALYSIS showed that at both normal and moisture stress levels, there was a significant correlation between the pair of CANONICAL variables obtained from the phenological traits and the yield components. Under the normal conditions in the greenhouse, to increase the spike density and length, the number of days to 50% flowering can be considered as a suitable selection criterion. According to the results of CANONICAL correlation ANALYSIS, under the stressed conditions in greenhouse, to increase the spike length, the number of days to the heading, maturity and 50% of flowering were among the important and effective factors. Under the optimum irrigation conditions in the field, the number of days to maturity was considered as one of the factors influencing the seed weight per spike. The results of CANONICAL correlation ANALYSIS under the field stress conditions showed that to increase the 1000-seed weight, the number of days to maturity can be considered an appropriate selection criterion.

Yeasts are a polyphyletic group of ascomycete and basidiomycete fungi characterized by having a unicellular growth phase and sexual stages that are not enclosed in fruiting bodies. An attempt was made to identify yeast species in uncultivated soils collected from different areas of Kermanshah province, Iran, by analyzing hypervariable D1/D2 domain of the large subunit (LSU) rDNA gene sequence and comparing the sequences with that available in NCBI database. In this study, 25 soil samples were analyzed and eight species including Rhodotorula toruloides (KP324973)*, Trichosporon coremiiforme (KP055040)*, Naganishia uzbekistanensis (KP324959), Candida catenulata (KP324968), C. paracilopsis (KP324965)*, C. boidinii (KP324 962)*, Lecythophora sp. (KP336745)* and Meyerozyma guilliermondii (KPKP324971, KP324978) were identified. Phylogenetic ANALYSIS based on D1/D2 regions allowed us to establish the precise taxonomic placement of each species. The CANONICAL CORRESPONDENCE ANALYSIS (CCA) indicated that elevation, EC, pH, and clay were important environmental parameters influencing basidiomycete yeast distribution in uncultivated soils. In this study, the presence of eight species is confirmed that asterisk species are the new records for the mycobiota of Iran.

In order to investigate the changes in weed flora in the irrigated wheat fields of Isfahan county over a 15-year period (from 2019 to 2004), a systematic sampling of weeds was conducted in 100 farms with W pattern during wheat tillering to stem elongation stages. In 2004, the dominant weed species was winter wild oat (Avena ludoviciana) with a abundance index of 76.1; however, in 2019 three weed species, including winter wild oat, wild barley (Hordeum spontaneum), and littleseed canarygrass (Phalaris minor) were recognized as the dominant species with abundance indices of 70.1, 42.3, and 28.6, respectively. In 2004, the dominant broadleaf weed species were lambsquarters (Chenopodium album) with a dominance index of 67.9 and prostrate knotweed (Polygonum aviculare) with a dominance index of 31.96. However, in 2019, the highest dominance indices were observed in lambsquarters, prostrate knotweed, and Flixweed (Descurainia Sophia) with abundance indices of 78.4, 38.5, and 39.04, respectively. The correlation between weed distribution and soil factors (nitrogen, phosphorus, potassium, soil texture, and electrical conductivity), crop rotation, and herbicides was examined using CANONICAL CORRESPONDENCE ANALYSIS (CCA). Littleseed canarygrass, wild barley, field brome (Bromus commutatus), licorice (Glycyrrhiza glabra), hoary cress (Cardaria draba), and yellow sweet clover (Melilotus officinalis) showed the highest correlation with soil nitrogen levels.

This study was carried out in Carpino-Fagetum orientalis, Rusco-Fagetum orientalis, Fagetum oriental and Alno-Fagetum orientalis forest communities of Namkhaneh, Gorazbon and Chelir districts of Kheiroudkenar forest. The aim of the research was investigation on relationship between understory vegetation and soil condition and to determine the indicator species for predicting of specific site situation of Fagetum communities of the study area. Selective stratification sampling method was used to locate samples. One plot is sampled on each aspect in each community. Totally, 120 sample plots were selected in the Fagetum communities in the study area. The plot size was 400 m2 considering to minimal area method. At each sample plot, floristic list and an estimate of percent cover and abundance of each vascular plant in separate strata were recorded by using of Braun-Blanquet scale. At the center of sample plots, two soil samples were taken from 0-10 and 10-30 cm layers of mineral soil. The physical and chemical soil properties in each sample were analyzed. Two ordinations approach, DCA and CCA, were applied to determine the relationships between vegetation data and environmental variables. Results showed that the distribution of plant species is mainly associated with aspect, clay, total nitrogen, organic matter, phosphorous and exchangeable cations. Geranium robertianum, Mercurialis perennis and Ruscus hyrcanus indicate high soil fertility, while Festuca drymeia, Blechnum spicant and Epimedium pinnatum show low soil fertility. Carex remota, Sanicula europaea and Carex divulsa indicate a moderate soil fertility conditions.

The relationship between vegetation and soil properties inKhojier National park, located in Tehran province was investigated. For this purpose, vegetation data was recorded in each plot, based along 3 tansects in each vegetation type. Minimal area method was used for plot size. Density and vegetatin cover were determined. TWINSPAN and DCA tests were used to classify vegetation. Soil sample was taken from 0-20cm of soil depth then transferred to laboratory and prepared for ANALYSIS including soil texture, percentage of CaCo3, CaSo4, and pH, EC, P, Ca, Ma and N. For ANALYSIS of soil properties in relation to vegetation changes, a multivariate ANALYSIS method such as CANONICAL CORRESPONDENCE ANALYSIS (CCA) was used. These analyzes were conducted using PC-ORD software. Results showed a significant correlation between vegetation and environmental factors. The most important soil properties affecting on vegetation types were gravel, clay, silt, sand, caso4, caco3, pH, EC, K and elevation. Statistical ANALYSIS of the results showed that the vegetation types had a significant difference in terms of percentage of Gravel, CaCo3, CaSo4, Sand, Clay.

Our planet is threatened by nuclear wars, climate change and degradation of biodiversity. The first two dangers are relatively focused on, but biodiversity degradation is not properly considered yet. Species diversity is mostly composed of biodiversity and is considered an index of changes in ecosystems. Many of researchers think of higher species diversity as an index of bio-system’s stability. This research aimed to study parametric models of species diversity on range vegetations of study sites and relationship of ecological factors such as climate, soil and topography with diversity index. Four range sites were selected on different geographic areas in Isfahan province and randomly- systematic sampling was conducted to collect density data on plant species by quadrates along transects of each site during six years (2002-2007). Broken stick, log normal, logarithmic series and geometric series models were fitted for each site, and log normal showed to be the most proper model of distribution with P>0.05. LSD’s test indicated a significant different at a=1% level between species diversity of steppe1 and semi-steppe2 sites. Log normal model seemed to be the most proper model in all sites. Generally, when this model is fitted successfully communities are considered stable. On the basis of some related studies with this research, Hill (N1) showed to be most proper index for species diversity in study sites, therefore effects of ecological factors such as soil, climate and topography on this index were studied by CCA method. Results of CCA revealed a high positive correlation between species diversity and percent organic matters of soil as well as precipitation levels and negative correlation with temperature.