The aim of this research was to identify the life form spectra in the Irano-Tourani region. Identifying these spectra can reveal the relevant life form species. By Comparison these spectra with other regions, life form spectra, the situation of this region among the other regions can be determined. It was carried out using Raunkiaer’s method to determine the life form spectra from Irano-Tourani region. It was applied using DETRENDED CORRESPONDENCE ANALYSIS ((DCA)) to identify variability among different vegetation life forms. The proportion of species in each life form class was analyzed and compared with Raunkiaer’s normal spectrum using a test. The result showed that in Irano-Tourani region the Hemicryptophytes and the Therophytes, were the main life form classes and usually the Phanerophytes were the least ones. Compared with life form spectra from other vegetation types, the Irano-Tourani region did not form a distinct group. The (DCA) indicated that the Mediterranean forests have more similar environmental conditions to the Irano-Tourani region.

The current study was conducted in the rangeland of Glandrood watershed in the province of Mazandaran. The main objective of this study was to investigate the responses of forbs species to some environmental gradients. For these purpose 153 plots of 1m2 were established along the altitude gradient and Trasp. The sampling method was randomized-systematic. In the area sampled, frequency of forbs species, altitude and slope were recorded. Soil samples were taken from 0-20 cm in each quadrate. In each sample plot, pH, nitrogen (N), electrical conductivity (EC), organic matter, organic carbon, percentage of sand, silt and clay were measured. In this study, HOF function were used to describe the realized ecological niches of forbs species to the primary axis of classification or floristic gradient, as extracted by DETRENDED CORRESPONDENCE ANALYSIS ((DCA)) and the ecological variables were assessed with standard Spearman rank correlation tests. The data were analyzed by R ver. 3. 0. 3 software. The results showed that the most species have monotonically increasing or decreasing (19%), symmetric (15%), unimodals (23%) or skewed (35%) and only (4%) one species have flat response curves. For altitude variable of the 26 forbs species included in the general ANALYSIS, 4 species showed symmetric (HOF model IV), 9 skewed (model V), 5 species monotone (model II) and 7 species flat (model I) response curves. Among the forbs species, Colchicum kotschy, Medicago rigidula, Tecrium polium, platyloba Echinopora and Campanula stevenii had the narrowest niche ecological.

Four streams with different sizes were selected for studying the effects of environmental factors on fish assemblages using indirect (DETRENDED CORRESPONDENCE ANALYSIS, (DCA)) and direct (Redundancy ANALYSIS, RDA) gradient ANALYSIS in Golestan province. (DCA) of presence-absence and relative abundance data showed well gradient and linear model of species variability. In the within-site RDA, environmental factors explained 74. 8 % variability for presence– absence data and 77. 5% for the relative abundance data. Evaluation of two first axis of RDA showed that first axis has a high correlation with habitat characteristics and second axis correlated with channel morphology attributes. Based on RDA diagrams, Paracobitis malapterura and Capoeta capoeta gracilis presented in Zaringol and Tilabad Streams and had a high correlation with percent of in-stream vegetation and percent of cobble in first axis and low flow mean depth and low flow width in second axis. While Alburnoides bipunctatus and Neogobius fluviatilis had high correlation with percent of snag, pool and sand within streams. It should be stated that factors such as the size of the catchment, hydrographical and geomorphological characteristics, and land use change the morphology and stream habitats, and ultimately lead to the removal of some species in adjacent streams.

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.

Variations in reproductive characteristics of plant communities result in a shift in composition and structure of plant communities. The main goal of this study was to investigate the variation in reproductive characteristics of plant communities caused by livestock grazing in steppe rangelands and simultaneously to examine whether this shift in plant community composition is accompanied with variation in reproductive traits. For this purpose, random-systematic method was used to estimate canopy cover, height, number of spike and spikelet, number of flower and floret and number of seeds in plots, randomly established along three 100-m transects in three grazing treatments including long and short term grazing and exclosure. DETRENDED CORRESPONDENCE ANALYSIS ((DCA) in PC-Ord4.2) and ANALYSIS of variance (with multiple comparison; Tukey test) were used to reveal the shifts in composition and reproductive characteristics of plant community. Results showed that there were differences in plot distribution in ordination diagrams of three grazing treatments and these areas could be distinguished from each other in terms of plant community composition and reproductive characteristics such as number of seeds, floret, and number of spikelet in graminoids, flower and spike. Moreover, seed production of different classes of plant palatability was significantly different among grazing treatments. Results indicated that shift in plant community composition, resulted from livestock grazing, were accompanied with a shift in reproductive characteristics.

In order to investigate the effect of traditional utilization on the diversity and composition of woody species diversity in the western oak forest, two disturbed and less disturbed stands were selected with similar physiographic and floristic conditions. Therefore, 30 circularly shape plots with 1000 m2 surface area were established based on random-systematic sampling with 50×50 m network dimensions. In each sample plot, the frequency and type of woody species were recorded in the prepared sheets of inventory. The average Margalaf species richness indices, Pielo evenness, Shannon-Weiner and Simpson species diversity were calculated in each plot and normalized by Kolmogorov-Smirnov test. To test the significance of the difference between the mean of indices, t-student test was used for normal data and Mann-Whitney U test for abnormal data. DETRENDED CORRESPONDENCE ANALYSIS ((DCA)) was used for ordination of the woody species samples. The results of the study showed that the means of richness and diversity indices in the disturbed stand were significantly lower than in the less disturbed stand; however, the mean of evenness index did not show any statistically significant differences between two stands. High correlation of first axis of (DCA) proves the importance of destructive factors, such as cutting, branching, frequency of copping, grazing, and qualitative factors, such as basal area and number of trees. These factors plays an important role in differentiation of the forest stands.

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.

The aim of this research was to assess the effect and range of each forest road geometric plans on biodiversity and composition of plants on its two sides. To this end, to study the biodiversity of species of lateral stands and the effects of environmental variables in the situation of establishment of plant species at different distances of the road, the comparison of Shannon biodiversity Index (H), Menhinick species richness and Smith-Wilson’s index of evenness, DETRENDED CORRESPONDENCE ANALYSIS ((DCA)) and canonical CORRESPONDENCE ANALYSIS (CCA) were used respectively, according to its geometric plans. Results of the comparison between biodiversity indexes showed that in both sides of the straight road to switch back, Shannon index and Menhinik richness increased, while Smith-Wilson evenness had an inverse trend. The results of (DCA) and CCA ANALYSIS showed that the distribution of demanding species was positively correlated with increasing light intensity and temperature on the road verge. The effect of the road on these species was up to a depth of 10 meters from its edge as well. Shade tolerant species were more in-depth of forest than the road.

Gully erosion is one of the most destructive types of hydraulic erosion and an important process in soil destruction that in some cases creates long, vast, deep canals. Study area was located in the northeastern Alborz, Mazandaran province and Nowshar County (Firozkola subbasin a portion of Kojur watershed). This paper examines gully morphometery in relation with physical and chemical characteristics of soil. The morphometery of gullies such as width, depth and slope were determined in field. Physical and chemical properties of soil such as exchange cation (EC), organic and inorganic carbon, soil acidity and soil texture were determined in the laboratory. Data analyses were performed by DETRENDED CORRESPONDENCE ANALYSIS ((DCA)). The (DCA) ANALYSIS indicated that the width and slope are correlated with OC and clay negatively but they have positive correlation with pH. Hence, it's expected that following reduction of OC and clay and an increase in PH, gully width boosts. Besides, if EC increases and CaCO3 decreases, depth and w/d ratio of gully will increase.

The forest structure and stand composition are controlled by several physiographic factors, because these factors play an important role in control the physical and chemical conditions of the environment, including access to light, soil moisture, and nutrients. In this study, the physiographic characteristics indices of the study area including landform index, terrain shape index and aspect slope index and the stand structural characteristics including density, basal area, canopy coverage, and the species important value index using the DETRENDED CORRESPONDENCE ANALYSIS and Redundancy ANALYSIS studied in Arasbaran forests. The results showed that the highest altitude range (1600 to 1850 m a. s. l) had the highest amount of physiographic indices value. The Redundancy ANALYSIS showed that the LI index had a positive correlation with the first axis and TSI and AS indices had a negative relationship with it. In addition, Caucasian oak was the most important species in terms of importance value index. DETRENDED CORRESPONDENCE ANALYSIS between species and sampling units showed that Caucasian oak had the smallest distance with sample units and followed by hornbeam. Correlation ANALYSIS of structural characteristics and physiographic factors showed that stand density had no significant relation with physiographic factors (p≤ 0. 05), but the correlation of the canopy coverage area with the direction of slop in the first and second altitude ranges and basal area with the landform shape in the third altitude was significant (p≤ 0. 05). This study showed that the trees structural distribution in the study area affected by the physiographic properties. Therefore, it suggested that the effect of other environmental factors to be investigated such as soil and climate on the forest structure.