جستجوی مقالات مرتبط با کلیدواژه « species richness » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

This research was carried out in an enclosure rangeland with four habitats of Artemisia sieberi, Zygophyllum eurypterum, Stipa barba and Amygdalus scoparia in the Shaskouh protected area, South Khorasan province. All the plant species of the rangeland were identified and counted in 200 plots, due to the different vegetation form and distribution of each of the dominant species, in each of the four habitats, 20, 40, 60 and 80 plots (respectively) were established with two plot size: 2 × 2 meters and 4 × 4 meters (60 plots each). Numerical indices and diversity ordering curves were used to compare four habitats. Alpha and gamma species richness were determined by numerical indices and single sample rarefaction and pooled rarefaction curves were used to compare species richness and determine data adequacy. The results showed that the total species richness (gamma) varies between 51 and 54 species. The habitat with 80 plots has the highest richness and diversity (S=43 and H=3.27) and 20 plots has the lowest richness and diversity (S=6 and H=1.41). The results of SHE analysis showed that with the increase in the number of plots, species evenness decreased. The pooled refraction curve showed that by increasing the number of plot to 110, all plant species will be observed. With the increase in plot size all values of species richness and diversity indices increased significantly (p≤0.01). Species evenness indices were not affected by plot size. The results of the present research showed that the numerical indices of species richness and diversity are dependent on plot size, and this is one of the disadvantages of evaluating biodiversity in rangeland using numerical indices.

Changing the use of natural ecosystems, including dam construction and also the conversion of pasture land to agricultural land, can cause irreparable damage to different parts of the ecosystem. Based on the research results the most destructive of them is the reduction of vegetation, the increase of erosion and also the reduction of biodiversity. In the management of natural ecosystems, monitoring vegetation changes is very important. The present research was carried out with the aim of investigating the changes in the vegetation cover indices and species diversity in the plowed and abandoned agricultural lands and the natural cover of the pastures around the Yan Chashmeh underground dam located in Ben city of Chaharmahal and Bakhtiari province.

To carry out this research, four sites including natural pastures around the dam, lands upstream of the dam (rain fields under cultivation), lands where the dam reservoir is being built (plowed and abandoned for less than 7 years) and lands downstream of cedars have been planted for more than 15 years) were selected and in each of the sites, three transects with a length of 50 meters parallel to each other and perpendicular to the slope of the area were established at a distance of 50 meters from each other. 15 plots of 2 x 2 square meters were placed on the transects with a distance of ten meters from each other. And then, in each plot, the percentage of canopy cover, biomass, percentage density of leaf litter and bare soil were recorded. The theoretical estimation method was used to determine the level of plant canopy in the plots. The biomass of the species was determined using the cutting and weighing method. In order to check species diversity, Simpson and Shannon-Wiener indices and to compare species richness, Margalf and Menhinik indices were calculated in Past software. Determining the condition of the pasture was done using two modified four-factor and six-factor methods.

 The results showed that plowing and changing the use of pasture land to agricultural land has caused a significant reduction in the crown cover and, as a result, a decrease in the amount of biomass density, and also a decrease in diversity and species richness in the plowed and abandoned lands compared to the sloping pastures of the region. The results showed that in addition to reducing the cover, plowing has caused a change in the species composition and an increase in annual and invasive species and a decrease in shrub species. According to the results of the change of pasture use, the surrounding pastures decreased from average to weak and very weak condition in plowed and cultivated pastures (upstream) with a negative trend.

The measures taken to build the dam and then the expansion of agriculture have caused plowing and soil manipulation in the region. Besides, it is possible that in the long term, abandoning agriculture due to the drop in the water level of the underground dam will cause more soil erosion. Therefore, it is necessary to continuously monitor the vegetation changes in the are

The impact of grazing on the carbon cycle in mountain rangelands depends on various factors, including management practices and environmental conditions. However, the effects of grazing on carbon stocks remain uncertain due to challenges in tracking small changes in rangeland carbon stocks, lack of baseline information, and limited long-term grazing management data. This study aims to investigate the relationships between plant and soil parameters and organic carbon storage in a 10-year-old exclosure in the mountain rangelands of Asadabad, Hamadan.

Two study sites, one under grazing and the other under a 10-year-old exclosure, were selected in a manner that minimized the gradient effect of ecological and biological factors. Vegetation and topsoil samples were collected along two 100-meter transects at 20-meter intervals, resulting in a total of 10 plots in each area. Vegetation parameters, including percentage cover, diversity (Simpson index), evenness (Shannon-Wiener index), and richness (Margaluf index), were calculated using Past 4.03 software. Soil organic carbon, phosphorus, potassium, and nitrogen were measured. Statistical analysis was performed using SAS V.4.1 software, and the distribution of variables was analyzed using principal component analysis (PCA) in Canoco 5 software.

The findings revealed higher vegetation cover and plant diversity (richness and evenness) in the exclosure area. The vegetation cover percentage and species count in the grazing area were 35.1% and 127, respectively, while in the exclosure area, they were 67.6% and 139. The carbon stocks in vegetation and soil were significantly higher in the exclosure area, with values of 83.13 and 74.35 ton/ha in the soil surface, and 0.00219 and 0.00273 ton/ha, respectively (p < 0.05). The exclosure area exhibited a significant increase in Simpson diversity index (13.83) compared to the grazed area (12.63). Additionally, the Margaluf richness index showed a significant increase in the exclosure area. Soil phosphorus, potassium, and nitrogen nutrient measurements indicated an increase of 51%, 25.7%, and 15% in the exclosure area (p < 0.05). Correlation analysis revealed a significant linear relationship between organic carbon and phosphorus (r = 0.55) and nitrogen (r = 0.80) (p < 0.05). However, no significant correlation was observed between plant diversity indices and vegetation organic carbon storage.

The study demonstrated the positive impact of long-term exclosure on soil and vegetation parameters in mountain rangelands (p < 0.05). Exclosure not only enhanced plant and soil organic carbon storage but also resulted in increased soil nutrient levels, vegetation cover, and diversity and richness indices. The significant increase in plant diversity highlights the suitability of the Simpson index for evaluating diversity in mountain rangelands. However, the lack of a significant linear relationship between diversity index and organic carbon stocks in plants and soils suggests that factors other than plant diversity directly influence carbon stocks in mountain ecosystems.

The loss of biodiversity worldwide and its impact on ecosystems' functions and performance over the past few decades has led to the conduct of many studies in this regard. On the other hand, identifying the reasons behind and the processes involved in changes made in species diversity has remained a challenge in ecological research. However, as vegetation is one of the factors that affect the richness of species, this study sought to investigate the relationship between species richness and vegetation percentage in the middle Taleghan rangelands.

considering the effects of livestock grazing, pasture condition and tendency, soil erosion, soil depth, and the percentage of rocks and pebbles at each site, the researchers of this study identified five levels of turbulence and stress in order of importance, including high turbulence and medium stress, medium turbulence and medium stress, medium turbulence and low stress, low turbulence, and moderate stress and low turbulence and low stress. To this end, random-systematic sampling was performed on the representative areas of each sampling unit to collect the required samples. Moreover, the number of plots was determined via the statistical method of 21 (one square meter) and the sampling was performed along two to three transects (100 to 150 meters long) in the representative areas of the study sites (a total of 735 plots). In each plot, first, the list of plants was recorded and their life forms were identified individually. Furthermore, different regression models were used to investigate the relationship between canopy cover percentage and species richness. These models were developed in such a way that the researchers were able to insert the amount of species richness (species per square meter) as a dependent variable (response) and the percentage of vegetation canopy as an independent variable in the relevant equations. On the other hand, to investigate the relationship between species richness and canopy cover percentage of plant species, first, the matrix of the data regarding the plant species cover percentage in different plots and sites was produced, followed by the modeling of regression equations via vegan and IME 4 packages in R software. Moreover, this study used a hybrid model to model the regression relationships between species richness and vegetation percentage. To this end, the best model was selected based on AIC standard statistics from among different regression models fitted on species richness and percentage of the vegetation canopy. It should be noted that as the results of such a statistic are separately calculated for each effect, and that the best model is selected based on the lowest value of the statistic, two or more models are selected as the best model in cases where the difference of the statistic is less than 2 in two or more models. Finally, R2C and R2m values were calculated for the best model using the MuMIn package in R software.      

The study's results indicated that the logarithm-quadratic model was the best-fitted model for the relationships between species richness and percentage of vegetation canopy for forbs, grasses, and shrubs. It was also found that the highest variance in modeling was explained by the fixed effect (based on R2m values). Therefore, the broad-leaf weeds and the shrubs had the highest and lowest variance, respectively. The results also showed that the relationship between species richness in different vegetative forms and the percentage of vegetation canopy were Gaussian but not complete. Moreover, the Gaussian model was observed more on the left side of the curve. Furthermore, in the broad-leaf weeds, the highest species richness was observed in moderate turbulence and stress and the lowest one was found in low turbulence and stress. On the other hand, in wheatgrass plants, the highest species richness was observed at high turbulence levels and the lowest one was found at low turbulence and stress. According to the study's results, the quadratic model was identified as the best-fitted model for the relationships between species richness and canopy cover percentage. Also, it was found that species richness was increased with increasing vegetation percentage and that the species richness decreased (Gaussian relationship) with increased vegetation percentage. Moreover, the highest amount of species richness was found in low turbulence and moderate stress and medium turbulence and low stress, and its lowest amount was observed in low turbulence and low stress. Furthermore, the highest species richness was found in 60-65% of the vegetation.

The results showed that the relationship between species richness and canopy cover percentage was of Gaussian type and that the amount of species richness increased with an increase in the percentage of vegetation, and this increasing trend continued almost to 60% of the vegetation. Moreover, it was found that the species richness decreased with an increase in the percentage of vegetation (more than 60% of vegetation), which may be attributed to reduced light intake, which, in turn, would lead to a Gaussian relationship. Furthermore, according to the study's results, the highest species richness was observed at moderate turbulence and stress, and the lowest was observed at the level of low turbulence and stress. On the other hand, in wheatgrass plants, the highest species richness was observed at a high turbulence level, which could be due to the effect of grazing intensity and turbulence on species of the wheatgrass family. In general, a Gaussian relationship was observed in the whole study area between species richness and vegetation. Therefore, as measuring vegetation is easier and more accessible than other parameters such as biomass, it can be used as a parameter to predict species richness in rangelands. Moreover, considering the fact that a few studies have so far been conducted on the investigation of such a relationship in Iranian rangelands, and on the threshold at which vegetation is at its maximum species richness, examining such a relationship can help the relevant officials manage and maintain vegetation as much as possible so that that optimal species richness is obtained in the ecosystem.

This study was was don to investigate the interaction  of fire and grazing effects on index of vegetation diversity in Semi-steppe rangelands in Chaharmahal - Bakhtiari Province.Therefore, 16 sites was selected with different periods of fire and grazing intensity and 18 quadrates along transects at each site were determined and then a systematic -random sampling method was don. Then, species diversity and Beta diversity indices were calculated. To determine the effects of fire, grazing, number of year and their interactions on the diversity indices, the method of General Linear Model (GML) and for determining the significant effect between fire site and unfired site the method of T- Test was used. The results showed that in areas with moderate grazing intensity and with different periods time of fire, Diversity, Simpson, Shannon and species richness indices, compared to control areas significantly increased. But beta diversity has decreased. Simpson's and Shannon Index compared to control areas significantly increased, in areas with high grazing and different time periods of fire, and in areas with 1-3 and 3-5 years fire, Species Richness was increased and decreased respectively. Also with different time periods of fire, beta diversity was decreased. Despite the restoration of some shrub species with the passage of time at burned areas, Compared to control, the grazing intensities was significantly decreased and the highest percentage of perennial grasses coverage was observed in fire areas in places with moderate grazing intensity. After the fire, appropriate management methods in Semi-Steppe Rangelands, can increase the Forage quality and also cause an increase in species richness.

Information of plant diversity and its relationship with environmental factors are necessary requirements for rangeland rehabilitation techniques and priority of biodiversity conservation in local habitats. To collect vegetation cover data, the Namin mountainous rangelands were selected and systematic random sampling in ecological units was used. The relationship between plant diversity and ecological unit’s characteristics (Sub-basins) was studied by recording the data in physiographic, topographic, chemistry and physics in the soil. To investigate the relationship between species diversity and environmental factors, the redundancy analysis (RDA) method was used as linear method based on gradient length. Based on the results, the physiographic and topographic had significant effect on the richness of the species. On the other hand, soil chemical properties had the greatest impact on the amount of species evenness and diversity of the ecological units and explained 89.64% of the variations. In general, slope, organic carbon amd EC are the most important effective characteristic on the enhancement species diversity idexes and the length parameters. It was also indicated that area and direction of sites are the most important factors on reduction of diversity indices. Therefore, in situations where the purpose of the management to be improve species diversity, places where are in endanger in terms of chemical properties of the soil (organic matter and, consequently, organic carbon) should be prioritized. If the aim of management to be increase in vegetation structure and percentage of plant protection from splash erosion, in this case, places where are in the southern direction and have a steep slope should be prioritized. Furthermore, rangeland rehabilitation techniques are a priority in larger-scale units due to the lower species richness, and smaller units, due to the high plant species richness, should be prioritized of conservation and protection.

This study aimed to investigate the effects of livestock grazing intensities (lenient, moderate, heavy and no-grazing) on herbaceous plant species composition and diversity (grasses and forbs) in understory of Quercus spp. and Pistacia spp. forest in Kebirkouh Mountain, Darehshahr city, Ilam Province, Iran. Vegetation sampling was carried out with randomized-systematic method at flowering time of the dominant plant species in April 2017. Within each quadrat, number of species, name of plants, density, life form and palatability class were recorded for herbaceous plants. Species diversity with the Simpson’s and Shannon-Weiner indices, species richness with Margalef and Menhinick indexes, and evenness with Peet and Sheldon indices were calculated in Ecological Methodology software version 6.1.4. The highest value of Simpson index for grasses and forbs was 0.972 (moderate grazing) and 96.95 (exclosure). Also, the highest value of Shannon index for grasses and forbs was 4.51 (heavy grazing) and 4.56 (heavy grazing), respectively. The highest richness of grasses and forbs was observed in grazed area with moderate intensity and no-grazing area, respectively. In the area without grazing, the richness of forbs was 4.4 and 2.75 according to Margalef and Menhinick indexes. The values of the Margalef and Menhinick richness indexes for grasses in grazed area with a moderate intensity were18 and 15 percent higher than the grazed area with heavy intensity. Peet and Sheldon evenness indexes were the highest for grasses and forbs in heavily grazed area and the lowest for grasses in the moderate grazing intensity and for forbs in the exclosure.

One of the ways of restoration and reclamation of damaged rangeland is to use different methods of rain harvesting such as pitting, counter furrowing, flood spreading, small arc basins system and etc., along with the reduction of runoff, it increases the soil moisture content and thus increases vegetation cover. Biodiversity is most commonly used to describe the number of species. It is studied in 3 levels, including genes, species, and ecosystems. However, species diversity is a major issue of biodiversity on a local and regional scale. Species composition and biodiversity are among the fastest and most important indicators for determining rangeland ecosystems condition. Due to the new construction of this structure in the rangelands of Iran, so far, little research has been done on the effect of small arc basins system on vegetation and forage production. Particularly, there is limited research on the variation of richness and species diversity by Construction of this structure. Abdollahi et al. (2016) investigated the effects of crescent pond structure on vegetation and soil parameters in Saravan rangelands of Sistan and Baluchestan province. The results of their research showed that, significant differences were found for all vegetation parameters between the crescent structure and control treatment, indicating the positive effect of crescent structure on vegetation parameters. The purpose of this study was to investigate the effect of constructing small arc basins system has been investigated on the composition of vegetation and biodiversity in the rangelands of South Khorasan province. Sampling in the rangelands of Sarbisheh, South Khorasan Province, was carried out in small arc basins area. Vegetation sampling was carried out in the rangelands by systematic-random method at the flowering stage of the dominant plant species in the spring of 2014.vegetation characteristics such as density, composition, cover percentage, and species richness indices (Margalef and Menhinick), species diversity indices (Simpson, Shannon - Wiener and Fisher's alpha) and species evenness (Pielou) were investigated in two areas (small arc basins area and the control area).The all biodiversity indices were calculated using PAST software. To compare the vegetation characteristics including density, composition, vegetation percentage, species richness, diversity and evenness, independent samples t-test were used. In general, 30 plant species were identified in two areas (small arc basins area and the control area), which belong to 17 families and 27 genera. The results showed that the number of plant species in the control area is 9 and in the small arc basins area is 30 species. The results of comparing the total vegetation cover percentage in both areas showed that the percentage of total coverage is very significant (p <0.01). The effect of construction of the small arc basins area system on the density of rangeland plants was very significant (p <0.01) and this system has significantly increased the density of rangeland plants., there is a significant difference in species diversity between the two regions in terms of Simpson diversity index and Shannon-Wiener's diversity index, but this difference is not significant in the alpha-Fisher's index. The results of the data on the study of richness indices also show that the Margalaf's richness index shows a very significant difference in the comparison of species richness in the two study areas, but this difference was not significant in terms of the Menhinick's index. Discussion and The results showed that the construction of small arc basins in the study area increased the number of plant species, species density and vegetation percentage compared to the control area, which indicates the positive effect of this structure on improving the ecosystem conditions. Research in this area also confirms this result. The results of this study indicate that the number of annual and perennial species in the control area (totally nine species) from 4 and 5 species in the control area has increased to 15 species for both species (a total of 30 species) in the small arc basins area. As well as, the results indicate that the vegetation cover percentage and frequency of perennial species is more than annual species. Several studies have indicated that species diversity has a significant relationship with soil texture and soil moisture. Since the construction of small arc basins leads to changes in soil moisture content and soil texture. Therefore, it has a significant effect on species diversity. Finally, according to the results of this research as well as previous researches, we can say that the effect of small arc basins system was positive on the ecological characteristics of vegetation in the study small arc basins treatment. Therefore, it can be considered as one of the most effective methods for the restoration of degraded rangelands.

In this study, the effect of cushion plants on spatial distribution of soil seed bank was studied in mountainous and hilly rangelands in Vaz watershed, Mazandaran province. Therefore, we selected randomly 20 Onobrychis cornuta individuals and sampled from soil at four positions around each individual (upslope, downslope, center and, outside as control). Soil samples spread out under natural conditions in greenhouse to germinate the seeds. Germinated seeds were identified then, the seed density per square meter and species richness were calculated and both of them were compared between the four sampling positions. Two and one-way ANOVA, T-test and Duncan test were used to compare the effect of location, depth and their interaction on soil seed bank characteristics. The results showed that the effect of the location and depth of the density and species richness at level of 0.01% were significant. The results of Duncan test showed that seed density in the upslope and center positions (average 5473 and 4099.5 seed/m2, respectively) was significantly higher than seed density in the downslope and outside positions (average 2685.5 and 2413.8 seed/m2, respectively). Similarly, species richness in the upslope and center positions (the average 9.7 and 9.5, respectively) was significantly higher than species richness in the downslope and outside positions (average 7 and 6.4, respectively). Density and species richness of soil seed bank at depth of 0-5cm was significantly greater than the depth of 5-10cm. This study clarified the positive significant effect of canopy of cushion plants on seed density and richness.

This research was aimed to study the effects of elevation and aspect on diversity components (alpha, beta and gamma) using additive partitioning in the Geno Mountain. All plant species were listed in nine elevation zones (400-1050 m a.s.l.) in southern and eastern aspects of Geno. The cover percentage was measured using five plots of 4m2 (in total 90 plots) in each elevation zone. Total plant species diversity (γr) was partitioned into additive components within plots (α1) and between plots (β1) and among elevation zones (β2) and among aspects (β3). The results showed that β3 diversity (72.36%) and β1 (8.19%) had the highest and lowest contribution to the total diversity (γr), respectively. The β3 and α1 values were higher and lower than the expected values, respectively, indicating the non-random distribution of plant species. The lowest observed percentage and expected values at the alpha level were recorded for both southern and eastern directions. In addition, the lowest observed values at the alpha level were recorded for the southern (5.95%) and eastern (5.73%) directions. Generally, beta components had a higher percentage, whose values were higher than that of the expected values. On the other hand, the alpha component in eastern and southern directions was lower than expected values. The results showed that the highest Shannon index (1.72) and richness (22) were obtained at elevations of 1200-1600 m a.s.l. and 1600-2050 m a.s.l, respectively.According to the results of this study, it is suggested that the regional scale (whole area) should be taken into consideration to protect and enhance the diversity.

This research was aimed to investigate the effects of exclosure on species diversity changes under grazing and exclosure conditions in the northeast rangelands of Delfan County, Lorestan province. For this purpose, 120 quadrates of 1*1 m2 were established in a randomized-systematic method along 12 transects of 100 m length at four altitude classes (three transects on each altitude class). In each quadrate, the list of species, density, the percentage of canopy cover, litter, stone and gravel, and bare soil were recorded. To evaluate the numerical indices of diversity, Ecological Methodology software (Ver., 6.2) was used and numerical indices of diversity and evenness were calculated. Data analysis was performed in SPSS software (Ver. 18). According to the obtained results, a number of 132 species were identified, belonging to 30 families and 104 genera, of which 124 and 108 species were recorded in the rangelands under exclosure and grazing conditions, respectively. Our results clearly showed higher numerical indices for richness, evenness, and species diversity under exclosure as compared with grazing condition. The canopy cover percentage of perennial grasses and forbs as well as litter percentage was higher inside the exclosure while the canopy cover percentage of annual grasses and shrubs as well as bare soil percentage was lower as compared with outside the exclosure. The density of perennial grasses and forbs increased, while the density of shrubs decreased inside the exclosure. In addition, a higher production was obtained from the rangeland under exclosure condition.

It has been paid less attention to effect of environmental factors on species richness and diversity indices in fragile ecosystems around Playa. Therefore this study was conducted to evaluate the effect of geographical directions and distance from Playa salt layer on the composition and species diversity in Sirjan Playa, Kerman Province, Iran. Determination of intervals 10, 1000 and 2000 meters in four main geographical aspects surrounding salt crust (North, South, East and West), were done using GPS positioning and field operation. Along the perpendicular direction, sampling of vegetation in each distanc by relevee (with dimensions equal to minimum level) in early May 2016 with three replications was carried out systematically. After determining the diversity of each unit in the software PAST and BIO-DAP, statistical analysis of data for analysis of variance (ANOVA) and mean comparison with Duncan's multiple range test was performed by SPSS software.The results showed that the main effects and interaction of geographical directions and distance from playa salt layer on all indicators of species diversity and richness were significant. In all directions at intervals of 10 meters of salt crust due to the dominance of one-dimensional of Halocnemum strobilaceum plant species and the absence of other plant species, dominance index and uniformity index of Jaccard were maximum and cotroversially richness (Menhing, Margarf and Fisher) and diversity (Shannon - Wiener, Simpson) were minimal. Due to the presence of other plant species with Halocnemum strobilaceum in 1000 meter of distance of all directions (except for the west), all the richness and diversity on the contrary of dominance and uniformity indicators increased significantly and the situation in most indicators were kept at a distance of 2000 meters. According to the development of a single plant species (Halocnemum strobilaceum) strip with very low species diversity and non-uniformly with increasing distance from center of playa in the west, likely to spread the risk of desertification and land degradation in this direction than in other directions.

A standardized sampling technique for measuring plant diversity is needed to assist in resource inventories and for monitoring long-term trends in vascular plant species richness.With considering to the estimated richness amount (via different methods) are changing influenced by interaction of plot distance and shape, and also, presenting of a plot design (that can be near to reality) is important due to the studing of species richness in ecological concepts. In this research, we compared the two sampling methods, Whittaker plot and Modified Whittaker plot in grassland and shrubland vegetation types in Taleghan rangeland of Iran. The result of this study showed that there is a significant difference between the two methods in determining species richness for grassland and shrubland vegetation types in Taleghan rangelands. The Modefied Whittaker design often returned significantly higher (P

In this study, species richness, evenness and vegetation biodiversity were investigated in stabilized and non-stabilized cut edge areas of Chachkam district forest roads in Sari forest of Iran. 18 micro plots 1×1m (36 micro plots) were sampled to carry out this research on two cut edge areas. Number of trees, shrubs and herbaceous were recorded in each micro-plot. Significant difference was investigated between the two regional diversity indices using
One-way (Duncan) in SPSS16 software. In addition, various diversity indices were calculated using of PAST software. The results showed that in the two cut edge areas, the number of herb species are 1185 and 366 respectively, the number of regeneration of tree species are 220 and 41 respectively and mean of richness Menhinick's index for regeneration of tree species are 0.61 and 0.35 respectively, mean of richness Margalef's index are 0.42 and 0.25 respectively, mean of diversity Shannon's index are 0.44 and 0.19 respectively and diversity Simpson's index are 0.26 and 0.12. Also mean of Menhinick's index herb species richness are 0.75, 0.73, richness Margalef's index are 1.21 and 0.75, diversity Shannon's index are 1.26 and 0.66 and Simpson's diversity index are 0.63 and 0.34. The statistical test results show that diversity and richness indexes have significant difference in the two cut edge areas of forest road but the significance difference have not been observed for the index of regeneration of tree species.

Species diversity differs in various spatial and temporal scales in response to different biotic and abiotic conditions. The aim of this study was to investigate the effects of grazing impact on species diversity components in local and regional scales in Ilam province. Vegetation sampling was carried out using 40 plots of 2×2 m2 (20 plots in exclosure and 20 plots in grazed area) in local scale and 8 sites (4 sites within exclusion and 4 sites within grazed area) in regional scales. Plant species richness (γr) partitioned into additive component among plots (α1), between plots (β1) and between sites (β2). We used the PARTITION software for analysis of species diversity components in different scales. According to the results, 72 plant species were observed in exclosure and 60 species in grazed area from a total of 89 recorded plant species. Additive partitioning of plant species diversity showed that, in two regions, observed plant species components (α1 and β1) was smaller than expected values in local scale, and in regional scale and observed plant species components (β2) was greater than the expected value. Species diversity among plot (α1) in exclosure area was significantly greater than the grazed area, but there was no significant trend for species diversity between plots (β1) and sites (β2), indicating non-random patterns of plant species. The beta diversity, with respect to more contribution to total species diversity, was more important diversity component in regional scale. This study showed that some components are more sensitive to grazing, so we suggest using these indices in vegetation management studies.