IRANIAN JOURNAL OF RANGE AND DESERT RESEARCH
Year:2018 | Volume:25 | Issue:1 (70) |Papers Count:26

Multivariate data analysis in ecology and biodiversity research is very important. Ecologists often need to test hypotheses about the effects of experimental factors on the entire community composition. To analyze multivariate data, the use of classical statistical methods is based on assumptions such as the normal distribution of data that are not usually observed in ecological data. To analyze multivariate data, the use of classical statistical methods is based on assumptions such as the normal distribution of data that are not usually observed in ecological data. Therefore, in recent years, nonparametric tests, based on permutation tests and distance or dissimilarity matrix, have been widely used to test the existence of differences in species composition in ecology sciences. The purpose of this paper is to introduce and familiarization with new ecological non-parametric multivariate tests related to ecology sciences such as SIMPER, ANOSIM, PERMANOVA and PERMDISP, with the aim of analyzing the composition of plant communities. In order to introduce these analyzes, vegetation data of six sites of rangelands located in the surrounding area of Tehran province were used and the composition of the plant communities of the mentioned areas was analyzed. SIMPER analysis showed that Stipa hohenackeriana and Bromus tomentellus, respectively, had the largest role in differentiating among the sites studied in arid and semi-arid regions. ANOSIM and PERMANOVA analyzes showed a significant difference of plant composition among the sites. According to the results of these tests, Firouzkooh-Alborz, Damavand-Semnan and Saveh-Salafchegan sites had more similarity in terms of composition of vegetation. PERMDISP analysis showed that heterogeneity and multivariate dispersion of species coverage were significantly higher in Salafchegan and Saveh sampling sites. Therefore, according to the results, it can be stated that in order to preserve biodiversity in the study sites, at least three separate management plans are needed. Also, according to SIMPER analysis results, management plans to preserve the biodiversity of the areas studied can be supported by the distinct species identified in each site.

The main objective of this study was to evaluate the effect of tree species canopy on production and diversity of grass species in the understory of trees in Fandoghlou, Ardabil. The study area was selected after extracting similar geomorphological units of Fandoghlou, Shoghal Dareh and Niaragh. Inventory was conducted by systematic random sampling and dimension of plots was determined regarding the structure of vegetation. The number of plots was selected using statistical formulas, and the list of species, canopy cover, litter, rock, and bare soil percentage were recorded. Sampling in open and forested rangelands was done in four slope classes including 0-10, 10-20, 20-35 and 35-50% and in four geographical aspects including northern, southern, eastern and western. The results showed that the highest vegetation cover percentage was observed in the understory of trees in Fandoghlou, Niaragh and Shoghal Dareh in slope classes of 10-20%, respectively, with 20, 25 and 25%. The highest vegetation cover in open rangelands were observed in slope classes of 10-20%, respectively, with 81, 86 and 86%. The northern aspect compared to other aspects had the highest vegetation cover in both rangelands. According to the results, the highest production was observed in open rangelands, showing a significant difference with forested rangelands. In addition, the production of grass species and interaction of rangeland type and aspect showed significant differences in the study rangelands. Accordingly, production in the open rangelands of northern slopes was significantly higher as compared with forested rangelands. On the other hand, the results of diversity and evenness indices in open and forested rangelands showed that the highest amounts of these indices were observable in forested rangelands.

Geomorphological map is one of the main information layers in natural resources studies. So far, various methods have been proposed for the classification and separation of various units and Geomorphological types, most of which are based on qualitative and descriptive information. In this study, the ability of geomorphometry parameters in separation of mountains from pediment and also separation of different types of pediments was investigated. First, ground truth map was prepared using visual interpretation of satellite data and topographic maps. Then the 1000-point sampling grid was designed randomly. Parameters including profile curvature, plan curvature, tangential curvature, cross-sectional curvature, longitudinal curvature, and general curvature were prepared from digital elevation model in the GIS software. Then, their values were extracted at all points of the sampling network. Then, artificial neural network with structure of 13_6_ 4 was used to separate the units. The results showed that the erosion pediment could be separated from epandage using artificial neural network; however, the separation of epandage pediment from covered pediment was not well. For this purpose, to improve network performance, the digital value of Landsat 7 data was added to the previous values. The resolution accuracy of mountain, erosion pediment, epandage pediment, and covered pediment was calculated to be 90, 79, 80, and 76%, respectively.

Due to the vast area and biodiversity, rangelands contribute to carbon sequestration, depending on grazing management and utilization. This research was conducted on six rangeland sites including Paveh, Ravansar, Javanrood, Einelcosh, Siahkamar, Varmenjeh, and Koohsefid in Kermanshah Province. There utilization types were included as exclosure, heavy grazing, and land use change from rangeland to rainfed orchard. The objective was to evaluate carbon sequestration capacity through different rangeland utilization. The plant biomass sampling including canopy cover and plant root as well as plant litter were carried out in the field along three transects of 50 m using plots. Soil sampling was also done in 0-20 and 20-40 cm soil depths. Plant organic carbon was determined by flame method and SOC was measured by the Walkley and Black method. The results explored that plant biomass variation through different land-use practices and utilization is significantly attributed to carbon sequestration, so that the highest level of carbon stock for plant biomass (4. 7 tha-1) and soil (114. 5 tha-1) was obtained in the exclosure site, while heavy grazing caused the lowest value of organic carbon in both plant biomass (1. 3 tha-1) and soil (53. 4 tha-1). In addition, the land use change from rangeland to rain-fed orchard led to 86. 8 tha-1 organic carbon storage in both soil and plant biomass.

Awareness of annual and monthly production of various rangeland types is essential for efficient management of rangelands. It would be achievement by determining the relationship between plant forage production and climatic variables affecting them especially rainfall which would make easier management. Achieving this goal is facilitated by determining the relationship between the amount of forage production and climatic variables affecting it, especially rainfall, in rangelands. Firuzkuh rangelands were studied to determine the relationship between rainfall and shrub forage production during 2006-2010. For this purpose, the annual and monthly forage production was measured during plant growth season in research exclosure plots by clip and weigh method. Each plant species studied had a specific production during the grazing season in different years. Relationship between forage production and precipitation in periods of winter and spring as well as each month of winter and spring was estimated. Results showed that correlation between the forage production of study species and precipitation in different periods including crop year (0. 06-0. 42), winter and spring (0. 01-0. 23), March and spring (0. 13-0. 35), March and May (0. 06 – 0. 45), February to June rainfall (0. 13 – 0. 40), was positive and reached its highest level in June (0. 63-0. 94). A significant relationship was found between the forage production of Acantholimon erinaceum, Acanthophyllum spinosum, Astragalus gossypinus, Onobrychis cornuta and Thymus fedtschenkoi and June rainfall.

In order to develop a clear and realistic desertification control plan, identifying and evaluation of processes as well as causes and current status of desertification are the basic needs of arid zones. In present study, the desertification assessment of Incheh – broun area in Golestan province was performed using three indicators of ESAs model (soil quality, vegetation cover quality and climate quality). Therefore, the map of each indicator was obtained from the geometric mean of its layers. From the geometric mean of these indicators and by classification of obtained map, the desertification sensitivity map of the study area (ESAI) was obtained. Finally, the study area was classified in three classes [no sensitive (7. 64%), fragile (14. 41%) and critical (77. 95%)]. The results demonstrated that poor drainage, heavy texture of soil, poor vegetation cover, besides climatic factor are the most important factors of desertification in the study area causing desert conditions. With regard to the results and in order to prevent the advance of desertification processes, the biological and mechanical land improvement techniques such as plantation of species resistant to heavy and saline soils and construction of drainage in water logging lands are recommended.

Soil contamination by heavy metals is a major environmental problem in the world. In polluted environments, especial plant species can grow, adapt, absorb, and uptake heavy metals. This study was carried out to investigate the phytoremediation potential of plant species including Acantholimon olivieri (Jaub. & Spach) Boiss., Astragalus glaucacanthus Fisch., Ebenus stellata Boiss., Scariola orientalis (Boiss) Sojak subsp Orientalis. and Stipa barbata Desf in Ahangaran lead and zinc mine, Malayer Province. For this purpose, in polluted and controlled sites, the sampling of aerial and underground tissue was performed in a completely randomized block design with three replicates in summer 2015. The results indicated that in polluted sites, lead and zinc concentrations in aerial and underground tissues were higher as compared with control site. Among the study species, Astragalus glaucacanthus Fisch., had the highest value of lead and zinc absorption in aerial tissue (118. 6 and 190. 69 mg/kg dry matter, respectively) and Scariola orientalis (Boiss) Sojak subsp Orientalis., had the highest value of lead and zinc absorption in underground tissue (41. 07 and 67. 76 mg/kg dry matter, respectively). Also, Astragalus glaucacanthus Fisch., Acantholimon olivieri (Jaub. & Spach) Boiss., and Ebenus stellata Boiss., had the highest translocation factor of lead (3. 39, 3. 19, 3. 16) and zinc (3. 24, 3. 06, 2. 92), respectively. Our results clearly showed that these three mentioned species could be used to refine the soils polluted to lead and zinc in similar conditions.

The aim of this study was to analyze the effects of global warming on plant growth degree day in the future decades. To this aim, simulated daily temperature data were drawn from EHOM database and under A1B scenario during 2015-2050 from Germany Plank Max. Then, daily degree data were downscaled with a separation of 0. 27*. 027 degrees longitude and latitude, covering around 30*30 km of Iran, by regional climate model designed at the Abdul Salam Center for Theoretical Physics, Italy. Finally, a matrix with dimensions of 13140*2140 was obtained that rows represent degree day and columns represent stations (cells). The threshold of 5 ° was selected to calculate the growth degree day. Finally, the monthly average of growth degree day was calculated in a matrix with dimensions of 12*2140 in MATLAB software. Then, the map of average of growth degree day was designed through Surfer software. The results showed that June and July had the highest average monthly growth rate in the 100-1000 degree-day. In summer months, the highest degree day was observed in Khozestan plain. With regard to the degree day in spring and summer, Iran can be divided into three areas of mountains and interior foothills, internal pits and external foothills, and plains and southern coast.

Rangelands cover over 53 % of the country’ s area. These areas require proper management practices for preservation, rehabilitation, development and optimal utilization. Nowadays, participation of people, particularly ranchers, is an essential step towards sustainable development in watershed management. The purpose of this study was to investigate social and economic factors affecting the willingness of ranchers to participate in rangeland rehabilitation and restoration projects in Dehgolan city. The number of samples was calculated to be 68 using Cochran equation and Krejcie and Morgan table. Results showed that there was a significant and positive relationship between social and economic factors with the willingness of ranchers to participate in the rangeland rehabilitation and restoration projects. Also, the results of stepwise regression showed that among the variables affecting the willingness of ranchers to participate, four variables including social factors, economic factors, education and the number of livestock could explain 80% of the variance.

Grazing is one of the most important factors in providing environmental conditions for change in species composition, structure and function of ecosystems. West oak woodlands of Iran as a valuable ecosystem are not immune from this threat. Therefore, it is essential to study the various aspects of this phenomenon in these ecosystems. The aim of this study was to examine the effects of relative grazing intensity on vegetation characteristics in an oak forest dominated by Quercus brantii. The research was conducted in Dalab Park, located in Ilam province, west of Iran. Information of vegetation, soil and other environmental variables were collected from 53 sample plots (16×16 m) using the random sampling method in various disturbances classes. Two-way indicator species analysis was used for classification of the ecological groups. Indicator species analysis was used to determine indicator species in each class and canonical correspondence analysis to identify the relationship between factors and the plant groups studied. The results showed that the grazing as well as soil, topographic factors and the light reaching to the forest floor was identified as the most influential factors on plant composition. Grazing explained the highest percentage of variance (11. 2%) in floristic composition and caused an increased frequency of non-palatable species and resistant species to grazing and soil compaction as well as increasing of annuals including Bromus tectorum, Picnomon acarna, Minuartia picta, Rochelia disperma, Holesteum umbellatum, Lophocloa phlorides, and Valerianella vesicaria. These species were identified as invasive species based on density, abundance, and available resources. On the other hand, it seems that the spread of palatable species such as Vicia sativa, Trifolium physodes, Lens cyanea, and Lathyrus inconspicaus in the moderate grazing site indicates the role of balanced livestock grazing in maintaining the proper species composition in rangelands.

In water efficiency studies, the values of runoff, evapotranspiration and range production are the main variables. Rangelands of Golestan province, Iran, have a high potential of run-off due to the geographical location, climate, and destruction of these resources as well as drastic land use change from forests and rangelands to agricultural lands. Therefore, in the present study, in order to determine the best management of rangelands, we developed a rangeland improvement model using the Soil and Water Assessment Tool (SWAT) in the Gorganrud Watershed, Golestan Iran. Calibration and validation of model was performed using Sequential Uncertainty Fitting Program (SUFI-2) in the eco-hydrological model SWAT. For this purpose, the SWAT was calibrated and validated for a 31-year period of discharge and 5-year period of range production and then the model was executed for different scenarios of rangeland management. The results showed that the model performance was satisfactory for predicting discharge. The values of Nash-Sutcliffe coefficient were calculated to be 0. 72, 0. 71 and 0. 64 in calibration period and 0. 59, 0. 48 and 0. 53 in validation period for Basirabad, Tilabad and Haji Ghoshan stations, respectively. As well, four range improvement scenarios (mechanical, biological, biomechanical and livestock grazing management) were defined in this study. On average, by applying mechanical, biological, biomechanical, and grazing management scenarios evapotranspiration was increased to 2. 3%, 12. 8%, 15. 5% and 2. 8%, respectively, in comparison with actual evapotranspiration. According to the obtained results, the biomechanical scenario was identified as the best one in increasing evapotranspiration in poor and moderate rangelands.

The presence of plant species together causes biotic interactions. These interactions are very complex and variable among species which facilitation and competition have the highest impact on ecosystem function. Disturbances including fire are among the environmental factors affecting the biotic interactions. This study aimed on understanding the effect of fire on biotic interactions of cushions and grassland species. Therefore, to survey the effects of fire on the biotic interaction, 30 individuals of non burned Onobrychis cornuta and also 30 individuals of burnt patches were selected. In addition, 30 paired plots for each individual was randomly established close to each patches. According to our results, the effect of fire was not significant on total cover, but fire increased the perennial forbs (from 4. 7 to 11. 3 %), geophytes (from 0. 1 to 0. 5 %), annual forbs (from 0. 1 to 2. 3 %), annual grasses (from 0 to 0. 1 %) and also decreased the perennial grasses (from 7. 2 to 4. 9 %), shrubs (from 3. 8 to 0. 8 %) and cushions (from 1. 7 to 0. 4 %) and no significant effects on legumes. Only the annual grasses increased under the burned patches. According to the T-test results of total biotic interactions, fire facilitated species but it was not significant for functional groups.

Identifying and evaluating rangeland ecosystems is the first step in managing these resources. Without knowledge of rangeland condition, no management plan can be developed for it. For this purpose, three sites with different dominant species were selected for sampling. In each site, 30 sampling units of 900 m2 were determined along three transects and sampling quadrates were established in these units. After correction and processing, the NDVI and SAVI indices were extracted from Landsat 8 images, and their correlation with vegetation cover percentage and production was calculated. The results showed that the correlation of indices with the vegetation cover percentage and production was significant in each of the three sites. In each site, the NDVI had the most correlation with dominant vegetation form, while SAVI reduced the effect of soil and was more related with low vegetation cover species. This is related to the SAVI equation and this index could reduce the effect of soil. The broadleaf species had the highest correlation with the NDVI index due to the plant structure and more reflection.

Halophytes may change different soil properties and nutrients availability by organic materials addition to soil and soil conservation against erosion agents. Destroying these lands and halophytes may have an undesirable effect on environment. To study the effects of physiographic position, plant variety and plant growth position (sole or under another plant) on soil properties of salt marshes, an investigation was carried out in Korsia region, Darab (Fars province). Soil samples were collected from the beneath of Tamarix aphylla and Salsola rigida (sole and under Tamarix) and between plants with triplicates in two different salt marshes with lowland and piedmont plain positions. Soil properties including particle size distribution, organic matter, pH, EC and equivalent calcium carbonates and nutrients availability including P, K, Fe, Mn, Cu and Zn were determined. Results indicated that lowland had more saline and heavier textured soil and shorter Tamarix aphylla as compared with piedmont plain. Tamarix aphylla increased organic matter, EC, P, K, Fe, Mn, Cu and Zn; however, it had no effect on soil texture and equivalent calcium carbonates. Salsola rigida increased organic matter and its effect on available Mn and Zn was more than other nutrients. Salsola rigida under short Tamarix aphylla did not change soil salinity; while Salsola rigida under long Tamarix aphylla decreased soil salinity. Generally, it seems that organic matter is the most important factor on different plant nutrients availability and soil fertility status of the soils studied. Organic matter affects mobility, precipitation or nutrient uptake by the effect on pH, chelating agent production, nutrient adsorption, and nutrient release due to decomposition and soil physical properties improvement.

To evaluate the effects of grazing on some physical and chemical properties of soil, in the summer rangelands of southern slopes of Sabalan, three regions with different grazing intensity were selected after field observation and 27 soil samples were randomly taken along three 200-m transects. Soil samples were taken from the depths of 15-0, 30-15 and 45-30 cm and transported to laboratory and soil properties such as texture, organic matter, organic carbon, phosphorus, potassium, EC and pH were measured. Analysis of variance and mean comparison were made using Duncan's test. Results showed that no significant difference was found for soil pH and phosphorus among the grazing intensity treatments and soil depths; however, significant differences were observed for other variables. The results showed that organic matter content decreased with increasing of grazing intensity and the lowest content was recorded for the 30-45 cm soil depth in the heavy grazing area. According to the results of this research it can be concluded that soil structure is degraded with increased grazing intensity; therefore, a balanced grazing need to be taken into account in summer rangelands to prevent soil degradation.

Plant species diversity always implies ecosystem stability against environmental and biological disturbances. This study was conducted to investigate the effects of grazing management on diversity indices of plant species in grazed and exclosed rangeland sites of Hanna station-Semirom. Sampling was performed using 30 plots (1 m2) along four transects. Canopy area and density of species were recorded in sampling units, and the floristic list was provided in the whole area. Species richness, heterogeneity and evenness indices were calculated from density data and parametric diversity indices including log normal, geometric, and broken stick were fited in both exclosed and grazed areas. The Chi-Square test was used to examine the significance of measured traits. The results of numerical indices showed a higher species richness, evenness and species diversity indices in grazed than in the ungrazed site. The logarithmic diagram in the exclosed and grazed areas followed the broken stick model, indicating the presence of dominant species. The floristic lists of the study sites showed that the number of specific plant species in the grazed site was higher than that of exclosed site. Overall, the results showed that moderate grazing conditions in Hanna station improved plant species diversity indices and increased climax plant species.

In order to study forage yield, seed yield and its components in two species of Stipa, 16 genotypes of S. barbata and 10 genotypes of S. hohenackeriana were collected from natural habitats in Esfahan province and evaluated with a completely randomized design with three replications in farm condition. Based on the results, there was a significant difference between two species for most of the important traits such as forage yield and seed yield. Rahmat Abad Khansar population of S. hohenackeriana and Polkale population of S. barbata showed higher forage yield (3333 and 3129 kg/ha, respectively). The first five components determined 73% of total variation. The first component named as yield factor, the second and the third factors as vegetative factors, the forth component as yield component factor and the fifth factor as dry weight/wet weight. Cluster analysis classified populations into two groups with distinct variations for seed yield and forage yield.

Bamou national park in Iran has many environmental functions such as ecosystem regulation functions. The ecosystem function of water regulation by forest and rangeland ecosystems includes seasonal water flow regulation, water supply for various uses, treatment and storage of water. In this study, effects of dominant vegetation in the Bamou National Park (including Astragalus gossypinus, Astragalus susianus, Ebenus stellate, Amygdalus scoparia, Amygdalus lycioides, Scariola orientalis and Scariola orientalis) on the runoff control were estimated in four soil erosion types using Justin method. According to the results, effects of vegetation on the runoff height reduction were estimated to be 1. 28, 0. 71, 0. 71 and 1. 19 centimeter in four erosion types of E1 to E4, respectively. In addition, the economic value of water conserved in the underground aquifers in the current area of park was estimated to be 68. 105 billion rials and 1. 792 million rials per hectare in 2012.

The reduced biomass in forests and rangelands ecosystems for any reason can affect the process of carbon sequestration and as a result of global warming. This study was conducted to assess carbon storage under different grazing intensities in rangeland of Chah Mary dominated with Artemisia siberi in Khuzestan province. Three sites under heavy, moderate and low grazing intensities were selected based on similar topographic features (slope, aspect and elevation), rainfall, soil and climate. Plant sampling was done in key areas by random-systematic method along three transects of 100m and 60 plots of 1m2. Then, aerial and underground biomass parameters were evaluated in each plot and carbon was determined by ash method. The data were analyzed by SPSS v. 16 software. According to the results, carbon sequestration decreased from 5704/3 in the low-grazing region to 3470/1 in the high-grazing region. Also, under lowgrazing intensity, the carbon stored in aerial biomass and underground biomass was 4360/9 and 2180/5, respectively.