Mansoureh Kargar; Zeynab Jafarian; Reza Tamartash; Seyed Jalil Alavi
Volume 25, Issue 3 , November 2018, , Pages 512-523
Abstract
Ecologists and environmental managers emphasize the use of predictive models to examine the species distribution patterns. The purpose of the present study was to investigate the efficiency of the generalized linear model (GLM) and generalized additive model (GAM) in determining the ...
Read More
Ecologists and environmental managers emphasize the use of predictive models to examine the species distribution patterns. The purpose of the present study was to investigate the efficiency of the generalized linear model (GLM) and generalized additive model (GAM) in determining the relationship between vegetation and environmental factors in Khetteh Riz Rangelands. Environmental factors studied included soil characteristics, topographic factors and climatic factors. A classified-random sampling was performed and three dominant species, Bromus tomentollus, Ferula ovina, and Agropyron repens, were identified. The results showed that in the GLM model for Ferula ovina species, the variables of phosphorus content and slope were effective. For species Bromus tomentollus and Agropyron repens, the variables of annual moisture, rainfall, silt, and slope were effective. In the GAM model, the available moisture, silt and organic matter were the factors affecting the distribution of Ferula ovina. The silt, potassium, pH, and annual moisture content were the factors affecting the distribution of Agropyron repens. In addition, slope and silt were the variables affecting the distribution of Bromus tomentollus in the GAM model. The values of AUC, calculated for the GLM (0.63) and GAM (0.70), indicate the accuracy of the model to be acceptable.
Rostam Khalifezadeh; Reza Tamartash; Mohammadreza Tatian; Mohammadreza Sarajian Maralan
Volume 25, Issue 3 , November 2018, , Pages 699-712
Abstract
Organic carbon is one of the most important soil quality indices, affecting almost all physical, chemical and biological properties of the soil. The purpose of this study was to investigate soil spectral and morphometric factors to estimate the organic carbon of topsoil, using factor analysis ...
Read More
Organic carbon is one of the most important soil quality indices, affecting almost all physical, chemical and biological properties of the soil. The purpose of this study was to investigate soil spectral and morphometric factors to estimate the organic carbon of topsoil, using factor analysis and multiple regression methods in semi-steppe rangelands of Lazour. Soil samples were taken with a stratified random method. For this purpose, 157 training sites were selected in homogeneous units. Of these, 127 sites were used to calibrate the model and 30 sites were used to validate the model. In each of the training site in a random manner, a soil sample including nine observations was taken from a depth of 0 to 20 cm of soil surface. Soil Organic Carbon (SOC) was measured using Walkley-Black titration method. The results showed that the variables of Albedo, Clay Index (CI), NDVI, Relative Relief and Tasseled-Cap's Brightness and Greenness indices had a significant correlation with the SOC (p<0.05). Also, the result of factor analysis by Principal Component Analysis (PCA) method with eigen-values greater than one indicated that the total cumulative variance, explained by the six variables, was equal to 81.1%.This variance was explained by two components. Using multiple regression model, an appropriate regression equation was calculated to predict SOC (R2=0.789). The Root Mean Square Error and the Mean Absolute Relative Error of the proposed model were calculated as 0.24 and 0.10, respectively. Due to the direct relationship between the SOC and the factors such as soil fertility and sustainability against erosion, a spatial distribution model of SOC could be an important sub-model to design other complex models such as the terrestrial ecosystems biomass and soil erosion models.
Fatemeh Montazeri; Reza Tamartash; Mohammad Reza Tatian; Mohammad Hojati
Volume 25, Issue 2 , August 2018, , Pages 278-288
Abstract
In this study, the potential of rangeland species Astragalus globiflorus and Acantholimon hohenackeri in heavy metals absorption including cadmium, lead, copper, zinc, and chromium was investigated around the Firoozkouh cement factory. Soil and vegetation sampling was performed at ...
Read More
In this study, the potential of rangeland species Astragalus globiflorus and Acantholimon hohenackeri in heavy metals absorption including cadmium, lead, copper, zinc, and chromium was investigated around the Firoozkouh cement factory. Soil and vegetation sampling was performed at distances of 500, 1500, and 2500 meters from the center of the factory. Astragalus globiflorus and Acantholimon hohenackeri with three replications were examined in a completely randomized block design. In this experiment, samples were determined using the acidic digestion method using atomic absorption device. The results indicated that, as the distance from the factory increased, the concentration of cadmium and zinc in Astragalus globiflorus and Acantholimon hohenackeri showed an increasing trend, contrary to the concentration of lead. In addition, a decreasing trend was observed for chromium concentration in Acantholimon hohenackeri. The results of mean comparison showed that the concentration of copper, lead and zinc in Astragalus globiflorus, and the concentration of cadmium and lead in Acantholimon hohenackeri were higher in leaves as compared with roots. According to the results, there was a significant relationship between Astragalus globiflorus and copper, cadmium, lead and chromium, and between Acantholimon hohenackeri and copper, zinc and lead (P <0.05). It can be concluded that the proximity to the factory was the most important factor for the accumulation of lead and chromium in the species studied. In this regard, it is suggested that the above species be used to remediate these elements from contaminated soil. It is also recommended that appropriate measures be taken regarding the use of these species by livestock around the factory.
seyedeh mohadeseh ehsani; gholamali heshmati; reza tamartash
Volume 24, Issue 3 , October 2017, , Pages 570-580
Reza Tamartash
Volume 19, Issue 3 , December 2012, , Pages 469-481
Abstract
In mountainous rangelands, there is a complex combination of factors such as topography, vegetation growth stages and water distribution which affect grazing distribution. This research was conducted to investigate the effect of topography on vegetation of summer rangelands of Vaz, Mazandaran province. ...
Read More
In mountainous rangelands, there is a complex combination of factors such as topography, vegetation growth stages and water distribution which affect grazing distribution. This research was conducted to investigate the effect of topography on vegetation of summer rangelands of Vaz, Mazandaran province. Five utilization units were selected on the basis of field survey and identifying homogenous grazing units. Key areas were obtained in each unit and sampling was done randomly. Size of the quadrates was 1m2 and the number was calculated by statistical method. In each quadrate, yield was measured by clip and weigh method and utilization rate was determined using height to weight ratio (based on dry weight). Vegetation cover percentage was also recorded. Finally, comparison of plant characteristics in utilization units was performed by SPSS in a completely randomized design with unequal replications. Then, correlation coefficient between each of the independent variables (slope, aspect and height) and dependent variables (yield, canopy cover percentage and utilization) was determined. Also, the most effective factor and interaction effects of independent variables were obtained by stepwise multiple regression analysis. Results showed that slope and aspect had the most correlation with livestock utilization respectively, but no relationship was found for elevation while it affected yield and canopy cover.
Reza Tamartash
Volume 19, Issue 2 , September 2012, , Pages 221-232
Abstract
With attention to importance of range condition for correct management of range ecosystems and relationship among biodiversity, canopy cover percentage and the importance degree of dominant species with range condition and health, this research was conducted with comparison of three methods including ...
Read More
With attention to importance of range condition for correct management of range ecosystems and relationship among biodiversity, canopy cover percentage and the importance degree of dominant species with range condition and health, this research was conducted with comparison of three methods including pastoral value, six factors and four factors methods in summer rangelands of Lasem, Haraz. Plant types was separated with use of aerial photos (1:20000) and field control on topographic maps (1:50000).The sampling was done by quadrat and transects using random-systematic method in key areas. In this points Shanon, Sympson indices, importance degree of dominant species, canopy cover percent and scores of range condition methods has calculated for determination of relation among them. In order to Pearson correlation test, liner regression and analysis of variance were run with Mini tab 13.3. The results showed that Shanon diversity index had significant relation with six factors, four factors and pastoral value but rate of this relationship to six factors was more than other methods. Sympson index had not correlation with them. The comparison of canopy cover index and importance degree showed that these factors had not significant relation to pastoral value and four factors methods while six factors method had high correlation with them. Thus in this research, the best suitable method of range condition is recognized six factors method.
Reza Tamartash; Gholamreza Tatian; Bahjat Reihani; Fatemeh Shokrian
Volume 16, Issue 4 , January 2010, , Pages 481-492
Abstract
Investigation on vegetation and soil charactristics of marl lands is important in management programs.The study area was Birjand plain. First, geomorphplogical units were identified using topographic, land usability, lithology maps and aerial photoes. After field controlling, sampling was done on homogenic ...
Read More
Investigation on vegetation and soil charactristics of marl lands is important in management programs.The study area was Birjand plain. First, geomorphplogical units were identified using topographic, land usability, lithology maps and aerial photoes. After field controlling, sampling was done on homogenic units by systematic-randomized method. Size and number of plots were determined by minimal area and statistical methods respectively. Vegetation and soil samples were taken in each plot. Soil parameters such as texture, pH, EC, SAR, lime and gypsum were measuered in the laboratory. Differences between plant communities and reaction to soil variations were determined by analysis of variance and CCA using SPSS and Canoco 4.0 softwares. Results showed that the different plant communities had different reactions to soil charactristics. Suaeda fruticosa, Chenopodium album, Salsola rigida and Aellenia glauca had the highest correlation with SAR but Salsola rigida and Aellenia glauca shown high correlation with EC, silt and gypsum amount. Also, entrance of invador species (Cousinia eryngium) caused to low reaction of plant communities to edaphic factors. Other species had negative reaction to soil salinity and none of them responsed to pH.