Showing 4 results for Soil Characteristic
Mohammad-Javad Ebrahimi, Hossein Bashari , Mehdi Bassiri , Massoud Borhani , Abdolreza Mohajeri ,
Volume 11, Issue 1 (6-2017)
Abstract
Understanding the effects of gazing on vegetation structure and soil characteristics is important in managing rangeland ecosystems. This study aimed to investigate the plant crown cover and composition changes as well as soil characteristics along a grazing gradient in Kalahroud Steppe rangeland- Isfahan province. The study area was stratified into three sites with respect to distance from village and watering points, including heavily grazed sites (<1 km), moderately grazed sites (1 to 2 km) and slightly grazed sites (> 2 km). Six transects with 150 meters lengths were established in each site. Vegetation characteristics were studied in 15 plots (1×1.5 m2), placed along each transect. 25 soil samples were collected randomly from the placed plots and Caco3, K, Na, saturated percentage, pH, electrical conductivity and organic carbon contents of samples were measured. Analysis of variance, cluster analysis and non-metric multidimensional scaling techniques were used to analyze the data and explore the relationships of soil and vegetation characteristics along the grazing gradient. According to the results, Artemisia sieberi percentage cover and frequency was decreased while these indices for Peganum harmala increased as grazing intensities increased in the study area. Anabasis aphylla indices were not differed significantly in all the various grazing intensities. Soil Na, Caco3 and EC were higher significantly in sites under greater grazing intensity while K, SP and OC were lower (α = 5%). Results suggest that moderately grazed sites represent a transitional status in rangeland vegetation and soil dynamics and immediate management action is required to reverse unwanted and hazardous permanent changes. The result of present research can be especially applied to identify ecological thresholds in Steppe rangeland ecosystems.
Esmaiel Sheidai Karkaj , Adel Sepehry , Hossein Barani , Javad Motamedi,
Volume 11, Issue 2 (9-2017)
Abstract
This study aimed to assess the soil factors affecting the amount of soil organic carbon storage and the development of a model to estimate carbon reserve using physical and chemical properties of soils in East Azerbaijan rangelands. Ninety two soil samples were collected randomly from various rangeland sites and their characteristics including their soil organic carbon contents were measured in the laboratory. Path analyses and stepwise regression were used to identify the most important factors affecting soil organic carbon content. Results revealed that soil saturated moisture, pH, silt, EC and clay have direct effects on soil organic carbon with path coefficients of 0.443, -0.244, 0.223, -0.204 and 0.175 respectively. Parameters such as bulk density, gravel, and total cation exchange capacity have indirect effects on soil organic matter contents with sum path coefficient of -0.349. Soil physical properties had more influence (with path coefficient of 0.55) on soil organic carbon compared to the chemical characteristics (with path coefficient of -0.09). Stepwise regressions revealed that factors such as clay, silt, moisture maintenance capacity, pH and electrical conductivity represent 57 % of variation in soil organic carbon content. Conserving soil fine particles from erosion and preventing soil salinization can enhance soil organic reserves and maintain rangelands functionality.
Amir Mirzaee Moosivand, Farajollah Tarnian,
Volume 14, Issue 2 (7-2020)
Abstract
Most of the time intensive grazing affects the lands either its vegetation or soil. This research aimed at determination of the exclosure, i.e. grazing ceased, effect on characteristics of vegetation and soil. Study area is located on northeast rangelands of Delfan County, Lorestan province. For this purpose, 120 quadrates of 1*1 m2 in a randomized-systematic method of sampling were put along 12 transects of 100 m long. In each quadrate, the list, density, the percentage of canopy cover of the species were recorded in addition, litter, stone and gravel, and bare soil were measured and recorded. Soil samples from the beginning, middle and end of each transect were taken from a depth of 0-30 cm in the exclosure and under grazing areas (36 samples in each area). Samples were taken to the laboratory and some soil characteristics including organic matter, potassium, phosphorus, electrical conductivity, Acidity and percentage of clay, silt and sand were determined. Independent t-test was used to compare the mean of the studied factors of both areas, in the SPSS18 environment. Principal component analysis (PCA) was used to determine the most important variables affecting exclosure and grazing areas. According to the results, 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. The canopy cover percentage of perennial grasses and forbs as well as litter percentage was higher inside the exclosure. The canopy cover percentage of annual grasses and shrubs as well as bare soil percentage was lower in comparison to outside of the exclosure. The density of perennial grasses and forbs increased, while the density of shrubs decreased inside the exclosure (P<0.01). In addition, a higher production and percentage of palatable plants was obtained from the rangeland under exclosure condition. In the exclosure area, the percentage of organic matter, nitrogen, phosphorus and potassium is higher than the grazing area (P<0.01) and the electrical conductivity is lower than the grazing area (P<0.05). Results of principal component analysis showed that organic matter, nitrogen, phosphorus, potassium and electrical conductivity had the most influence on vegetation characteristics of exclosure and under grazing areas.
Shokoofeh Hassaanvand, Alireza Sepahvand, Farajolah Tarnian, Parvin Sihak,
Volume 15, Issue 3 (11-2021)
Abstract
Infiltration of water into the soil is a pant water supply key process. It has also an essential role in controlling surface runoff and groundwater. The objective of this study is to investigate and model the infiltration rate in different vegetation types (Annual Grass- Astragalus rhodoseminus, Astragalus ecbatanus- Euphorbia denticulata, Quercus brantii, Annual Grass). Infiltration rate was measured by double ring infiltrometer (DRI). Three samples were taken from each vegetation type, and infiltration indices and some soil characteristics were measured. One-way ANOVA was used to test the changes in infiltration indices and soil characteristics of different vegetation types and the Pearson correlation coefficient was used to test the relationships between infiltration rates and soil parameters. The performance of Kostiakov, Philip, Horton, Soil Conservation Service (SCS) and modified Green–Ampt models were evaluated by statistical criteria such as Nash-Sutcliffe (NS), efficiency coefficient (EF), root-mean-square error (RMSE), etc. The results showed that silty soil is not similar in different vegetation types. Although the infiltration did not show a significant difference in the vegetation types, the average infiltration rate in the Astragalus ecbatanus- Euphorbia denticulata type was equal to 14.4 cm/h, as the highest and the lowest value was observed in the Annual Grass-Astragalus rhodoseminus type with 6.25 cm/h, so that the former is 2.3 times larger than latter. Correlation results showed that infiltration has the highest relationship with porosity. The modeling result suggests that the modified Green–Ampt has a very high performance for estimating the infiltration rate in Annual Grass- Astragalus rhodoseminus, Astragalus ecbatanus- Euphorbia denticulata, Quercus brantii, annual Grass types with EF of 0.976, 0.945, 0.886, and 0.927, respectively. The results indicate that the infiltration varies in the different vegetation types that should be considered in the management of ground water rechage.
