Nematollah Madadi Zadeh; Hossein Arzani; Ghavaloddin ahedi; Najmeh Faryabi
Volume 21, Issue 1 , June 2014, , Pages 128-138
Abstract
In the current study, the effects of exclosure were examined on rangeland vegetation at two study sites including, reference site (inside the exlosure) and critical site (outside the exclosure). Research was conducted by the systematic-random method and 160 2*1.5 m plots were established. Inside each ...
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In the current study, the effects of exclosure were examined on rangeland vegetation at two study sites including, reference site (inside the exlosure) and critical site (outside the exclosure). Research was conducted by the systematic-random method and 160 2*1.5 m plots were established. Inside each plot, the percentage of canopy cover, litter, gravel and bare soil as well as density of class I, II, and III species were recorded. Dry matter yield was also calculated. Four-factor method and trend balance method were applied to determine the range condition and range trend, respectively. According to the obtained results, due to the exclosure, litter, yield, canopy cover percentage and class I species composition increased up to 24.72%, 37.42%, 23.6%, and 80.6%, respectively. On the other hand, the percentage of bare soil, gravel, and class III species composition decreased to 34.29%, 17.16%, and 26.96%, respectively. Mean differences in all parameters inside and outside the exclosure were significant at both study sites. Our results also indicated that exclosure led to the improvement of range condition and range trend.
Zeinab Jafarian; Hossein Arzani; Mohammad Jafari; Ghavamedin Zahedi; Hossein Azarnivand
Volume 19, Issue 3 , December 2012, , Pages 371-381
Abstract
This research was aimed to investigate the relationships between dominant rangeland species and environmental factors in the Rineh rangelands located on the southern slope of Damavand Mountain. Stratified random sampling method was applied and the study area was classified to 37 sample units based upon ...
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This research was aimed to investigate the relationships between dominant rangeland species and environmental factors in the Rineh rangelands located on the southern slope of Damavand Mountain. Stratified random sampling method was applied and the study area was classified to 37 sample units based upon elevation, slop and aspect.
In the study area, 750 plots 1m2 and 75 plots 25m2 were established. One hundred and fifty soil samples were dug at the depth of 0-30 cm and 16 soil properties including pH, CaCo3, bulk density, particle density, total phosphorus, total nitrogen, absorbed potassium, organic matter, saturation moisture, soil texture, field capacity, permanent wilting point, available water capacity and water holding capacity were measured in laboratory. After collecting the climate data, 16 climate factors including average relative humidity, average rainfall, average temperature, average minimum temperature, average maximum temperature in spring, summer and annual as well as annual frost days were selected to reconstruct the missing data. IRS images including red and near-infrared bands and PAN band as well as combined bands derived from RVI, NDVI, and PCA were selected. Regression equation was developed for each species using logistic regression. Results indicated that most of the factors including slop, aspect, average minimum temperature in spring, number of frost days, average daily temperature in summer, and most of the soil factors were entered in regression models. Also, satellite data were used as effective tools in showing the presence of plant species.
Hamid Torang zar; Qavam aldin Zahedi; Mohammad Jafari; Hojat ... Zahedi pur
Volume 18, Issue 3 , September 2011, , Pages 384-394
Abstract
The main objective of the present study was finding spatial relationship model of the plant species composition to physico-chemical soil variability, in north-west of Mighan Desert in Arak. According to the condition of the studied habitats, the study was based on a survey of three identified vegetation ...
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The main objective of the present study was finding spatial relationship model of the plant species composition to physico-chemical soil variability, in north-west of Mighan Desert in Arak. According to the condition of the studied habitats, the study was based on a survey of three identified vegetation types. Sampling method for vegetation study was randomized systematic. Quadrate size was determined for each vegetation type using minimal area method. Soils sample were taken from 0-20 and 20-100 cm depths. The measured soil factors included, EC, organic matter, texture, lime, gypsum, available moisture, pH, and soluble ions (Ca2+, Mg2+, Na+, Co32- , H-Co3, Cl-, So42). The classification of vegetation was analyzed by TWINSPAN and DCA methods. To determine the most edaphically effective factors in distribution of vegetation, PCA and CCA were applied. Three main vegetation groups were identified by TWINSPAN analysisand DCA. The result indicated that soil salinity, soil texture, lime, and soluble ions (Mg2+, So42) played the main role in the distribution of plant species.
Akbar Javadi; Hosein Arzani; Ali Salajeghe; Mahdi Farahpor; GHavam ... Zahedi
Volume 14, Issue 4 , February 2008, , Pages 513-523
Abstract
Proper use from water resources, especially in arid and semi arid rangeland are very important. Water is one of a valuable ecosystem component in rangeland management. In this study for surveying of water suitability, tree models including quality model, quantity and distance model made final model. ...
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Proper use from water resources, especially in arid and semi arid rangeland are very important. Water is one of a valuable ecosystem component in rangeland management. In this study for surveying of water suitability, tree models including quality model, quantity and distance model made final model. FAO (1991) method (recommended for land capability evaluation) was used for suitability classification. The study was conducted in Halvan region is located in Yazd province. According to the results, water resources distance and accessibility to water is the most declining factor for suitability. Quality factor is a limiting factor in part of the study area, too. Based up on, areas more than 15km far from water point are not suitable, but less than 6km are very suitable. Proper distribution of water resources increases water suitability and cause better and monotonous utilization of rageland.