Journal of Rangeland
Year:2007 | Volume:1 | Issue:3|Papers Count:11

Shrublands of Bonab in Arsanjan as a part of Zagros ecosystems have high ecological and floristical diversity but currently are used improperly. This study aimed to assess the relationship between vegetation and environmental factors as a tool for better management of these shrublands. After a perimary survey of the flora, vegetation sampling was done in the key area using 52 plots based on random-systematic design.Climate of this area was determined by Emberger method. Vegetation analysis was performed using a combination of CA, PCA, and CCA techniques. Results showed three climatic classes including cold semi-arid, very cold semi-arid and very cold subhumid.Clustering analysis showed three plant associations which were Pistacia atlantica-Amygdalus scoparia, steppic vegetation and umbelliferae. Results of PCA analysis showed that the most species scattered along the first axis. Also, CCA analysis showed that Ferula ovina, Prangos ferulaceae and Bromus tomentellus correlated with elevation. Also we found that elevation together with aspect influenced vegetation distribution probably by affecting the temperature and humidity. This study determined the most important environmental factors on vegetation of Bonab shrublands but the effects of human activities on sustainable management of these shrublands are undeniable.

The goal of this study is to assess the ecological needs of Ephedra inter media as a medicinal species and imporatant for soil and water conservation in Damghan. First the study area was deter mind on topography map (1: 50000).With field observation we identified three vegetation types with dominance of E.intermedia and then the slope, aspect, elevation, lithology and geomorphologic features of each vegetation type were determined. Vegetation sampling was done in 10 quadrats (1 x 1 m) on random systematic method. In each quadrat the species composition, cover percentage, and geomorphologic features were recorded. Also in half of the samples in each vegetation type a soil profile was dug and soil sample was taken from 0-50 cm depth to determine texture, percent of lime, gypsum, organic matter, Ph, EC, SAR and ESP. Results showed that there was an significant effect of pH, SAR, percent of gypsum, elevation, slope, and EC. The percentage of canopy cover of E.intermedia increased with an increase in the amount of gypsum and lime in the soil. So, we can consider this species as a perferable gypsophite and calciphite species.Because of the high ability of the species to adapt itself with hard environmental condition such as high percentage of Cas04 and Cac03, and also its medical and conservation values, it can be used for grazing (especially for goat), reclamation and preservation of its habitate.

Artemisia aucheri is an indicator plant of semi-steppic rangelands in Iran, which covers most of this area. This species is important because of its coverage, forage production, soil conservation and medicinal value.In this study, the quantity of Crude Protein and NDF in forage of A. aucheri is measured in three phenologic stages in Vard- Avard, Karaj at three altitude levels (2000, 2200, 2400m). Then samples were analyzed in laboratory and statistical differences in content of CP and NDF was investigated. The results showed that the amount of CP declined from the early growth to the end of growth season and the difference between growth stages was significant. Also, the average of NDF content increased but there was no significant difference between vegetative and flowering stages. Hence, grazing is recommended at the flowering stage as the quantity and the quality of forage is desirable.

Ecologists are more concern about the aerial organs of plants and their responses to the environmental and management conditions as a compare to underground organs of plants. This study aimed to assess the effects of grazing on below-ground phytomass during spring and summer in part of mountain grasslands in Zagros. Soil sampled in two sites (grazed vs. ungrazed) using a soil core with 7 cm diameter and 30 cm depth. After washing soil samples, the live and dead parts were separated according to the color and their resistances. Live parts classified into four groups including fine roots, coarse roots, rhizomes and bulbs. The sum of four groups was considered as the total below-ground phytomass. Results showed that in both sites and sampling times most below-ground phytomass belonged to the fine roots. Total phytomass of below-ground, fme and coarse roots biomass were significantly graeter in ungrazed sites than grazed area. There was no significant differences between phytomass of rhizomes in two sites but phytomass of bulbs were significantly greater in grazed area than ungrazed area. Total below-ground phytomass and fine root phytomass only significantly changes with time within ungrazed site where greater phytomass was found at the end of summer. Similar results were found for coarse roots and rhizomes but it was independent of site. Finally, it can be concluded that grazing reduced below-ground phytomass.

Ecologically, it is necessary to know the effects of grazing on vegetation structure and the subsequent changes in rangeland ecosystem.This study was carried out to find the effects of different grazing intensities on plant species richness along elevation gradient in a part of Alborz mountains rangelands.For this purpose, effects of light, moderate and heavy grazing intensities on plant richness was studied in three elevation classes (2000-2300, 2300-2600, and>2600 m) using 0.1 ha Whittaker plot. To compare species richness group regression model was used.Results showed that under light grazing intensity no changes occurred in plant species richness as elevation increased, while in moderate and heavy grazing species richness increased significantly with an increase in elevation. In light and moderate grazing intensities, hemicryptophytes were the dominant species while heavy grazing intensity resulted in terophytes.

During last few decades, considerable development in satellite data production has lead to wonderful progress in taking valuable ground data. These data help managers and decision makers to get comprehensive updated information which could be used in ground and environment resources plannings. Current research was carried out to find the relations between spectral indices and erosion caused factors in Mehran watershed using satellite data. For this purpose, at first brightness and wetness indices were studied. After classification of mentioned indices, their relationships with aspect and soil status was examined. Based on obtained results, relationship of ranges and dry farming areas erosion with spectral indices was detected. Results showed that the areas with high brightness index and low wetness index commonly settled on south-eastern skirts and the regions with low brightness index have high wetness index. Areas with high and moderate brightness index were related to abandoned dray farming’s or ranges with moderate condition and negative trend located on hills with shallow or semi deep soils. High intensity erosion of understudy watershed occurs in these regions. Areas with low brightness index were those located on North-western skirts with deep and matured soil and mainly surface erosion.

Proper estimation of range improvement benefits increases their efficiency and prevents misusing the national budget. We collected reports on 25 range management projects, and studied the list of their costs and benefits. Ignoring costs of rangeland rest (88% of projects), investment interest (80%), and underestimating project period (56%), had resulted in false estimation of project benefits. Hence, we proposed a new approach for evaluating economics of range management projects. Nevertheless, further research projects are needed to clarify some sources of costs and incomes, and also to estimate ecological services of a range management project.

Frequent droughts, improper grazing management and exploitation of rangelands caused degradation of vegetation. Currently several shrubs especially Atriplex canescens is used for restoration of the rangelands as a result a vast areas have been planted by this species. However, no study was conducted to assess the echo hydrological aspect of this species. The present study was therefore taken place to investigate the soil moisture distribution, as one of the controller factor for proper rangeland management, in root zone of three A. canescens in a planted area located in Birjand Township, eastern of Iran. For this propose, an area was surrounded around the plants and then irrigated. A profile was then dug after two days with a dimension of 180 cm length to adepth of 100 cm. The soil samples were then taken from 10 points in depth with intervals of 10 cm and 21 points in horizontal direction at 0, 10, 20, 30, 40, 50, 75, 100, 125, 150 and 180 cm. The volumetric moisture of the soil samples was measured using weighing technique and data was analyzed using SPSS11.5 software.The results showed that the soil moisture content is radially decreased as distance increased from plants. The comparison also revealed that the soil moisture is the highest and lowest rate at depth of 20-30 and 60-100 cm, respectively, owing to controlling interaction between atmospheric condition and root distribution system.