مجله مرتع
سال چهارم شماره 1 (پیاپی 13، بهار 1389)

Vicia monantha is an important Legume that produces part of required forage for livestock from early spring to summer. Germination is an important stage of plant growth which is often sensitive to environmental stresses including water and salinity stresses. The aim of this study was to assess the effect of salinity and drought stresses on seed germination of Vicia monantha. We applied a factorial trial under completely randomized design using six salinity treatments (0, 50, 100, 150, 200 and 300 mM of NaCl) and six drought treatments (0, -0.2, -0.4, -0.6, -0.8, 1 MP of PEG) separately. Results showed a significant effect of both stresses on seed germination indices. The percentage of germination, seed germination rate and plumule and radicle length, coefficient of alometri, dry weight of plumule, seed vigour, significantly reduced under both stresses. We found seed germination in most of understudy salinity levels whereas few drought treatments showed seed germination. Therefore, it seems this species is more sensitive to drought stress than salinity.

The type of plant-plant interaction has prominent influences on the structure and composition of the natural plant communities. Facilitation between shrubs and their understory plants leads to the positive spatial associations, and hereby enhances the survival rates of the understory plants. We studied the type and extent of spatial association between four rangeland shrubs (Astragalus mesedensis, Artemisia khorasanica, Acantholimon prostegium, and Acantholimon erinaceum) and two perennial forage grasses (Bromus kopetdaghensis, and Festuca alaica) in their natural habitats, Baharkish, Quchan, Iran. Results indicated positive association (facilitation effect) between shrubs and perennial grasses, with no negative association (competition effect) being found for any species pairs. Among the nurse species, A. mesedensis showed greater and Acantholimon species indicated smaller positive association, while A. khorasanica did not show any association with the grasses. Between the beneficiary species, greater association with the nurse shrubs was found for F. alaica than B. kopetdaghensis. Accordingly in this study, A. mesedensis and F. alaica are the best nurse and beneficiary species, respectively. Our findings indicate the important role of nurse shrubs in preserving forage range plants. These results can also be used in the rangeland restoration projects, especially for seeding forage plants under the canopy of nurse shrubs.

The aim of this research was to find plant – site factor relationships in mid Taleghan rangelands to determine the most important effective factor in the distribution of the understudy plants. For this purpose, in indicator region of every vegetation type plant sampling was done by random–systematic method. Plot size was determined by minimal area method and plot number was assigned according to vegetation changes of the study area. In each sampling point the characteristics of elevation, slope and aspect were recorded. Also, at the starting and ending points of each transect soil samples were gathered from 0-30 cm. The following soil properties were determined in laboratory; soil texture, phosphorous, potassium, nitrogen, organic matter, lime, pH and EC. To find the relationship between vegetation and environmental factors PCA (Principal Component Analysis) was made. The results indicated that there is significant relation between distribution of plant types and environmental factors. Our findings showed that elevation, slope, texture, lime, phosphorous and soil depth have meaningful impact on distribution of plant types in mid Taleghan rangelands.

Irrational human activities such as wars, high fossil fuel consumption, deforestation, desertification, chemical pollution and some environmental disasters are important factors for environmental and biological diversity degradations. Biological diversity is based on species diversity which makes gene pools, so any decline in species diversity leads to genetic chute. In this study species diversity was studied by nonparametric methods in 2 steppe and 2 semi-steppe range sites in Isfahan province during 6 years (2002-2007). Species richness, heterogeneity and evenness indices were calculated from density data during study period. In steppe sites because of high species dominance (Hill) index and in semi-steppe sites (Hill) index seemed to be suitable to determine species diversity. Generally statistical test indicated that species richness, evenness and diversity between semi-steppe and steppe vegetations are significantly different. Results indicated that species richness and diversity of Aghcheh and Vardasht sites were significantly different, while evenness was not significantly different in mentioned sites. In steppe sites of Shadian and Khondab evenness and diversity were significantly different but species richness was similar. Ttherefore, based on this study findings, species richness in semi-steppe and evenness in steppe sites were more effective in creation of diversity index.

Concepts of animal equivalence have been developed to express different kind and classes of grazing animal in common form. This concept is not fixed and usually determinate on the basis of live weight and metabolic weight. More than 27 sheep breeds with different body size have been adapted and grazing on rangeland in different climatic zones of Iran. So it is not correct to use the same animal unit weight for all. Therefore is necessary for each breed, animal unit weight is determinate. In this study, two herds of West Azarbayjan Ghezel breed were selected, 3 and 4 years old ewes, 3 and 4 years old rams and 3 and 6 months lambs were weighted in two stages in each breed. For determination of dry matter requirement forage quality was taken in to consideration. Daily requirement of animal for maintenance condition was calculated using of NRC (1985) tables and MAFF (1984) equation. On the basis of results; Animal unit was obtained 71.57 kg. Daily requirement of animal was evaluation 14.33 Mj and dry matter requirement was calculated 2.49 kg.

Accessibility to a major portion of information about vegetation cover function of ecosystem is provided by the way of autecological study of plant species. Autecological study of Desmostachya bipinnata carried out in Sistan plain. This species is a perennial plant from Poaceae. For autecological study of D. bipinnata,at first vegetation habit of this species in Sistan plain was determined. Then, ecological characteristics such as climatic and edaphic characters of habitats, root system, phenology, reproduction, preference value and chemical compounds were assessed. The results showed that this species grows intensively in north eastern parts of study area. Based on the collected data in several years, annual rainfall of the study area is 60.8 mm and mean annual temperature is 22 0C. This species appears on soil with loam and sandy loam texture, pH of 8.03 – 8.31 and salinity of 10 – 60 ds.m-1. The plant has a adventitious root system and rhizome that penetrates in the soil about 2 meters. Root has a lot of subsidiary branches in soil surface. At different habitats, canopy cover of this species was about 14 – 28 %. Vegetation growth stage of Desmostachya bipinnata usually starts in late February and flowering complete at May and seed ripening start at July. Above ground materials of Desmostachya bipinnata contains 7.56 and 6.71% crude protein in their leaf and stem, respectively. Preference value of this plant is 25% for sheep and goats. This species has a high level of resistance against grazing and relatively harsh natural conditions. With above mentioned characteristics, this plant is a suitable species to be used in management and amendment programs for Sistan plain.

We studied the effects of shoot clipping frequency on biomass production, biomass allocation and shoot number on two range species (Agropyron elongatum (Host) Beauv., and Festuca ovina L.). Plants were grown during a 15-week experiment in experimental garden. The above ground parts were clipped at a height of 7 cm following four treatments: frequent (every one week), moderate (every two weeks), low (every four weeks) and unclipped (control). Total biomass and root mass of A. elongatum were reduced by frequent defoliation until 40% whereas F. ovina maintained a similar production for two plant components (above-ground and roots biomass) when clipped. The latter one was able to compensate for the biomass loss even after five consecutive clippings. The changes in biomass production patterns of A. elongatum were accompanied with variations in biomass allocations. Biomass allocated to roots was significantly lower for A. elongatum in clipped plants than in control plants. The shoot mass and root mass fraction of F. ovina were similar among clipping treatments. Shoot number was significantly increased until 30% for A. elongatum and F. ovina in clipped plants than in control plants. Finally, in the experimental conditions, F. ovina was the most tolerant species to clipping, while A. elongatum showed moderate tolerance.

“Crown cover area” is one of the multiple-use ecological characteristics in natural resources studies. Current research has been done to evaluate capability of different vegetation indices, derived from ASTER-L1B image processing, to estimate crown cover area of single trees in very sparse forest stands in arid rangelands. The main hypothesis of the research is based on using spatial, spectral and radiometric resolution of ASTER imageries to estimate crown cover area of single trees, more accurately and precisely. Study area, a natural site of wild pistachio (Pistachio atlantica L.), is located in Tag-Ahmadshahi, southern Khorassan province. The geometric correction of the images has been accomplished, using non-parametric method of TPS and Digital Elevation Model (DEM); derived from topographic map of 1:50000, with a RMSE of less than 1 pixel. The filed data belong to 50single trees, sampled from a complete inventory of trees in the study area. Vegetation indices and soil line equation have been calculated and the values have been extracted from the indices in the place of the corresponding sampled trees. Then, regression equations have been established between vegetation indices and the crown cover area. The results indicate significant correlations between them. Among the indices, NDVI and MSAVI presented stronger statistical correlation than the other indices with crown cover area, having the correlation coefficient of 0.61 and the standard error of 5.58.

The presence of heavy metals is one of the important environmental stresses that reduce growth and produce reactive oxygen (gases). In this study different effects of two heavy metals, cadmium and copper sulphate and their interplays were evaluated on seed germination and growth of A. lentiformis. For this purpose, A. lentiformis seeds, placed on watman paper and influenced by cadmium (10, 20 and 30 mg/lit) and copper sulphate (10, 20 and 30 mg/lit) in a period of 9 days. Also distilled water was used as control treatment. Each treatment included 4 replications and 25 seeds were placed for each replication (Petri dish). Germination of seeds was evaluated everyday and growth index was determined by measuring root length, shoot length, seedling length and seed vigour index. Additionally germination speed was evaluated, too. Results indicated that there were not significant difference among the treatments for germination percentage and speed. Length of roots, length of shoots, length of seedling and vigour index had significant difference (α=99%) in different treatments. Application of heavy metals different concentrations resulted in significant decline in growth characteristics of A. lentiformis.

In order to study the changes of water soluble carbohydrates in different phenological stages, sampling of Bromus tomentellus, Agropyron intermedium and Dactylis glomerata was performed in Taleghan. Samples were taken randomly. Three samples in five repetitions (5 samples from each stem) were taken during three phenological steps (growth, flowering and complete growth). Percentage of soluble carbohydrates was measured using NIR. Analysis of variance of data was done based on factorial. Results showed that there was a significant difference between main and reciprocal effects in different steps of phenological growth. In all mentioned species percentage of carbohydrates increased with the growth rate. Quality of different species of grasses in terms of soluble carbohydrates showed significant difference. Mean values of water soluble carbohydrates in A. intermedium، D. glomerata and B. tomentellus were 13. 8%, 9. 4% and 8. 2%, respectively. Percentage of water soluble carbohydrates in A. intermedium and D. glomerata increased with growth rate and in B. tomentellus was highest in vegetative period. The highest level of water soluble carbohydrates was measured in A. intermedium (17. 4%) in complete growth stage. This shows that this species is valuable for delayed grazing.

Nowadays, ecological condition and capacity of rangeland is considered to be one of the effective parameters in ranchers motivating to participate in range management plans for proper utilization of rangelands. The over all objective of this study was to analyze the correlation between range condition and participation of ranchers in accomplishing range management plans in Baladeh summer ranches in the northern Iran. The research tool was 4-factorial method for determining ranges condition, and questionnaire for assessing participation of the ranchers. Sampling was done using randomised stratified method. Statistical population included 102 ranches, where in 72 of them restoration projects were performed at least for three years. The findings show a positive significant relationship between range conditions with the participation of the executors at each ranch. Also ¬ANOVA showed a significant difference between degrees of range condition with the participation rate of the executors. Comparison of the mean values using Duncan's test showed that those ranch with good and excellent range condition had the highest participation of the executors. The results also indicated that there was no significant relationship between permissive numbers predicted livestock in unit area- determined by the expert- and the range condition at each ranch.