Journal of Rangeland
Year:2011 | Volume:5 | Issue:1|Papers Count:14

Calotropis procera is a perennial shrub adapted to arid climate which is widely used for desert reclamation practices. Seed germination is a critical stage of plant survival. Seeds of Calotropis procera have poor germination rate under field condition. To investigate the effects of light and temperature on seed germination of Calotropis procera, a seed germination experiment was established using a complete randomized block design with four replicates. The treatments were included two levels of light (light and darkness) and 9 levels of temperature(0،5، 10، 15، 20، 25، 30, 35, 40oC). The ANOVA results showed that light treatments have no significant effect on seed germination rate. The seed germination rate, seedling length and dry weighthave increased with an increase in temperature level from 5 to 30oC but decreased at higher temperater levels (30-40oC). The highest and lowest germination rate were recorded at 30oC and 20oC, respectively. The highest seedling length and dry weight were obtained at 35oC and the lowest ones at 20oC. The regression line fitted to relative germination rates at 20oC to 30oC and 30oC to 40oC showed that germanation threshold of Calotropis procera seed is about 30oC. Germination of Calotropis procera seed was was negatively affected by temperature of above 30 and below 20oC. In conclusion, suitable period of time for seed germination and seedling stablishment of Calotropis procera seems to be very short.

In this study alfalfa hay and corn silage were used in the diet of dairy cows as gross forage to investigate the effect of their quality on milk production. Fifteen Holstein cows (37 ±10 DIM) were used in completely random design during 9 weeks. Treatments included three levels of alfalfa hay and corn silage include: 1) 10% alfalfa -30% silage corn (CS)2) 20% alfalfa -20% silage corn (CSAH) and 3) 30% alfalfa -10% silage corn (AH). Alfalfa hay was packed down second cutting in the mid-flowering. The ratio of forage: concentrate was 60:40 in all treatments. Cows were fed the total mixed rations (TMR) twice daily. Experimental diets were analyzed weekly. Individual dry matter intake was also measured daily. The results indicated that high dry matter intake was achieved when cows were fed by CSAH. Milk production was affected by all treatments (P = 0.014). Replacing corn silage with alfalfa hay increased the milk fat. There was not significant differences between total tract digestibility of dry matter, organic matter, crude protein and neutral detergent fiber in all treatments. Cows that received CS had higher apparent total tract digestibility of crude protein. There was significant difference in the total chewing time (minutes per day) and chewing activity decreased when alfalfa ratioin cow's diet were increased.

Establishment and growing of plant formation is challenged by severe changing of climate in nowadays. Knowing and understanding the effects of environment factor on plant communities are quite important in order to reach the sustainable development on forest and rangeland areas. Regarding of investigation of some climatic and topographic effects on plant formation, the rangeland of northern Alborz from 1600 to 3750 m from see level of Javaherdeh (Ramsar) was selected. One square meter plot was usedand plant froms, altitude and slope percentage of each plot were recorded. Precipitation and temperature line for each elevation line were obtained by rain stations. Distribution of plant formations with some environmental and climatic factors were investigated by Canonical Correspondence Analysis and cluster analysis. The results indicated that bushy trees formation prefer more humid area in elevation belt of 1600-2200 m. Forbs and grasses formations were located in next altitudinal class (2200- 2850m). Cushion formation with less water requirement and resistance to cool condition were located at upper studied elevation range. Therefore, understanding relationships of plant formation with climatic changing, can assist managers to have ecological sound management decisions.

Determination of nutritive substances of forage and deficiencies diagnosis assist managers to improve nutrition of ruminants in rangelands.. Nutrition experts believe that deficiency of protein of grains and low energy of woody substances and imbalance of mineral elements of range forage are among the most limiting factor range animal nutrition. Magnesium, calcium, sodium, potassium and phosphorus content of dominant and halophyte shrubs of Salsola arbuscula, Salsola richteri, Halothamnus glauca, Seidlitzia rosmarinus species at three phenological stages: vegetative, full flowering and seed dissemination in desert rangeland of Sabzevar was investigated. Samples were taken to laboratory and mineral elements of them were measured. Comparison of mineral elements with the requirement of ruminant showed that the P was lower than its requirement in all three phenological stages. The highest contents of calcium, sodium, phosphorus, magnesium and ash and the least value of potassium belonged to Seidlitzia rosmarinus.

In this study some of the factors influencing growth of plants were investigated to determine the reason of improper growth of Atriplex canescens. Studied factors were leaves chemical contents, soil physico-chemical factors, topography, and climate. Two contacting sites with good and week growing condition were selected. Random- systematic method of sampling was conducted along 3 hundred meter transects for sampling soil and vegetation. Along each transect 9 plots were established. In order to evaluate vegetation, canopy cover of plants in each plot was measured and Na, K, Ca and Mg of green leaves were measured. In addition, along each transect 3 profiles (in start, medium and end points of each transect) were dug and samples were taken from two depths (0- 30 cm and > 30 cm). The results of this study showed that soil texture, climate, EC and pH of both sites are compatible with ecological requirements of Atriplex canescens. Probably lack of sufficient drainage due to clay texture and lower infiltration, hardpan resulted from high amount of lime (CaCo3), have affected improper growth of Atriplex in weak growing Atriplex site.

Understanding vegetation dynamics of arid rangelands is a prerequisite for their proper management. Rainfall is the most crucial environmental factor for range plant growth and forage production in vegetation communities of such regions. This study was conducted in the Nodoushan steppe rangelands over nine years (2000-2008) to assess the effect of variability in meteorological factors including rainfall, temperature and wind velocity on forage production of dominant range plant species. Seven dominant plant species were selected and every year their forage productions were estimated using double sampling method in both permanently and randomly located plots. Data on precipitation, temperature and wind velocity were collected from nearby climatological stations. Relationships between meteorological factors and annual forage production of different species were analyzed using multivariate method of Redundancy Analysis (RDA) in CANOCO 4.0 software. Results showed that RDA axis 1 is highly associated with temperature in May and rainfall in January and December to March. The species correlated to this axis were Artemisia sieberi and Iris songarica. While RDA axis 2 showed significant correlations with temperature in July and rain in autumn and spring as well as forage production of Eurotia ceratoides, Stipa arabica and Stachys inflata. Wind velocity had no significant correlation with any of RDA axes.

Knowledge of grazing behavior and diet selection of animal has an important role in grazing management of rangeland ecosystems. In order to investigate grazing behavior and diet selection of sheep and goats under various weather conditions, upland rangeland of Javaherdeh (Ramsar) was selected. The study was carried out under three weather conditions (sunny, cloudy and semi-cloudy) at summer time. Investigation was carried out based on four main plant life forms (perennial grasses, perennial forbs, shrubs and bushy trees) during grazing periods (end of Jun, July, and August 2009). Grazing behavior and diet selection of animal were studied by direct vision from 0.5 to 2 m distance with half an hour concentration on target animal. Range condition was analyzed by Range Value method as well as variation of range condition was obtained by Trend Balance method in each grazing period. Data obtained from different weather conditions, animals and plant life forms were analyzed using ANOVA in PASW v.18 software. Results showed that animal graze on different strata of vegetation in their own grazing land, and that weather and rangeland condition effectively changed grazing behavior and diet selection of animals. Also under undisturbed condition, sheep preferred to graze on the forbs while goats preferred to browse on the shrubs and bushy trees. Hence, studying of grazing behavior and diet selection of animal has an important role in regulation of grazing program and suitable using of forage capacity of the rangeland ecosystems.

In order to investigate the effects of sewage sludge (SS) application on concentration of heavy metals in plant parts (root and shoot), a field experiment was conducted as split-plot arrangement based on randomized complete block design with three replications in 2008. The main factor was SS that was applied in 3 levels (020, and 40 Mg ha-1). Application year was considered as sub-factor with three levels of 2006 2006-2007, and 2006-2008. The results indicated that application of sewage sludge in three years was significantly affected the amounts of lead and chromium in root and shoot of Wheatgrass and Berseem. The maximum amount of lead and chromium in the root and shoots of Wheatgrass and Berseem were recorded in 40 Mg ha-1 in three-year application. These amounts were also increased compared to control in one-and two years application. In addition, the accumulation of lead and chromium were higher in the roots of Wheatgrass and Berseem compared to their shoots. Finally, in all levels of SS application, the accumulated effect was more than the residual effect.

Nitraria schoberi L. a shrub in the family of Zygophyllaceae, is widely distributed in many sandy and saline areas in central part of Iran. Green house experiments were carried out to assess the effects of salinity on seedling germination and growth of Nitraria schoberi during a 30 days period. The germination rate and root and shoot elongation and also number of leaves of the emerged seedlings were assessed over a wide range of salinities (0، 4، 8,12، 16 and 20 ds/m NaCl and Na2So4). The highest germination percentages (34%) were obtained under non-saline conditions (0 ds/m). seedling germination was not affected by NaCl and Na2So4 at concentration levels below 4 ds/m, but it was significantly decreased by both salts at concentration levels of 8–12 ds/m. No seedling germinated at 16 ds/m NaCl and 20 ds/m Na2So4. An increase in NaCl or Na2So4 concentration level progressively inhibited seedling growth. Stem elongation and number of leaves of emerged seedlings significantly decreased with an increase in both NaCl and Na2So4 concentration level, while root elongation was not affected significantly. Results showed that under the same concentration level, sulphate has less inhibitory effect than chloride.

Mismanagement in rangelands and law deficiencies are among the reasons for destruction and illegal plowing of rangelands. These could lead to job insecurity of pastoralists and they experience the effects of this land conversion in their economy and living conditions. They are unable to express their wills because of poor communication skills, and not being involved in decision making processes. This study aimed to describe the most important social and ecological issues and challenges in laws and managements. Local community participation by facilitating approach and participatory action research is needed for presentation of pastoraliststo local and national decision makers. Invasion, destruction, and illegal plowing of rangelands were identified as the most concerns of pastoralists and experts in summer rangelands of Shesboloki sub tribe. In the process of surveying and analyzing these common phenomena in rangelands and with setting up social facilitating workshops, either in local communities or for natural recourses administrators and court officials,laws problems were identified as the first motive for this problem. For instance some problems in commission of the article one and its complaints,"Commission of the article 34, the religious law of cultivation".Incompetence of punishments laws in natural resources and then management and structure problems such as range survey and range separation in common rangelands of peasants and nomads. Procrastination in following the subject by natural resources administration and courts, inefficiency of court systems in natural resources subjects, the problems of low enforcement and sentences, and at the end,the general policies of government, unprofessional words of government officials and the interference of some local government officials. In this essay the second group of challenges (management and structure) are discussed.

This study aimed to compare point of view of experts and pastoralists in connection with grazing systems in Range Management Plans. This research carried out in 2008 at Semnan province. All of experts in Natural Resources offices and selected livestock managers thatwere whole/reference population in this study. Based on stratified random sampling method and Cochran formula, the sample volumes (30) of Range management Plans were estimated. According to weight of stratums (Cities) suitable sample size were allocated. Questioner and field survey was used for data collection. Descriptions result showed that rank of grazing systems evaluation is 2.8 from 5 that shows grazing systems condition in Range management Plans in Semnan province are medium according to Likert Scale. Appreciation result showed that there are significant differences between point of view of experts and exploits in connection with grazing systems project (P<0/01). Correlation coefficient showed that there are significant differences between point of view of responders and survey factors(P<0/05).

Evaluation of soil erosion by existing models is required as an important tool for appropriate water and soil conservation purposes. The present study aimed to assess the applicability of Hill slope Erosion Model (HEM) as one of the newest erosion models for prediction of storm-wise sediment yield. This study was conducted in Khosbijan rangeland with 9، 15، 20 and 25 percent slope steepness by using soil erosion standard plots. Runoff depth, vegetation cover density, land surface cover, soil texture, slope steepness and length were determined for 16 storm events. The results showed that the uncalibrated HEM didn’t simulate the observed sediment yields, properly. Calibration of soil erodibility parameter and developing regression between observed and estimated data indicated that the model could not predict sediment yield in plots with 9 and 15 percent slope steepnesses with determination coefficient of less than 0.4 (p≤0.135). The model could successfully predict the soil erosion rate in plots with 20 and 25 percent slope steepnesses by applying soil erodibility parameter of 0.8 with determination coefficient of 0.355,0.803 and estimate error of 56 and 35 percent, respectively.