JOURNAL OF RANGELAND SCIENCE
Year:2016 | Volume:6 | Issue:1|Papers Count:9

Salinity is one of major stresses which can severely limit plant production, especially in the arid and semi-arid regions. The present study was carried out to evaluate the impact of salinity stress on some physio-biochemical parameters in nitre bush plants (Nitraria schoberi). Thus, an experiment was carried out under natural conditions and salinity stress was induced by a combination of different salts (NaCl, MgCl2 and CaCl2) at four levels. The salinity treatments were: Control (Ctrl), Low Salinity (LS), Medium Salinity (MS) and High Salinity (HS) of the combined salts. In this study, photosynthetic apparatus of N. schoberi was damaged to a certain extent as it has been observed from leaf chlorophyll fluorescence parameters (Chl. FPs) such as minimal fluorescence (F0), maximal fluorescence (Fm) and maximal photochemical efficiency (Fv / Fm). A significant alteration in chlorophyll content of leaf was not noticed with the increased soil salt content up MS and thereafter, it significantly declined at HS. The reduced level of total chlorophyll content under salt stress conditions can be attributed to chloroplastid membrane deterioration leading to lesser accumulation of chlorophyll. The amount of inorganic ions in nitre bush plant leaves altered with an increase in salinity stress. The concentration of Na+and Cl- steadily increased and on the contrary, the concentrations of K+, Ca2+and Mg+showed significant decreases only at HS. This phenomenon is explainable by the inhibition of K+uptake by high Na+levels because these cations are transported by the same proteins. In our experiments, we did not observe significant differences between control plants and those grown in presence of 300 mMol salt kg-1 dry soil (DS). Thus, nitre bush is considered to be a salt tolerant species.

One of the most important methods to investigate heavy metals as pollutants is more likely to use bio-monitors which can be applied as an appropriate index to express the quality of environment. In current study, in order to investigate the effects of dominant plants in the desired region and role of aquatic macrophytes in monitoring such elements as zinc (Zn), lead (Pb), copper (Cu) and cadmium (Cd) in underground organs, leaves and stems of a specific aquatic macrophyte named Phragmites australis as well as sediment samples of Dez River, Iran in 2012 were studied. Given samples were prepared with the ratio of 4 to 1 nitric acid to perchloric acid and the concentrations of elements were measured by atomic absorption spectrometry. In this study, Enrichment Factor (EF), Bio-accumulation Index and Translocation Factor (TF) were measured. Results indicated that the concentration of metals was reduced in the underground organs, leaves and stem, respectively (stem<leaves<underground organs). Also, there was a positive correlation between the concentration of Pb in the sediments and roots (P<0.05); thus, it was expected that the roots of Phragmites australis may be of suitable monitoring for pollution resulting from Pb in the regional sediments of Dez Watershed. Enrichment Factor showed that because of anthropological resources, stations of two, three and five were more polluted. In addition, the underground organs of Phragmites australis were introduced as the accumulator of Cu, Zn, Pb and Cd by Bio-accumulation Index. Translocation Factor was increased from the underground organs to aerial organs for Pb, Cd, Cu and Zn, respectively.

Climate change due to increasing the level of greenhouse gases including CO2 is the main environmental issue of the world in the new century. One of the effective way for reducing atmospheric CO2 is carbon sequestration by plants and soils. A vast area of Iran has desert condition with special adapted plant species in which can be devoted for carbon sequestration. Hammada salicornica as a shrub plant of chenopodiaceae grows as dominant or key species of vegetation types in many parts of desert areas in south of country. So, potentials of carbon sequestration of H. salicornica vegetation types were estimated in seven sites in South Khorasan provice, Iran. For this purpose, 113 individual plants were measured for height, and long and short diameters of plant crown area and then were cut from ground level. To estimate underground biomass, roots of 10 individual plants were pulled from soil by digging the root zone. Dry matter production of shoots and roots were weighted and some samples were burned for determination of organic carbon. Organic carbon of soil of three sites were measured by soil sampling. Results showed that carbon has been sequestered between 133 to 3293 kg/ha in different sites in which James and Sefarsakh had the highest and the lowest amount of organic carbon in plant vegetation parts. Soil organic carbon obtained about 6313 kg/ha on average. The best linear regression equation (R2=0.90) for estimating aerial biomass of H. salicornica obtained by using crown area in the equation. It seems that conservation of natural vegetation of H. salicornica and or restoration of degraded lands by this plant, have good potentials for carbon sequestration for globally action commitment and providing benefits such as forage and fuel for local people.

The drought caused a series of effects on many sectors of economy, especially natural resources. During two last decades, Iran has suffered from several severe to extreme agricultural droughts which caused significant decreases in rangeland and agriculture yields. This paper discusses the detection of agricultural drought severity over the rangelands of Markazi Province between 2000 and 2014 using remotely sensed data. Vegetation Temperature Condition Index (VTCI) is a near-real time drought assessment and monitoring approach which have been developed using Terra-MODIS normalized difference vegetation index (NDVI) and Land Surface Temperature (LST) products. VTCI is defined as the ratio of LST differences among pixels with a specific NDVI value in a sufficiently large study area. VTCI has capability of drought stress classification which therein lower VTCI is for drought and higher one for wet conditions. The ground-measured precipitation data from the synoptic stations of Markazi Province are used to validate the VTCI drought monitoring approach (11 stations). For this objective, after the calculation of Standardized Precipitation Index) SPI) with different periods and VTCI month of July during 2000 to 2014 (warm and cold edges from NDVI and LST scatter gram extracted), linear regression analysis between VTCI (15 maps) and SPI 1, 3, 6, 9, 12, 18 months were surveyed and finally, the best map was extracted. Based on the statistical analysis, higher correlations were found for July 2006 (R2=0.73 for warm edge and R2=0.86 for cold edge) and the best linear correlation was created for SPI-18 month in July. Results showed that within VTCI classified map, moderate and low drought classes constituted most area of studied region. Also, the results showed that VTCI is closely related not only to recent rainfall events but also to past rainfall amount (18 month) indicating that VTCI is a better and near-real time drought monitoring approach for rangelands.

Feed resources availability at cheap and affordable prices for livestock consumption are major factors determining capability of livestock production to supply products for increasing urban and cities consumers in Nigeria. To take advantages of the high demand in urban areas, livestock producers on extensive pastoralism are moving closer to cities and urban communities such as Abuja the Nigeria capital city. As these pastoralists moves closer to places like Abuja, traditional livestock production systems change from complete pastoralism to agro-pastoralism whereby hitherto pastoralists get settle down on suitable land where they can both rear their livestock and cultivate land for crop production. This practice is gaining ground not only among the hitherto pastoralists but among all farmers living closer to Abuja. An example of such location is Tafa Local Government where this study was carried out. But, increasing intensity of agro-pastoralism in the area is causing poor range productivity and livestock performance due to over-stocking, poor pasture utilization and seasonal variability effects on pasture plant yield. Therefore, an assessment of current feed resources use and farming practices in the area by agro-pastoralists was carried out for the purpose of suggesting positions for improved range and livestock performance through nutritional manipulations. The study confirmed that proximity of the study area to the Nigeria federal capital city is a factor supporting growth of agro-pastoralism in the area, it was discovered that between January and May annually; there is shortage of feeds and feed resources for livestock consumption, it was also discovered that prices of livestock is reasonable year round and average price of milk per litre is highest between January and April annually. The study concluded that livestock feed resources management practices such as protein supplementation, processing of green fodders into silage and improve utilization of crop residues and by-products are suitable for reducing shortage of feeds and feed resources between January and April annually in the area.

Common burnet (Poterium sanguisorba) is a perennial herb from rose family (Rosaceae) which is used to construct pastures. The studied plant can resist against freezing, cool and drought. The present study was conducted to study the seed germination parameters of common burnet in different thermal treatments as completely randomized design in 4 replications in 2013. Treatments involved the effects of constant temperature including 5, 10, 15, 20, 30, 35 and 45°C on germination parameters of 25 seeds which were used at each replication. The results showed that the effects of different thermal treatments on seed germination of common burnet were significant so that the lowest germination speeds at 5 and 10oC were 0 and 2.78 seeds a day and the highest germination speeds at 35 and 30oC were 8.95 and 7.77 seeds a day, respectively. The longest plume lengths were observed at temperatures of 10 (4.94 cm) and 15oC (4.47 cm) and the shortest plume lengths were 35 and 45o (1.28 and 0 cm, respectively). The longest radicle lengths also were observed at 10 (5.13 cm) and 15oC (5.05 cm) and the shortest ones occurred at 35 and 45oC (0.88 and 0 cm, respectively). According to the fitted regression models between germination speed and temperature, minimum, optimum and maximum values of temperature were obtained at the ranges of 3.38-6.65, 26.82-34.5 and 45-46.78oC, respectively. According to the seed germination of studied plant at maximum and minimum temperatures, it can be used in constructing the pastures in arid and semi-arid areas.

Medicinal plant species constitute a considerable part of the flora in Iran and play a major role in the composition of plant communities. Therefore, it is necessary to recognize the factors leading to the establishment and distribution of vegetation. For data sampling (2012), land units were specified. The plot size was determined using minimal area method and number of plots was determined by statistical methods according to the changes in vegetation cover.120 1 m2 plots were selected and within each plot, the presence and absence of species and cover percent were estimated. The soil samples were taken in each plot in (0-30 cm) depth. Data were collected and analyzed using Principle Component Analysis (PCA). Results indicated that the first three axes explained the total variation. The variables of altitude, OM, N, pH, and sand had significant correlations with the first axis and explained the 60% variation. For the second component, topographic properties and EC were more important traits and explained the 29% variation. These two components explained the 89% vegetation cover variation in Ghorkhud region as G1 (Eryngium bungei-Asperula arvensis) and G2 (Conium maculatum-Acantholimon pterostegium) types were grown in sandy soils (low OM, N, pH and high EC) coupled with high altitude and slope, G3 (Asperula arvensis-Cichorium intybus) type had a higher adaptability with sandy soils (low OM, N and pH) coupled with lower EC, higher altitude and lower slope and G4 (Artemisia sieberi-Convolvulus arvensis) type tended to be established in clay soils (lower sand% and higher OM, pH and N) and lower altitude.

The degradation rate of Mediterranean steppes, especially in North Africa is 1% per year, and this considered a high rate of degradation. This study conducted in 2014 in the south slope of the Al-Jabal Al-Akhdar, northeast Libya to quantify the vegetation recovery rate and assess selected Vegetation Indices (VIs) for mapping rangelands degradation status using remote sensing technology. Through a review of VIs we found that NDVI (Normalized Difference Vegetation Index) and MSAVI2 (Modified Soil Adjusted Vegetation Index) are the most useful indices for the study area to achieve the research objectives. Two Landsat (ETM+) satellite images (captured in September 2006 and 2014) used to map, monitor and assess the patterns of changes in plant cover. Three exclosures (fenced areas) with moderately to severely degraded soil and vegetation, were selected along a strong north-south rainfall gradient. Landscape Function Analysis (LFA) technique used to calculate Total Patch Area (TPA) for comparison purpose. According to the results, NDVI and MSAVI2 can be employed as a consistent and comparatively simple to use a tool in management and assessment of desertification processes in the Mediterranean rangelands. It seems that MSAVI2 more reliable than NDVI when the vegetation cover is very low. Overall, the plant cover did not change or increase for a large portion of regions at a time when 80% of the study area still under very severe and severe conditions of land degradation status.

The impacts of Dust and Sand Storms (DSS) on people, crops, livestock, infrastructure and health are well documented. Data have accumulated on the deleterious effects of dust aerosols when they settle on plants. Sand blasting of low growing plants is a common cause of failure in reforestation efforts. Burial of plants by moving sands are also a cause of much damage. The physics of moving sand and dust particles is outlined and the mechanics of each type of damage is elaborated. The physical effects of dust accumulating on leaf surfaces, leaf physiology such as photosynthesis, transpiration, stomatal conductance and leaf temperature of many different species of plants were investigated. It was found that dust decreases stomatal conductance in the light, and increased it in the dark by plugging the stomata, when the stomata were open during dusting. When dust of smaller particles was applied, the effect was greater. However, the effect was negligible when the stomata were closed during dusting. The dust decreased the photosynthetic rate by shading the leaf surface. The paper also reviews experimental work on the physiological effects of dust on photosynthesis, stomatal function, respiration and transpiration. Examples are drawn from western Iran where oak woodlands (Quercus brantii) are under threat from dust that blows in from Iraq and Syria.