جستجوی مقالات مرتبط با کلیدواژه « بیوماس » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

Due to the limitations of field measurements of vegetation, the application of plant indexes to estimate rangeland biomass using satellite data can be very useful in rangeland studies. For this purpose, it is necessary to identify appropriate vegetation indices. The aim of this study is to investigate the possibility of estimating rangeland biomass using plant indices obtained from digital data of Landsat 8 satellite and determining the most appropriate ones in semi-arid regions of the northeast of the country. For this purpose, the average values of plant indices NDVI, TDVI, SAVI, ARVI, EVI, OSAVI, IPVI, GRVI, and GNDVI within each unit of one hectare of the studied basin network were calculated. Then, the correlation of these values with the average measured field values of these units was examined by linear regression, and the regression model of each index was determined to estimate biomass. Finally, the results were validated and a field biomass map was prepared for each index. The results showed that all indexes had a high and acceptable correlation with real biomass data. Based on the validation results, the SAVI plant index with a coefficient 0.79 and root-mean-square error of 14.73% was the most suitable plant index for estimating biomass in the region. By using the wavelengths located in the blue band, these indicators modify the effect of dust in the calculations, which reduces the atmospheric effect and improves the results of calculating the NDVI index, and it can be called the modified NDVI index. According to the results, plant indices obtained from the ratio of near and visible infrared bands are highly correlated with biomass. In general, the shorter the wavelengths used by plant indices, the lower the accuracy of estimates in arid and semi-arid regions.

The microbial habitats formed through plant patches, as fertile islands, are an effective factor in the development of vegetation and improve the soil surface characteristics of saline ecosystems. The pulping plant is the most economical solution for improving the saline soils, in this way, toxic ions, especially chlorine and sodium, are removed from the soil by salinity resistant plants. The purpose of this study was to evaluate the effect of various halophyte species on soil characteristics in aradiation zone and to determine the species with the highest positive and maximum effect on soil condition improvement in Urmia Soporghan region saline habitats.

To conduct research, the plant type Halocnemum strobilaceum-Atriplex verrucifera which represents a large area of saline rangelands around the Lake Urmia, has been selected by spotting along two 150-meter transects parallel to the salinity gradient and the distances between them, was considered as a patch between patches. Soil samples were taken from the inside of the stains and the space between the patches from the soil depth with three replications. In each of the patches, the morphological characteristics of the Halocnemum strobilaceum and Atriplex verrucifera species included the large crown diameter, crown diameter, base height, collar diameter and number of spikes with three replications and the ion accumulation value (Elements) in their air organs. Using independent t-test, the values ​​of measured parameters between the spots and the space between the spots as well as the average reserve of elements in the air biomass between the two species were compared.

The results showed that presence of Atriplex verrucifera has a significant effect on the increase of nitrogen content inside the droplets, but shows an increase in external staining in the case of electrical conductivity and sodium ion. For other elements, there were no significant difference between the inside and outside of the stains. There was no significant difference between the inside and outside of plantlets in the case of Halocnemum strobilaceum species, for no element. It was also observed that the amount of magnesium ion outside the stains was higher than inside them, but the amounts of calcium, sodium, and chlorine in the stains were more than opaque. The results of the analysis of the elements in the aerial biomass of species showed that there was a significant difference in the amount of sodium, potassium and magnesium elements in the two species, but there was no significant difference for other elements. Since the sodium element is the most significant element in determining the salinity index, and the storage of this ion in the strobilaceum Halocnemum is more than Atriplex verrucifera, Halocnemum strobilaceum can be introduced as a high-purity salt species.

Discussion and Conclusion: Since the sodium element is the most significant element in determining the salinity index, and the storage of this ion in the Halocnemum strobilaceum is more than Atriplex verrucifera, Halocnemum strobilaceum can be introduced as a high-purity salt species.

Carbon storage is a strategy that helps to reduce atmospheric carbon and reform of climate change consequences. In the present study, the carbon sequestration potential of the pharmaceutical industry _ Jashirmountain pastures Khalyfan Mahabad region, was studied. The study area Jashir site, four transects 100 m along each transect 5 randomly spaced 20 m plots, were carried out systematically. Jashir biomasses in all plots were measured by Cutting and weighing method. At the beginning and end of each transect, profiles in both 0-15 and 15-30 were drilled. Samples were sent to the laboratory and carbon storage rates for each of them were determined. The results indicate that in soil Jashir of Second depth, there is a greater proportion of carbon storage. Significant at the 5% level, there is a meaningful gap between air and ground carbon storage in biomass is observed. The contribution of carbon storage industries - pharmaceutical Jashir it is more than biomass.

Low doses of gamma radiation are widely used to stimulate seed germination, growth and crop production. This study was conducted to study effect of irradiation with doses of 20, 30, 50, 100 and 150 Gy of gamma ray on seeds of two species of Ag. elongatum and Br. tomentellus. For this purpose, for each species in an experiment with completely randomized design, three replications of treated seeds with gamma ray were sown in plastic pots and the parameters of germination capacity, germination rate, germination value and biomass of shoots and roots was evaluated. The results showed the treat of 30 gray had the most significant effects on the evaluated parameters of Ag. elongatum, and the most increase in germination rate, germination value (P

Livestock Grazing is as the most effective factor in changing dimensional characteristics and plant biomass in rangelands that affected different aspects of ecosystem production. Regarding to the fact that Artemisia fragranus is the main species of mountainous rangeland in Khoy and the limited quantitative information about the effect of different grazing intensities on structural characteristics, aerial biomass and especially underground biomass is available, so in the present study the effect of different grazing intensities (light, intermediate and heavy) on structural characteristics, aerial and underground biomass was assessed. Therfore, three rangeland sites with various grazing intensities are selected and 60 plots of 1 m2 along 100 m transects were established. Thus, structural characteristics, litter, aerial and undergrlound biomass of Artemisia fragrans were measured in the study sites. To compare the means of dimensions and biomass components of species in three study areas, analysis of variance and multiple Duncan mean comparison test were used. The results proved that there are significant differences among studied parameters (except for collar diameter and collar area) of studied species among three grazing intensities. The most and the lowest means of aerial biomass in 2 places with low and heavy grazing intensity were 18.5 and 42.76 gr. also, the most amount of ground biomass was 32.95gr and the lowest amount of ground biomass was 56.46gr that belong to places with low and high grazing intensity. Calculating of variation percent of the parameters in each sites of moderate and heavy intensity in relation to light grazing showed that all parameters have declined and the most variation percent of study species parameters belongs to heavy grazing site. Generally, decline amount for collar diameter and collar area is the lowest and also for aerial and underground and litter parameters is the highest.ý

In last decades، CO2 has become one of the most important glasshouse gases in which increased its concentrations in atmosphere and followed by global warming. The global warming may have negative impacts on the environment and natural ecosystems. Leniency of decreasing atmospheric carbon dioxide concentrations could be possible via carbon sequestration in biomass and soil organic matter of rangelands ecosystems in Iran and all around the world. Astragalus rangelands covering about 17 million hectare (10%) of Iran territory so could play much important role in carbon sequestration. In order to investigate the role and potential of Astragalus rangelands in carbon sequestration، a study was carried out in a key rangeland area covered by Astragalus brachycalex- Agropyron sp. in Gholestankoh of Khansar. The content of carbon in aboveground and underground biomass، litter carbon and soil organic carbon were determined. The results showed that the total carbon sequestration was 94. 90 ton/hectare and 94. 66 % of total carbon sequestration was soil organic carbon. The results of biomass carbon distribution showed that the carbon content in aerial biomass was higher than underground biomass. Correlation and stepwise regression analyses revealed that the content of carbon sequestration was positively related to Astragalus height and volume، aerial and underground biomass، total biomass، litter amount and soil organic carbon (SOC) content. It was concluded that the Astragalus rangelands have a tremendous potential to sequester carbon and the soil is the most important sink for organic carbon storage in Gholestankoh of Khansar rangeland.

Atmospheric carbon dioxide concentrations have substantially increased in recent decades. Land management practices, however, offer opportunities to mitigate the rise in atmospheric CO2 concentration through sequestration of this additional carbon via storage in plant biomass and soil organic matter in a process termed terrestrial C sequestration. Rangelands ecosystems have a large potential to sequester C because they occupy about half of the world's land area. In Iran, the Astragalus rangelands with about 17 million hectare area have 10% of the country land area and have the important role in carbon sequestration. In order to investigation the role and potential of Astragalus rangelands in carbon sequestration, a study was carried out at a key area of Astragalus verus-Bromus tomentellus vegetation type in Malmir rangeland site, Shazand township of Markazi province and the content of aboveground and underground biomass carbon, litter carbon and soil organic carbon was determined. The results showed that the total carbon sequestration per hectare was 32.95 ton and 87.43 % of total carbon sequestration was soil organic carbon. The results of biomass carbon distribution showed that the carbon content in aerial biomass was higher than underground biomass. Correlation and stepwise regression analysis revealed that the content of carbon sequestration was positively related to Astragalus height and volume, aerial and underground biomass, total biomass, litter amount and soil organic carbon (SOC) content. It was concluded that the Astragalus rangelands have a large potential to sequester carbon and the soil is most important sink for organic carbon storage in this rangelands.