Showing 29 results for Range
S. Rastegar , M. Rahemi,
Volume 11, Issue 42 (1-2008)
Abstract
Navel oranges and Clementine mandarin are classified as early cultivars and when fruits are left on the trees, fruit firmness and juice content will decrease. Plant growth regulators have been used to improve fruit quality. Gibberellic acid (GA3) and 2,4-D isopropyl ester sprays were used to increase juice content ,peel firmness and delay senescence in Navel oranges and Clementine mandarin. Factorial experiments were arranged in a complete randomized block design with three replications and each block consisted of three trees. Chemicals were sprayed on the branches (north and south of each tree) with 10 liter sprayer to the point of run-off during fall of 2004 and 2005 ,in a commercial orchard in Jahrom in the south east of Fars province, Iran . In both years of study, GA3 at 100,150 and 200 mgl-l and isopropyl ester 2,4-D at 8,12 and 24 mgl-1 were sprayed on September 30 (diameter of Navel 64 mm and diameter of Clementine 46 mm), October 14 (diameter of Navel 69 mm and diameter of Clementine 48 mm ) and November 7 (diameter of Navel 70 mm and diameter of Clementine 50 mm) and fruits of Navel oranges and Clementine mandarin were harvested 45 and 35 days after last the spray treatment, respectively . The results of experiment revealed that Navel oranges responded better with second application (Oct.14, diameter 69 mm ) and Clementine mandarin with the first application (Sept.30, diameter 46 mm ). Juice content and fruit firmness at harvest increased. GA3 increased juice content even better than 2,4-D isopropyl ester but delayed senescence, 2,4-D was more effective in increasing fruit sizing in both cultivars. GA3 at 150 and 200 mgl-1 and 2,4-D at 24 mgl-1 when compared with the untreated resulted in highest juice content of fruits.
M. Khodagholi, Z. Eskandari, M. Saeidfar, S. Chavoshi,
Volume 12, Issue 44 (7-2008)
Abstract
The effect of nitrogen and phosphorous fertilization on range species production was studied using factor combination method as factorial with 3 blocks and 12 treatments. Nitrogen in 4 levels of 0،25،50 and 75 kg N/ha and phosphorus in 3 rates of 0،30 and 60 kg N/ha were used. Results indicated no significant difference between nitrogen rates in different growth forms of grass, bush and Eurotia ceratoides. Nitrogen in 75 kg/ha rates caused an increase of 40 and 106% in grass and Eurotia production, respectively. The maximum rate of production was seen in N50 with 100 percent increase compared to N0. Moreover, no significant difference in phosphor rates of leguminous and grass was observed. P 60 kg caused 500 and 56 % increase in leguminous and grass production, respectively.
Z. Karimi , M. Rahemi,
Volume 12, Issue 45 (10-2008)
Abstract
Pathogens are the most important factors inducing postharvest losses on citrus fruit. Experiments were conducted as a CRD with 4 replications on sweet lime (Citrus limetta) and Valencia orange (Citrus sinensis) in 2003 and 2004. Treatments were pure essential oils of clove and thyme and in 25% ethanol solution at concentrations of 0.1, 0.3 and 0.5% and imazalil (2 ml/l). Results indicated that in the first year, pure essential oils of clove and thyme reduced the decay percentage of blue mold of Valencia orange fruit from 90 % (control) to 0 and 12.5 %, respectively. Pure essential oils of clove and thyme reduced the decay percentage of sweet lime in the first year of experiment from 95 % (control) to 0 and 6 %, respectively. In the second year, with the same treatments decay percentage of blue mold was reduced from 90 % (control) to 0. Solutions of 0.1, 0.3 and 0.5 % of clove and thyme oil extracts in 25 % ethanol solution reduced decay percentage of sweet lime fruits form 85 % (control) to 65, 41 and 26 % for thyme oil and to 60, 30 and 22.5 % for clove oil. Comparison of pure clove and thyme oil extract with imazalil showed that pure clove and thyme oil extracts were not significantly different with fungicide treatment. Treatments of clove and thyme oils in 25 % ethanol treatment were not as effective as fungicide.
F Parsa, R Azadi Gonbad, A Moghadam Dorodkhani,
Volume 12, Issue 46 (1-2009)
Abstract
Every year lots of waste will produce in factories from black tea. These waste will remain unusable or through away but only little amount will be used in industry. In this survey, important components of tea dust and three kinds common tea wastes was studied from 1382 to 1383. Four compounds (caffeine, protein, fiber and fluor) were extracted and measured separately from four samples of wastes (dust, fluff, footstalk and stalk) as experimental component. In three periods of plucking (spring, summery and autumn) from two kinds of arrangement (from curve and flat bushes). The experiment were conducted in four experimental components with replications and were analyzed with Duncan method. The results indicated that effects all of wastes, plucking periods and two kinds of arrangement (except effect of that on amount of caffeine) were significant on caffeine, protein, fiber and fluor whereas maximum amounts of caffeine, fluor and protein in dust but maximum amounts of fiber was in stalk and Effect of plucking period indicated maximum amount of fluor and caffeine in summer plucking and maximum amount of fiber and protein in autumn plucking and effect of plots indicated maximum amount of fiber in flat plot and maximum amount of fluor and protein in curve plot.
S.h Sadeghi, S.h Pourghasemi, M Mohamadi, H Agharazi,
Volume 12, Issue 46 (1-2009)
Abstract
The use of suitable empirical models for estimation of soil erosion and sediment yield is essential because of nonexistence or shortage of associated data in many watersheds. In the present study, the applicability of the USLE and its different versions Viz. MUSLE-S, AOF, MUSLT, MUSLE-E, USLE-M and AUSLE in estimation of storm-wise sediment yield from standard plots installed in dry farming, ploughed and rangeland treatments was evaluated. To conduct the study, the entire input data were collected from plots installed in three replicates in each treatment in Khosbijan Natural Resources Research Station in Arak Township. The models’ estimates were then compared with the observed sediment data for 12 storm events. Contrary to high correlation among different models’ estimates, the models used in estimation of measured sediment data were found inapplicable. However, significant relationship (r=94.4%) and non-significant relationship with correlation coefficients less than 50% were found between MUSLE-E, and MUSLE-S and MUSLE-E estimates and measured data in rangeland, dry farming and ploughed treatments, respectively.
H Arzani, M Mosayebi, A Nikkhah,
Volume 12, Issue 46 (1-2009)
Abstract
Information on animal requirements for determination of rangeland grazing capacity is essential. Animal requirements depend on its live weight, age, physiological condition and quality of available forage. There are more than 20 sheep breeds with different body sizes grazing in various climatic zone's rangelands of Iran, so animal unit equivalent of each breed should be determined independently. In this research, live weight of animal unit of Fashandy sheep based on average live weight of 3 and 4 year old ewes was determined. Three herds with more than 100 Fashandy ewes among existing herds in Taleghan region were selected. In each herd, 15 three year old ewes, 15 four year old ewes, 5 three year old rams, and 5 four year old rams were selected. They were weighed three times including at the time of beginning of grazing in highlands, end of grazing season in highlands, and once in winter. In each herd, also 5 three month old lambs in the beginning of grazing season and 5 six month old lambs at the end of grazing season were weighed. The amount of daily forage requirement according to live weight and energy requirement of animal unit equivalent for maintenance condition was calculated using NRC (1985) tables and MAFF (1984) formula. It was multiplied by 1.5 because of mountainous condition of rangelands and distances from watering points and villages. The SAS statistical software was used for data analyses according to factorial experiment in the form of completely random design. According to the results, the live weight of animal unit of Fashandy breed was 60.7 Kg. The average live weight of 3 and 4 year old rams were 80.3 and 85.3 kg, respectively. Live weights of 3 and 6 month old lambs were 21.4 and 37.8 kg, respectively. Therefore, animal unit equivalents for rams, 3 and 6 month old lambs were 1.36, 0.35 and 0.62 respectively. According to NRC tables, daily metabolisable energy requirement was 13.8 Mj, and based on MAFF formula it was 11.8 Mj (including that multiplied by 1.5).
M. Riahi , F. Raiesi,
Volume 16, Issue 59 (4-2012)
Abstract
Mountainous landscapes in Central Zagros are mainly used as grazing rangelands to feed animals and are heavily degraded. Overgrazing may impose a negative effect on rangeland productivity and sustainability through significant changes in soil properties. Soil nitrogen (N) mineralization is one of the key biological processes that might be affected by biotic and abiotic factors including range grazing regime or intensity. The primary objective of this study was to assess the effects of rangeland management (grazing and ungrazing regimes) on soil N mineralization in natural rangelands of Chaharmahal VA Bakhtiyari province. Three range management regimes including a) long-term ungrazed, b) controlled grazed and c) freely- (over)-grazed plots in a close vicinity were selected in three regions consisting of SabzKouh (protected from grazing for 18 years), Boroujen (protected from grazing for 23 years) and Sheida (protected from grazing for 2 years), and soil samples were collected from 0-15 cm depth for some physical and chemical properties. Soil N mineralization was measured under standard laboratory conditions. At SabzKouh, the effect of range management on the cumulative N mineralization and the proportion of N mineralized (%) was significant (P<0.05) and ungrazing regime resulted in 89% and 96% increases in soil N mineralization in ungrazed rangelands compared with controlled grazed and freely- grazed rangelands, respectively. Similarly, soil N mineralization was significantly greater (P<0.05) in ungrazed rangelands (3.3- to 3.5-folds) than in controlled grazed and freely-grazed rangelands at Boroujen site. However, at Sheida site with short-term ungrazing period and cropping history there were no significant and considerable differences in soil N mineralization among the three grazing regimes. Briefly, degraded rangelands at SabzKouh and Boroujen sites seem to recover rather quickly from long-term overgrazing with a proper grazing management, while rangeland ecosystems at Sheida site need a much longer period for steady-state conditions and for improvements in soil quality and fertility after long-term soil degradation and disturbance.
E. Gavili Kilaneh, M.r. Vahabi,
Volume 16, Issue 59 (4-2012)
Abstract
Vegetation is the most important factor in sustainable and dynamic equilibrium of natural ecosystems. Considering the relation between environmental factors and vegetation is an essential step in order to identify the effective factors in the habitats. The purpose of this study was to evaluate the relations between vegetation and soil characteristics in rangelands of Ferydounshahr (Sardab-Sibak watershed). The flora and vegetation types were studied using Physionomic-floristic method in the field and eight vegetation types were identified. Vegetation was sampled by Systematic–randomized method in 1× 2 m plots. The canopy cover and species composition percentage were estimated in each plot. After digging a soil profile in vegetation types, the physical and chemical factors were measured. The influences of edaphic factors on vegetation were analyzed using RDA ordination technique. Results showed that based on soil characteristics the eight vegetation types can be classified in to three main range habitats including, Ferula ovina, Astragalus adscendens and Astragalus brachycalyx. The most important factors which cause the separation in these three habitat ranges were clay percentage, organic matter, soil depth, CaCO3, pavement and barren soil.
R. Karimi, M. Hassan Salehi, F. Raiesi,
Volume 18, Issue 69 (12-2014)
Abstract
Improper use of rangelands may lead to their destruction. Therefore, the conversion of these degraded rangelands to agricultural lands and other land uses may improve their soil quality. The purpose of the present study was to evaluate the impact of cultivation in the degraded rangelands on some soil characteristics in Safashahr region of Fars province. Four land uses including the rangeland with sparse vegetation (degraded rangeland), the rangeland converted to agricultural land over 17 years, the agricultural land converted to apple orchard for 4 years and also to an apple orchard for 40 years were selected. Samples were randomly taken from each land use at two depths (0-20 and 20-50 cm) with five replications. The results revealed that land use change significantly increased organic matter and MWD in both soil depths. Bulk density and water dispersible clay increased in agricultural land and new orchard while a decrease was observed for old apple orchard. It is suggested the traditional farming to be replaced with new cultivation methods like minimum tillage and no tillage. Overgrazing of the rangelands must also be avoided.
F. Parsadoust, Z. Eskandari, B. Bahreyninejad, A. Jafari Addakani,
Volume 19, Issue 71 (6-2015)
Abstract
Evaluation of chemical and biological indicators of soil in different land uses could be helpful in sustainable range management, preventing degradation of soil quality trend. This study was conducted in Friedan in Isfahan province in 2010 to compare chemical and biological indicators in three land uses (rangeland, degraded dry land and dry land), during two growing seasons (May and September) in three slopes (0-10, 10-20, 20-30 %). Nitrogen, phosphorus, potassium, organic matter, cation exchange capacity and microbial soil respiration were measured. Results showed that all measured characteristics except potassium decreased over an increase in the slope. Maximum values of phosphorus, organic matters, cation exchange capacity and soil respiration were obtained in pasture (28.4 mg/kg, 0.62%, 20.38 cmol/kg, 33.2 mgC/day, respectively)but potassium maximum rate was seen in dry land form (406.8 mg/kg).The effect of season on all measured parameters was significant except for N, while the highest amounts of phosphorus, potassium, cation exchange capacity and soil respiration (28.7 mg/kg, 377.3 mg/kg, 19.6 cmol/kg and 25.9 mgC/day, respectively) were seen in May and the highest organic matter rate (0.68%)in September. The results of this study showed that an increase in the slope, poor range management, and the end of the growing season could be major factors degrading the soil quality indices and soil productivity.
B. Khalili Moghadam, M. Afyuni, A. Jalalian, K. C. Abbaspour, A. A. Dehghani,
Volume 19, Issue 71 (6-2015)
Abstract
With the advent of advanced geographical informational systems (GIS) and remote sensing technologies in recent years, topographic (elevation, slope, and aspect) and vegetation attributes are routinely available from digital elevation models (DEMs) and normalized difference vegetation index (NDVI) at different spatial (watershed, regional) scales. This study explores the use of topographic and vegetation attributes in addition to soil attributes to develop pedotransfer functions (PTFs) for estimating soil saturated hydraulic conductivity in the rangeland of central Zagros. We investigated the use of artificial neural networks (ANNs) in estimating soil saturated hydraulic conductivity from measured particle size distribution, bulk density, topographic attributes, normalized difference vegetation index (NDVI), soil organic carbon (SOC), and CaCo3 in topsoil and subsoil horizon. Three neural networks structures were used and compared with conventional multiple linear regression analysis. The performances of the models were evaluated using spearman’s correlation coefficient (r) based on the observed and the estimated values and normalized mean square error (NMSE). Topographic and vegetation attributes were found to be the most sensitive variables to estimate soil saturated hydraulic conductivity in the rangeland of central Zagros. Improvements were achieved with neural network (r=0.87) models compared with the conventional multiple linear regression (MLR) model (r=0.69).
H. R. Eshghizadeh, M. Kafi, A. Nezami, A. H. Khoshgoftarmanesh, M. Karami,
Volume 19, Issue 73 (11-2015)
Abstract
This study was conducted to determine some mineral content concentrations in soils and plants of three elevation classes (1500, 2200 and 3000m) and two phenological stages of flowering and seedling in north facing slopes of Sabalan rangelands. Soil samples from the depth of 20cm and plant samples using 1×1m plots with 10 replications were collected. After sample preparation, the concentrations of minerals such as calcium, phosphorous, sodium, potassium, ion, copper, zinc and magnesium were determined using spectrophotometer and flame photometer. Data was analyzed by SAS9.1 software using a Completely Randomized Design with a Generalized Linear Model procedure. Results showed that elevation had a significant effect on Ca, Fe, Cu, Zn and Mn of soil and P, Na, K, Mg and Mn of plants in the study areas (P&le0.05). Growing stages had a significant effect on all elements of plants except Ca (P&le0.05). Moreover, results showed that in three elevation classes the high demand minerals' concentrations were higher at the starting seedling stage in comparison with the flowering stage. In contrast, the low demand minerals' concentrations in three elevation sites were higher in the flowering stage in comparison with seedling stage. Interaction effect of elevation and growing stage was also significant in relation to all elements except Ca (P&le0.05).
R. Valizadeh Yonjalli, F. Mirzaei Aghjehgheshlagh, A. Ghorbani,
Volume 19, Issue 73 (11-2015)
Abstract
This study was conducted to determine some mineral content concentration in soil and plant of three elevation classes (1500, 2200 and 3000m) and two phenological stages of flowering and seedling start in north-facing slopes of Sabalan rangelands. Soil samples from the depth of 20cm and plant samples using 1×1m plots with 10 replications were collected. After sample preparation, the concentrations of minerals such as calcium, phosphorous, sodium, potassium, ion, copper, zinc and magnesium were determined using spectrophotometer and flame photometer. Data was analyzed by SAS9.1 software using Completely Randomized Design with a Generalized Linear Model procedure. Results showed that elevation had a significant effect on Ca, Fe, Cu, Zn and Mn of soil and P, Na, K, Mg and Mn of plants in the study areas (P&le0.05). Growing stages had a significant effect on all elements of plants except Ca (P&le0.05). Moreover, results showed that in three elevation classes the high demand minerals’ concentration was higher at the starting seedling stage in comparison with the flowering stage. In contrast, the low demand minerals’ concentration in three elevation sites was higher in the flowering stage in comparison with seedling stage. Interaction effect of elevation and growing stage was also significant in relation to all elements except Ca (P&le0.05).
A. Shabani, A. Jahanbazi, S. H. Ahmadi, M. M. Moghimi, M. Bahrami,
Volume 22, Issue 1 (6-2018)
Abstract
In this study, five infiltration models including Kostiakov, Kostiakov-Lewis, Philip, Soil Conservation Service (SCS) and Horton were fitted to the experimental data using the double rings, and the empirical coefficients of these models were determined. Infiltration experiments were conducted in the gravelly sandy loam soil under and between the olive and orange trees in Fasa city, Fars Province, Iran. The results showed that all five models were fitted accurately to the measured data. The accumulated infiltration under the trees was higher than those measured between two trees. Higher infiltration under the tree canopies was probably due to the higher soil organic matter, the lower soil bulk density, and the tree root channeling, which were more pronounced when compared to the small pores in these soils. Despite the positive effect of sand particles on soil infiltration, the big gravel occurrence in soil would decrease the cross section area of water flow path, thereby reducing the infiltration. Therefore, changing the land use and planting olive and orange trees in the gravel soils would increase the infiltration rate and consequently, decrease runoff and erosion rates in such soils.
S. Parvini, Z. Jafarian, A. Kavian,
Volume 22, Issue 2 (9-2018)
Abstract
Due to the lack of necessary equipment for measuring and recording changes in watershed runoff and flood situation after the implementation of corrective actions, using hydrologic models is considered as an efficient tool to assess the undertaken actions and simulate the behavior of the watershed before and after the implementation of these measures. The present study aimed to simulate the effects of corrective actions on runoff components using HEC- HMS hydrological models in the form of a rangeland and watershed plan in 2006 and the predicting plan of applicable operations in a region in the Meikhoran watershed, Kermanshah. For this purpose, three scenarios including the conditions before running the rangeland and watershed plan, the conditions after running the project and requirements and enforcement actions resulting from the proposed location map were considered in the spring of 2006. First, a map of the curve number (CN) changes was prepared under all three scenarios caused by the vegetation changes and by implementing HEC-HMS model, the curve number criteria, the peak discharge and flood volume were determined to assess the changes in hydrological basins and their values for all three scenarios were calculated and compared. The results showed that the HEC- HMS model for the base period (first scenario) with Nash-Sutcliffe coefficient 0/551 and the coefficient of determination 0/63 had an acceptable accuracy in predicting runoff. Nash-Sutcliffe coefficient for the second and third scenarios was 766/0 and 0/777, respectively. Also, the results showed that in the second scenario, there was an 8/85 and 7/74% decrease in the peak flows and runoff volumes, respectively, and these values for the proposed operation were estimated to be 12.84% and 6.33%, respectively. Overall, the results indicated the considerable impact of rangelands and watershed management (third scenario) on the reduction of effective runoff components, particularly flood peak, on the basis of the location model.
V. Shahrokh, H. Khademi, H. Shariatmadari,
Volume 23, Issue 2 (9-2019)
Abstract
Despite the great importance of potassium applied as a fertilizer in the orange orchards, no information is currently available regarding the rate of potassium release from rhizosphere and the bulk soils of such trees. The objectives of this study were to investigate the weathering of micaceous minerals and their non-exchangeable K release and also, to examine the status of different forms of K in the rhizosphere and bulk soils of orange orchards with different ages in Darab, Fars Province. Samples were, accordingly, taken from the rhizosphere and bulk soils of orange orchards with the ages of 5, 10 and 20 years; also, virgin soils (control) were obtained from three soil depths including 0–30, 30–60, and 60–100 cm. Water soluble, exchangeable and nonexchangeable K, and the clay mineralogy of the soils were determined. The results demonstrated that the concentration of soluble and exchangeable K in the cultivated soils was less than that in the control soil and that the concentration of nonexchangeable K in the soils of 20-year-old orchards was less, than that in other soils. Soluble and exchangeable K values decreased with depth in all soils. Clay mineralogy investigation also showed that the quantity of illite decreased and that of smectite and illite-smectite increased as the age of orange trees was raised. With increasing the age of orange trees and root development, more potassium could be taken up from soil and more changes occurred in the soil minerals. In order to avoid a very high decline in the reserved K in the soils under orange trees, particularly in the orchards with older trees, K fertilization has to be taken more seriously based on the soil testing results.
A. Ghorbani, E. Hassanzadeh Kuhsareh2, M. Moameri, K. Hashemi Majd, A. Pournemati,
Volume 23, Issue 3 (12-2019)
Abstract
In this study, the effect of some soil parameters on the life forms and total aboveground net primary production (ANPP) in meadow rangelands in Fandoghlou region of Namin county in Ardabil Province were investigated. ANPP in 180 plots of 12 by harvesting and weighting method were measured. Eighteen soil samples were collected along transects. Some physical and chemical attributes of the soil were measured by standard methods. The relationship between these parameters and ANPP was performed using multivariate regression (enter) method. To determine the effects of important soil parameters on ANPP variation, principal component analysis (PCA) was used. The results of regression analysis showed that electrical conductivity (EC), magnesium (Mg), spreadable clay (WDC), volumetric moisture content (VM), organic carbon (OC), soluble potassium (KS), exchangeable potassium (Kexch), sodium (Na) and phosphorus (P) were the effective parameters on the life forms and total ANPP (p<0.01). The accuracy of obtained equations for grasses, forbs and total ANPP were calculated 79, 76 and 70%, respectively. Moreover, results of PCA showed that soil parameters justify 84.52 percent of total ANPP variation and in comparison, with regression results with 28% it provides better results.
S. Najmi, M. Navabian, M. Esmaeili Varaki,
Volume 27, Issue 3 (12-2023)
Abstract
The increasing need for water resources and controlling the discharge of wastewater into the environment shows the necessity of wastewater treatment. Green methods such as constructed wetlands and phytoremediation use biological processes in the environment for wastewater treatment. Considering the effect of cultivated constructed wetland performance from wastewater quality and climatic factors, the objective of this study was to evaluate the performance of hybrid and subsurface vertical and horizontal wetlands to improve the biological and chemical oxygen demand of the wastewater treatment plant in Rasht City. The effect of Phragmites australis and Typha latifolia plants on the treatment performance was investigated. Wastewater retention time in wetlands varies from monthly in winter and weekly in spring and summer. The results showed that the performance of wetlands in reducing biological oxygen demand (BOD) was more than chemical oxygen demand (COD). Plants improved the performance of the wetland by more than 50%, but no significant difference was observed between the performances of the two plants. The arrangement of the plant's cultivation was not effective in the amount of biological and chemical oxygen removal. The hybrid wetland was able to improve the wastewater quality twice as much as the vertical wetland. Comparing the concentration of the effluents from the wetlands with the standards showed that the effluents from the hybrid wetlands could only be used for agricultural consumption.
B. Attaeian, F. Teymorie Niakan, B. Fattahi, V. Zandieh,
Volume 28, Issue 3 (10-2024)
Abstract
The objective of this study was to investigate the effect of wildfire in the rangelands of the Gonbad region of Hamedan on soil organic carbon storage in two control and fire areas after three years of fire, and the feasibility of using remote sensing in indirect estimation of soil carbon. Therefore, 20 soil surface (0-10cm depth) samples were collected from the burned area and 20 samples from the control area (40 samples in total) by the systematically random method after three years of fire time. Changes in organic carbon, total nitrogen, acidity, and salinity of surface soil were tested by independent t-test between control and fire areas. Then, to investigate the linear relationship between the storage of soil organic carbon with other parameters, the Pearson correlation was used in SPSS v. 26. The results of the independent t-test showed that there was no significant difference in EC, acidity, and soil organic carbon of the control and fire areas, but the amount of total soil nitrogen showed significantly different. The results showed a significant positive correlation was observed between soil organic carbon and total nitrogen at the level of one-hundredth of 0.830 (p< 0.01) in the fire area, and the BI index showed a significant negative correlation of 0.727 (p< 0.05). In the control area, a significant positive relationship was observed between organic carbon and total nitrogen at the rate of 0.627 (p <0.05). The results of processing Landsat 8 images (OLI-TIRS sensor) in the fire area showed that there was a statistically significant relationship between soil organic carbon and light and wetness index obtained from tasseled cap (-0.726 and 0.674, respectively) and PC1 component obtained from principal component analysis and -0.724 (p <.05). These results indicate that it is possible to use tasseled cap images to predict soil organic carbon in fire areas.
A. Keshavarz, R. Modarres, S.a.r. Gohari,
Volume 28, Issue 4 (12-2024)
Abstract
This study was conducted to present rangeland bioclimatic zoning for Iran based on the changes in the power spectrum of the average monthly Net Primary Production (NPP) of the rangelands of Iran. Fluctuations of the mean monthly power spectrum of the NPP signal of rangelands of Iran from 2000 to 2022 were analyzed using the Power Spectrum Density (PSD) method in the frequency band between 0-100 Hz. In 24 bioclimatic subzones, there are four common periods in all sites at frequencies of 0 (no change is repeated), 8.34 (3.59 days), 16.66 (1.80 days), and 25 (1.2 days) Hz observed, which shows that the major data changes occur in those periods and that the NPP changes of Iranian rangeland are more influenced by global and regional effects than local effects. The maximum power of these spectra is concentrated in high time scales. Therefore, cycles with lower frequency (higher time scale) are more important than cycles with higher frequency (shorter time scale) and show that the changes of NPP in Iranian rangelands have long-duration cycles under climate fluctuations. In the present research, Iran was classified into 5+1 rangeland bioclimatic zones using the results of the monthly mean power spectrum of the NPP signal of rangelands, the Wards clustering method, and the Euclidean square distance. It seems that this method provides a proper match between biological boundaries and climate. Pearson correlation coefficient was used to investigate the coherence of rangeland bioclimatic regions within each homogeneous group. Correlation results showed a significant spectral density similarity within groups at the significance level of 0.01% between rangeland bioclimatic regions, especially in the second and fifth clusters.
