محمدجواد روستا

Flood spreading is one of the most important soil protection and improvement measures, which both prevent flood waste and help fight desertification. This research aimed to investigate the effect of flood spreading and plant type on the activity of some physicochemical and biological properties of the soil in pasture fields with and without flood spreading in the Garbayegan, Fasa in 2019-2020. Soil sampling was carried out in spring and autumn to a depth of 20 cm in three repetitions around the rhizosphere of plants and modified according to the materials and methods section. The averages were compared with Duncan's test at the level of 1.5% and using R software. The results showed that the amount of usable phosphorus and potassium in the flood spreading conditions and the control area was without significant difference, but the amount of carbon and nitrogen in all the studied species in the flood spreading area was significantly different. It was more significant than the witness was. However, the amount of respiration in the flood spreading area was the highest, while the respiration and microbial biomass in the control area showed the highest amount. However, the amount of basal heat and microbial biomass in flood spreading areas showed a lower amount, which can be the result of the low amount of organic matter in the soil as a result of excessive livestock grazing in these areas. Finally, it is recommended to implement flood-spreading projects in arid and semi-arid areas to increase the productivity of soil characteristics.

Introduction and Goal:

In recent years, the use of flood spreading systems is one of the most effective ways to control surface water, especially in arid and semi-arid regions which In addition to the reduction of the harmful effects of floods, it results in the reduction of soil erosion, the strengthening ground water tables, the improvement of agricultural lands and the rehabilitation of rangelands vegetation. In flooded rangelands, there is little information about the characteristics of the soil seed bank. This, in turn, has cost and wasted a lot of time. The presence of many species in the seed bank can explain the effects of environmental and management factors in the past. Identification of this resource plays an important role in the protection and restoration of vegetation. In this regard, the aim of the current study is to assess the biological diversity indicators of the existing seed bank due to flood spreading in order to restore and improve the vegetation cover in such rangelands.

In order to investigate the effects of flood spreading on the composition, density, diversity, richness and evenness species of the soil seed bank in two areas with flood spread and without flood spread (Control) in Gareh Bygone Fasa region, seed bank research was carried out for three years from 2020. In June 2020, was done after the preliminary identification of the rangelands of the flood spreading area, the location of two representative areas inside and outside the flood spreading area (Control). Sampling of the soil seed bank in the fall of 2020, before the seeds in the soil began to grow. Inside the representative area (rangeland flooded in 6 strips) and Control (rangeland without flooding), 1 transect of 150 meters was established in the direction perpendicular to the slope of the land. At 10-m intervals along each transect, a 1-m2 plot was randomly selected (total of 15 plots or repetitions). A pit with a diameter of 7 cm and a depth of 0 to 5 and 5 to 10 cm was dug in the four corners and center of each plot. Soils of each depth were combined separately in five points of one square meter plot and considered as a sample for planting in special trays in the greenhouse. The soil seed bank samples were kept in the refrigerator for four months to break the seed dormancy and then transferred to the greenhouse environment for one year for cultivation and by the seedling emergence method, the seeds in the soil which gradually they turned green, were identified and counted.Analyzes related to the seed bank were performed based on the number of germinated seedlings and counted in the greenhouse. The density of species in the soil seed bank was calculated by calculating the total number of seeds of all species per square meter. The diversity, richness and evenness of species were assessed using PAST software. For species richness of the soil seed bank, Margalef and Menhinic indices were used, Shannon-Wiener and Simpson indices were used for diversity, and Hill index was used for evenness. To compare the properties of the soil seed bank (density, richness, diversity and evenness of species) was also used between two representative areas of flooded rangeland and non-flooded rangeland (control) independent t-test and paired t-test were also used to compare between two depths of 0-5 and 5-10 cm. The analysis was conducted via R software, employing one-way analysis of variance and Duncan's method for comparison of means.

The results of the greenhouse studies showed that a total of 5340 seeds germinated in the greenhouse, 3756 seeds germinated in the flood spreading area at a depth of 0-5 cm and 1190 seeds germinated at a depth of 5-10 cm. In the area without flooding (control), 329 seeds grew at a depth of 0-5 cm and 65 seeds grew at a depth of 5-10 cm. In the flood spreading area of Aquifer Management Kowsar Station, in terms of the average density of the seed bank, at a depth of 0-5 cm, a total of 113 seeds per square meter (from 18 plant families and 61 species) sprouted. At a depth of 5-10 cm, a total of 36 seeds per square meter (from 18 plant families and 56 species) germinated. In the control area, in terms of the average seed bank density, at a depth of 0-5 cm, the average of 9.96 seeds per square meter (from 10 plant families and 23 species) germinated. At a depth of 5-10 cm, the average of 1.96 seeds per square meter (from 8 plant families and 15 species) germinated. The average density of sprouted seeds in the soil depth of 0-5 cm was 3.14 times higher than that in the soil depth of 5-10 cm. In the control area, the average density of germinated seeds in the soil depth of 0-5 cm was 5.08 times higher than that of the soil depth of 5-10 cm. The results of variance analysis showed that in terms of biodiversity indices (density, number of species, diversity, and richness species evenness) between the strips of Bisheh Zard 1 and control flood spreading network at the depth of 0-5 and 5-10 cm of the bank, there is a significant difference between soil seeds at the level of 1% and 5%. The results of the t-test showed that in terms of biodiversity indices between the depths of 0-5 and 5-10 cm of the soil seed bank both in the flood spreading area and in the non-flooding area (control) there is a significant difference in there are 1% and 5% levels.

Conclusion and Suggestions:

In general, it can be concluded that the implementation of flood spreading operations in the studied area has created a special ecosystem that has improved the environmental conditions such as sufficient humidity and suitable organic matter in the area. Also, it has a significant effect on increasing the density and diversity, richness and evenness of the soil seed bank species, as well as the species composition. Therefore, the potential of the existing seed bank can be used to rehabilitation this area and similar areas. In general, the results of this research showed that the soil seed bank of this region had a positive response to the implementation of the flood spreading operation, so that the highest density, diversity, richness and evenness of the soil seed stock was observed in the flood spreading area. It is suggested to carry out projects on the effects of flood spreading on biodiversity indices in forestry plots with different species of Eucalyptus, Acacia, as well as shrub planting plots with Atriplex species, as well as a control plot be compared in Gareh Bygone, Fasa. This research's findings can be used in preserving plant diversity, preserving genetic reserves, and revitalizing and managing vegetation in the region.

The rangeland ecosystems of arid and semi-arid regions play the most important role in the distribution and density of vegetation in these areas due to the specific environmental conditions governing the soil, which is the bridge between living and non-living parts of ecosystems. Soil enzymes play important biochemical roles in the decomposition of organic matter at all stages in the soil system. These enzymes play an important role in the stability of the soil structure, the decomposition and formation of organic matter, the cycle of elements and the activity of soil microorganisms. Environmental stresses, such as drought, have negative impact on plant growth and soil microorganism's activity. Therefore, evaluating the effect of flood spreading on soil quality indicators can be a useful step in improving knowledge in this field. Therefore, this research was conducted during 2018 and 2019 to investigate the effect of flood spreading, plant types and characteristics on biological soil in the Kowsar floodplains located in Gareh-Bygone, Fasa.

Sampling of the soil around the roots of Artemisia sieberi Besser, Dendrostellera lessertii (Wikstr) Van Tiegh. and Heliantemum lippii (L) Pers, in two situations: with flood spreading and without flood spreading (control area) in spring and autumn from a depth of 0-20 cm and in three repetitions. After ensuring the normality and homogeneity of the variance of the data by the Shapiro–Wilk and Levene tests, the data were analyzed using the two-way variance method and mean comparison were made using Duncan's test at the 1% and 5% level and using the R software.

The results of soil fertility characteristics showed that there was no significant difference in the amount of phosphorus and potassium in the three pasture species studied under flood spreading and the control areas. However, the amount of carbon and nitrogen in all studied species was significantly higher in the flood spreading area (containing 0.3% organic matter) than the control area (with 0.15% organic matter). In addition, the results of this research indicated that the highest activity of acid phosphatase enzyme was observed in the rhizosphere of D. lessertii species and in the spring season, and on the contrary the lowest activity was observed in the rhizosphere of H. lippii species under the flood spreading condition. Alkaline phosphatase activity in all species was significantly higher in spring than in autumn season. The highest activity of this enzyme was observed for A. sieberi in the spring season with an average of 186 (µg p-nitrophenol g-1 soil h-1) in the flood spreading area and the lowest level was observed for H. lippii in the control area with an average of 57 (µg p-nitrophenol g-1 soil h-1) in the autumn season. In general, the level of phosphatase enzyme activity for the A. sieberi species in the spring season was approximately 89% higher in the flood spreading area than in the control area. The dehydrogenase enzyme activity was higher in spring than in autumn. Also, the highest activity of this enzyme was observed in the spring season for the D. lessertii  species with an average of 8.5 (µg TPFg-1 soil 24 h-1 ) in the control area, and the lowest level was observed in the autumn season for the A. sieberi species in the flood spreading area with an average amount of triphenol formazan was 1 (µg TPFg-1 soil 24 h-1 ) .In other words, the amount of dehydrogenase enzyme activity in the spring season was approximately 66% higher than that in the fall season in both areas (control and flood spreading). The results of this research showed that the activity of urease enzyme under flood spreading conditions in both seasons (autumn and spring), with an average of 270 and 300 (µg N/g.dm.2h) is more than the control area with an average of 173 and 250 (µg N/g.dm.2h). Also, the soil quality indices in all three studied species in the two (control and flood spreading) areas have a significant difference, so that the flood spreading operation has upgraded the value of these indices for the H. lippii species and the A. sieberi, while which has reduced the soil quality index of D. lessertii.

The results of this research showed that the flood spreading system is a desirable method for improving soil organic carbon, and its efficiency increases with the plant planting. The increase in moisture and the amount of organic matter in the flood spreading area can be a reason for increasing the activity of enzymes in the flood spreading area, so that in both autumn and spring, the activity of soil enzymes is more in the region. Considering the important role of organic matter in improving biological indicators and soil quality and health, the restoration of floodplains with native species can play an important role in providing these conditions. In addition, it is recommended that these tests be repeated with more samples and in different areas and the nitrogen, carbon, sulfur and phosphorus cycles and its relationship with the activity of other soil enzymes related to this cycle should be investigated.

Arbuscular mycorrhizal fungi, due to their very beneficial effects in the growth and development of plants through supplying the water needed by plants, especially in drought stress conditions and increasing their tolerance to salt stress and in general, helping the plant to overcome living and non-living tensions, they are the focus of many researchers. This research was conducted during 2020-2022 with the aim of investigating the effect of flood spreading, vegetation type on the abundance and diversity of mycorrhizal fungi in Kowsar Station.

In spring and autumn, in different land covers, including planted Eucalyptus and Acacia forest, planted pasture with Atriplex bushes with 37 years old and natural pasture in two situations with flood spate irrigation and without spate irrigation. Three samples were prepared from roots less than 1 mm of trees and dominant plants (Heliantemum, Dendrostellera, and Artemisia) in the pasture and the rhizosphere soil up to a depth of 20 cm. After separating and staining the roots, their microscopic examination to determine the presence of symbiosis in the root tissue and to determine the extent of root colonization with mycorrhizal fungi and the extent of mycorrhizal symbiosis based on the extent of root contamination with structures of mycorrhiza was done. The soil passed through a 2 mm sieve was used to separate the spores, and the genus and species of mycorrhizal fungi were identified based on the morphology of the spores using identification keys and information available in scientific sources.

The results showed that the spore density of mycorrhizal fungi in both sampling seasons was higher in areas with flood spreading than areas without flood spreading. The highest spore density in the field of flood spreading in the autumn season is related to H. lippii with the number of spores 50.20 per gram of soil and the lowest with the number of spores 18.80 per gram of soil related to this species in the field without flood spreading in spring. So that the difference between the two was statistically significant with Duncan's test at the 5% level. Also, in all land uses, spore density was higher in autumn than in spring. The highest percentage of root colonization or the percentage of symbiosis was related to Acacia with 61.81% in the field without flood spreading in spring season and the lowest value was related to Eucalyptus with 12.26% in the field without flood spreading in autumn season. In this research, 21 species belonging to 9 genera Acaulospora, Claroideoglomus, Diversispora, Entrophospora, Funneliformis, Glomus, Rhizophagus, Scutellospora and Septoglomus were identified in with and without flood spreading areas. Septoglomus constrictum was the most abundant with 100.0% frequency. Glomus heterosporum and Rhizophagus aggregatum were in the second category with a frequency of 50.0% and Funneliformis mosseae, Glomus ambisporum, Glomus intraradices and Rhizophagus fasciculatus were in the third category with a frequency of 33.3%.

Considering the fact that the identification of mycorrhizal fungi in the rhizosphere of tree plants and pasture bushes in dry areas and their use can be a fundamental step to reduce the negative impact of various stresses, including drought stress, it is suggested the active and effective species of these fungi may be identified and propagated and used as inoculum (biofertilizer) to restore rangelands in these areas.

Biochemical activities of soil have been proposed as one of the most well-known indicators of soil quality and health, which are considered in evaluating the effect of afforested species on soil characteristics. This research was conducted with the aim of investigating the long-term effect of flood spreading operation and type of vegetation on the activity of acid and alkaline phosphatase, urease and dehydrogenase enzymes and soil microbial activity, including basal respiration and stimulated respiration, in 2019.

Sampling the soil around the roots of Acacia salicina Lindl., Eucalyptus camaldulensis Dehnh., Atriplex lentiformis (Torr.) Wats. (0-20 cm depth) was carried out with 6 treatments in three replications. Statistical analyzes were performed using SPSS software as a factorial test in the form of a randomized complete block design and the means were compared with Tukey test at P<0.05.

The results showed that the interaction between flood spreading and vegetation type on the activity of acid phosphatase, alkaline phosphatase, urease, dehydrogenase, stimulated respiration and organic carbon was significant at P<0.01. The activity of acid phosphatase and alkaline phosphatase enzymes in the soil under cover of Acacia and Eucalyptus plantations was higher than the activity of these enzymes in the soil under cover of Atriplex, especially in the situation with flood spreading. The activity of urease enzyme showed the highest value in the soil under the Atriplex with flood spreading and the lowest value in the soil under the Atriplex without flood spreading, and this difference is statistically significant with Tukey's level test at P<0.05. The activity of dehydrogenase enzyme showed the highest value in the soil under the Atriplex with flood spreading and the lowest value in the soil under the Atriplex without flood spreading, and this difference is statistically significant with Tukey's test at P<0.05. Dehydrogenase activity in the soil of Atriplex with flood spreading compared to the activity of this enzyme in the soil of Acacia with flood spreading and also the activity of dehydrogenase in the soil of Acacia and Eucalyptus in the situation with flood spreading, statistically with the test Tukey did not show a difference at P<0.05. In the conditions of flood spreading, the basic respiration rate in the understory soil of Acacia, Eucalyptus and Atriplex was higher than the basic respiration in the soil under the cover of these plants without flood spreading, although the difference in the basic respiration in the two situations with flood spreading and without flooding were not statistically significant at P<0.05. The amount of stimulated respiration in the soil of Atriplex with flood spreading was higher compared to the amount of stimulated respiration in the soil of Eucalyptus with flood spreading, but it was not statistically different from the amount of stimulated respiration in the soil of Acacia with flood spreading and Acacia without flood spreading. The highest and lowest amount of stimulated respiration was observed in the soil under the cover of Acacia and Eucalyptus, respectively, in the condition without flood spreading, and these differences were statistically significant at P<0.05.

Conclusion and Recommendations:

The results of this study showed that the activity of soil enzymes can potentially predict the amount of nutrient deficiency. In addition, afforestation in arid areas, improves soil quality indices. Considering the important role of organic matter in improving the biological properties, quality and health of the soil, in order to increase the amount of organic matter in the soil, rehabilitating flooded rangelands with native and compatible trees and bushes, managing grazing and increasing non-grazing periods are recommended.

Enhancing the soil organic carbon (SOC), not only sequesters the atmospheric CO2, but also often improves the processes and soil physical, chemical and biological properties. This investigation with the aim of evaluating vegetation cover and soil chemical properties on SOC was carried out in 2019 in the flood spreading fields of Kowsar station located in Gareh-Bygone Plain (Fasa, Fars Province). Flood spreading for feeding aquifers has been carried out since 1982 in an area of 2034 ha in this plain.

Land uses included Acaci (Acacia salicina Lindl), Eucalyptus (Eucalyptus camaldulensis Dehnh), Atriplex ([Atriplex lentiformis (Torr.) (Wats.)]) Plantation and natural rangeland, all of which are irrigated by flood spreading. By sampling of soils (depth 0-30 cm) in three replications in mentioned land uses, 13 characteristics: pH, ECe, CaCO3, SOC, TN, C/N, P, K, Na, Ca, Mg, Ca+Mg, SAR were measured and determined. After confirming the normality of the data by Kolmogorov-Smirnov test, the obtained data were analyzed in a randomized complete block design (RCBD) and the means were compared with Tukey test at p<0.05.

The analysis of variance showed that the effect of treatment (vegetation cover) on the all studied variables, except SAR was significant at p<0.01 and p<0.05.  Stepwise regression method was used to present the model. The results showed that C/N, TN, and ECe affect the amount of SOC and explain 99.7% of the changes in SOC. According to the standardized coefficients in the regression equation, for each unit increase of C/N ratio, the value of 0.939 units and for each unit of TN, the value of 0.338 units and with the increase of each EC unit, the value of 0.109 units is added to the SOC.

In general, recognizing the factors affecting the organic carbon storage in the soil, can provide appropriate management strategies to increase the organic carbon content and develop carbon storage capacity in the soil, improve soil fertility and mitigate the negative effects of climate change to a great extent.

Land use change is a major factor in changes in soil organic carbon and nitrogen storage and the global carbon cycle. The aim of this study was to investigate the changes in soil organic carbon and nitrogen storage after afforestation and rangeland cultivation along with flood spreading.

This investigation was carried out on the sandy lands of Gareh-Bygone Plain of Fasa located at southeastern of Fars province. A total of 45 soil composite samples were collected from Acacia, Eucalyptus, Atriplex and Planted Range from a depth of 0-30 cm in two conditions with and without flood spreading. The organic carbon and the total nitrogen content were measured in laboratory. Then, the amount of carbon and nitrogen storage was calculated and their economic value was determined by carbon tax method. The data were analyzed using SAS software as a factorial experiment in a completely randomized block design and the means were compared with Duncan's test at p<0.05.

The results showed that the effect of flood spreading on the percentage of organic carbon and the amount of organic carbon storage in the soil was significant at the p<0.01, not significant on the percentage of the total nitrogen, but its effect on the amount of nitrogen storage at the p<0.05 was significant. The effect of land use (vegetation type) on all these indices were significant at the p<0.01. The interaction effect of flood spreading and land use on the percentage of organic carbon and soil nitrogen storage at the p<0.01 was significant, but its effect on the amount of carbon storage and the percentage of total nitrogen was not significant. The amount of organic carbon storage in the soils of Acacia, Eucalyptus, Atriplex and Range, from 10.23, 22.49, 12.3 and 6.21 Mg/ha in conditions without flood spreading, respectively, increased to 23.14, 40.23, 24.12 and 13.96 Mg/ha in flood spreading conditions. The spread of floods on these land uses increased the economic value of carbon and nitrogen storage equal to 53.59, 48.00, 75.46 and 43.52 percent, respectively.

On average, flood spreading increased the economic value of total carbon and nitrogen storage in the soil equal to 54.31%.

Soil properties and land use affect the soil carbon content and reduce the adverse effects of climate change. This study aims to assess the effect of some physical properties of soil and land use on the amount of soil organic carbon content (SOC) and model development to estimate the amount of SOC. This investigation was carried out in 2020 in the areas of flood spreading in of Fasa (Kowsar station). Land uses included acacia (Acacia salicina Lindl.), eucalyptus (Eucalyptus camaldulensis Dehnh.), atriplex (Atriplex lentiformis (Torr.) Wats.) plantation, and natural rangeland, all of which are irrigated by flood spreading. By sampling in three replications of the soil of different land uses from the depth of 0-30 cm (15 composite samples), percentage of sand, silt, clay, silt+clay, percentage of soil saturation moisture (SP), bulk density (BD), particle density (PD), porosity percentage (PS), void ratio (VR) and SOC were determined. Obtained data were statistically analyzed in a complete randomized design and the means were compared with the Duncan test at P<0.05. The analysis of variance showed that the effect of land use (PT) on the percentage of sand, silt, silt + clay, SP, BD, PS, VR, and SOC has been significant at P<0.01, and the clay, at P<0.05. Comparison of the means of SOC in different land uses showed that the Eucalyptus forest, with 1.68%, has the highest value and the control with 0.14% organic carbon has the lowest value. There was no statistically significant difference between the SOC in Acacia forest, Atriplex, and rangeland. Stepwise regression analysis was used to present the model. Soil physical properties and land use were considered as independent variables and SOC was considered as a dependent variable. The results showed that the variable of silt explains 77.00% of the changes in organic carbon. Based on the principal component analysis (PCA) method, according to the specific values, considering the first two axes, about 91.70% of the changes can be explained. Considering the first axis, 69.71% and considering the second axis, 21.99% of the changes are justifiable. The PT, with 91.40%, sand with 84.30%, BD, 82.70%, showed a negative correlation with SOC. While the SP had 90.30%, percentage of clay+silt had 84.80%, PS, 80.70%, VR, 79.10%, silt, 78.50%, clay, 78.50%, had a positive correlation with SOC.

Soil in forest ecosystems is a giant source for storage of atmospheric carbon that would increase its contribution against climate warming under proper management. In the current research, soil and litter contribution in carbon sequestration were compared between a 50 years old enclosure (less degraded) and un- enclosure (degraded) wild pear stands. Besides, some soil characteristics including soil moisture, bulk density, organic carbon, total nitrogen, phosphorus, and soil microbial respiration were studied. In each stand, 5 soil samples and 10 litter samples were collected from each plot and the characteristics were compared with T-student independent analysis. The results clearly indicated that soil carbon storage and carbon storage in coarse litter due to greater tree covers in enclosure field were two times higher than un- enclos6ure. Meanwhile, carbon storage in fine litter was same in the both stands. Phousphurus content and total nitrogen in soil of enclosure field were 6 and 2 times higher than un- inclosure, respectively. Moisture content Not only was higher in less degraded field (36%) in comparison with degraded one (21%) but also soil microbial respiration in less degraded field was higher around 31% when compared with degraded field. Finally, it can be proposed that enclosure management not only can improve soil carbon storage more than two times but also can increase soil fertility. This finding highlights the importance of enclosure management in Zagros region for maintaining of soil functions.

Carbon storage by natural forests, plantation forests, pastures and soils is the best way to reduce atmospheric carbon. This study was conducted in 2018 with the aim of evaluating the effect of spate irrigation on the biomass and carbon storage in various organs of Eucalyptus camaldulensis and Acacia salicina plantation at the Kowsar station located in Gare-Bygone Plain. After truncating the trees, trunk, branches and leaves were separated. In addition, the amount of litter produced under the trees was also collected and weighed. Afterwards, the dried samples were powdered by electric milling and the carbon content in the samples including trunk, branch, leaf and litter was measured by electro-ash method. Data were analyzed using randomized complete block design and the means were compared by Tukey test at P<0.05. The results showed that leaves had the lowest amount of carbon storage and trunk had the highest amount of carbon storage. In eucalyptus stand (first strip), the highest carbon content of 187.56 t/ha was stored as living tissue including trunk, branch and leaf litter. Given that each ton of carbon equals 3.67 tons of carbon dioxide gas, it can be concluded that the amount of 688.34 tons of carbon dioxide gas in the air in different organs of the plant and in litter stored as organic matter. In acacia, however, the amount of carbon stored was 72.81 t/ha and the equivalent of stored carbon dioxide was 267.21 t/ha. The economic-environmental value of this amount of stored carbon was calculated to be $137619.05 and $5333.33 per hectare, respectively. With respect to 32 years of spreading water in these areas, each hectare of eucalyptus and acacia trees averages 21.51 and 8.35 tons of carbon dioxide gas have been stored as organic matter per year, respectively. In this respegt, the eucalyptus plantation has played a greater role in reducing air pollution. The economic value of the oxygen produced in the forests of eucalyptus and acacia ($11190.5 and $1774.28, respectively) is also adds to the economic value of reducing carbon dioxide, and their economic performance value reach to $148809.52 and $55238.10, respectively. Therefore, the development of eucalyptus afforestation toghether with spate irrigation method in similar prone areas is more economically justified and recommended from a carbon storage perspective.

Nowadays, the oak decline is the most important challenge in the Zagros forests for the last decade. Concerning the importance of soil physical, chemical, and biological properties in the forest ecosystems performance, the impacts of oak decline on soil characteristics were studied. In spring, two declined stands and two healthy stands of Brant`s oak (Quercus brantii Lindl.) with one ha area (100×100 m) in the north and south aspects were selected and then soil samples were collected systematically from 0-10 cm depth. Next, soil texture, reaction, EC, moisture content, organic carbon, nitrogen, potassium, and phosphorus content of collected soils were analyzed. Furthermore, basal soil microbial respiration, induced soil microbial respiration, and nitrification potential were measured. The results showed that pH, organic material and carbon, and nitrogen did not have any significant difference between the declined and healthy stands. On the other hand, EC (around 28-29 %), moisture (around 3-4 times), potassium (around two times), and phosphorus (around 4-5 times) content were considerably higher in the healthy stands. Furthermore, the highest induced microbial respiration were recorded in southern (2.06) and northern healthy stands (1.67) and southern decline stand (1.38 mg CO2.100g-1.dm.h-1), respectively while we did not find any reasonable trend for basal respiration. Nitrification potential did not response to oak decline occurrence. Although soil nutrient significantly declined in response to oak decline, it can be supposed that dried leaves and branches can repair deficiency of soil organic material to some extent in the declined stands but over time, as trees weaken, soil quality will decline. Finally, monitoring of soil fauna and soil enzymes can be suggested for future research.

The aim of this study was to evaluate the effect of 35 years of spate irrigation on total biomass (TB) and carbon stock (CS) of dominant species of rangeland plants in Kowsar station located in Gareh Bygone Plain, Fasa, Iran . Samples of Heliantemum lippii, Dendrostellera lessertii and Artemisia sieberi were taken from two sites, irrigated through flood spreading and without flood spreading as the control in autumn 2018. The TB and CS of the plant samples were measured. The obtained data were analyzed using randomized complete block design and the means were compared with Duncan test at P<0.05. The results showed that the effect of spate irrigation, plant species and their interactions on TB and CS was significant at P<0.01. The comparison of the means showed that the reaction of the H. lippii was very high compared to the flood spreading, so that the TB of this species increased from 671.63 to 2013.94 and its CS from 381.90 to 1106.20 Kg/ha, respectively, i.e. 2.00 and 1.90 fold. In the case of D. lessertii, the TB and CS increased 40.00 and 38.64%, respectively. A. sieberi showed a slight negative reaction to flood spreading, so that its TB decreased from 1005.25 in non-flood conditions to 780.9 99 Kg/ha with spate irrigation. The A. sieberi showed a slight negative reaction to flood spreading, so that its TB and CS decreased from 1005.25 and 547.10 in control to 780.99 and 429.30 Kg/ha in flood spreading stripes, respectively. Although, this decreases were not significant at the P<0.05. With respect to the vastness of rangelands in our country, it is possible to store large amounts of carbon dioxide present in the atmosphere (entry the international arena of carbon trade) and reduce the effects of climate change through the flood spreading.

Carbon sequestration (CS) by forests, pastures, afforested stands and soils is the most appropriate way to reduce atmospheric carbon. A combination of all these activities can help balance the global warming process by reducing the concentration of atmospheric CO2. The amount of CS and quality of carbon storage in the soil depends on the interaction between climate, soil, tree species, litter chemical composition and their management. The results of Dinakaran and Krishnayya (2008) research showed that the type of vegetation cover has a significant effect on soil carbon storage. So that the amount of carbon storage in the soil depends on the amount of carbon entering the soil through plant debris and carbon loss through decomposition. To increase carbon in the soil, management activities such as increasing the amount of carbon entering the soil by adding litter and crop residues as well as reducing the rate of decomposition of soil organic matter should be done. Decomposition rate of soil organic matter is affected by soil condition (humidity, temperature and access to oxygen), sequestration of organic matter, placement of organic matter in the soil profile and the degree of physical protection by aggregates. Evaluating the role of aquifer management in reducing via storing the atmospheric CO2, to organic carbon (O.C) is the aim of this study. The studied land uses were as follows: 1-Rangeland-without flood spreading-with grazing (control), 2- Range without grazing-without flood spreading, 3- Six rangelands stripes-with grazing-with flood spreading, 4- Rangeland-Atriplex plantation-with spreading of flood, 5- Eucalyptus control forest-without flood spreading, 6- Eucalyptus forest-first strip-with flood spreading-BisheZard 4 (BZ4), 7- Eucalyptus forest-second strip-with flood spreading-(BZ4), 8- Eucalyptus forest-third strip-with flood spreading-(BZ4), 9- Acacia forest-with flood spreading-(BZ4). Soil and plant were sampled from each land use type. Then, the amount of O.C was measured in the laboratory and CS was calculated. The economic-environmental value of carbon stored in the soil is based on Rivers' proposal, which declares a carbon tax rate of $200 per tonne of CO2. The dollar is equal to 42,000 Iranian rials. Data were analyzed using randomized complete block design and Duncan test (at p < 0.05 ) was used to compare mean values using the SAS software. The analysis of variance showed that the effect of different land uses on the bulk density (BD), %O.C and the CS in the soil was significant at the level of 1%. Comparison of the mean of BD in various land uses showed that the eucalyptus forest (third strip) had the lowest BD compared to others, and the difference between this land use and other land uses was statistically significant. The first strip of Eucalyptus forest had the highest %O.C and the highest amount of CS in the soil, and the statistical difference between these two indices in this land use with other land uses was significant. Among the studied land uses, the lowest amounts of CS were related to the control range and range without grazing-without flood spreading. The interaction of plant to plant species on plant dry weight and plant carbon storage showed that the rangeland species of Heliantemum lippii and Dendrostellera lessertii in the range with flood spreading have the highest dry-weight and the species of Helianthomus has the highest amount of carbon storage. This indicates that the impacts of flood spreading on plant biomass production and carbon storage have been greater than the impact of no grazing on these indicators. In all uses, Artemisia sieberi showed the lowest dry weight and carbon storage. Planting of Eucalyptus camaldulensis irrigated with flood water spreading increased the soil O.C from 0.51% in the control to 1.68% in the first strip of eucalyptus forest (3.29 times). By calculating the mean of the three strips in which the eucalyptus was planted, it was found that the highest carbon content of 121.84 ton/ha was stored in the plant, litter and soil of this land use. Given that, each tonne of carbon is equivalent to 3.67 tons of CO2 gas, it can be concluded that 447.15 tonnes of CO2 gas from the air is stored as organic matter. The economic-environmental value of this CS is 3.76 billion rials ($89523.81) per hectare. The studied land that was irrigated with flood spreading, especially the eucalyptus forested area at Kowsar station, captured significant amounts of CO2 from the air and stored it as organic matter in the root and shoot of plants and in the soil. Also, this may lead to the release of a large amount of oxygen gas to the environment which play an important role in reducing air pollution. Considering the economic-environmental value of the carbon stored in the eucalyptus plantation forest areas, the development of this method in flood prone areas is quite economically justifiable. Due to the high potential of tree species in improving soil carbon storage, it seems that increasing the percentage of woody species and their physiological diversity have increased the carbon storage capacity of these species. Therefore, in order to improve the carbon storage capacity of flood distribution systems, it is suggested that the planting of native and perennial compatible species in these systems should be considered.

The carbon sequestaration by plants and soil is one of the easiest and the most econimical ways to reduce atmosphere carbon. This study was conducted on the planted land use of Fraxinus rotundifolia, Cupressus arizonica, obinia pseudoacacia L., Elaeagnus angustifolia, Cedrus libani, and Quercus brantii (persica) in the Arjan plain of Fars province. For each plantation land use, there were three plots with 125 m2 area where 25 trees were planted with 2.5-meter distance. Also in the vicinity of these land uses, which were established about 50 years ago as a adaptation experiments, were a natural oak forest and a 10-year-old alfalfa farm land. In each plot, five soil samples were taken from 0–20 cm depth. Then simple soil samples from each plot were combined and a composite sample was prepared for each replicate. Totally three composite soil samples from each land use were transformed to the lab and organic carbon and total soil nitrogen were measured and carbon and nitrogen sequestration rate and their economic value were calculated. The total economic value of carbon sequestration in the soil under the cover of C. libani and Q. brantii natural forest was calculated to be $77571.43 and $69809.52, respectively. Each hectare of soil under the cover of these two species captured 387.9 and 348.6 tons of carbon dioxide, respectively. Unexpectedly, the values of carbon and nitrogen stock was higher under cedar trees, as non-native species, when compared with the other tree species. Therefore, these species can be considered as proper options for forest restoration plans. Transformation of natural forest to agriculture led to decreasing of soil carbon stock till 79.63%. According to the results of this study, it is recommended to avoid conversion of natural forest to agricultural lands and native trees like oak and non-native forest species adapted to climate conditions should be considerded to restore deforested forest lands.

Soil salinization and sodification are important factors in soil degradation, especially in arid and semi-arid regions, which, if not considered, can lead to erosion that threatens soil stability in different regions of watersheds. Effects of organic matter application on some soil physical properties under irrigation with saline waters was investigated. The experiment was conducted as factorial based on complete randomized design with three replications for a period of one year. Treatments included two levels of irrigation water salinities of 7 and 14 dS/m, two soil textures, namely sandy loam and clay loam, and four sources of organic matters, namely licorice and lemon dregs and chicken and sheep manure. Results showed that organic matter had a significant effect on moisture retention and evaporation from the soil surface (P <0.01) and reduction of soil bulk density (p < 0.05). The percent moisture content of the loamy sandy soils treated with licorice and lemon dregs and chicken and sheep manure increased by 25, 20, 15 and 15%, respectively. The lowest evaporation from the soil columns occurred in licorice treatment amounting to 39.99 cm, which was 8% lower compared to evaporation from the control treatment (43.26 cm). This decrease was statistically significant at the 5% level with the Duncan's test. The results also showed a significant effect of soil texture on soil moisture content at lower depths (P <0.01). Regarding the prominent role of licorice treatment in reducing evaporation from the surface and maintaining soil moisture, further studies are suggested on the feasibility of applying the results in soil and water conservation programs, especially on sloping lands.

Given the various advantages of applying conservation tillage methods in the agriculture, including reducing the effects of climate change by decreasing the carbon dioxide emissions to the atmosphere caused by carbon sequestration in soil, this study was conducted with two wheat-cotton and wheat-sesame rotations at Agricultural Research Station Bakhtajerd, in Darab, the southeast of Fars Province, which had a warm and dry climate; this work was carried out in a loam soil during four years. The aim of this investigation was to compare the carbon sequestration (CS) in the soil after application of different conservation tillage methods with the conventional method. The results showed that in wheat-cotton rotation, the maximum and minimum amount of CS in the 0-20 cm depth of soil with the average 17.160 and 13.810 t/ha could be obtained by using no-till and conventional tillage, respectively. Therefore, no-till increased CS by 24.26% in wheat and cotton cultivation, as compared to the conventional tillage. The economic value of this CS increment for the environment was $2459 per hectare. In the wheat-sesame rotation, the highest and lowest CS was obtained with an average of 25.850 and 12.505 t/ha in no-till and conventional tillage, respectively. Namely, direct seeding of wheat and sesame increased the CS at the 0-20 cm depth of soil by 107%, as compared to the conventional tillage with the economic value of $9809.5 per hectare. Under similar conditions, in wheat-cotton and wheat-sesame rotations, the conventional methods could be replaced by no tillage.

Gully erosion is one of the main types of water erosion and is known as one of the destroying forms of land degradation and soil loss in the world. Therefore, knowing the most effective factors on extending this type of erosion is utmost important. Beside, management and control of gully erosion require knowing the most effective factors on gullies extension. So, the present study was performed to determine the most effective factors on gullies in Khorrambid Watershed, North of Fars Province through measuring the permanent gullies during 13 years (2004-2016). Results showed that the average of gully length extension was 21.67 m throughout this period. This data indicated that the length of gully extension was 1.67 m per year. Further, it is determined that the length expansion of permanent gullies in this region was a function of bare soil and saturated electrical conductivity, using SPSS and backward multivariable regression. In conclusion, it is suggested different management solutions to increase the soil resistance against the erosion be prioritized in management and implementation plans such as increasing adoptable cover vegetation for the natural condition of the region and exclude the area to restore vegetation cover and pay more attention to control erosion in gully head cuts.

To understand the effects of forest degradation and their conversion to farmlands, the current research was conducted with emphasis on some soil biological indexes. In this regard, two different land use including an oak natural stand and a farm next to the forest and under cultivation since 20 years ago were surveyed. Within the each land use, three sampling plots with 10×10 meter dimension were randomly set and the soil was sampled form 0-10 cm depth and transformed to the laboratory. Afterwards, some biological variables such as soil basic microbial respiration, substrate induced respiration, microbial biomass carbon and microbial biomass nitrogen, metabolic quotient, carbon availability index, Cmic/Corg, urease, alkaline and acid phosphatase and dehydrogenase enzymes were measured on the sample soils. The data were statistically analyzed by independent t-test. The results indicated that all of the microbial variables in the natural forest were higher around 2-3 folds than those in farmland. Although value of Cmic/Corg in the forest land use was higher around 10% than the farmland, the values of metabolic quotient, carbon availability index were same for the both land use. On the other hand, activity of alkaline phosphatase, due to phosphate fertilizers, was higher in the alfalfa cultivated farmland. According to our results, protection of the natural oak ecosystems can maintain soil quality.

Due to soil degradation and abundant of sediment production, the exact recognition of affecting factors on gullies erosion, and the impact of various factors on gully’s formation and development, require a more accurate study. In this regard, in the present study the length of gully, the area above headcut, headcut slope, percent of closed grain, bare soil, cover vegetation, litter, saturated electrical conductivity, pH, percent of organic matter, sodium absorption ratio, and percent of clay, silt and sand were measured in 30 gullies in 2018. Factor analysis with SAS software (version 9.1) was performed to determine the factors affecting the samples classification. Backward regression method in SPSS software (version 16) was used to determine the affecting factors on extension length of gullies, considering the length of gullies as dependent variable and other measured parameters as independent variables. The results of this study showed that the saturated extract electrical conductivity, the area above headcut and the percentage of bare soil factors play the most important role on the length extension of gullies in the Ghazeian watershed, located in the north of Fars province. Therefore, it is recommended to control erosion at headcut and through establishing the adaptable and resistance canopy copy cover, reduces the uncover area and increases the roughness coefficient. Also, it is essential to have a watershed in different part (climate) of the country having gully erosion to perform accurate research on soil particles, canopy cover, type and rate of rainfall, runoff height, shear stress, flow velocity, morphological characteristics, type of slope and its cover, mechanism of creation and expansion of gullies, and the gully erosion control methods.

Gully erosion is known as one of the most important and destructive forms of land degradation, and the loss of soil throughout the world. As estimation of soil volume loss and understanding the economic costs of soil erosion are of great importance; this study has been carried out to calculate the amount of soil volume loss due to gully erosion and estimate its economic cost in Ghazeian watershed located in north of Fars province. To do so, the volume of gullies was calculated and thereafter, the mass of soil loss was determined using soil bulk density. Then, total amount of soil loss mass was determined by summation of the mass of soil loss from gullies. The results showed that an average of 201.10 m3 (263.43 ton) soil eroded and loss each year due to gullies erosion in this region, and it damaged the soil resources by an average of 7376.25 dollars (295050000 Rials) per annum. These results indicate the destructive effect of gully erosion on soil loss, and therefore, more attention is required to control this type of erosion by establishing native and consistent vegetation, increasing the roughness coefficient, diverting runoff path, and performing precise research in different regions of the country.

One of the important relations in the erosion of gullies is to study the threshold of erosion creation and expansion. In recent decade, creation of new knowledge in determination of relation between variables was led to develop prediction methods in different science and therefore, investigating the ability to use these methods in erosion and soil conservation is essential. Also, in order to control the erosion of the gully, the mechanism of gullies growth and its dimension expansion, especially increasing in gullies length, has to be carefully determine; for this purpose, the present study aimed to determine the threshold of the most effective factors on increasing the length of the gully, using the K-Means data mining algorithms and the CART decision tree in the Ghazian watershed in the north of Fars province. The results of this study, which include measuring various variables of gullies under field condition and in laboratory, and using data mining techniques, showed that increasing the length of gully in this area depended on the factors of the area above headcut, saturated extract electrical conductivity, forehead slope, canopy cover percentage, and sodium adsorption ratio. It is recommended control of erosion in the foreheads is highly important in reducing the increase in gullies length and sediment production. Also, improving the soils of this area with soil amendments and the restoration of compatible vegetation and the increase in soil organic matter should be considered as the priority of effective actions to control the increasing length of gullies.

The concept and effect of the condition of non-responsibility as one of the examples of reduced liability is lesser interest in insurance and existing laws. The ambiguity of the conditions of these terms and the referral of the condition of these terms to the particular circumstances of the insurance policy is critically criticized by the extension of the insurance contract and the superior trading power of the insurance companies, which often leads to the loss of the doctors, paramedics and other losers. Not be generally, the terms of non-liability in the insurance contract are of two legal and contractual origins. However, with some legal bases, you can cancel the condition of non-responsibility of the contractor to the main obligation of the insurer, but this ambiguity continues with the insurer's subsidiary obligations. In some cases, franchising is an example of a non-liability condition, and in other cases, franchising is a condition of limitation of liability, which in both cases should be considered as such a condition. In general, the referral of the condition of non-compliance to the private situation has allowed the abusive agent to escape the burden of compensation. For this reason, a review of existing laws and regulations seems to be necessary from this perspective.

Please cite this article as: Roosta Sekehravany MJ, Tabaie MA, Amini M, Jamali J. Review of the Non-Liability of the Insurer in Insurance Contracts under the Responsibility of Doctors and Physicians. Iran J Med Law 2019; 13(49): 65-85.

This study was conducted using a randomized complete block experimental design with five treatments and four replications in Marvdasht region, Fars province, for four years. Treatments included: 1) reduced tillage, 2) wheat and corn direct seeding, 3) corn direct seeding for four years, wheat direct seeding for the first two years and the fourth year, and conventional planting in the third year, 4) wheat direct seeding for four years, corn direct seeding for the first two years and the fourth year, and conventional planting in the third year, and 5) conventional tillage. Results showed that direct seeding and reduced tillage methods decreased fuel consumption, compared to the conventional tillage for 80% and 58%, respectively. Effective field capacity for seed bed preparation and planting increased in direct seeding and reduced tillage methods compared to the conventional tillage for 6 and 3 times, respectively. Conservation tillage methods also increased soil moisture retention (maximum of 32%) with respect to conventional tillage. However, there was no significant difference between tillage methods from the soil aggregates point of view; conservation tillage methods had more stable soil aggregates. For the first three years, wheat yield was significantly affected by the tillage methods (conventional tillage was practiced in most of these years); whereas, there was no significant difference between tillage methods for wheat yield in the fourth year of the study.

Carbon sequestration (CS) in soils is a phenomenon consistent with the principles of sustainable development. Further, it is a vital solution for reducing the atmospheric CO2 and other GHGs. To identify the role of spate irrigation (SI) of afforested plots and rangeland in CS, 36 soil samples were collected from the 0–30 cm top soil in different spate-irrigated and control treatments in November 2017. Organic carbon (OC) was measured by the standard laboratory procedures, and then converted to the sequestered soil carbon (SOC). The data were analyzed using the randomized complete block design benefitting from the SAS software. The means were compared with the Duncan test at P2; this amounts to 4.6 tons of CO2 per year on average.The total income from the carbon rent of the dense Eucalyptus camaldulensis Dehnh. aforested plots at the Kowsar Station is $32381.00 per hectare with an annual mean of $925.17 per hectare.