نشریه تخریب و احیاء اراضی طبیعی
پیاپی 4 (پاییز و زمستان 1400)

Today, soil erosion has become one of the most severe problems in the world, especially in arid and semi-arid regions, affecting environmental, agricultural, and food security. The growth and development of human activities, land-use change, and resource degradation are among the factors affecting erosion intensity. However, preventive approaches based on soil erosion risk assessment have received less attention to taking proper management measures. Due to the importance of preventive measures and soil erosion control, this study was conducted in the costal Sourak Watershed in Hormozgan Province using the ICONA model to investigate erosion risk and identify erosion-sensitive areas.

The information input layers of steepness, rock surfaces and land- use are overlapped for the employ of this model in the study watershed. Soil erodibility risk map was also developed using complying soil erodibility and soil conservation maps.

The results, besides prioritizing sub-watersheds, portrayed the erosion risk at different levels of very low, low, moderate, high, and very high with relative area extension of less than one percent, 31.08, 23.28, 12.01, and 28.67%, respectively.

The findings of the current research, in addition to confirming the ability of the applied model to estimate the risk of soil erosion in the study watershed, emphasized the possibility of using the erosion risk map as a suitable tool for managers and executive experts in the effective management of water and soil in the region.

Dracocephalum lindbergii is one of the native medicinal plants in Lamiaceae family of Iran and it is growing natural habitats in the north east of Iran. In order, this plant know ecological characteristic for introduce and artificial revegetation on dryland farming and then use in medical industries. Such as this plant natural sites were controlled of destroying. This study was executed in rangeland and dryland artificial revegetation from 2018 to 2021 in Bojnourd. 

In the range site, the studies were climatically (precipitation, temperature, climate) characteristic and vegetable variation including plant height, length and wide of diameter, density, Canopy cover percentage and Estimating biomass, physical and chemical analyses of the soil. In order to artificial revegetation the medicinal species of Dracocephalum lindbergii, a special dryland was selected at an altitude of 1500 meters above sea level on the northern slope in Godali Salakh area. Planting was done by two methods of plant division and transplanting. Statistical analysis of the obtained data was performed using independent t-test and principal component analysis.

The results revealed that this species could be adapted for regions with semiarid- cold climate, annual rainfall average of 295 mm and annual temperature average of 11.28 c°. This species has dispersed in north, south, east and west slope and altitude 1200- 1900 m of sea level in rocky areas. The soil of area is calcareous with sandy-loom texture. Principal component analysis (PCA) showed that the variables of sand, silt, lime percentage, organic matter and cation exchange capacity had significant correlations with the first axis and explained the 37.2% variation. In the site and dryland artificial revegetation, Average of canopy covers and production were 0.147, 57.68% and 2.83, 1619.68 kg in hectare respectively.

The present survey findings can property a suitable management approach for farmer, planners and policymakers to make a sound decision regarding the soil and plant protects in similar areas.

Some soil properties are spatiotemporally variable. The proper handling of soil as a source of food, improving factor for climate changes and the environment, as well as for the production of fossil fuels, is definitely essential. The spatial and temporal variations of different parameters affect the formation of soil and its characteristics. The high expenses of soil sampling operation and the inaccessibility of some parts, make the use of indirect methods for the prediction of soil properties including texture unavoidable. It is essential to use and establish methods, which minimize the time and expenses of sampling and analysis for soil texture mapping. Geostatistics can suitably investigate and predict soil properties such as texture in a large scale, by reducing time and expenses. Investigating the spatial variability of soil texture under different land uses is helpful for the determination and stimulation of soil ecosystem properties subjected to the different climate and environmental variation. The spatial variability of soil texture is a function of physical parameters and land uses, and accordingly, using suitable techniques for investigating the spatial variability of soil texture is essential. For this purpose, the IPMs and ANNs consisting of Simple-Kriging, Co-Kiriging, IDW and MLPs were used to study the spatial variability of textural components of the eastern Mazandaran.

In the present research, the study of the spatial variability of soil texture affected by different land uses and elevation at inaccessible places, was done by kriging, co-kriging, inverse distance weights (IDW) and also artificial neural network (ANN). Compound soil samples (249) were randomly collected from the 0-15 depth. The precision of each method was determined using mean error (ME) and residual mean square error (RMSE). The data of each parameter were log converted and plotted using the method of normal box-cox and variograms. The comparison of means affected by different land uses including farming, orchard, forest, rangeland and uncultivated as well the elevation was conducted by Statistixs 9. The study area consisted of different elevations including -20-0, 0-100, 100-500, and > 500 m. The variograms were plotted by spherical, Gaussian, exponential and linear models, and the amounts of semiovariograms were calculated in the GS+ software, and the soil map was plotted by Arc GIS software.

The normalization of data, which indicates the distribution of soil texture, was done by the Kolmogorov-Smirnov test. The coefficient of variation of silt particles, which is affected by soil, fertilization and drainage activities was less than 50% indicating the rate of variation is not high in the study area. Accordingly, the exponential model was selected as the best fitted one for the prediction of soil texture affected by the experimental treatments. Although the amounts of clay were not significantly affected by different land uses, the amounts of sand and silt were significantly different as the amount of sand was the highest by rangeland, forest, farming, uncultivated and orchard, respectively, and the highest amount of silt was related to the orchard, farming, forest, uncultivated and rangeland. Similar research has also indicated that the change of land use from forest to farming, increases sand and decreases silt, which is due to soil erosion. In addition to different land uses, elevation (-20 - > 500 m) also significantly affected soil texture. The highest rate of sand, was related to the -20-0 m elevation. The highest and the least rate of clay was resulted by the 100-500 and > 500 m elevations, respectively, which is due to the leaching and erosion of clay particles from the higher elevation, resulting in the higher rate of sand in higher elevations, and higher rate of clay in the less elevated areas. 

Conclusions:

 Among the most important objectives of the present research was to investigate the possibility of predicting soil texture with an acceptable accuracy by kriging, co-kriging, inverse distance weighting and artificial neural network. According to the results, ANNs was the most suitable method for predicting soil texture affected by different land uses and elevation. It is suggested to: 1) examine the tested methods in other places, 2) other artificial methods be also tested for predicting soil texture, 3) if possible, a regular sampling be done in such types of research areas, and 4) the prepared mapping be used as a base for investigating the spatial and temporal variability of soil texture.

Rangeland management is more difficult than other areas because the management of these areas includes integration and management of forage production, livestock production and forage utilization at one time and one place. Therefore, it is important to consider the various dimensions of the stakeholder groups in the management and long term planning of rangelands. This research was conducted with the aim of investigate the attitude of stakeholders towards rangeland apportion in three provinces of Lorestan, Markazi and Semnan. This included apportioning between and within utilization units and determining the boundaries of rangeland using common parlance, law, or both.

In order to collect data, levels were first considered for each of the variables. Then the data were collected using a a standardized questionnaire and analyzed using the chi-square test in SPSS software.

From the results of the frequency of the variables, it was found that from the point of view of the most of the respondents, the apportion between the utilization units has been done; While the apportion within the utilization units has not been done. In addition, in Lorestan and Central provinces, 68.90% and 68.35% of stakeholders, respectively, gave more importance to the legal in determining the boundaries of rangelands. But in Semnan province, 40.67% of the stakeholders have given more importance to custom. Also, the result showed that most stakeholders were satisfied with the apportion of utilization units between and within units. In Lorestan province there was a significant relationship between the job variable (P <0.01) and invasion to rangelands (P <0.05) with satisfaction with the apportion between utilization units, invasion to rangelands (P <0.05) with satisfaction with apportion of utilization units and education (P <0.05) and tendency to leave the job in custom or legal way in determining rangeland boundaries. Also in Markazi province, there was a statistically significant relationship between the variable of nomadic cooperative company (P <0.05) with the apportion between utilization units and in Semnan province between the variable of rangeland condition and the variable of apportion within utilization units (P <0.05).

According to the findings of this research, from the point of view of the stakeholders, the apportion utilization units is a problem in Iran, but in other countries, the apportion utilization units has not been a problem.Therefore, it is necessary to solve this problem based on local knowledge of the region. Because this leads to making unbiased decisions based on scientific and objective information. In addition, rangeland protection policies and measures can be improved based on the attitude of the stakeholders. In general, investigating the attitude of the stakeholders, in addition to providing important insights about the observations, understanding and interpretation of the social effects and ecological results of the destruction of rangelands, guarantees the support of the stakeholders in the long term.

There were relationships and interactions between plant species and environmental factors. Because there are many effecting environmental factors in natural ecosystems such as rangeland, it is necessary to determine the most important of them to save on cost and time in the management and rehabilitation programs.  To achieve these relationships, there are several methods such as statistical methods including regression and ordination to use. The object of this research is to use logistical regression in the dry Sorkhdeh Rangelands in the Semnan provinces for determination most important soil, topography and climate factors.

The area was divided into 23 homogenous units based on slop, aspect, height and geology, and 10 plots 1m2 were established in each unit for the sampling of vegetation. 6 plant species were recognized as dominant in the study area. 3 soil samples were taken at depths of 0-15 cm in each unit, with a total of 69. Overall, 16 environmental factors were measured, including 3 climatic (mean annual temperature, mean annual precipitation and men annual humidity), 3 topographic (slop, aspect and height) and 10 edaphic (carbon, nitrogen, calcium, phosphorus, potassium, CaCo3, pH, EC, percentage of sand, silt and clay) factors.

The results showed that the vegetation distribution is mainly related to soil characteristics such as soil texture, Caco3, N, EC, and topographic factors such as aspect, and slop. The presence of Salsola dendroides, had a relationship with EC and pH and Hypocylix kerneri had most effectives from sand percent. Salsola arbusculiformis had a direct relationship with Caco3 and clay percent. and Artemisia aucheri with C, mmps, Mmts. Salicornia herbaceae had direct relationships with pH, Clay, K, and Halocnemum strobilaceum with EC. All of the models were significant at p<0.01 level.

As the results of the present research showed, this method was able to extract the most important factors and their effectiveness. Among the advantages of this method, can be referred the possibility of using data on the presence or absence of plant species without using other vegetation information, such as the percentage of plant cover, density and frequency, which are affected by the sampling method, plot size and fluctuation of rainfalls.

Natural crises such as landslides are capable of inflicting irreparable damage on humans and the environment. Therefore, risk assessment is critical in order to properly manage and reduce damage. Risk assessment is characterized by the process of estimating the probability of an event occurring and the significance or severity of its adverse effects. The aim of the present study is landslide risk zoning in Nekarud watershed using fuzzy logic and remote sensing.

The most important indicators used in the research include: precipitation classes, altitude classes, geology, NDVI, distance from the river, distance from the fault, slope were identified after reviewing the research literature and expert opinions.

In the AND operator fuzzy inference zoning maps, 1% are in the very low risk category, 2% in the low risk category, 3% in the medium risk zone, 18% in the high risk zone, and 76% in the very high risk zone. The logic of AND, because of the sharing between the criteria, has zoned many highly exposed areas and identified 80% of the basin as high risk. High-risk areas in this model are located in the whole basin. In the OR zoning model, 72, 12.4, 10, 2% are located in very low, low, medium, high and very high risk areas, respectively. Therefore, most of the area in this zoning model is in a very low class, and this logic considers many areas as safe due to the aggregation between criteria, which are located in the west and center of the basin, and only a very small part of the center of the study area is very risky. Highly detected in the eastern basin. Finally, the GAMA operator zoning model was 49%, 9%, 14%, 15%, 13%, respectively, in the very low, low, medium, high, very high risk classes, and the very low risk class covered most of the study area.

In this zoning, most of the vulnerable areas are located in the eastern part of the study basin and are more in line with reality. As the results of the present research showed, the use of RS and GIS technology is a useful and powerful tool in the field of zoning and landslide risk assessment.

Fire is an ecological factor in the forest, during which most of the growing plants are damaged. By burning the vegetation on the soil surface, fire can cause negative or even positive effects on the physical, chemical, biological, and vegetation properties of the soil. Due to the fact that so far many studies have been done on the effect of natural fires on the characteristics of soil and vegetation, but researches on the impact of fire at different times of the growing season and the effect of those characteristics on soil and vegetation in Iran and other parts of the world are few. There are minimal resources in this field, so this research can provide appropriate information about the condition of the soil after the fire, as well as the ability to restore and restore valuable plant species and preserve the Zagros forests at the discretion of researchers. In this research, the effect of fire in the three seasons of spring, autumn, and winter on the chemical and biological characteristics of soil was investigated.

 The studied area was a part of Zagros forests in Kermanshah province. In this research, a control area was also considered in addition to the burned forests. For this purpose, the desired points (9 points for under the crown and 9 points for outside the crown in both control and burned areas) were determined by measuring with a meter on the transects (6 transects) and regularly and with time intervals. Specified (once every 2 months), they were sampled. The distance of the samples from each other in each row was 20 m and the distance between the rows was 50 m so that 3 rows were identified in the burned area and 3 rows in the control area. Soil properties were measured by conventional laboratory methods.

The results of the investigations show that the fire that occurred in the studied area (under the canopy and outside the canopy of trees in the Zagros region) was superficial and was capable of causing small changes in the chemical and biological factors of the soil. Only soil respiration rate and absorbable phosphorus were affected in this surface fire. The amount of phosphorus in the soil increased and then decreased to its initial level in the first month of sampling.

Considering that the fire in the study area was superficial and caused slight changes in soil characteristics in all sampling months. Probably, severe fires have the ability to cause extensive changes in the chemical, physical and biological characteristics of the soil, and the sampling time in different months did not have much effect on the results.

Destruction and forest fire are one of the most important environmental problems. Annually, forest fire destroys thousands of hectares of trees, shrubs and forest plants and the vulnerability of the livelihood of villagers and forest dwellers increases. The present research was conducted with the aim of investigating the effects of forest fires on the livelihood of villagers in forest areas.

This research is a descriptive-survey type and a researcher-made questionnaire was used to collect data. The geographical area of ​​the research includes Chehelchai watershed, Minoodasht city, Golestan province. To investigate and measure the index of vulnerability caused by forest fires, five dimensions of sustainable livelihood index including natural capital, financial capital, physical capital, human capital and social capital were used with a total of 19 items. Each item was measured based on a five-point Likert scale. The statistical population of the research included 400 households in the villages of the Chehelchai watershed, where the highest number of fires have occurred in recent years in their geographical area. In this research, using Cochran's formula, 200 rural households were selected and interviewed by stratified random sampling method. Spearman's correlation coefficient test was used to determine the relationship between the respondents' personal characteristics and their opinions regarding the effect of forest fires on the villagers' livelihoods. Mann-Whitney test was used to compare the opinions of the respondents regarding the extent of the impact of forest fires on the livelihood of villagers.

The results showed that forest fires had the greatest impact on the livelihood of villagers, respectively, on natural capital with a non-weighted linear combination of 4.08 and the least impact on social capital with a non-weighted linear combination of 1.63. The results of the correlation coefficient test showed that there is a positive and significant relationship between the amount of agricultural land under ownership and the agricultural history of the respondents with their views on the impact of forest fires on the livelihood of villagers. There is a negative and significant relationship between the variable of age and also between the variable of the number of dependents and the opinion of the respondents regarding the effect of forest fire on livelihood. The findings also showed that there is a positive and significant relationship between the level of education and the opinion of the respondents regarding the effect of forest fires on the livelihood of villagers. The results of the Mann-Whitney test showed that there is no significant difference between the views of different groups of respondents regarding the extent of the effect of forest fires on the livelihood of villagers.

The local communities studied in this research unanimously believe that forest fires have negative effects on their livelihoods through the impact on natural, financial and human capitals. Therefore, it is suggested that the responsible organizations strengthen the efficiency of protection measures, reforestation, and reduce damages caused by forest fires by planning and implementing social and cooperative forestry.