مجله مرتع
سال هفدهم شماره 2 (پیاپی 66، تابستان 1402)

The cultivation and subsequent abandonment of rangelands due to economic non-viability have become prevalent in recent years. Assessing plant productivity in these abandoned rangelands is essential for their restoration. This study aims to compare the effectiveness of vegetation indices in natural and abandoned rangelands, evaluate variations in plant productivity, and provide insights into their ecological conditions.

Three semi-steppe regions in Chaharmahal and Bakhtiari province were selected as study areas. These regions were previously degraded for agriculture and subsequently abandoned. Field sampling and satellite data were used to assess plant productivity. Plant indices, including NRVI, CTVI, RATIO, TTVI, and TVI, were calculated using Landsat 8 satellite images from 1393. The indices were employed to evaluate plant productivity and compare natural and abandoned rangelands.

NRVI, CTVI, RATIO, TTVI, and TVI exhibited a significant correlation with plant productivity, while other indices did not accurately represent it. The NRVI index provided the most accurate estimation of plant productivity in abandoned and cultivated rangelands. Uncultivated rangelands showed higher productivity compared to cultivated ones. The study areas displayed variations in plant productivity, with Marjen Borujen having the highest productivity in uncultivated sections and Sefid Dasht having the lowest. In the cultivated sections, Sefid Dasht had the lowest productivity, while Hoorah had the highest. Shrubs experienced the most substantial reduction in plant productivity among the vegetation forms.

Remote sensing, particularly the NRVI index, proved valuable for assessing plant productivity in these rangelands. Utilizing the NRVI index can aid in the management and restoration of abandoned and cultivated rangelands. Conducting similar research and employing remote sensing techniques for assessing and monitoring various rangeland areas are crucial for sustainable land management and conservation efforts. These approaches contribute to the overall health and sustainability of these valuable ecosystems.

Organic carbon is a crucial parameter for assessing soil fertility, productivity, and quality, particularly in dry and semi-dry lands. Rangelands cover approximately 50% of the Earth's land area and store over 33% of the global carbon reservoirs. Considering rangelands as significant terrestrial ecosystems and natural carbon reserves, understanding and quantifying carbon sequestration in these ecosystems is of great importance.

This research focused on rangelands in the southern domain of Damavand mountain. Four height groups were selected based on geographic conditions, regional plant cover, and slope. Each height group represented a different elevation range: group 1 (2504-2664 m), group 2 (2730-2896 m), group 3 (2923-3050 m), and group 4 (3119-3545 m). Soil sampling was conducted at two depths (0-15 cm and 15-30 cm) using 13 random points within each height group. Soil organic carbon and bulk density were measured, and carbon sequestration was calculated at the hectare level by multiplying organic carbon and depth. Regression equations and response surface models (RSM) were developed using design software to predict carbon sequestration and compare their accuracy.

Analysis of variance (ANOVA) showed that only sampling depth significantly affected soil carbon sequestration, while sampling height and the interaction between depth and height had no significant effect. Carbon sequestration was higher at a depth of 15-30 cm compared to 0-15 cm. Among the height groups, group 4 (3119-3545 m) exhibited the highest soil carbon sequestration, followed by group 1 (2504-2664 m). The highest carbon sequestration (6046.54 g/m2) was observed in height group 4 at a depth of 15-30 cm, while the lowest (2250 g/m2) was found in height group 2 at a depth of 0-15 cm. The quadratic model of the response surface methodology demonstrated higher accuracy (R2 = 0.7363) in predicting soil carbon sequestration compared to the linear model (R2 = 0.6014) and the less accurate regression model (R2 = 0.428). The response surface method successfully optimized the inputs, suggesting a height of 3500 meters and a specific depth to achieve a soil carbon sequestration amount of 8088.117 g/m2 with a satisfaction level of 0.976.

The response surface methodology (RSM) proved to be a valuable tool for predicting and optimizing soil carbon sequestration in rangelands, considering different sampling depths and heights. It can also be utilized for predicting various parameters in rangeland science, such as above and underground biomass volume and plant species coverage. RSM offers a novel approach for understanding and managing rangeland ecosystems.

Ensuring the availability of high-quality forage and a balanced diet is essential for cost-effective milk and meat production in buffaloes. In Iran, limited forage supply, poor access to forage, and imbalanced diets are major constraints that negatively impact buffalo production and hinder profitable breeding. To address these challenges, a comprehensive understanding of buffalo breeding areas, methods, production issues, problems, and feeding practices is crucial. This study aimed to determine the nutritional value of feed consumed by breeding buffaloes under stable and rangeland grazing conditions in the primary buffalo breeding habitats across different climatic regions of Ardabil province.

The nutritional value of feed consumed by buffaloes was assessed using gas production techniques in a completely randomized design. Digestibility, metabolizable energy, gas production and degradability parameters, microbial mass production, volatile fatty acids, and grazing diets were evaluated. The study was conducted in three selected locations: Damirof in Bilesavar, Gharabaghlar in Meshginshahr, and Arpatapeh Fandoghlu in Namin counties. Grazing periods and paddocks for buffalo herds were determined based on the Deputy of Livestock Production Improvement's recommendations. Plant samples grazed by buffaloes were collected at three stages of the grazing season in Meshginshahr and Namin (May 15 to June 15, June 15 to July 15, and July 15 to August 15), and one month earlier in Bilesavar (March 15 to July 15). Chemical composition and digestibility tests were conducted on the plant samples. Two types of diets, a "traditional diet" commonly used by buffalo breeders (control diet) and a "standardized diet" formulated based on metabolic energy and protein requirements for buffaloes with an average weight of 550 kg, were selected for feeding buffaloes in stable conditions. Chemical composition and digestion tests were performed on the fodder and concentrate used in the diets.

The results revealed that the balanced diet (standard diet) had significantly higher values of gas production, parameters b and c (slow decomposition and gas production rate), metabolizable energy (ME), net lactation energy (NEL), apparent organic matter digestibility (AOMD), true organic matter digestibility (TOMD), apparent fermentation of organic matter (AFOM), true fermentation of organic matter (TFOM), volatile fatty acids (SCFA), and rumen microbial biomass (MB) production and efficiency compared to the traditional diet (control) (p < 0.05) in all paddocks. Gas production, parameters b and c, ME, NEL, AOMD, TOMD, AFOM, TFOM, SCFA, and rumen microbial biomass and efficiency showed higher mean values during the early grazing season in each paddock compared to the middle and end of the grazing season. Overall, these parameters exhibited a decreasing trend throughout the grazing season (p < 0.05). The TOMD and TFOM values were higher in the early grazing season in the warm semi-arid region of Bilesavar compared to the cold regions of Namin and Meshginshahr (p < 0.05). However, SCFA and MB values were higher in the early grazing season in the cold regions compared to the warm semi-arid region (p < 0.05).

The study demonstrated that balanced diets (standard) had superior nutritional value compared to traditional diets (control) commonly used by buffalo breeders in the selected paddocks. Therefore, these balanced diets can be recommended as alternatives to traditional diets for feeding buffaloes. Additionally, the nutritional value of rangeland habitats varied depending on plant species composition, growth stage, and climatic conditions. For effective stocking intensity and livestock feeding planning in the rangeland, these variations should be considered.

Predictive models of plant species distribution are essential for assessing, restoring, protecting, and developing rangeland ecosystems. Understanding the ecological factors influencing plant composition, species response to environmental changes, and the potential of target species in specific areas is crucial for effective habitat management. This study employed multivariate analysis to identify ecological factors affecting plant composition, analyze species response to environmental changes, and determine the potential of Astragalus retamocarpus in Mazandaran Province's rangelands. The findings will contribute to recommendations for utilizing this species in rangeland improvement programs in similar habitats.

Vegetation sampling was conducted using a systematic-random method from 2016 to 2018. Five transects with equal distances between them were established, and six plots (2 x 2 meters) were placed on each transect. The vegetation study included measurements of canopy cover percentage, species density, litter percentage, bare soil percentage, and stone percentage within the plots. Soil samples were collected from the top 0-30 cm depth and analyzed for physical and chemical properties in the laboratory. Average annual rainfall and temperature data were obtained from weather stations. Detrended Correspondence Analysis (DCA) was performed to investigate the relationship between environmental variables and vegetation cover. A generalized additive model was utilized to predict species response to environmental changes. Canoco software version 4.5 was used for data analysis.

Astragalus retamocarpus was found to thrive at elevations ranging from 1800 to 2800 meters above sea level. The habitat exhibited electrical conductivity values of 0.98-1.1 ds/m, pH levels of 7.5-7.73, lime content of 1.6-2.6%, soil organic carbon ranging from 2.01 to 6.85%, nitrogen content of 0.28-0.54%, and loamy sand soil texture. Among the 22 primary variables studied, six variables were identified as significant factors influencing vegetation changes in the habitat. These factors, including litter percentage, clay percentage, slope percentage, average annual rainfall, organic carbon percentage, and phosphorus content, explained 36.3% of the variation in vegetation. The species exhibited a monoexponential response to variables such as sand percentage, silt percentage, electrical conductivity, altitude, average annual rainfall, and temperature. Conversely, the response to variables such as aspect, bare soil, stone, and gravel indicated a decreasing trend, with increased factors leading to decreased abundance and vegetation cover percentage. The response to variables such as organic carbon percentage, litter percentage, potassium and phosphorus content followed a monotonic increasing model. Lime percentage, saturated soil moisture, and soil apparent specific gravity demonstrated a bi-exponential response.

The generalized additive model employed in this study provides valuable insights into the ecological requirements of Astragalus retamocarpus. The findings can be utilized in vegetation management and rangeland improvement operations in similar areas. This species is significant in terms of high forage production and is recommended for increasing vegetation cover in rangelands.

Shirazi thyme (Zataria multiflora Boiss) is a widely consumed and exported medicinal plant in Iran. It is primarily grown in the central and southern regions of Iran, as well as parts of Pakistan and Afghanistan. Studies have shown that this plant possesses immunomodulatory, analgesic, anti-inflammatory, antioxidant, antibacterial, antiviral, and disinfectant properties. It is also used in traditional medicine for its antifungal effects and to alleviate pain, treat infectious diseases, and address digestive problems. Due to the high demand, extensive harvesting, and indiscriminate collection from southern pastures, this valuable plant is facing the risk of extinction. Therefore, cultivation efforts are being undertaken. This research aims to compare the quantity and quality of essential oil in ecological and agricultural samples of Shirazi thyme.

Flowering branches of the plant were collected from the Marwarid area of Darab city in Fars province. Additionally, a cultivated sample was obtained from the research farm located in the Faculty of Agriculture and Natural Resources in Darab. Essential oil was extracted using the distillation method with water, and gas chromatography (GC) was used for analysis. The essential oil was obtained by distilling 100 grams of crushed flowering branches using a Celevenger device for 3 hours in the medicinal plants laboratory of the Faculty of Agriculture and Natural Resources in Darab. Gas chromatography-mass spectrometry (GC/MS) was employed to identify essential oil compounds.

The relative percentage of each constituent compound in the essential oils was determined based on the area under the curve in the chromatogram spectrum. The comparison of essential oil compositions between agricultural and natural conditions revealed their similarity. In the cultivated sample of Zataria multiflora Boiss, 40 compounds were identified, while the sample collected from the natural habitat contained 32 compounds. The yield of essential oil in the cultivated sample was 1.3%, with the main compounds being linalool (54.33%), carvacrol (24.83%), and thymol (2.48%). The essential oil from the plant sample had a yield of 1.7%, with the major compounds being thymol (51.20%), carvacrol (20.08%), paracimen (7.74%), and gammaterpinene (7.25%). A comparison of the two essential oils indicated that linalool and carvacrol were the predominant compounds in the cultivated sample, while thymol and carvacrol were dominant in the wild sample. Oxygenated monoterpenes were the main group of constituents in the essential oil, followed by hydrocarbon monoterpenes and sesquiterpenes, with hydrocarbons having a smaller share. The essential oil composition of the cultivated sample showed an increase in carvacrol compared to the wild sample, while the essential oil of the wild sample exhibited a 58% increase in thymol composition compared to the cultivated sample.

Considering the economic importance of Shirazi thyme, the higher content of essential oil in the cultivated sample compared to the wild sample, and the presence of significant carvacrol and linalool compounds in the cultivated sample, it is recommended to prioritize the domestication of this species and its introduction into agricultural and rangeland management systems. Furthermore, the cultivation of this plant should be encouraged in biological restoration projects of rangelands to promote employment and empower rangeland owners.

The impact of grazing on the carbon cycle in mountain rangelands depends on various factors, including management practices and environmental conditions. However, the effects of grazing on carbon stocks remain uncertain due to challenges in tracking small changes in rangeland carbon stocks, lack of baseline information, and limited long-term grazing management data. This study aims to investigate the relationships between plant and soil parameters and organic carbon storage in a 10-year-old exclosure in the mountain rangelands of Asadabad, Hamadan.

Two study sites, one under grazing and the other under a 10-year-old exclosure, were selected in a manner that minimized the gradient effect of ecological and biological factors. Vegetation and topsoil samples were collected along two 100-meter transects at 20-meter intervals, resulting in a total of 10 plots in each area. Vegetation parameters, including percentage cover, diversity (Simpson index), evenness (Shannon-Wiener index), and richness (Margaluf index), were calculated using Past 4.03 software. Soil organic carbon, phosphorus, potassium, and nitrogen were measured. Statistical analysis was performed using SAS V.4.1 software, and the distribution of variables was analyzed using principal component analysis (PCA) in Canoco 5 software.

The findings revealed higher vegetation cover and plant diversity (richness and evenness) in the exclosure area. The vegetation cover percentage and species count in the grazing area were 35.1% and 127, respectively, while in the exclosure area, they were 67.6% and 139. The carbon stocks in vegetation and soil were significantly higher in the exclosure area, with values of 83.13 and 74.35 ton/ha in the soil surface, and 0.00219 and 0.00273 ton/ha, respectively (p < 0.05). The exclosure area exhibited a significant increase in Simpson diversity index (13.83) compared to the grazed area (12.63). Additionally, the Margaluf richness index showed a significant increase in the exclosure area. Soil phosphorus, potassium, and nitrogen nutrient measurements indicated an increase of 51%, 25.7%, and 15% in the exclosure area (p < 0.05). Correlation analysis revealed a significant linear relationship between organic carbon and phosphorus (r = 0.55) and nitrogen (r = 0.80) (p < 0.05). However, no significant correlation was observed between plant diversity indices and vegetation organic carbon storage.

The study demonstrated the positive impact of long-term exclosure on soil and vegetation parameters in mountain rangelands (p < 0.05). Exclosure not only enhanced plant and soil organic carbon storage but also resulted in increased soil nutrient levels, vegetation cover, and diversity and richness indices. The significant increase in plant diversity highlights the suitability of the Simpson index for evaluating diversity in mountain rangelands. However, the lack of a significant linear relationship between diversity index and organic carbon stocks in plants and soils suggests that factors other than plant diversity directly influence carbon stocks in mountain ecosystems.

Understanding the spatial distribution of vegetation and its relationship with ecological factors, particularly soil properties, is crucial for effective rangeland management. This study aimed to evaluate soil properties, including organic carbon, nitrogen, phosphorus, potassium, electrical conductivity, and acidity, in Goshchi rangeland of Urmia, representing the Azerbaijani vegetation climate in West Azerbaijan province. The study utilized the adaptive neuro-fuzzy inference system (ANFIS) and response surface methodology (RSM) approaches to predict these soil properties and compare the results.

Soil properties were assessed in two sites, one under exclosure and the other under grazing, using ANFIS and RSM approaches. The collected data were used to train ANFIS in MATLAB software and RSM in Design Expert software.

The correlation coefficients (R2) between the predicted data from the ANFIS model and RSM method, and the measured data for organic carbon, nitrogen, phosphorus, potassium, electrical conductivity, and acidity were 0.75, 0.93, 0.44, 0.95, 0.68, and 0.95, respectively, and 0.84, 0.93, 0.24, 0.96, 0.54, and 0.98, respectively. The results indicated that grazing conditions (exclosure vs. grazed) and distance from plants (near vs. between plants) significantly influenced acidity, nitrogen, potassium, and organic carbon, while they had no significant effect on electrical conductivity and phosphorus. The exclosure conditions and proximity to plants resulted in higher levels of organic carbon, nitrogen, and phosphorus, highlighting the sensitivity of these factors to grazing. The RSM results showed that grazing conditions and distance from plants had no significant effect on phosphorus and electrical conductivity but had a strong significant effect on other soil properties. The lower R2 values observed for phosphorus and electrical conductivity in both ANFIS and RSM methods suggest their limited accuracy in predicting non-significant outputs.

The findings from both ANFIS and RSM methods demonstrate their effectiveness in accurately predicting soil properties under the investigated conditions. However, their performance is more accurate for factors that exhibit a significant effect on the input variables, while their accuracy is limited for non-significant outputs.

The distribution and establishment of plant species are influenced by various environmental conditions. Calligonum bungei, a species of the genus Calligonum, is widely distributed in arid and semi-arid climates in Iran. This research aimed to investigate the environmental conditions governing the distribution of Calligonum bungei in the desert rangelands of Kerman province. The study focused on identifying different types of Calligonum bungei habitats, assessing canopy cover, density, and associated species, and examining the influence of environmental factors, such as climate, topography, and soil, on the species' distribution.

Four representative areas in Kerman province were selected to represent the dominant types of Calligonum bungei habitats. Geomorphological types were identified using satellite images and field visits. Environmental factors, including climate, topography, soil properties, and characteristics specific to the species (density, canopy cover, associated species), were evaluated in each habitat type. Vegetation studies were conducted along 300-meter transects, with plot sizes determined based on vegetation type and distribution (100 square meters). A total of 40 plots (10 plots per studied area) were investigated. Canopy cover was determined by measuring two perpendicular diameters of the plant canopy. Principal component analysis (PCA) using PC-ORD software was employed to analyze the relationship between environmental factors and species establishment in the study areas.

The results showed that Calligonum bungei was present in the altitude range of 1400-1750 meters, slopes ranging from 1% to 18.4%, and in all directions. The average annual rainfall in the areas varied from 55.5 to 163.4 mm, while the average annual temperature ranged from 16.7 to 26.4 degrees Celsius. The minimum and maximum absolute temperatures recorded were between -20.8 and 48.8 degrees Celsius, respectively. The average annual humidity ranged from 29.6% to 42.5%, and the length of the dry season varied from 8 to 12 months per year. Soil analysis revealed shallow soil with sandy-loamy to sandy-loamy texture, sand content between 67% and 84%, lime content between 8.5% and 20%, carbon content between 0.1% and 1.35%, nitrogen content between 0.0% and 0.7%, absorbable phosphorus between 9.5 and 13.5 milliequivalents, absorbable potassium between 200 and 217.5 milliequivalents, salinity between 0.36 and 1.02 decisimians, and pH values between 7.8 and 8.09. In terms of vegetation, Calligonum bungei was observed to be scattered in all studied areas, with densities ranging from 10 to 280 plants per hectare and canopy cover varying from 0.1% to 5.7%.

The principal component analysis revealed that the first component (annual temperature, humidity, sand, and silt) explained 46.9% of the variation, the second component (altitude, slope, annual rainfall, phosphorus, lime, and potassium) explained 35.3%, and the third component (clay, nitrogen, and salinity) explained 17.8%. Environmental factors influencing the establishment of Calligonum bungei varied among the studied areas. In Anar and Kerman regions, increasing sand content and decreasing annual temperature, humidity, and silt were significant factors. In the Bam region, increasing phosphorus and potassium content and decreasing altitude, slope, annual rainfall, and lime were influential. In the Jiroft region, reducing sand content and increasing annual temperature, humidity, and silt played a role. Overall, these findings indicate that the identified environmental factors act as limiting factors for the establishment of Calligonum bungei in the study areas.

The shift from single-purpose grazing to the multi-purpose utilization of rangelands has become important due to increased societal needs and awareness among researchers and stakeholders. Understanding the ecological capabilities and evaluating natural ecosystems are essential for proper management and planning of natural resources. Beekeeping is one potential utilization of rangeland ecosystems, as Iran's four-season climate provides favorable conditions for honey production. However, the lack of knowledge regarding the quantitative and qualitative status of plant species in terms of their value and importance for bees, as well as the absence of effective indicators, hinders proper exploitation of pastures for honey production. This research aimed to investigate and identify the natural and management indicators influencing honey production.

Thirteen natural indicators and sixteen management indicators affecting honey production were selected as independent variables using a Likert scale questionnaire. Honey production index was used as the dependent variable. A sample of 67 beekeepers was randomly selected from a population of 81, based on Cochran's formula. Questionnaire validity was assessed by professors and experts, and reliability was measured using Cronbach's alpha statistic.

Statistical analysis using rank mean test in SPSS software revealed that the percentage of nectar-producing and pollinating species had the highest rank (3.14) among the natural indicators, followed by the duration of the flowering period (3.01). Among the management indicators, the type of nutrition consumed by bees ranked first (3.05), followed by the existence of water resources (2.97). Spearman correlation coefficient indicated a positive and significant correlation (99% confidence level) between natural and management indicators. Additionally, Spearman's correlation coefficient and Kendall's tau-b showed a positive and significant correlation (99% confidence level) between natural and management indicators. The percentage of nectar-producing and pollinating species, length of the flowering period, amount of rainfall, cloudiness, pasture condition, and slope direction had a positive and direct relationship with the honey production index. Conversely, the number of migrations, light livestock grazing with bees, and type of ownership had a negative and inverse relationship with the honey production index.

Natural factors were found to have a greater impact on honey production compared to management factors in the study region. To increase honey production, it is recommended for beekeepers to enhance their technical efficiency and knowledge through training and extension programs. They should establish hives in rangelands with suitable vegetation percentage and attractive species for bees, consider rainfall and the availability of healthy water resources, and carefully time hive migrations. Understanding the ecological factors and indicators accurately and implementing proper management strategies can potentially increase honey production by 17% in the region.

The multi-purpose utilization of rangelands is a challenge that can alleviate grazing pressure, enhance rangeland well-being and empowerment, and preserve rangeland ecosystems. This research aimed to assess the suitability of mountain rangelands in the Marghevar region of Urmia for dual-purpose grazing and the exploitation of medicinal plants.

During the growing season of 2018-2019, vegetation data were collected in 60 plots of two square meters, spaced 10 meters apart along six 100-meter transects. Ecological indicators, including crown cover percentage, species density, forage production by grazed species, and medicinal plant organs used, were measured. Economic indicators, such as economic rent and expected value per hectare, were evaluated for both medicinal plants and forage. Social indicators, including marketability desirability and willingness to harvest medicinal plants, were extracted from questionnaire studies. Physical characteristics of the plant types (PTS) and soil erosion information from previous studies were also considered. Suitability classes (S1, S2, S3, N) for livestock grazing (sheep) and medicinal plant utilization were determined based on the total points of each indicator using the guidelines provided in the Manual of Suitability for Sheep Grazing (MSSG) and Manual of Suitability for Medicinal Plants (MSMP). The priority of dual-purpose use of rangelands was determined by comparing the merit classes of PTS for livestock grazing and medicinal plant utilization.

The results revealed that the crown cover percentage of medicinal plants in the composition of each PTS ranged from 5% to 40%. The share of medicinal plants in the habitat's plant composition ranged from 20% to 62%. The composition of medicinal plants and grazed species varied from 3% to 30%. Forage production by grazed species ranged from 65 to 850 kg/ha, while medicinal plant production ranged from 4 to 159 kg/ha during one growing season. The suitability assessment indicated that 77% of the rangeland area in the region had high suitability for dual-purpose use, 10.7% had moderate suitability, 0.9% had low suitability, and 3.3% were unsuitable based on ecological, environmental, economic, and social indicators. The presence and production capacity of medicinal plants were identified as limiting factors for the ability of PTS to exploit medicinal plants.

Not all PTS are suitable for the utilization of medicinal plants, emphasizing the need for preserving genetic reserves. The policy regarding medicinal plants should consider this aspect and prioritize multi-purpose rangeland plans.