Mahnaz Amini; Hosein Bashari; Mohammad Taghi Feizi
Volume 31, Issue 2 , August 2024, , Pages 129-148
Abstract
Background and objectivesVarious environmental and managerial stresses are severely threatening wetland ecosystems in Iran. The Gavkhouni Wetland, one of the largest and most strategically significant wetlands in the central plateau of Iran, faces numerous challenges. Given its unique ecological importance ...
Read More
Background and objectivesVarious environmental and managerial stresses are severely threatening wetland ecosystems in Iran. The Gavkhouni Wetland, one of the largest and most strategically significant wetlands in the central plateau of Iran, faces numerous challenges. Given its unique ecological importance and the diverse plant habitats surrounding it, studying the vegetation in this area is crucial. Understanding the various conditions of the plants, including dominant families, geographical distribution, biological forms, and conservation status, is essential for any conservation, management, or ecological research activities in this region. MethodologyThe study area encompasses the upper reaches of the Zayandehrud River in Isfahan Province, covering 50,000 hectares with elevations ranging from 1,470 to 2,533 meters above sea level. This region has an arid climate characterized by saline soils, including solonchaks, marshy areas, and sandy soils. The average annual temperature at Gavkhuni Wetland is 17.6 degrees Celsius, with total annual precipitation measuring 91 millimeters. According to the Ambrothermic curve, the area experiences a prolonged dry period from April to November. Field surveys were conducted using 1:25,000 scale topographic maps from early October to November 2021. During these surveys, plant samples were collected, pressed, dried, and identified at the herbarium of the Natural Resources Department of Isfahan University of Technology, with consultation from experts and reliable scientific sources. This research resulted in a comprehensive list of plant species, detailing their scientific names, families, genera, life forms, geographical distribution, and conservation statuses. ResultsThe study identified 100 plant species from 16 families and 65 genera in the region, with 27 species possessing medicinal and industrial properties. The Amaranthaceae family, with 31 species, and the Asteraceae family, with 14 species, collectively constitute 45% of the vegetation cover. Other prominent families include Poaceae with 10 species and Fabaceae with 9 species. In terms of life forms, therophytes dominate at 40%, followed by hemicryptophytes at 23%. Geographically, 71% of the identified species belong to the Irano-Turanian floristic region. Despite the ecological challenges faced by the area, its diverse topography and edaphic factors have fostered significant species diversity. ConclusionGavkhuni Wetland's flora is highly sensitive to climate and management practices. Despite facing severe biological constraints, the region exhibits relatively robust plant diversity. Inadequate management of the Zayandehrud watershed, particularly in Gavkhuni Wetland, has resulted in declining groundwater levels and increased aridity, threatening many plant species with drying, pest infestations, shrub encroachment, and overgrazing. Continued adverse conditions, exacerbated by climate change, pose a significant threat to the region's flora.
Zahra Jaberalansar; Babak Bahreininejad; Alireza Eftekhari; Masoud Borhani
Volume 30, Issue 3 , January 2024, , Pages 424-440
Abstract
Background and objectivesThe study of vegetation changes under habitat protection conditions has a significant role in rangeland management. The studies confirm that permanent changes in rangelands in terms of plant composition, canopy cover, and forage production are influenced by ecological and management ...
Read More
Background and objectivesThe study of vegetation changes under habitat protection conditions has a significant role in rangeland management. The studies confirm that permanent changes in rangelands in terms of plant composition, canopy cover, and forage production are influenced by ecological and management factors. This research was conducted to investigate and monitor the plant vegetation indices of semi-steppe rangelands of central Zagros for five years (2016-2020) at the Zayandehrud watershed management research site (Isfahan province). Methodology Vegetation sampling was performed by a systematic random method in each exclosure and grazed site during 2016-2020. Vegetation characteristics, including the percentage of canopy cover of species, the percentage of gravel, bare soil, and litter were determined in each plot. For this purpose, four 100-meter segments were used. Then, ten plots (with 1 x 1-meter dimensions) were established with the same distance. In total, vegetation cover was measured in 80 plots of one square meter in exclosure and grazed sites. To calculate rangeland production, ten samples of each plant species were collected, and their canopy cover percentage was measured. After drying and weighing the samples, by establishing regression equations between the canopy cover percentage and the weight of the dried samples, the amount of production of plant species was determined separately for growth form and palatability class. Rangeland's condition was also evaluated according to the four-factor method and by scoring the factors of soil, vegetation, plant composition and age classes, and plant vigor. After collecting the data in Microsoft Excel, the variance analysis for the vegetation traits was done as a completely random design in a factorial format. This was done through the GLM (General Linear Model) method. Tukey's test investigated vegetation traits mean comparison in MINITAB 16 software. ResultsThe analysis of variance showed a significant difference between vegetation indices, including total canopy cover and production, separately for growth form and palatability class. This was in the exclosure and grazed sites during the assessment period. The average percentage of canopy cover in exclosure sites during different years was 26.7%, 13.7%, 25.84%, 33.74%, and 13.33%. In grazed sites, it was 22.33%, 12.65%, 27.09%, 30.9%, and 11.59%, respectively. Total production at the exclosure site during different years was 624.26, 349.86, 556.79, 894.54, 664.53 kg/ha. Production at the grazed site was 456.45, 243.85, 455.6, 605.47, and 323.44 kg/ha, respectively. The highest values of canopy cover and production belonged to 2019, which was a wet year based on meteorological indices. The lowest canopy cover and production were assigned to 2017 (a drought year). The highest amount of litter was found at the exclosure site. The highest percentage of bare soil and annual plant canopy cover was obtained from the grazed site. The highest percentage of canopy cover and production in the exclosure site belonged to Stipa hohenackeriana. At the grazed site, Hedysarum criniferum and Stipa hohenackeriana accounted for the highest canopy cover and production, respectively. According to the four-factor method, the rangeland condition at the disclosure site was fair in 2016, 2018, and 2019 and poor in 2017 and 2020. At the grazed site, the rangeland condition was fair in 2018 and 2019 and poor in the rest of the years. Conclusion The comparison of vegetation parameters inside and outside the exclosure shows the good condition of vegetation inside the exclosure. It also shows the effectiveness of the exclosure in rangeland rehabilitation. Balanced livestock grazing on the vegetation caused no significant difference between vegetation characteristics, such as canopy cover in the exclosure and grazed sites. Continuous evaluation and monitoring of rangelands through creating a regular database of vegetation indicators and investigating their changes under different managements. This investigation of their relationship with climatic factors can provide the necessary background for fundamental rangeland planning and management.
hadi Eskandari Damaneh; Hamed Eskandari Damaneh; Zahra Sayadi; Asadollah Khoorani
Volume 28, Issue 4 , November 2021, , Pages 772-786
Abstract
Due to the prevailing arid and semi-arid climate, Iran has always suffered from the production and spread of airborne substances, especially dust. This phenomenon is very destructive due to its direct impact on the environment and human health. Therefore, this study aimed to investigate ...
Read More
Due to the prevailing arid and semi-arid climate, Iran has always suffered from the production and spread of airborne substances, especially dust. This phenomenon is very destructive due to its direct impact on the environment and human health. Therefore, this study aimed to investigate the variation trend of aerosol optical depth (AOD), normalized difference vegetation index (NDVI), rainfall, temperature, wind speed, and correlation between AOD and climatic parameters in Iran. Data on AOD and NDVI were collected from Modis sensor images and other data from the ECMWF climate site over 2000-2019 with a spatial resolution of 10 km. The Mann-Kendall trend analysis was used to investigate the trend of changes in these parameters, and the linear correlation model was used to check the correlation between AOD and climatic data. The results of the variations trend of AOD, NDVI, and climate data showed that the trend of these parameters was different in different regions of Iran so that NDVI and rainfall had decreased by 85.13% and 67.57%, respectively, while AOD, wind speed, and the temperature had increased by 71.43%, 71.86%, and 99.37% across the country, respectively. The correlation of AOD, NDVI, rainfall, temperature and wind speed revealed that AOD had a negative correlation with NDVI and rainfall in 50.94% and 51.31% of the country, respectively, while its correlation was positive with temperature and wind speed over 68.42% and 50.36% of the country, respectively. Therefore, the increase in airborne suspended particles strongly depends on the trend of variations in vegetation cover and climatic factors, including rainfall, temperature, and wind speed, which can be well studied using satellite and climatic data with appropriate spatial and temporal resolution.
Leila Bakhshandehmehr; Mohammadreza Yazdani; Reza Jafari; Saeid Soltani
Volume 27, Issue 3 , October 2020, , Pages 463-484
Abstract
Research on the environmental controllers in plant communities is one of the research fields for many ecologists. Identifying the factors affecting the vegetation cover in the arid regions is the first step to recognize the destructive factors, which inhibit the growth and development of vegetation. ...
Read More
Research on the environmental controllers in plant communities is one of the research fields for many ecologists. Identifying the factors affecting the vegetation cover in the arid regions is the first step to recognize the destructive factors, which inhibit the growth and development of vegetation. In the current study, using the structural equation modeling method and Partial Least Square – Structural Equation Modeling (PLS-SEM), climatic and pedological variables that affecting the vegetation cover in steppe rangelands of Zayandehrood basin of Isfahan province were identified and modeled. According to the results, soil clay content, maximum runoff height on the soil, temperature, and dryness of the environment are the most important variables affecting the quantity and quality of vegetation in the rangelands of the Zayandehrud basin. Besides, the role of climatic factors is more than soil factors in the distribution of vegetation in the region. The model presented in this research has good accuracy and high flexibility for modeling ecological phenomena.
Mohammad Gheytouri; Mosayeb Heshmati; Yahya Parvizi
Volume 26, Issue 3 , September 2019, , Pages 772-785
Abstract
Inappropriate exploitation methods, particularly changes in rangeland use, excessive grazing, and fire have led to sever degradation of rangelands with even worse consequences observed in winter rangelands. The present study, conducted in the poor rangelands of Naftkhane Qasreshirin ...
Read More
Inappropriate exploitation methods, particularly changes in rangeland use, excessive grazing, and fire have led to sever degradation of rangelands with even worse consequences observed in winter rangelands. The present study, conducted in the poor rangelands of Naftkhane Qasreshirin Plain, aimed to study the effects of practices carried out to improve the conditions of rangelands on vegetation cover and carbon sequestration. The study included four types of treatment including a) furrow and brush- planting, b) pitting and brush- planting, c) managing grazing system, and d) a control treatment with usual exploitation conditions. Details of vegetation cover of the rangelands including condition, trend, biomass, forage production, and rate of carbon sequestration in the four treatments were assessed using transects and quadrates. The highest production rate for biomass and forage, and carbon sequestration in rangelands was 573, 551, and 266 kgha-1, respectively, which belonged to the pitting treatment, and the lowest rates 298, 196, and 137 kgha-1 were for the control treatment. In addition, rangeland condition and trend in studied rangelands were assessed to be positive under pitting and furrow treatments whereas in the control treatment a poor condition and a negative trend were observed. Results of the study indicated that pitting, furrow, and management of the grazing system were respectively the most effective treatments in improving biomass, vegetation cover, forage production, carbon sequestration, and erosion control.
Hosein Arzani; Jalal Abdollahi; Mehdi farahpour; Mojganolsadat Azimi; ali Ashraf Jafari; Mahmoud Moalemi
Volume 12, Issue 3 , August 2019, , Pages 263-286
Hosein Arzani; Hamidreza Mirdavodi; Mehdi Farahpour; Mojganolsadat Azimi; Seyed Hasan Kaboli; Abasali Sanadgol; Morteza Akbarzadeh; Valiollah Mozafarian
Volume 12, Issue 4 , August 2019, , Pages 409-436
Hesam Ahmadi Birgani; Parisa Ravan
Volume 26, Issue 2 , July 2019, , Pages 487-499
Abstract
Researchers and target groups studying the vegetation are seeking to answer the question “what ground indicators determine the establishment and distribution of vegetation types and vegetation communities of a basin and which landforms can best determine the boundaries of each ...
Read More
Researchers and target groups studying the vegetation are seeking to answer the question “what ground indicators determine the establishment and distribution of vegetation types and vegetation communities of a basin and which landforms can best determine the boundaries of each plant type or community?”. In this regard, the Gardaneh-Ghooshchi basin, overlooking the Urmia Lake in West Azarbaijan Province was selected. Vegetation cover map, land capability evaluation map, geology map, soil map, geomorphology map, and land units map, were precisely and accurately generated based on the technical methods and field surveys. The multinomial logistic regression method was used to compare, describe and accurately predict vegetation types with different landforms. The results showed that homogeneous units with a quantitative value of 0.432 had the highest impact, followed by geomorphology, geology, and soil with quantitative values of 0.389, 0.351 and 0.156, respectively, in the next rank. Therefore, slope, aspect, and elevation (physiographic characteristics of the basin) have a more effective role in the distribution of vegetation, which could be used before ground monitoring as a baseline map in mountainous areas.
Bahram Gholinejad; Arian Farhadi; Parviz Karami
Volume 26, Issue 1 , June 2019, , Pages 260-269
Abstract
Collection of appropriate quantitative data is necessary for proper management and planning in rangelands. One of the ways to access this information is choosing the appropriate methods of sampling and determining the appropriate length of transect for vegetation cover measurement. Therefore, this study ...
Read More
Collection of appropriate quantitative data is necessary for proper management and planning in rangelands. One of the ways to access this information is choosing the appropriate methods of sampling and determining the appropriate length of transect for vegetation cover measurement. Therefore, this study was conducted in 2016 in Ariz rangelands located in the northwestern of Sanandaj city. For this purpose, transects with a length of 20, 50, 100, 150, 200, 300 and 400 meters, each with four replications were established perpendicular to slope and parallel to slope in the vegetation type of Bromus tomentellus - Festuca ovina. The 400-m transect was considered as a control for calculations. The obtained data from sampling were compared by ANOVA. The obtained results from different transect lengths were also compared by (E%) 2×T factor. The mean comparisons of vegetation cover percentage of transects were performed using t-student test. According to the results of this study, the transects of 20, 50, 100 and 150m length showed a significant difference with the control transect (400 m) in terms of accuracy index ((E%) 2 × T). However, there was no significant difference among the transects of 200, 300 and 400 meters length for the accuracy index. Therefore, the application of 200-meter transect is recommended regarding the cost and time.
shahla Ghaderi; Alireza Amirian Chekan; Amaneh Karim Zadeh; Masoume Difrakhsh; Javad Pourrezaie
Volume 24, Issue 3 , October 2017, , Pages 478-493
Leila Mostafavi; Gholamali Heshmati; hamid mostafalou
Volume 23, Issue 4 , March 2017, , Pages 785-799
Abstract
Range suitability assessment for different objectives is along with management principles and guarantees sustainable development. A considerable area of Golestan Province plains is covered with halophytes, grazed by different livestock including sheep. A study was done to assess the suitability of saline ...
Read More
Range suitability assessment for different objectives is along with management principles and guarantees sustainable development. A considerable area of Golestan Province plains is covered with halophytes, grazed by different livestock including sheep. A study was done to assess the suitability of saline winter rangelands with dominant species of Halocnemum strobilaceum and Aleuropus lagopoides for sheep grazing. The F.A.O method in GIS environment was used in this research for Gomishan Plain, Golestan province, Iran. In the method, three criteria of vegetation, water and soil erodibility were used as the sub-models and constituted the final model components. For vegetation sub-model, vegetation types, cover percentage, forage production, range condition and trend and range capacity were determined. Distance from water resources, water quantity and quality were determined for water sub-model. For the soil erodiblity sub-model evaluated by the EPM model, slope, rock and soil sensitivity to erosion were determined. The final model of range suitability for sheep grazing revealed that 38.69 and 61.31 percent of the region were classified as low suitability and no suitability, respectively. Among all factors determined in sub-models, the distance from water resource was the most limiting factor for sheep grazing and forage production was the most reducing factor of range suitability. Finally, utilization of rangelands in the region could be improved by reducing grazing intensity and implementing range restoration practices.
Mina Bayat; Hosein Arzani; Adel Jalili
Volume 23, Issue 2 , September 2016, , Pages 372-357
Abstract
In this study, the effects of three important climate factors including rainfall, temperature, and relative humidity were studied on vegetation cover and forage production for ten years (1997-2007) as well as in the Alavijeh and Khondab steppe rangelands, Isfahan province, in 2013. The results of the ...
Read More
In this study, the effects of three important climate factors including rainfall, temperature, and relative humidity were studied on vegetation cover and forage production for ten years (1997-2007) as well as in the Alavijeh and Khondab steppe rangelands, Isfahan province, in 2013. The results of the eleven-year study in steppe rangelands showed that shrubs and grasses had the highest and lowest vegetation cover and production and the average vegetation cover and average production were calculated to be 12% and 124.5 kg per hectare. The results of simple regression analysis showed that in steppe rangelands, the total vegetation cover is affected by annual rainfall and temperature, so that vegetation cover increased with increasing annual rainfall and decreasing temperature. The total production in the study rangelands is affected by annual rainfall, cold season rainfall, and minimum temperature. The long-term production was calculated to be 55 and 176.6 kg per hectare for the Khondab and Alavijeh sites, respectively. According to the results of stepwise regression, using climatic factors, the relative humidity with temperature of December and annual rainfall was identified as the best equation to estimate the annual vegetation cover in the Khondab and Alavijeh sites. In the Khondab site, the temperature of November and total rainfall from March to May was identified as the best equation to estimate the annual production. However, in the Alavijeh site, the total rainfall of growing season, minimum temperature of March, and temperature of May and December was the best. Therefore, the impact of climate conditions on vegetation cover and annual production and different life forms are not similar in the steppe rangelands.
Hamzeh Ali Shirmardi; Atosa Mojiri; Mostafa Saeedfar; Mohamadreza Tatian; Parviz Gholami
Volume 23, Issue 1 , June 2016, , Pages 138-149
Abstract
Livestock grazing can lead to changes in plant composition. In this study, the effect of four grazing intensities including heavy, moderate, light and no grazing (exclosure) were studied on vegetation indices in order to improve management practices and proper planning for sustainable use of rangelands ...
Read More
Livestock grazing can lead to changes in plant composition. In this study, the effect of four grazing intensities including heavy, moderate, light and no grazing (exclosure) were studied on vegetation indices in order to improve management practices and proper planning for sustainable use of rangelands in Karsanak and Bardeh area in Chaharmahal & Bakhtiari province of Iran. Therefore, vegetation sampling was done to record canopy cover percentage and vegetation composition under four grazing intensities. Data were analyzed by one-way ANOVA, t-test,andordination method (CCA) to assess vegetation changes under different grazing intensities. Results showed that plant species such as Agropyron repens, Bromus tomentellus, Astragalus effuses and Poa bulbosa were more found in exclosure and light grazing area.The major species found in heavy grazing area were Boissiera squarrosa, Echinops leiopolyceras, Sisymbrium irio and Euphorbia heteradenia. Due to the vegetation damage and reduction of palatable species, a moderate grazing is recommended in the study rangeland.
Sina Sarabi; Ali Heshmatpour; Choghi Bayram Komaki; Abolfazl Tahmasebi
Volume 22, Issue 2 , August 2015, , Pages 392-405
Abstract
Analysis of drought and factors affecting it using remote sensing data has a high potential to improve scientific knowledge about the properties of drought and the effects of this phenomenon on vegetation. The present study was aimed to investigate the relationship between satellite indices and the SPI ...
Read More
Analysis of drought and factors affecting it using remote sensing data has a high potential to improve scientific knowledge about the properties of drought and the effects of this phenomenon on vegetation. The present study was aimed to investigate the relationship between satellite indices and the SPI index in northern rangeland of Golestan province. For this purpose, SPI index in one, three, and six month- moving averages was calculated and then zoning maps were prepared using kriging. Then, using MODIS images and the corrections, required for this type of sensor, made on the images, a vegetation map was prepared using the indices of NDVI, SAVI and VCI. In order to synchronize the climate data with satellite images, a 9 -year-old common time base was selected . Finally, in order to investigate the relationship between vegetation indices with the SPI indices correlation coefficient and linear regression were used. The results indicated a good correlation between satellite indices and SPI indices in the peak months of vegetation growth. In addition, correlation between vegetation cover indices and three and six-month moving average in non-growing season, and with a one-month moving average of SPI in growing season was higher.
Vahideh abdollahi; Farhad zolfaghari; Mitra Jabari; Mohamad rafie dehghan
Volume 22, Issue 4 , March 2015, , Pages 658-672
Abstract
This research was aimed to investigate the effects of crescent pond structure on soil and vegetation properties in the Saravan rangelands. For this purpose, two treatments including crescent pond and control treatment were determined. For each treatment, the density, canopy cover percentage, and litter ...
Read More
This research was aimed to investigate the effects of crescent pond structure on soil and vegetation properties in the Saravan rangelands. For this purpose, two treatments including crescent pond and control treatment were determined. For each treatment, the density, canopy cover percentage, and litter were estimated by random-systematic sampling using five transects of 100 m and 50 plots. Two soil samples were taken along each transect from 0-30 cm depth and soil physico-chemical properties were measured. Data were analyzed statistically. According to the obtained results, significant differences were found for all vegetation parameters between the crescent structure and control treatment, indicating the positive effect of crescent structure on vegetation parameters. The results of soil properties indicated reduced soil salinity; however, the organic matter, potassium, and pH showed no difference between the two regions. According to the results, due to the climatic conditions of the study area, longer time is needed to achieve better results.
Hossein Arzani; Zeinolabedin Hosseini; Khosro Mirakhorlou
Volume 21, Issue 1 , June 2014, , Pages 24-31
Abstract
This study was aimed to assess the applicability of LANDSAT ETM+ satellite images for estimating vegetation production and cover. The images were digitized using topographic maps and geometrized in 1:25000 scales. Required processes such as spectral ratio measurement and vegetation indices were applied ...
Read More
This study was aimed to assess the applicability of LANDSAT ETM+ satellite images for estimating vegetation production and cover. The images were digitized using topographic maps and geometrized in 1:25000 scales. Required processes such as spectral ratio measurement and vegetation indices were applied on the images. Collection was carried out for vegetation cover and production in various vegetation types in homogeneous units. Sampling points' locations were recorded with GPS. Sampling method was random-systematic in such a way that in each unit, a circle with 20 meters radius was considered. One and 9 sampling plots were placed on the centre and on the perimeter, respectively. The plot size was 1m * 1m. In each plot, vegetation percentage was estimated and the production was calculated using double sampling method. Then, DN values for each sampling unit (9 pixels for one unit) were elicited in respect to primary bands' images, vegetation indices and spectral ratios. Correlation and regression analyses between geo-information and satellite information (Digital numbers) were carried out. Results revealed that 7th and 5th Bands and IR1, MIRV2 and VNIR2 indices had a significant correlation with production and given parameter could be estimated through regression models. Likewise, RA, IR1 and TVI indices had a significant correlation with vegetation percentage and this parameter could be estimated through regression models.
Elham Fakhimi Abarghouie; Seyed Akbar Javadi
Volume 21, Issue 1 , June 2014, , Pages 109-118
Abstract
From the perspective of rangeland ecology, awareness of the effects of livestock grazing on the changes of structure, plant vegetation and soil characteristics is essential. The aim of this study was to determine the effect of different grazing intensities including heavy (0-200 m distance from water ...
Read More
From the perspective of rangeland ecology, awareness of the effects of livestock grazing on the changes of structure, plant vegetation and soil characteristics is essential. The aim of this study was to determine the effect of different grazing intensities including heavy (0-200 m distance from water point), moderate grazing (200- 800 m) and light grazing (800-1200 m) intensities on vegetation indices and soil characteristics in Nodushan region, Yazd province of Iran. For this purpose, plant vegetation cover and composition were recorded under three grazing intensities. Soil was sampled from depths of 0-30 cm. Data were analyzed by one way ANOVA, t-testandordination method (CCA) to assess the vegetation response in different grazing intensities. Results showed that plant species such as Astragalus achrochlarus, Salsola arbusculata and Tragopogon sp.were found in light grazing area.Allysum minus, Artemisia sieberi, Poa sinacia, Iris songarica, Lactuca glacifolia and Stipa barbata were identified in moderate grazing area. Eryngium sp., Cousinia desertii, Bromus tectorum and Peganum harmala were the major species in heavy grazing area.Soil properties including N, P, K, OC, EC and pH were measured. According to the results, nitrogen and soil organic matter were decreased by increasing grazing intensities but P, K, EC and pH were increased. Since grazing pressure causes damage to vegetation and some soil properties, a moderate grazing is recommended for sustainable utilization of rangelands.
Shokoufeh Shokrollahi; Hamidreza Moradi; Ghasem Ali Dianati Tilaki
Volume 19, Issue 4 , March 2013, , Pages 655-668
Abstract
Vegetation cover is one of the most important factors for sustainability of ecosystems, thus recognizing and understanding factors that affect establishment and distribution of vegetation communities are necessary. This study was aimed to determine the relationship between vegetation properties (vegetation ...
Read More
Vegetation cover is one of the most important factors for sustainability of ecosystems, thus recognizing and understanding factors that affect establishment and distribution of vegetation communities are necessary. This study was aimed to determine the relationship between vegetation properties (vegetation cover and density) and environmental parameters of rangelands. The study area was about 4600 ha, located at Polour, Mazandaran province. Land units were considered as the basis of research, and after preparing maps of slope, aspect, elevation, lithology and geomorphology and combining the maps, a single working map was generated. Systematic randomized sampling was used and performed along 3 transects of 100 m length. Ten quadrates of 1m2 were established along each transect at 10-meter intervals. Three soil samples were taken in each area and topography properties were recorded. Multivariate analysis and Canonical Correspondence Analysis (CCA) were used to determine relationship between soil and vegetation data using CANOCO software. Results showed that the percentage of canopy cover and density of the species was different and was influenced by soil properties and physiographic factors. Among physiographic factors, aspect and slope had a significant relationship whit vegetation cover and density. Among soil factors, texture, N, P, pH and litter were the most important factors that influenced vegetation cover, and OM, P, pH and Ec had the most influence on density.
Hassan Ghelichnia; Hosein Arzani; Mohammad Akbarzadeh; Mahdi Farahpour; Mojgan sadat Azimi
Volume 19, Issue 2 , September 2012, , Pages 203-220
Abstract
Rangeland assessment and recognizing changes in vegetation, yield and their affecting factors are of important issues for planning and optimum utilization management. Firstly in 2000, main habitats of Mazandaran province were determined and then a site was selected in each reference area for collecting ...
Read More
Rangeland assessment and recognizing changes in vegetation, yield and their affecting factors are of important issues for planning and optimum utilization management. Firstly in 2000, main habitats of Mazandaran province were determined and then a site was selected in each reference area for collecting statistical data. Vegetative factors (vegetation cover and yield) were measured in 10 sites along six transects of 200 meter length in sixty plots of one square meter. According to the results, maximum average percentage of vegetation cover (50.22) and maximum yield (417.87) were recorded for 2003. Minimum average percentage of vegetation cover (47.38) was obtained in 2001 and average yields of 391.46 and 391.63 were obtained in 2001 and 2002, respectively. Consequently, a relationship was found between vegetation cover percentage and yield with precipitation. Most of the sites in which average rainfall especially in late winter and spring of 2003 was more than that of the other years, higher average of canopy cover percentage and yield were recorded in the mentioned year. Also, livestock grazing management was effective on amount of yield and vegetation cover. The sites located in highlands showed a better condition due to the cool Mediterranean climate and higher precipitation and proper grazing management in rangelands. The condition of class I and class II species of these sites was better than that of downstream rangelands. In the sites located in lower regions with a cold semi-arid climate especially in sagebrush lands, range condition was lower than that of the highlands due to semi-arid climatic conditions and the use of rangeland in Spring and Autumn. Class III species were dominant in these sites. Precipitation affected all vegetative forms and for perennial grasses vegetation cover percentage and yield were affected. Since cushion plants were not considered in yield calculation, the increment of vegetation cover percentage had no effect on yield. Annual plants also affected the yield due to increased spring rainfall in some sites.
Asghar Kohandel; Hossein Arzani; Morteza Hosseini Tavassol
Volume 17, Issue 4 , November 2011, , Pages 518-526
Abstract
Different grazing intensities change the chemical and physical properties of soil and plant composition of rangelands. Accordingly, effect of livestock grazing intensities on soil and vegetation characteristics were investigated in the southeastern of Hashtgerd using Principal Component Analysis. Principal ...
Read More
Different grazing intensities change the chemical and physical properties of soil and plant composition of rangelands. Accordingly, effect of livestock grazing intensities on soil and vegetation characteristics were investigated in the southeastern of Hashtgerd using Principal Component Analysis. Principal Component Analysis is a statistical method for defining new variables based on a linear combination of original variables. Three 5-ha areas were selected in the study area under treatments of no, moderate, high and continuous grazing intensities. Afterward, vegetation and important physical and chemical soil characteristics including moisture, specific gravity, soil porosity, infiltration, mechanical resistance, nitrogen, phosphor, potassium, pH, EC, soil texture and organic matter were measured in three grazing treatments for two years (2004 and 2005). According to the results, increase of grazing intensity increased forbs while grasses and shrubs decreased. Among soil properities, soil porosity and Mechanical resistance decreasid and pH, EC and K had the highest relationship with grazing intensity.
Aazam Khosravi Mashizi; Gholamali Heshmati; Aadel Sepehri; Hossein Azarnivand
Volume 17, Issue 4 , November 2011, , Pages 549-563
Abstract
Considering previous studies which showed no significant relation between the distance from water point and total vegetation cover, in current research plant species were classified based on life forms (shrub, bush, perennial grass, perennial forbs and annual forbs) and palatability classes (I, ...
Read More
Considering previous studies which showed no significant relation between the distance from water point and total vegetation cover, in current research plant species were classified based on life forms (shrub, bush, perennial grass, perennial forbs and annual forbs) and palatability classes (I, P and PI). One way ANOVA was applied to determine the variations with distance from water point 8 main directions. Results showed that 8 main directions had no significant effect on vegetation cover and palatability classes of studied life forms. While life forms and palatability classes had different reactions to grazing according to the distance from water point. As shrubs, bushes, perennial grasses and palatability class I increased and annual forbs and palatability class PI decreased with distance from water point. Perennial forbs and palatability class P had uniform distribution. Using results of Duncan multiple range test a critical area was determined at 400 m distance from water point. In the mentioned critical area, shrubs and bushes showed a decrease in vegetation composition while annual forbs increased. Palatability class I also was eliminated in this area. According to the variations in perennial grasses and palatability classI, very sensitive to grazing, it can be concluded that grazing intensity had been very severe at a distance of 800-1000 m from water point.
Masoud Borhani; Hossein Arzani; Zahra Jaberolansar; Mojgan Azimi; Mahdi Farahpor
Volume 17, Issue 1 , September 2010, , Pages 1-20
Abstract
Range condition is known as an important indicator for assessment in range management. Many techniques have been exploited for determining this indicator, from which four-factor method has been used in this study. Some communities at stepic regions of Isfahan province were selected. In each selected ...
Read More
Range condition is known as an important indicator for assessment in range management. Many techniques have been exploited for determining this indicator, from which four-factor method has been used in this study. Some communities at stepic regions of Isfahan province were selected. In each selected community, an area was chosen as key area, and a total of eight sites were selected in the key areas. Soil erosion, canopy cover, plant composition, and plant vigor were monitored for each site. The results revealed a significant difference between the sites in terms of the above mentioned parameters, as well as their rainfall (p<0.01). Moreover, there was a significant correlation between annual precipitation and range condition score. The correlation showed different patterns within years in each site, where the difference between years was significant in terms of plant vigor and canopy cover, but non-significant in terms of soil erosion and plant composition. There was also a positive correlation between the trend of individual parameters and the overall condition score. Cluster analysis grouped Aluyjeh, Northern Shahreza, and Charmshahr sites in one branch, Mooteh, Shoorabad, and Golpayegan in another, and finally Komeshcheh and Southern Shahreza in a third branch. The lowest rank for canopy cover, canopy production and soil erosion belonged to Komeshcheh and Southern Shahreza sites. Aluyjeh, Northern Shahreza, and Charmshahr sites were in better condition than the previous group, yet in poor conditions, and the rest of the sites showed the best conditions among study sites. Generally speaking, Isfahan's stepic rangelands are ranked as poor to very poor, while their condition showed a constant trend.
Maryam Heidarian Aghakhani; Ali asghar Naghipour Borj; Hosein Tavakoli
Volume 17, Issue 2 , September 2010, , Pages 243-255
Abstract
It is important to know soil propoerties, particulary its chemical aspects, for the proper management of rangeland ecosystems. The aim of this study is to find the impact of grazing on vegetation and some soil chemical properties, in three areas, the key, reference, and critical, Sisab rangelands, Bojnord. ...
Read More
It is important to know soil propoerties, particulary its chemical aspects, for the proper management of rangeland ecosystems. The aim of this study is to find the impact of grazing on vegetation and some soil chemical properties, in three areas, the key, reference, and critical, Sisab rangelands, Bojnord. The vegetation cover data was collected from 30, 1m2 quadrats in each area through random –systematic method. The soil data was sampled from two depths 0-15, 15-30 cm and five composite samples were collected (each sample was mixed of six samples) from each depth in the each area. Some factors such as the organic carbon, the percentage of soil organic matters, total nitrogen, absorbable phosphorus, pH and EC were measured. The results showed that carbon, nitrogen, soil organic matters, phosphorus, and EC were been decreased by grazing, but pH was increased. According to results, forbs were the dominant life form in the reference site. Shrubs cover percentages were been increased as grazing increased. In addition, reference site had species that are more palatable and invaders were more abundant in critical area. It was concluded that heavy grazing intensity cause to decrease of vegetaton and conversion of composition of the species cause to negative conversion in alimentary mineral of soil, sustainable of ecosystem would be endangered.
Ebrahim Farahani; Mohammad Khosroshahi; Majid Hosseni; Seyamak Loghmani
Volume 14, Issue 4 , February 2008, , Pages 490-499
Abstract
Vegitation cover is one of the important environmetal factors which can determine desert areas. In this article, we determine desert areas in Tehran province by GIS. In the study area, dominant plant types and some of main ecological properties of them were assigned. Finally, by available information ...
Read More
Vegitation cover is one of the important environmetal factors which can determine desert areas. In this article, we determine desert areas in Tehran province by GIS. In the study area, dominant plant types and some of main ecological properties of them were assigned. Finally, by available information and public characteristics of every plant type, desert area was separated. In this area, we distinguish 43 plant groups that 7 types of them belong to desert areas. This area is 307647 hectares which is formed 16.43 % of Tehran province.
Golriz Hossienzadeh; Hamid Jalilvand; Reza Tamartash
Volume 14, Issue 4 , February 2008, , Pages 500-512
Abstract
Regarding to the importance and role of enclosure as an appropriate management in the natural resources, specially protection of vegetation cover and the soil of pastures, the effects of different grazing intensities on the vegetation cover changesand chemicalsoil properties in countryside pastures ...
Read More
Regarding to the importance and role of enclosure as an appropriate management in the natural resources, specially protection of vegetation cover and the soil of pastures, the effects of different grazing intensities on the vegetation cover changesand chemicalsoil properties in countryside pastures of Esklim Rood district (placed in west of Savad kooh township) was studied. These pastures investigated to reveal the effects of prohibition on the vegetation cover changes and some soil chemical properties at three conditions of Reference, Key and Critical areas. The results show that delicious (Class I) in the reference region, average delicious (Class II) in the key region, and low delicious or non delicious plants (Class III) in the critical region, have the most vegetation cover percentage. So that, perennial and delicious grasses such as Festuca ovina L, Ermopoa persica T. Dactylis glomerata L. had the highest vegetation cover percentage in the reference region but by the increase of grazing, delicious species decreased gradually and average or non delicious plants increased. This study revealed that soil of the reference region which had the highest density and vegetation cover had more organic material, total nitrogen, phosphorus, potassium, and less acid in the surface horizon than that of grazing region. Also, results show that short- term enclosure affected on the protection of soil and vegetation cover due to high productivity.