Eshagh Omidvar; Hossein Arzani; Saeed Mohtashamnia; Seyed Akbar Javadi; Mohammad Jafary
Volume 28, Issue 1 , April 2021, , Pages 1-10
Abstract
Regardless of rangeland plant production, it is not possible to plan and manage livestock and rangeland. Attention to rangeland forage production is essential for efficient and effective rangeland management. This importance is determined by identifying the relationship between forage ...
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Regardless of rangeland plant production, it is not possible to plan and manage livestock and rangeland. Attention to rangeland forage production is essential for efficient and effective rangeland management. This importance is determined by identifying the relationship between forage production of plants and climatic variables which affect them in the field. For this purpose, the annual forage production values of rangeland index species were measured in Omidabad Eastern site during the years of 1998-2008 for 10 years in the national plan for rangeland assessment of different climatic zones and their re-measurement during the years of 2017-2018 for two years by cutting and weighing in 60 random plots of two square meters along four 300-meter tracts. The amount of rainfall and monthly temperature in this time interval were also calculated using the data of Abadeh meteorological station in all months separately each year. The amount of annual dry forage production of each species as a dependent variable and the amount of rainfall and temperature calculated as independent variables and relationships between them were investigated using a linear multivariate regression program in SPSS software. The results showed that rainfall, winter, and fall temperatures had a significant effect on species production and spring rains as well as the temperature of the growing season, in April and May, alone did not affect the forage production of the species and based on the results research, with the availability of rainfall and temperature data, the annual forage production of the studied species and the annual production of the coming years can be estimated with high accuracy.
Negar Ahmadian; Mehdi Abedi; Mohammad Sohrabi
Volume 26, Issue 2 , July 2019, , Pages 474-486
Abstract
In Golestan National Park Steppe Rangelands, a variety of shrub plants such as Artemisia are sporadic, and terrestrial surfaces between these plants are covered by biological soil crusts (including moss and cyanobacteria). These crusts are known as a critical factor in ...
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In Golestan National Park Steppe Rangelands, a variety of shrub plants such as Artemisia are sporadic, and terrestrial surfaces between these plants are covered by biological soil crusts (including moss and cyanobacteria). These crusts are known as a critical factor in arid and semi-arid areas. The effects of them on the moisture and temperature of soil, which play a very important role in ecological and hydrological processes, are still not well-known. In order to know more about this, the effects of moss and cyanobacteria on moisture and temperature regimes and the effect of Artemisia shrub on moisture regimes were investigated. The soil moisture content was measured at four times: first winter, last winter, spring, and summer using a moisture meter (TDR), and soil temperature was recorded in three different seasons: last winter, spring ,and summer using a thermometer for 117 days with two-hour intervals. The most important factor affecting soil moisture and soil temperature was the season, which was determined using a general linear mixed model. Based on the results, the ability to maintain the cyanobacteria moisture content is higher than that of moss and Artemisia shrubs treatments, as well as the daily fluctuation of soil temperature under cyanobacteria (4/3 °- 35 ° C), more than moss (4/25 ° -26 ° C).
Saeed Rashvand; Ali Ehsani; Hasan Yeganeh; Anvar Sour
Volume 21, Issue 4 , March 2015, , Pages 591-603
Abstract
Knowledge of the phenological stages of species constituting a plant community has a considerable importance in grazing management to achieve the goals of sustainable production. The study of plant phenology is critical for monitoring, management and conservation of ecosystems. In this research, ...
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Knowledge of the phenological stages of species constituting a plant community has a considerable importance in grazing management to achieve the goals of sustainable production. The study of plant phenology is critical for monitoring, management and conservation of ecosystems. In this research, the phenology of two shrub species including Artemisia aucheri and Thymus kotschyanus was investigated for four years during 2007 to 2010. For this purpose, 10 samples were selected from each species and the phenological data were recorded every 15 days and every 7 days in the vegetative and reproductive stages, respectively. Results showed that the start and end time of growth in different years in these two species differed under the influence of temperature and precipitation. The flowering stage of Thymus kotschyanus began in the first half of June, and the seeding stage started in the first half of July, continuing to the first half of August.The vegetative growth of Artemisia aucheri started from the second half of May, the flowering stage began in the late August and the seeding stage started from the last week of September, continuing for 2-3 weeks.
Ali Ehsani; Mamak Ahmadian; Saeed Rashvand; Mohammad Ali Dehghani Tafti; Mostafa Zare
Volume 21, Issue 1 , June 2014, , Pages 13-23
Abstract
Study of the phenology of range key species is important to regulate and apply proper management for sustainable utilization of rangeland forage. In this study, the phenological stages of Artemisia aucheri were examined as a key species at three sites of different semi-steppe regions during 2007-2010. ...
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Study of the phenology of range key species is important to regulate and apply proper management for sustainable utilization of rangeland forage. In this study, the phenological stages of Artemisia aucheri were examined as a key species at three sites of different semi-steppe regions during 2007-2010. For this purpose, in each site, 10 individuals were selected and different phenological stages were recorded in 15-day and 7-day intervals for vegetative stage and reproductive stage, respectively. In addition, meteorological data including temperature and precipitation were recorded from the nearest synoptic station for each site. Results indicated that the occurrence of phenological phenomena of Artimisia aucheriwas more affected by temperature and precipitation indices of the growing season. According to the obtained results, the start and end of grazing were determined as early May to late October for Shirkooh (Yazd province), late May and early June to mid-July for Anjadan (Markazi province), and second half of May to mid September for Alamoot (Ghazvin province). Consequently, a complete understanding on the phenological stages of Ar. aucheri enables us to plan grazing management in order to determine the time of livestock entry into and exit from rangelands, optimal number of livestock for grazing and proper grazing systems.
Mostafa Jafari
Volume 21, Issue 1 , June 2014, , Pages 139-153
Abstract
Iran faced with climate and environmental changes in past years and it is projected that some climatic changes will occur in the future. Net Primary Production (NPP) is an important index to evaluate production in natural ecosystems including forest, rangeland and desert. Climate change impact will cause ...
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Iran faced with climate and environmental changes in past years and it is projected that some climatic changes will occur in the future. Net Primary Production (NPP) is an important index to evaluate production in natural ecosystems including forest, rangeland and desert. Climate change impact will cause changes in biomass production in natural ecosystems. In this research, the vulnerability of NPP in Iranian forest, rangeland and desert ecosystem has been considered. Results of this consideration presented here in six selected climatic zones in Gilan, Mazandaran, East Azerbyjan, Kermanshah, Khorasan and Systan and Baluchestan provinces. According to the result outcomes, total NPP of forest, rangeland and desert ecosystem in Gilan, East Azerbyjan, and Khorasan provinces, under temperature and precipitation changes, has been increased in the year ended 2039. While, the amount of NPP in Mazandaran, Kermanshah, and Systan and Baluchestan provinces would have been decreased. These changes in Khorasan provinces (including North, South and Razavi) will show highest increase, indicating suitable increase of precipitation and temperature in the region. Quantitative changes in NPP depend on total biomass and changes of precipitation and temperature. As an example, these changes in forest ecosystems of Gilan, and Khorasan provinces, will increase and in Mazandaran, and Kermanshah provinces, will decrease. Also, these changes in range ecosystems of East Azerbyjan, and Khorasan provinces, will increase and in Kermanshah, and Systan and Baluchestan provinces, will decrease. While, changes in desert ecosystems of Khorasan provinces mainly will increase and in Systan and Baluchestan provinces, will decrease.
Manuchehr Farajzadeh; Aman alah Fathnia; Bohlul Alijani; Parviz Zeaiean
Volume 18, Issue 1 , May 2011, , Pages 107-123
Abstract
The aim of this research was to evaluate the effect of climatic factors on vegetation in rangelands of Zagross with normalized difference vegetation index (NDVI) derived from Advanced Very High Resolution Radiometer (AVHRR) sensor, and climatic data. The study area was rangelands of Zagross with ...
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The aim of this research was to evaluate the effect of climatic factors on vegetation in rangelands of Zagross with normalized difference vegetation index (NDVI) derived from Advanced Very High Resolution Radiometer (AVHRR) sensor, and climatic data. The study area was rangelands of Zagross with 51-75, 26-50 and 10-25 density. Satellite images and climatic factors were respectively studied from January to October 2006 and from September 2005 to October 2006. Effects of seven monthly climatic variables (precipitation, temperature and relative humidity (maximum, mean and minimum) were studied on monthly NDVI. Zoning was performed by geostatistical method and Multivariate Ordinary Least Squares regression (MOLS) was applied to study the effect of climatic factors on vegetation changes. According to the Results CO-Kriging was identified as the best method for zoning, and Inverse Distance Weighting (IDW) only in mean temperature showed a better distance. Vegetation responses to precipitation of last two months, and temperature and relative humidity of last one month. Results of MOLS showed higher correlation in rangelands with a density of 51-75 %, but generally, correlation was low in rangelands with a density of 10-25 %, that can be due to the low altitude from sea level, effect of soil background and agricultural field margins. Also, low height in rangelands with a density of 10-25 % increased the temperature and transferred the start of leaf greenness to March, while in rangelands with a density of 51-75 % greenness started in May. The highest and lowest R2 values were calculated as 0.6478 for dense rangelands in May and 0.136 for low density rangelands in August.