Reza Tamartash
Volume 19, Issue 3 , December 2012, , Pages 469-481
Abstract
In mountainous rangelands, there is a complex combination of factors such as topography, vegetation growth stages and water distribution which affect grazing distribution. This research was conducted to investigate the effect of topography on vegetation of summer rangelands of Vaz, Mazandaran province. ...
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In mountainous rangelands, there is a complex combination of factors such as topography, vegetation growth stages and water distribution which affect grazing distribution. This research was conducted to investigate the effect of topography on vegetation of summer rangelands of Vaz, Mazandaran province. Five utilization units were selected on the basis of field survey and identifying homogenous grazing units. Key areas were obtained in each unit and sampling was done randomly. Size of the quadrates was 1m2 and the number was calculated by statistical method. In each quadrate, yield was measured by clip and weigh method and utilization rate was determined using height to weight ratio (based on dry weight). Vegetation cover percentage was also recorded. Finally, comparison of plant characteristics in utilization units was performed by SPSS in a completely randomized design with unequal replications. Then, correlation coefficient between each of the independent variables (slope, aspect and height) and dependent variables (yield, canopy cover percentage and utilization) was determined. Also, the most effective factor and interaction effects of independent variables were obtained by stepwise multiple regression analysis. Results showed that slope and aspect had the most correlation with livestock utilization respectively, but no relationship was found for elevation while it affected yield and canopy cover.
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 ...
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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.
Maliehe Oushib Nataj; Hasan Shekarchi; Maryam Keshavarzi,; Mohammad Akbarzadeh
Volume 18, Issue 1 , May 2011, , Pages 90-106
Abstract
Autecology is the study on behavior and performance of a plant species and its relationship with other living and non living components of a habitat. These kinds of studies provide basic information for management in rangeland ecosystems. In the current research, autecology of Lolium perenne was studied ...
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Autecology is the study on behavior and performance of a plant species and its relationship with other living and non living components of a habitat. These kinds of studies provide basic information for management in rangeland ecosystems. In the current research, autecology of Lolium perenne was studied in Mazandaran province. Geographical distribution, phenology, companion species, dryness index, edaphic and climatic parameters were considered as effective factors on distribution of Lolium perenne. According to the results, the altitude range for the mentioned species was from -22 to 1700 m above sea level. This species is frequently found in different places like road sides, irrigation canals, clay slopes, rocky and sandy hills, and also as a weed in farm fields. Presence percentage in lowlands was also more than that in uplands. Lolium perenne is resistant to cold and harsh conditions and grows mainly in humid to sub humid climates and alpine to Mediterranean and semi-arid habitats. Our results indicatedthat Lolium perenne prefers clay, clay loam, loamy sand, silty clay loam and silty clay soils. These observations show that Lolium perenne can grow in a wide range of ecological conditions.
Shahram Khalighi Sigaroudi; Ali Sadeghi Sangdehi; Khaled Awsati; Usef GHavidel Rahimi
Volume 16, Issue 1 , December 2009, , Pages 44-54
Abstract
Annual rainfall data related to a 26 year period from a number of Mazandaran climatological stations were employed to analyze and model the precipitation toward a determination of drought as well as wet years. Results indicate the occurrence of different intensity drought phenomenon in all stations. ...
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Annual rainfall data related to a 26 year period from a number of Mazandaran climatological stations were employed to analyze and model the precipitation toward a determination of drought as well as wet years. Results indicate the occurrence of different intensity drought phenomenon in all stations. As regards the classification of the annual wet and dry years, normal precipitation among various alternate dry and wet years can be observed with the normal years having more stability and continuity as compared to wet and dry years. The Standardized precipitation Index (SPI) was recognized better and more accurate model compared to the other models because of more potential such as high sensitivity to precipitation variation and more punctual separating of drought and wet year classes in every events.
Shirvan Razaghi Kamroodi; Mohammad Akbarzadeh
Volume 9, Issue 2 , September 2001, , Pages 523-536