mina bayat; Hossein Arzani; adel jalili; hassan ghalij nia
Abstract
In this study the effects of three important factors: the climatic precipitation, temperature and relative humidity on the amount of canopy cover and forage production in a period of five years (1381-1385) and 1392 in semi-steppe rangelands Reineh and Polur in the Mazandaran province studied. The statistical ...
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In this study the effects of three important factors: the climatic precipitation, temperature and relative humidity on the amount of canopy cover and forage production in a period of five years (1381-1385) and 1392 in semi-steppe rangelands Reineh and Polur in the Mazandaran province studied. The statistical models (simple and multiple regression) to find the relationship between various forms of vegetative cover and annual forage plants using climate variables in different periods of time with Minitab.14 and Excel software was used for data analysis. The results of six years of study in a semi-steppe rangelands Polur and Reineh showed an average canopy cover of 51 percent and the average yield was 372 kg per hectare. The total vegetation cover of Rineh pastures had the most relation with a total rainfall of the growth season and the March and the average temperature. The temperature was more effectively than rainfall in annual yield. And The yield affected by July temperature. The total vegetation cover of polur had not significant relation with climate factors but each of the vegetation form in Different time base had significant relation. The total grazing species yield of plour affected by growth season rainfall. So instead of one year measurement of vegetation cover and production can be estimated the production and vegetation cover fluctuation according to climate parameters. With long-term vegetation cover and production data, can be determined the available forage and pasture capacity to prevent the range degradation.
fatemeh naghizadeh; mohammad jafari; hosein azarnivand; Mohammad Ali Zare Chahouki
Abstract
In this study, the role of soil properties in making difference between plant communitieswas examined. First, four plant types were identified, including Pteropyrumaucheri-Salsolarigida، Astragalus gossypinus - Acanthophyllum herateens، Amygdalus scoparia – Achilla millefolium and Ephedra intermedia ...
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In this study, the role of soil properties in making difference between plant communitieswas examined. First, four plant types were identified, including Pteropyrumaucheri-Salsolarigida، Astragalus gossypinus - Acanthophyllum herateens، Amygdalus scoparia – Achilla millefolium and Ephedra intermedia – Erigon capestra, through randomized systematic sampling and field survey in representative area of each type. In each plant type, three 500-meter transects were selected and in each transect, ten plots were placed along each transect. Characteristics of vegetation such as type and percentage of cover, gravel percentage, litter percentage and bare soil percentage were determined within each plot. In addition, in order to study the soil properties, at the beginning and at the end of each transect, a profile was dug and soil samples were taken from the depths of 0-20, 20-80 cm. Soil physical and chemical properties (texture, pH, electrical conductivity, organic matter percentage, gypsum percentage, lime percentage, salts such as sodium, potassium, calcium and magnesium, sodium absorption ratio, sodium exchange percentage) were determined in soil laboratory. Then, the role of soil properties in making difference between plant communitieswas determined by using ANOVA statistical analysis, and the key factors making this difference were introduced as sand percentage, organic matter percentage, and electrical conductivity.
Shafagh Rastgar; Hossein Barani; Ali Darijani; Vahedberdi Sheikh; Jamshid Ghorbani; Mohammad Ghorbani
Abstract
Vegetation cover as the main factor affecting the water erosion plays an important role in preventingsoil loss. To this end, for better understanding the impact of vegetation cover on soil erosion andsediment yield over the major existing geological formations in the summer rangelands of Balade inthe ...
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Vegetation cover as the main factor affecting the water erosion plays an important role in preventingsoil loss. To this end, for better understanding the impact of vegetation cover on soil erosion andsediment yield over the major existing geological formations in the summer rangelands of Balade inthe Mazandaran province, rainfall simulation studies have been carried out using a portable rainfallsimulator. Among many geological formations across the study area, the three major lithological unitsof mica sandstone, clay and shale sandstone with coal seams of “SHEMSHAK”, structures of tuffshale and dark gray to green shale with volcanic rocks of “KARAJ” and limestone of “LAR” havebeen selected as lowly, moderately and highly resisting formations to degradation. For eachcombination of geological formation and vegetation cover (low, moderate, and high density) threesampling plots of 1x1m have been selected and rainfall simulation has been conducted over them. Foreach plot, the surface characteristics including the vegetation cover, runoff and sediment yield and soiltexture were measured. The measured data were statistically analyzed. Results showed that“SHEMSHAK”, “KARAJ” and “LAR” formations were respectively ranked from highest to lowestwith respect to the volume and weight of sediment yield. Also, there was a strong inverse relationshipbetween vegetation cover percentage and volume of runoff and sediment for all investigatedgeological formations specially in poor vegetation situation that indicate interaction effects betweenvegetation cover and type of geological formations.
Fatemeh Hadian; Reza Jafari; Hossein Bashari; Saeed Soltani
Abstract
Because soil moisture condition affects vegetation changes hence, monitoring of drought and vegetation changes are among valuable management tools in these ecosystems. Nowadays, satellite images are used as a low-cost and fast method for vegetation study in different scales. Vegetation change is assessed ...
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Because soil moisture condition affects vegetation changes hence, monitoring of drought and vegetation changes are among valuable management tools in these ecosystems. Nowadays, satellite images are used as a low-cost and fast method for vegetation study in different scales. Vegetation change is assessed using vegetation spectral characteristics. This study aimed to analyze and monitor the vegetation cover changes in 4 rangelands and one forest type site in south of Isfahan and southeastern of Chaharmahal and Bakhtiary province during 1997-2009 ّField sampling were used for measuring the percentage of canopy cover in all vegetation types using step-point method in radial direction (6000 points per vegetation type). Regression analysis technique was used to ensure if vegetation cover can be measured properly using a Landsat images from 2009. Then NDVI indices were derived from 12 Landsat images between 1997 to 2009 (all images were taken from 22th of May to 5th of Jun each year) to monitor vegetation changes. According to results, there was significant correlation between NDVI indices and canopy cover in all vegetation types. Evaluating the canopy cover changes indicated that the precipitation had various effects on different vegetation types based on their plant form and ecological condition. T
Alibeman Mirjalili; Mohammad Musaei Sanjeraei; Shahabodin Zarezadeh Mehrizi
Abstract
A better understanding of rangeland vegetation cover and its variation in different years basedon wetness and droughtiness fluctuations is a great importance. Economical priority setting ofrangelands is based on variations in rainfall and drought patterns, because it yields to bettercharacterization ...
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A better understanding of rangeland vegetation cover and its variation in different years basedon wetness and droughtiness fluctuations is a great importance. Economical priority setting ofrangelands is based on variations in rainfall and drought patterns, because it yields to bettercharacterization of vegetative cover. Yet a comprehensive and continuous monitoring ofvegetative cover of rangelands has not been established. To study the influence of droughtinessand wetness on vegetation cover and production forage, 11 sampling areas and 3 referenceareas were selected in Herat. Three 100-m transects were located 25-m apart within eachsampling area. Production and cover were estimated within 10 located 2- plots along eachtransect. Data were analyzed using Duncan›s test Design a completely random with a factorialGLM procedure at 99% and 95% confidence levels. Results showed that the vegetation coverand production in wetness were significantly different from those in droughtiness (P<0.01).The vegetation production and cover increased by 36.3% and 34% respectively in the wetnesscompared to the droughtiness. The influence on production and cover was positive and efficientin the wetness with the average rainfall higher than the 30-yr average. Finally, the results offlood spreading increased vegetation cover and production forage in dams.
Fazel Amiri; Hassan Yeganeh
Abstract
فرآیند ارزیابی پوشش گیاهی به وسیلة تصاویر ماهوارهای نیازمند استفاده از شاخصهای گیاهی است. شاخص گیاهی بطور گستردهای برای ارزیابی و پایش تغییرهای بو شناختی (اکولوژیک) ...
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فرآیند ارزیابی پوشش گیاهی به وسیلة تصاویر ماهوارهای نیازمند استفاده از شاخصهای گیاهی است. شاخص گیاهی بطور گستردهای برای ارزیابی و پایش تغییرهای بو شناختی (اکولوژیک) مانند پوشش گیاهی، بیوماس پوشش سطح خاک و شاخص سطح برگ استفاده میشود. اهداف این مطالعه شامل بررسی قابلیت دادههای ASTER به منظور برآورد پوشش گیاهی در حوزه آبخیز قره آقاچ و همچنین انتخاب شاخصهای گیاهی مناسب در تهیه نقشه پوشش گیاهی منطقه، میباشد. پیشپردازشهای مختلف شامل تصحیح هندسی با استفاده از تصاویر موجود مربوط اردیبهشت 1387 با RMSE حدود 5/0 پیکسل انجام شد و تصحیحات اتمسفری و توپوگرافی به ترتیب به کمک روش تفریق عارضه تاریک و مدل لامبرت انجام شد. از شاخصهای گیاهی و طبقهبندی نظارت شده برای تهیه نقشه پوشش گیاهی استفاده شد. عملیات برداشت زمینی در اردیبهشت ماه 1387 در سطحی معادل 25/8962 هکتار آغاز شد. تیپهای مختلف گیاهی به روش نمونهبرداری سیستماتیک- تصادفی، سطحی که اختلاف مهمی در ترکیب فلورستیک- فیزیونومیک نداشت، به عنوان تیپ گیاهی مستقل و یکنواخت در نظر گرفته شد. در کل منطقه حدود 60 نقطه تصادفی انتخاب و اندازهگیری پوشش گیاهی به روش برآورد انجام گرفت. اطلاعات رقومی و شاخصها به عنوان متغیر مستقل و اطلاعات زمینی به عنوان متغیر وابسته معرفی شدند. معادلات مختلف با استفاده از شاخصها بر روی تصاویر اعمال و سپس تصاویر به 5 کلاس پوشش طبقه بندی شد. در نهایت نقشه پوشش و نقاط نمونهبرداری برای بررسی صحت نتایج، کنترل گردید. نقشه پوشش منطقه با اعمال پردازشهای گوناگون بر روی تصویر تهیه گردید. با بهره گیری از سامانه اطلاعات جغرافیایی تمام لایههای اطلاعاتی با یکدیگر ترکیب و نقشه پوشش اراضی منطقه تهیه شد. نتایج این پژوهش نشان داد که، شاخص NDVI همبستگی بالایی با درصد پوشش گیاهی داشت (01/0P?). صحت کلی و ضریب کاپا برای نقشه پوشش با شاخص NDVI به ترتیب برابر 5/68 % و 4/72 % بدست آمد. نتایج این مطالعه نشان داد که پوشش گیاهی با درصد تاج پوشش 40-20 درصد، وسیعترین طبقه تراکمی پوشش این منطقه میباشد. نتایج این پژوهش همچنان نشان داد که تصاویر سنجنده ASTER و شاخصهای گیاهی ابزار قدرت مناسبی برای تهیه نقشه پوشش گیاهی میباشد. بنابراین، می توان از نقشه پوشش تهیه شده از دادههای ASTER برای برآورد پوشش و تولید و ارزیابی مراتع استفاده کرد.
