fa اثر حفاظتی گلسنگ در حفظ رطوبت و تعدیل نوسانات دمایی خاک مستعد فرسایش بادی مدلسازی و تحلیل زمانی و مکانی رخداد انواع مختلف فرسایش محیطی مستخرج از پایان‌نامه / رساله / طرح پژوهشی <strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">فرسایش خاک از جمله فرآیندهای تخریبی مناطق خشک و نیمه&shy;خشک است که بیابان&shy;زایی را در بخش بزرگی از منطقه در پی دارد. </span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">حضور پوسته&shy;های زیستی از جمله گلسنگ&shy;ها در مراتعی که خاک آن به طور بالقوه از توان بالایی برای فرسایش بادی برخوردار است، به دلیل کاهش فرسایش اهمیت دارد؛ بنابراین، </span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">در تحقیق حاضر تأثیرگذاری گلسنگ&shy;ها بر دو عامل مؤثر بر فرسایش یعنی رطوبت و درجه&shy;حرارت خاک در فصول مختلف بررسی شده&shy;است. به این منظور رطوبت خاک دارای گلسنگ و بدون گلسنگ در چهار بازه&shy;ی زمانی با استفاده از رطوبت&shy;سنج (</span></span></strong><strong><span dir="LTR"><span style="font-family:times new roman,serif;">TDR</span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">) اندازه&shy;گیری شد و درجه&shy;حرارت خاک دارای گلسنگ و بدون گلسنگ در سه فصل مختلف با استفاده از دماسنج تکمه&shy;ای. نتایج به دست آمده از مدل خطی ترکیبی عمومی و آزمون توکی با استفاده از نرم&shy;افزار </span></span></strong><strong><span dir="LTR"><span style="font-family:times new roman,serif;">R</span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">، نشان داد که از بین عوامل تیمار و فصل، فصل مهم&shy;ترین عامل مؤثر بر رطوبت خاک است. میزان رطوبت خاک دارای گلسنگ و خاک لخت در فصل زمستان تفاوت چندانی با هم نداشت، اما در طول فصل بهار و تابستان میزان رطوبت گلسنگ از خاک لخت بیشتر بود. همچنین نوسان دمایی گلسنگ </span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">(</span></span></strong><strong><span style="font-family:b compset;">4- 23</span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;"> درجه&shy;ی سانتی&shy;گراد) </span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">در دو فصل بهار و تابستان کمتر از خاک لخت </span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">(</span></span></strong><strong><span style="font-family:b compset;">5/3 </span></strong><strong><span style="font-family:times new roman,serif;">&ndash;</span></strong><strong><span style="font-family:b compset;"> 35</span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;"> درجه&shy;ی سانتی&shy;گراد) </span></span></strong><strong><span style="font-family:b compset;"><span style="font-size:12.0pt;">است و در آخر زمستان بین دو تیمار تفاوت معنی&shy;داری مشاهده نمی&shy;شود. از نتایج این تحقیق می&shy;توان در تحلیل چگونگی نقش گلسنگ&shy;ها در حفظ رطوبت و درجه&shy;حرارت خاک استفاده کرد.&nbsp;</span></span></strong> <strong>Extended abstract</strong><br> &nbsp;<br> <strong>1- INTRODUCTION</strong><br> &nbsp;<br> Soil erosion is one of the most destructive processes of arid and semi-arid areas, which leads to desertification in a large area of the region. In windy areas, the wind in the region increases the probability of wind erosion. Soil moisture and soil temperature are the two effective factors in soil erosion control. Vegetation is also one of the effective factors in maintaining moisture, but in the arid and semi-arid areas where vegetation is distributed and&nbsp; Scattered, biological soil crusts between dispersed vegetation can be effective in maintaining moisture and soil temperature. Currently, the results of the effects of biological soil crusts on the moisture and soil temperature are contradictory, and these opposite results may be due to differences between different types of crusts or different climatic conditions. Rangeland is one of the most important sources of sediment production, so studying the factors affecting the process of reducing soil erosion is very importantt. The aim of this study is to evaluate the effectiveness of lichens in maintaining moisture, soil temperature and wind erosion control.<br> &nbsp;<br> <strong>2- THEORETICAL FRAMEWORK</strong><br> &nbsp;<br> It is expected from the lichens, due to their unique characteristics and structures, to increase the amount of moisture and reduce the temperature of the soil during warm and dry seasons. So far, the role of lichens in different seasons has not been studied on microhabitat characteristics and wind erosion control, so we need to know how the lichens act in maintaining moisture and modulating the temperature fluctuations.<br> &nbsp;<br> <strong>3- METHODOLOGY</strong><br> &nbsp;<br> The study area is located in the steppe rangelands of Golestan National Park. The wind speed is relatively high in this region and the dominant vegetation of the region is <em>Artemisia</em><em> Sieberi </em>which is distributed sporadically in the region<em>, </em>in free space sparse vegetation, lichens are present in the form of a patch. Soil moisture under the lichen and bare soil during 4 time intervals using a moisture meter and also minimum, maximum, mean and diurnal temperature fluctuations (DTF) soil under lichen and bare soil during the three different seasons were measured using the thermometer ibutton. To determine the most important factor affecting soil moisture and temperature including treatments, season and their interactions, GLMM was applied and Tukey test was used to compare the means.<span dir="RTL"></span><br> &nbsp;<br> <strong>4- RESULTS</strong><br> &nbsp;<br> According to GLMM results, the season (F= 182.41; P < 0.0001) had the highest significant impact on soil moisture. The mean comparison results indicate that soil moisture content of lichen and bare soil did not differ significantly in winter, but during the spring and summer, the moisture content of the lichen was higher than bare soil. The temperature fluctuations of lichen (4-23&deg; C) in spring and summer are lower than bare soil (3.5-35 &deg; C) and at the end of winter there is no significant difference between two treatments. The maximum temperatures were observed in the bare soil and the minimum temperatures in both lichen and bare soil treatments were the same. Therefore, the temperature equilibrium created by the lichen is higher than the bare soil.<span dir="RTL"></span><br> &nbsp;<br> <strong><span dir="LTR">5- CONCLUSIONS & SUGGESTIONS</span></strong><br> Biological soil crusts are important in maintaining soil moisture, so that high humidity can be effective in reducing temperature and erosion control. Lichens with mucilage secretion, the aggregate stability increases so that soil moisture amount is increased and soil erosion decreases. Also biological soil crusts affect the temperature equilibrium, the temperature equilibrium created by biological soil crusts in the warm and cold seasons, improves the water status, available food, soil structure, decreases erosion and controls desertification. The reason for the decrease in the degree of soil temperature by biological soil crusts is related to the evaporation rate, so when evaporation increases, it causes more water to exit. In addition, most of the dominant lichens in the area have light color, which has a significant role in reducing the degree of soil surface temperature. پوسته زیستی خاک, درجه‌حرارت,رطوبت, گلسنگ, مرتع. Biological Soil Crust, Temperature, Moisture, Lichens, Rangeland. 71 86 http://magazine.hormozgan.ac.ir/browse.php?a_code=A-10-449-2&slc_lang=fa&sid=1 Negar Ahmadian نگار احمدیان n.ahmadian1993@gmail.com 10031947532846005108 10031947532846005108 No Tarbiat Modares University دانشگاه تربیت مدرس Mehdi Abedi مهدی عابدی abedimail@gmail.com 10031947532846005109 10031947532846005109 Yes Tarbiat Modares University دانشگاه تربیت مدرس Mohamad Sohrabi محمد سهرابی mycolichiran2010@gmail.com 10031947532846005110 10031947532846005110 No Tarbiat Modares University سازمان پژوهش‌های علمی و صنعتی ایران