پاسخ گونه مرتعی اسپرس کپه داغی (.hedysarum kopetdaghi boriss) نسبت به برخی گرادیان‎های محیطی در رویشگاه‌های طبیعی استان خراسان رضوی

معرفی گونه های گیاهی مناسب و مطالعه رفتار آ‌‌ن‌ها نسبت به عوامل اکولوژیکی، راهنمای موثری در برنامه های مدیریتی در اراضی دیم با هدف تولید علوفه و پایداری تولید غلات و همچنین اصلاح و احیای مراتع تخریب شده است. با توجه به تولید علوفه مناسب و اندمیک بودن گونه اسپرس کپه داغی (hedysarum kopetdaghi boriss.)، پاسخ این گونه به برخی از متغیرهای خاک و توپوگرافی، در رویشگاه‌های غالب گیاه در ارتفاعات شمالی رشته کوه‌های بینالود (کلاته آهن) و هزار مسجد (مریچگان) استان خراسان رضوی با استفاده از مدل‌‌جمعی تعمیم‌‌یافته (gam؛ generalized additive models) مورد مطالعه قرار گرفت. نتایج نشان دادند که الگوی پاسخ این گونه در امتداد شیب درصد لاشبرگ سطح خاک و آهک خاک، از مدل افزایشی (monotonic increase)، پیروی کرده، لذا با افزایش مقادیر این عوامل، فراوانی و درصد پوشش ‌‌گیاهی آن نیز بیشتر می‎شود. برعکس، پاسخ این گونه در امتداد شیب درصد سنگ و سنگریزه سطح خاک، از مدل کاهشی (monotonic decrease) و در امتداد شیب درصد شن، درصد عصاره اشباع و اسیدیته خاک، از مدل زنگوله‌‌ای (unimodal) و در پاسخ به درصد سیلت و کربن آلی خاک از مدل دو نمایی (bimodal) پیروی کرد. نتایج همچنین نشان دادند که میانگین تولید علوفه خشک این گونه در رویشگاه‌های مورد مطالعه برابر 38/5 گرم در بوته بود. این گونه عمدتاً در خاک‌های لومی شنی تا لومی سیلتی پراکنش دارد. حد بهینه رشد آن برای درصد شن، درصد عصاره اشباع به‌‌ترتیب 50، 35 و برای اسیدیته خاک، 7.8 است. رابطه بین تراکم گونه با ارتفاع از سطح دریا تا حدی افزایشی است، امّا پس از آن با افزایش ارتفاع به بیش از 1700 متر روند نزولی دنبال می‎کند. با توجه به نتایج فوق، کشت این گیاه به‌عنوان یک علوفه خوش‌خوراک در دیم‌زارهای کم‌بازده با میزان بارندگی بالاتر از 200 میلی‌متر توصیه می‎شود.

Kopetdaghi Sainfoin (Hedysarum kopetdaghi Boriss.) as a Rangeland Plant Response to some Environmental Gradients in Nature Habitats of Khorasan Razavi Province

Introduction[1]A significant area of the country’s rangelands has been destroyed, or their population has been severely reduced due to various factors such as uncontrolled exploitation, climate change, and other factors. Irregular and outofseason grazing in different regions and the mismatch of the number of livestock with forage production capacity in the country’s rangelands has reduced the population of edible plants in a region and reduced livestock’s power supply in the country. Hedysarum kopetdaghi plant is an important species that grows in the rangeland ecosystems of North Khorasan, Khorasan Razavi, and Golestan provinces. It is one of the highquality perennial herbaceous species that is mainly seen as a companion species in combination with summer pasture types in the country’s northeast. The forage of this plant is of good quality and is grazed in all vegetative and reproductive stages. Considering the importance of forage, determining ecological factors affecting vegetation changes and examining the response of this species to changes in ecological factors in different ecological conditions, and determining the different stages of growth of this species in Khorasan Razavi province was studied by generalized Additive Model (GAM). Materials and MethodsKopetdaghi sainfoin (H. kopetdaghi) responses to some environmental gradients were studied ‎in its natural habitat in the northern heights of Binalood )Kalate Ahan( and the heights of Hezar Masjed (Marichgan), respectively. Vegetation sampling was done by the systematicrandom method. The plant growth calendar (phenology) was recorded in different stages of vegetation, flowering, maturation, and seed fall, plant drying, and the phenological diagram of the plant were drawn in accordance with the Embrothermic curve. At the data preparation stage, initially the nominal and sequential variables such as soil texture and the relative data in the column related to each factor were identified. Generalized Additive Model (GAM) was used to investigate the response of this species to soil and topographic factors. The percentage of canopy cover of O. chorassanica was used to explore the relationship between species and the environment, and the ecological range was calculated as a function of the Gaussian response. Results and DiscussionThe results indicated that H. kopetdaghi is more distributed on sandy loam to silty loam soils. It has the highest yield in moderate amounts of sand (about 50%) and silt (about 35%). The results also showed that the relationship between the density of H. kopetdaghi and altitude (m. ASL) increases but then decreases with increasing altitude more than 1700 meters. It seems that altitude is a limiting factor (e.g. decreasing temperature and increasing light intensity) that affects species distribution. The response pattern of H. kopetdaghi along the gradient of litter and lime percentage of the soil followed the monotonic increase model, but along the gradient of the soil stones and pebbles, percentage followed the monotonic decrease model. The results also showed that the range of H. kopetdaghi canopy cover was 0.5%1.82%, the density was 0.050.21 plants m2, and dry biomass was 2.146.64 g.m2, and the mean of ‎dry forage yield was 38.5 g.plant1. ConclusionOverall, this study indicated ‎that H. kopetdaghi showed a significant response to changes in factors such as soil texture, saturation moisture content, lime percentage, organic carbon content, acidity, soil slope percentage, and litter percentage of soil surface. Among these factors, soil texture, lime content, and soil saturation moisture content are the most important factors affecting the presence and performance of this species, which can provide valuable information for the use of this species in degraded rangeland operations in areas with similar ecological characteristics. According to the above results, the cultivation of H. kopetdaghi is recommended as a palatable forage in lowyielding drylands with precipitation more than 200 mm. It is necessary to continue research on planting this species as well as its role in forage production and sustainable production in rainfed grains.