اثر فرسایش آبی بر تنوع زیستی خاک در اکوسیستم‌های خشک

نوع مقاله : علمی -پژوهشی

نویسنده

استادیار گروه جغرافیا، دانشکده ادبیات و علوم انسانی، دانشگاه فردوسی مشهد

چکیده

فرسایش خاک به عنوان یک فرایند ژئومورفیک علاوه بر تلفات خاک، اثرات شدیدی بر تنوع زیستی خاک دارد. دینامیک تنوع زیستی خاک می­تواند شاخصی برای ارزیابی میزان سازگاری اکوسیستم­ها در برابر تغییرات محیطی باشد. از آنجا که اکوسیستم­های خشک و نیمه­خشک نقش مهمی در انتشار کربن به اتمسفر دارند، عملکرد فرآیندهای فرسایشی می­تواند شرایطی را برای توقیف کربن و متعاقباً اثرات مثبت در راستای افزایش سازگاری این اکوسیستم­ها در برابر تغییرات محیطی فراهم آورد. در این مطالعه با هدف بررسی اثرات فرسایش آبی بر تنوع میکروبی خاک، نمونه­های خاک از بخش­های مختلف سه مخروط افکنه برای اندازه­گیری فعالیت­های آنزیمی، کربن زیست توده میکروبی، کربن آلی، کربن آلی ناپایدار (محلول)، توزیع اندازه ذرات خاک و رطوبت خاک برداشت شد. نتایج نشان داده است، میزان کربن آلی و نیتروژن کل در سایت­های رسوبی به­طور معنی­داری کمتر از سایت­های فرسایشی بوده است. در حالی که بیشترین میزان کربن آلی محلول و کربن زیست توده میکروبی در سایت­های رسوبی دیده شده است. همچنین در مقایسه با سایت­های فرسایشی، فعالیت آنزیم­ کاتالاز بیشترین مقدار را در نمونه­های مربوط به سایت­های رسوبی نشان داده است. براساس این یافته­ها، معدنی شدن و تجزیه کربن آلی در سایت­های فرسایشی و رسوبی به شدت مرتبط با تغییر در ویژگی­های بیوژئوشیمیایی خاک است. به طوری­که از مجموعه ویژگی­های زیستی خاک، اثرگذاری کیفیت کرین در افزایش ارتجاع پذیری اکوسیستم­ها بسیار مهم‌تر از کمیت کرین می­باشد.

کلیدواژه‌ها

عنوان مقاله [English]

Impact of water erosion on soil biological diversity in arid ecosystems

نویسنده [English]

  • neda mohseni
Assistant Professor, Department of Geography, Faculty of Letters and Humanities, Ferdowsi University of Mashhad
چکیده [English]

Soil erosion is a geomorphic process that can increase soil losses and affect the dynamics of soil biological diversity. Soil biological diversity can considers as an indicator for assessing adaptation rate of arid ecosystems against environmental changes. This study evaluates variations in soil microbial diversity and physiochemical properties in erosional landscapes. Since, arid and semi-arid ecosystems have a critical role in flux of carbon dioxide to atmosphere; many erosional landforms belonging to these ecosystems can occur a condition for sequestrating carbon and subsequently positive impacts for increasing resilience level against environmental harshness. One of the common landforms in arid landscapes is alluvial fan. Soil samples were collected from different topographic positions of the three alluvial fans for measuring enzyme activities, particle size distribution, soil water, soil microbial activity, and soil organic carbon. The findings showed that different positions exhibit different conditions in terms of carbon mineralization and sequestration causing the heterogeneous dynamics of soil biological properties.

کلیدواژه‌ها [English]

  • Geomorphic process
  • Water erosion
  • Biological diversity
  • Enzyme activities
  • Arid ecosystem

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پژوهشهای دانش زمین
دوره 10، شماره 2 - شماره پیاپی 38
پژوهشی
خرداد 1398
صفحه 21-33

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