بررسی عوامل محیطی کنترل کننده کربن آلی خاک در مراتع مناطق خشک (مطالعۀ موردی: منطقۀ یانسی گناباد)

نوع مقاله : مقاله کامل علمی پژوهشی

نویسندگان

1 استادیار، عضو هیأت علمی، گروه مرتع و آبخیزداری، دانشکده کشاورزی و منابع طبیعی، دانشگاه تربت‌حیدریه،

2 دانشگاه تربت حیدریه

چکیده

سابقه و هدف: مراتع مناطق خشک و بیابانی علی‌رغم پوشش گیاهی ناچیز، اما به‌دلیل سطح وسیع در مقیاس جهانی، بیش از یک سوم ذخایر سطحی و زیرزمینی کربن خشکی‌های زمین را در خود جای داده‌اند، مدیریت کربن آلی خاک مراتع، نیازمند آگاهی از مقدار موجود و شناخت عوامل مؤثر بر آن می‌باشد. میزان کربن آلی خاک، نتیجه تعادلی است که بین کربن گیاهی افزوده شده به خاک و کربن خارج شده از خاک توسط آب شویی، پوسیدگی و فرسایش برقرار است. تحقیق حاضر به ارزیابی تغییرات کربن خاک و چگونگی رابطه‌ی آنها با پارامترهای محیطی در مراتع خشک و نیمه‌‌خشک می‌پردازد. به این منظور، مراتع منطقه یانسی گناباد، به‌عنوان الگویی از مناطق خشک کشور انتخاب شده و با هدف بررسی تأثیر ویژگی‌های خاکی، مدیریت اراضی و پوشش گیاهی بر تغییرات کربن آلی خاک مورد مطالعه قرار گرفتند. از این رو در تحقیق حاضر، بررسی رابطه کربن آلی خاک با برخی خصوصیات خاک و عوامل اقلیمی و تعیین مهمترین عوامل تأثیرگذار بر کربن آلی خاک از بین متغییرهای مطالعاتی مد‌‌‌‌‌‌نظر است.
مواد و روش‌ها: محدودۀ مورد مطالعه در منطقۀ یانسی در محدودۀ جغرافیایی '20 °32 تا '39 °32 عرض شمالی و '57 °59 تا '13 °60 طول جغرافیایی قرار گرفته است. آماربرداری پوشش گیاهی منطقه، با کمک روش تلفیقی ترانسکت‌‌ دایره‌ای انجام شد، پارامترهای محیطی اندازه‌گیری شده شامل ارتفاع از سطح دریا (فیزیوگرافیک)، متوسط بارندگی سالانه، متوسط دمای سالانه و متوسط نم نسبی سالانه (اقلیمی)، واکنش خاک، هدایت‌الکتریکی، کلسیم، منیزیم، سدیم، پتاسیم، فسفر، کربن آلی و بافت خاک بودند. برای تعیین عوامل محیطی مؤثر بر تغییرات کربن خاک، از آنالیز مؤلفه‬های اصلی (PCA) بر مقادیر عوامل و ضرایب همبستگی به‌عنوان معیاری از تشابه بین پلات‌ها استفاده گردید.
یافته‌‌ها: نتایج تحلیل مؤلفه‌های اصلی نشان داد که پارامترهای پوشش گیاهی، اقلیمی، بافت خاک و ارتفاع نقش زیادی در کنترل کربن آلی خاک در این مراتع دارند. میزان کربن خاک، دارای همبستگی مثبت با رس (39%)، شن (33%)، پتاسیم (30%) و منیزیم (21%) و همبستگی منفی با ارتفاع (32%-)، ازت (18%-)، بارندگی (39%-)، رطوبت‌نسبی(39%-) و پوشش‌گیاهی (34%-) بود.
نتیجه‌گیری: در این مطالعه مشخص شد که در مراتع خشک و نیمه‌خشک کشور، میزان کربن آلی خاک در درجه اول تحت تأثیر بارش و درجه حرارت و در مرتبه دوم، تحت تأثیر بافت خاک و در درجات بعدی تحت تأثیر ارتفاع و پوشش گیاهی است، بنابراین ترکیبی از فاکتورهای مختلف به‌ویژه موارد ذکر شده برای درک و برآورد معنی‌دار سطوح کربن آلی خاک نیاز است و بدون درنظر گرفتن کامل عوامل کنترل کننده کلیدی با هم، هرگونه برآوردی از از کربن آلی خاک غیر قابل اتکا خواهد بود.

کلیدواژه‌ها

عنوان مقاله [English]

Investigating environmental factors controlling soil organic carbon in rangelands of arid regions (case study: Yansi region of Gonabad)

نویسندگان [English]

  • Iman Haghian 1
  • Amir Salari 2
1 Assistant Professor, Department of Range and Watershed Management, Faculty of Agriculture and Natural Resources, University of Torbat Heydarieh,
چکیده [English]

Background and Objectives: Rangelands of arid and desert areas despite the insignificant vegetation cover, but due to the large global scale, more than one third of the surface and underground carbon reserves have landed. Organic carbon dioxide management in rangelands requires knowledge of the amount of organic carbon and the factors that affect it. The amount of soil organic carbon is the result of the balance between the carbon that is added to the soil and the carbon released from the soil by watering, carving and erosion. The present study evaluates the changes in soil carbon and how they relate to environmental parameters in dry and semi-arid rangelands. For this purpose, the rangelands of Yansi region of Gonabad have been selected as a model of arid regions of the country. The aim of this study was to study the effect of soil characteristics, land management and vegetation cover on soil organic carbon changes. Therefore, in the present study, the study of the relationship between organic carbon of soil and some soil characteristics and vegetation cover and determining the most important factors affecting soil organic carbon are among the studied variables.
Materials and Methods: The study area in the Yancei region is located in the geographical area '20 and 32 ° to 39 ° 32 ° north latitude, and '57 ° 59 ° to 13 ° and 60 ° longitude. The average rainfall and temperature is 157 mm, 14 ° C. Vegetation inventory of the area was carried out using cross-sectional method. The measured environmental parameters are: altitude from the sea level, average annual rainfall, average annual and average annual precipitation, acidity, conductivity, calcium, magnesium, sodium, potassium, phosphorus, carbon Organic and soil texture. To determine the environmental factors affecting soil carbon changes, principal components analysis (PCA) has been used on the values of factors and correlation coefficients as a criterion for the similarity between the plots.
Results: The results of main component analysis showed that vegetation, climatic, maternal and altitude parameters have a great role in soil organic carbon control in these rangelands. The soil carbon content was positively correlated with clay (39%), sand (33%), potassium (30%) and magnesium (21%), and negative correlation with altitude (32%), nitrogen (18%), precipitation (39%), moisture content (39%) and coating (34%).
Conclusion: In this study, it was determined that in the dry and semi-arid rangelands of Iran, soil organic carbon is primarily affected by rainfall and temperature, soil texture, elevation and vegetation. Therefore, a combination of different factors, especially those mentioned above, is needed to understand and estimate the soil organic carbon levels and without considering the key controller factors together, any estimation of the organic carbon of the soil would be unreliable.

کلیدواژه‌ها [English]

  • Range
  • Organic Carbon
  • soil
  • Environmental Factors

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مجله پژوهش‌های حفاظت آب و خاک
دوره 25، شماره 3
مرداد و شهریور 1397
صفحه 281-289

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