حساسیت دمایی نرخ دی‌اکسیدکربن متصاعد‌شده از خاک توده جنگلی راش- ممرز (پژوهش موردی: جنگل شصت‌کلاته گرگان)

نوع مقاله: علمی- پژوهشی

نویسندگان

1 دانشجوی دکتری جنگل‌شناسی و اکولوژی جنگل، دانشکده علوم جنگل، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران

2 دانشیار، دانشکده علوم جنگل، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران

3 دانشیار، بخش تحقیقات جنگل، مؤسسه تحقیقات جنگل‌ها و مراتع کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران

چکیده

چگونگی اثرات تغییر دما بر تنفس خاک از ناشناخته‌هایی است که موجب عدم قطعیت در پیش‌بینی وضعیت آینده چرخه جهانی کربن می‌شود. حساسیت دمایی تنفس خاک (Q10) مؤلفه‌ای کلیدی به‌منظور تخمین بازخورد تنفس خاک به گرمایش جهانی است. هدف از پژوهش پیش‌‌‌رو، بررسی حساسیت دمایی تنفس کل خاک براساس تغییرات سالانه دما و محتوای رطوبتی خاک در یک توده راش- ممرز بود. به‌منظور انجام این پژوهش، ابتدا 12 قطعه‌نمونه به ابعاد 3 × 3 متر (شش قطعه‌نمونه در زیر تاج‌پوشش و شش قطعه‌نمونه در روشنه) مشخص شد. سپس نمونه‌برداری در سه نقطه تصادفی از هر قطعه‌نمونه انجام شد. تنفس ماهانه خاک با استفاده از چمبر دینامیکی بسته در نقاط تعیین‌شده طی یک سال اندازه‌گیری شد. نتایج این پژوهش بیانگر همبستگی معنی‌دار بین حساسیت دمایی تنفس خاک و متغیرهای محیطی شامل دمای خاک، محتوای رطوبتی خاک و دمای هوا در سطوح اطمینان 95 و 99 درصد بود. همچنین، حساسیت دمایی تنفس خاک در قطعه‌نمونه‌های زیر تاج‌پوشش بیشتر از روشنه بود. در حالی‌که کمترین نرخ تنفس خاک در فصل زمستان مشاهده شد (0/94 میکرومول بر متر مربع در ثانیه)، بیشترین حساسیت دمایی تنفس خاک نیز به همین فصل و قطعه‌نمونه زیر تاج‌پوشش (4/23) اختصاص یافت. بر این‌ اساس، افزایش جزئی در دمای خاک به‌ویژه در فصل زمستان منجر به تغییر چشمگیری در نرخ تنفس کل خاک و به‌هم‌خوردن تعادل چرخه کربن در توده‌های جنگلی این منطقه خواهد شد.

کلیدواژه‌ها


عنوان مقاله [English]

Temperature sensitivity of soil carbon dioxide efflux in beech-hornbeam stand (Case study: Shast-kalateh Forest, Gorgan)

نویسندگان [English]

  • Fatemeh Rafiee 1
  • Hashem Habashi 2
  • Ramin Rahmani 2
  • Khosro Sagheb-Talebi 3
1 Ph.D. Student of Silvicultural and Forest Ecology, Faculty of Forest Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
2 Associate Prof., Faculty of Forest Science, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran
3 Associate Prof., Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
چکیده [English]

The way temperature affects the soil respiration remains still unknown, which causes uncertainties in predictions of future trajectories of the global carbon cycle. Temperature sensitivity of soil respiration (Q10) is a key indicator for estimating soil respiration feedback to global warming. The purpose of this study was to investigate the temperature sensitivity of total soil respiration based on temporal changes in soil temperature and moisture contents in a beech-hornbeam stand. Therefore, we first determined 12 sample plots (six sample plots in the gaps and six under canopy cover) with 3×3-meter dimension. Sampling was conducted in three randomized points of each sample plot. At each sample point, soil respiration was monthly measured using a closed dynamic chamber throughout the year. The results showed a significant correlation between Q10 and some environmental variables, including soil temperature and moisture contents and also air temperature (p < 0.05 and p < 0.01). In addition, the temperature sensitivity of soil respiration was higher under canopy cover plots than that of in gaps. Although the lowest soil respiration rate was observed in winter (0.94 mmol m-2 s-1), the highest temperature sensitivity of soil respiration in this season (4.23) was observed under canopy cover plots. Thus, a slight increase in soil temperature, especially in winter, would result in a significant change in the rate of respiration of the entire soil and the adoption of a carbon cycle equilibrium in the forest stands of this area.

کلیدواژه‌ها [English]

  • Climate changes
  • global warming
  • Q10
  • soil temperature and moisture contents
  • temperature sensitivity of soil respiration

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