بررسی کمی و کیفی خشک‌دارها در توده‌های طبیعی جنگل‌های هیرکانی (مطالعه موردی: سری گرازبن جنگل خیرود، نوشهر)

نوع مقاله: علمی- پژوهشی

نویسندگان

1 کارشناس ارشد جنگل‌شناسی و اکولوژی جنگل، دانشکده منابع طبیعی دانشگاه تهران، کرج، ایران

2 استاد، گروه جنگل‌داری و اقتصاد جنگل، دانشکده منابع طبیعی دانشگاه تهران، کرج، ایران

3 استادیار، گروه منابع طبیعی، دانشکده کشاورزی و منابع طبیعی، دانشگاه محقق اردبیلی، اردبیل، ایران

چکیده

اهمیت اکولوژیک خشک‌دارها موجب شده است تا جمع­آوری اطلاعات مربوط به آن‌ها به‌طور روزافزون گسترش یابد و در طرح‌­های مدیریتی مورد توجه قرار گیرند. با توجه به نقش کلیدی خشک‌دارها در اکوسیستم جنگل، مطالعه کمی و کیفی خشک‌دارها و تشریح چگونگی وضعیت آن‌ها پیش از هرگونه دخالتی حائز اهمیت است. در این پژوهش، برای مطالعه کمی و کیفی خشک‌دارها و تعیین نسبت حجمی آن­ها به حجم توده زنده سرپا، پارسل 307 واقع در شیب جنوبی راشستان‌های سری گرازبن جنگل خیرود انتخاب شد که تا تاریخ اجرای پژوهش، در آن بهره‌برداری انجام نشده بود. برای جمع‌آوری داده‌های مربوط به خشک‌دارها (قطر میانه ≥10 سانتی‌متر) و توده زنده سرپا (قطر برابر سینه ≥ 7/5 سانتی‌متر)  آماربرداری صددرصد انجام شد. بر اساس نتایج به‌دست آمده، متوسط تعداد در هکتار درختان زنده سرپا 357، خشک‌دارهای سرپا 8 و خشک‌دارهای افتاده 26 تکه محاسبه شد. همچنین، حجم در هکتار برای توده زنده سرپا 445/64 و برای خشک‌دارها 15/19 متر مکعب محاسبه شد. ممرز بیشترین سهم گونه‌ای را هم در توده زنده سرپا و هم در خشک‌دارها داشت. حدود یک‌پنجم از کل حجم خشک‌دارها از نوع خشک‌دارهای ایستاده بود و به‌طور تقریب نیمی از خشک‌دارها در مراحل ابتدایی پوسیدگی (درجه 1 و 2) قرار داشتند. در مجموع، نسبت حجمی خشک‌دارها به درختان زنده سرپا 3/4­% محاسبه شد. این مقدار کمتر از مقدار مطلوب خشک‌دارهاست که برای جنگل­‌های معتدله طبیعی درنظر گرفته می­شود و می‌تواند تصمیم‌گیری‌های مدیریتی در منطقه مورد مطالعه را تحت تأثیر قرار دهد.

کلیدواژه‌ها


عنوان مقاله [English]

Quantitative and qualitative assessment of deadwood in natural stands of Hyrcanian forests (Case study: Gorazbon district of Kheyrud, Nowshahr)

نویسندگان [English]

  • Saboura Rahanjam 1
  • Mohammad Reza Marvi Mohadjer 2
  • Mahmoud Zobeiri 2
  • Kiomars Sefidi 3
1 M.Sc. Silviculture and Forest Ecology, Faculty of Natural Resources, University of Tehran, Karaj, Iran
2 Prof., Department of Forestry and Forest Economics, Faculty of Natural Resources, University of Tehran, Karaj, Iran
3 Assistant Prof., Department of Natural Resources, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
چکیده [English]

The conservation value of Coarse Woody Debris (CWD), as critical microhabitat component, in forest ecosystems led to increasingly expand interests in researches about it. The scientific CWD information had gradually considered by decision-makers for implementing forestry planning. In this study, due to evaluate qualitative and quantitative characters of CWD and its proportion to live standing trees, full callipering method was applied. Data were collected from an unmanaged parcel (parcel no. 37, Gorazbon district, Kheyrud forest) situated in southern slopes of Caspian beech forests. The study site has never been under wood exploitation. The data of CWD (middle diameter ≥ 10 cm) and stand (D.B.H ≥ 7.5 cm) were measured using full calipering method. The results of this study illustrated the average number of live standing trees, snags, and fallen trees were 357, 8, and 26 per ha, respectively. Between all species, hornbeam had the highest volume proportion both in live standing trees and CWD. One fifth of total CWD volume was accounted to sangs and stumps and about half of the total volume was exposure in low degree of decomposition. CWD volume amounted 3.5% of total yield of site study. In summary, total CWD volume is lower than optimal value considered for CWD in temperate forests which sets alarms that any removal of CWD could bring irrecoverable consequences in site study.

کلیدواژه‌ها [English]

  • Decomposition rate
  • full calipering method
  • hornbeam
  • live standing trees
  • snag
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