تأثیر اجرای شیوه تک‌گزینی بر تنوع گونه‌های علفی در جنگل آمیخته راش (مطالعه موردی: ناو اسالم، گیلان)

نوع مقاله: علمی- پژوهشی

نویسندگان

1 کارشناس ارشد جنگل‌شناسی و اکولوژی جنگل، دانشکده منابع طبیعی، دانشگاه گیلان

2 استاد، دانشکده منابع طبیعی، دانشگاه گیلان

3 دانشیار، دانشکده منابع طبیعی، دانشگاه گیلان

4 کارشناس ارشد جنگل‌داری، اداره منابع طبیعی و آبخیزداری تالش

چکیده

تغییرات پوشش گیاهی جنگل تحت تأثیر عامل‌های متعددی قرار دارد که یکی از مهمترین و تأثیرگذارترین آنها تاج‌پوشش درختان است. پژوهش پیش‌رو با هدف بررسی تأثیر تاج‌پوشش باز و بسته درختان بر تنوع گونه‌های علفی در جنگل‌های ناو اسالم انجام شد. سه اندازه روشنه کوچک (100 تا 200 مترمربع)، متوسط (200 تا 300 مترمربع) و بزرگ (300 تا 400 مترمربع) هر کدام با پنج تکرار انتخاب شد. سطوح شاهدی نیز با همین اندازه زیر تاج‌پوشش بسته درنظر گرفته شد. در طول دو قطر اصلی روشنه، زیرقطعه‌نمونه‌های 2×2 متر با فاصله یک متر به روش تصادفی منظم پیاده شد و درصد پوشش گونه‌های گیاهی در آنها براساس مقیاس دومین برآورد شد. به‌منظور ارزیابی تنوع گیاهی در قطعات نمونه از شاخص‌های تنوع سیمپسون و شانون- وینر، یکنواختی اسمیت- ویلسون و شمارش گونه‌های علفی (غنا) استفاده شد. نتایج نشان داد که با افزایش مساحت روشنه، مقادیر شاخص‌های تنوع گونه‌ای و غنا افزایش معنی‌داری پیدا می‌کنند. مقایسه شاخص‌ها بین سطوح مختلف روشنه و جنگل شاهد تنها درمورد شاخص‌های تنوع گونه‌ای و غنا در روشنه کوچک و جنگل شاهد معنی‌داری نبود.

کلیدواژه‌ها


عنوان مقاله [English]

The effect of single tree selection cutting on herbaceous diversity in mixed oriental beech forest (Case study: Nav-e Asalem, Guilan)

نویسندگان [English]

  • Zahra Moradi 1
  • Hasan Pourbabaei 2
  • Ali Salehi 3
  • Alireza Sayyadi 4
1 M.Sc. Silviculture and Forest Ecology, Factually of Natural Resources, University of Guilan
2 Prof., Faculty of Natural Resources, University of Guilan
3 Associate Prof., Faculty of Natural Resources, University of Guilan
4 M.Sc. Forestry, Natural Resources and Watershed Management Office of Talesh
چکیده [English]

Variations in forest vegetation are effected by several factors, one of the most important of which being the crown canopy. This study aims to survey the effect of close and open crown canopy on the herbaceous diversity in Nav-e Asalem forests in Guilan province. To this aim, 15 canopy gaps of small (100-200 m2), medium (200-300 m2) and large (300-400 m2) sizes were selected with 5 replications each. Moreover, control plots of the same sizes were selected under the tree canopy. Along small and large diagonals in each gap microplots of 2×2 m each were measured in a randomized systematic design. The percentage of herbaceous cover was estimated using Domin scale. To assess plant diversity in each plot, diversity indices of Simpson, Shannon-Wiener, Smith-Wilson Evenness Index and herbaceous richness were derived. Results showed that increasing the gaps area resulted in a significant increase of diversity and richness. Furthermore, no significant difference was observed between diversity and richness indices between small area gaps and control areas.

کلیدواژه‌ها [English]

  • Forest canopy
  • Gap
  • diversity indices
  • Nav-e Asalem
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