بررسی تنوع گونه‌ای گیاهان تحت تأثیر توپوگرافی خرد در جنگل‌های آمیختۀ راش (مطالعۀ موردی: جنگل‌های دلدره، نوشهر)

نوع مقاله : مقاله پژوهشی

نویسندگان

1 استادیار پژوهشی، بخش تحقیقات منابع طبیعی مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان گلستان، سازمان تحقیقات، آموزش و ترویج کشاورزی، گرگان، ایران

2 استادیار گروه علوم و مهندسی جنگل، دانشکده کشاورزی و منابع طبیعی، دانشگاه محقق اردبیلی، اردبیل، ایران

3 دانشیار گروه علوم و مهندسی جنگل، دانشکده کشاورزی و منابع طبیعی، دانشگاه محقق اردبیلی، اردبیل، ایران

4 مربی مهندسی کشاورزی، بخش تحقیقات گیاه‌پزشکی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان گلستان، سازمان تحقیقات، آموزش و ترویج کشاورزی، گرگان، ایران

چکیده

ریشه‌کن شدن درختان بزرگ سبب تشکیل فرورفتگی‌هایی در محل ریشه و عوارضی بشقاب‌شکل در کنار آن می‌شود که به آن عوارض پیت و ماند گفته می‌شود. در این پژوهش برای بررسی تنوع گونه‌های گیاهی روی این عوارض، طرح جنگلداری دلدرۀ شهرستان نوشهر انتخاب شد. بدین منظور همۀ پیت و ماندها در سطح 70 هکتار شناسایی شد، حضور و فراوانی گونه‌های گیاهی روی این عوارض ثبت شد و در فاصلۀ 25 متری این عوارض، قطعات نمونه‌ای با ابعاد 4×2 متر به‌عنوان نقاط شاهد در نظر گرفته شد. سپس مقدار تنوع گونه‌ای گیاهی برای هر کدام از عوارض محاسبه شد. به‌منظور بررسی اهمیت نسبی گونه‌های گیاهی در هر یک از موقعیت‌ها، شاخص‌های فراوانی نسبی، تراکم نسبی و چیرگی نسبی نیز به‌دست آمد. مطابق نتایج، به‌جز شاخص سیمپسون، دیگر شاخص‌های تنوع و غنای گونه‌ای بین عوارض تحت بررسی، تفاوت معنی‌داری نشان دادند و در مقایسۀ دو موقعیت پیت و شاهد، موقعیت شاهد و در بین دو موقعیت شاهد و ماند، موقعیت ماند مقادیر بیشتری از شاخص‌ها را در بر داشتند. شاخص‌های یکنواختی پیت و هیل، بین موقعیت‌های شاهد و پیت و نیز شاهد و ماند تفاوت معنی‌داری نداشتند. بررسی اهمیت نسبی گونه‌های گیاهی نیز نشان داد که در همۀ موقعیت‌های تحت بررسی، منحنی روندی لگاریتمی نرمال دارد. یافته‌های پژوهش حاضر، بیانگر قابلیت زیاد عوارض پیت و ماند در افزایش غنای گونه‌ای در مناطق جنگلی است. از این‌رو طراحی فنون جنگل‌شناسی باید به‌گونه‌ای باشد که با حفظ و افزایش زمان حضور درختان قطور، همواره شمار معینی پیت و ماند در واحد سطح باقی بماند.

کلیدواژه‌ها


عنوان مقاله [English]

Studying the plants species diversity under microtopography in mixed beech forests, case study: Deldareh forests, Nowshahr

نویسندگان [English]

  • S. Shabani 1
  • s. varamesh 2
  • K. Sefidi 3
  • A.A. Haghighi 4
1 Research Assistant, Research Dept. of Natural Resources, Golestan Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Gorgan, Iran
2 Assistant Prof., Forest Science & Engineering, University of Mohaghegh ArdabiliProfessor, Forest Science & Engineering, University of Mohaghegh Ardabili
3 Associate Prof., Forest Science & Engineering, University of Mohaghegh Ardabili
4 Lecturer Assistant, Dept. of Plant Protection, Golestan Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Gorgan, Iran
چکیده [English]

The uprooting of large trees leads to the formation of depressions in the root area and plate-like features next to it, which are referred to as pit and mound microtopography. For studying the plant species diversity in these positions, Deldareh forests, Nowshahr was selected. For this purpose, all pits and mounds were identified in 70 ha of the study area. The presence and frequency of plant species were recorded on these positions and each pit and mound was compared with a plot 2×4m located 25m far from these positions. Firs, to analyze the plant species, biodiversity indices were computed. Then, to study SIV in each position, relative frequency, relative density, and relative dominance were also calculated. The results indicated all indices of diversity and richness had significant difference between positions, except the Simpson one. Accordingly, in the comparison between the pit and control positions, the control position, and between the control and mound positions, the mound position had higher values of the indices. Also, neither of both evenness indices showed a significant difference between different positions. The study of the SIV also showed that in all positions, there is a normal logarithmic curve. The findings of the present study show the high ability of pit and mound effects on increasing the species richness in forest stands. Therefore, the design of silviculture methods should be such that by maintaining and increasing the thickn trees, a certain number of pit and mound microtopography remains per unit area.

کلیدواژه‌ها [English]

  • Plant Species Diversity
  • Uprooted Trees
  • Species Important Value
  • Species Richness
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