بررسی ترکیب بانک بذر خاک محدوده مرزی و قسمت‌های مرکزی رویشگاه جنگلی (مطالعه موردی: حوضه واز در استان مازندران)

نوع مقاله : علمی- پژوهشی

نویسندگان

1 استادیار، دانشکده منابع طبیعی و علوم دریایی دانشگاه تربیت مدرس

2 دانش آموخته کارشناسی ارشد مرتع‌داری، دانشکده منابع طبیعی و علوم دریایی دانشگاه تربیت مدرس

چکیده

 
تحقیق حاضر با هدف مقایسه خصوصیات بانک بذر خاک (تراکم، تشابه بانک بذر خاک با پوشش روزمینی و تنوع گونه­ای) قسمتهای مرکزی رویشگاه جنگلی و محدوده مرزی آن (مرز بین جنگل و مرتع) به‌عنوان دو رویشگاه با تراکم تاج‌پوشش درختی متفاوت انجام شد. در هر رویشگاه هفت ترانسکت با فاصله 25 متر از یکدیگر مستقر شدند. سپس نمونه­های خاک از اعماق 5-0 و 10-5 سانتی‌متری از داخل پلاتهای 2 مترمربعی برداشت و پس از اعمال تیمار سرما به گلخانه منتقل و کشت شدند. بذرهای ظهور یافته هر دو هفته یکبار شناسایی و حذف گردید. تشابه بانک بذر با پوشش روزمینی با استفاده از شاخص تشابه سورنسون و تنوع گونه­ای با استفاده از شاخص تنوع شانون- وینر محاسبه گردید. در نهایت خصوصیات بانک بذر خاک (تراکم، تشابه بانک بذر خاک با پوشش روزمینی و تنوع گونه‌ای) با استفاده از آزمون t مستقل بین دو رویشگاه مقایسه شد. نتایج نشان داد که تراکم، تنوع گونه­ای بانک بذر خاک در منطقه مرزی به‌طور معنی­داری بیشتر از منطقه مرکزی جنگلی بود. در هر دو رویشگاه تشابه ضعیفی بین بانک بذر خاک با پوشش روزمینی وجود داشت. ضمن اینکه تشابه بانک بذر خاک با پوشش روزمینی عمق سطحی در منطقه جنگلی به‌طور معنی­داری بیشتر از محدوده جنگل- مرتع بود. تراکم و تنوع گونه­ای بانک بذر نیز در عمق سطحی به‌طور معنی­داری بیشتر از عمق پایینی بود. به‌طور کلی می­توان گفت که منطقه مرزی به‌علت داشتن فضای بازتر تاج‌پوشش درختی، موقعیت قرارگیری و تنوع گونه­ای بیشتر نسبت به قسمتهای داخلی مرکزی دارای بانک بذر غنی­تری می­باشد.

کلیدواژه‌ها

عنوان مقاله [English]

Investigation of soil seed bank composition in boundary and interior of forest habitat (case study: Vaz watershed in Mazandaran province)

نویسندگان [English]

  • Reza Erfanzadeh 1
  • Sayyed Hamze Hosseini Kahnuj 2
1 Assistant professor, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University
2 M.Sc. graduated, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University
چکیده [English]

This study aimed to compare soil seed bank characteristics (density, species diversity and similarity with above ground vegetation) between the boundary and interior of forest habitat. Boundary and interior of forest habitat were different in term of the cover percentage of woody plants. Therefore, the zone between forest and rangeland was selected as non-dense forest (Ecotone) with less cover percentage of woody plants and the interior of forest adjacent to the ecotone was selected as dense forest habitat with higher cover percentage of woody plants. In each habitat, seven transects were established with 25 m distance between transects. Then, soil sampling was done using quadrates in two depths: 0-5 and 5-10 cm. After the chilling treatment, soil samples were transferred and spread in the greenhouse. Germinated plant species were identified, counted and then removed. On the other hand, the percentage cover of plant species in each plot was recorded in the growth season. Finally, the number of seeds germinated in the greenhouse was recalculated per square meter and then the similarity between seed bank and aboveground vegetation was calculated in each plot using Sorenson’s similarity index. Non-paired t-test was applied to compare soil seed bank characteristics between the two depths and between the two habitats. The results showed that seed density and species diversity were significantly higher in the ecotone than the dense forest. The density and species diversity of soil seed bank was significantly higher in the upper layer than the deeper layer. There was low similarity between soil seed bank and aboveground vegetation in the both habitats. However, the similarity between seed bank related to upper layer was significantly higher in the dense forest than the ecotone. It can be concluded that ecotone zone has more enrichment from interior part of the forest due to more open crown cover, position and more species diversity.

کلیدواژه‌ها [English]

  • Seed density
  • Canopy cover density
  • species diversity
  • above ground vegetation
  • Sorenson’s similarity index
  • ecotone zone

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