معرفی سطح بهینه روشنه‌‌های تاجی برای زادآوری استقراریافته راش شرقی (Fagus orientalis Lipsky) در جنگل‌‌های طبیعی و آمیخته هیرکانی

نوع مقاله : علمی- پژوهشی

نویسنده

استادیار، بخش تحقیقات جنگل‌‌ها و مراتع، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان مازندران، سازمان تحقیقات، آموزش و ترویج کشاورزی، ساری، ایران

چکیده

استقرار زادآوری درختان در ارتباط با انواع روشنه‌‌ها و عوامل مرتبط به آن‌ها مانند ویژگی‌‌های فیزیوگرافی و درختان حاشیه، تضمین‌کننده پویایی و چرخه جای‌گشت در جنگل‌‌های طبیعی است. هدف پژوهش پیش‌رو، تعیین سطح بهینه روشنه‌‌ها در ارتباط با تغییرات تنوع گونه‌‌ای درختان حاشیه و واحدهای فیزیوگرافی برای بررسی تراکم و ارتفاع زادآوری‌‌ مستقر راش (Fagusorientalis Lipsky) در مراحل مختلف رویشی است. بدین‌منظور، زادآوری مستقر درون روشنه‌‌ها در قطعه شاهد سری سه در گلندرود نور، آماربرداری صددرصد شد و مساحت هر روشنه با استفاده از روش شعاعی اندازه‌‌گیری شد. پس از تفکیک طبقه‌های سطحی روشنه‌‌ها، زادآوری استقراریافته درختان راش برمبنای قطر آن‌ها به سه طبقه 3/1 تا 5/2 (نهال)، 5/2 تا پنج (خال) و بزرگ‌‌تر از پنج سانتی‌‌متر (پیش‌‌به‌‌جا) تقسیم‌‌بندی شدند. تجزیه‌وتحلیل اطلاعات نشان داد که تغییرات تراکم هیچ‌کدام از انواع زادآوری، رابطه معنی‌‌داری با تغییرات سطح روشنه‌‌ها و عوامل مرتبط با آن‌ها نداشتند، اما ارتفاع نهال‌‌ها در ارتباط با واحدهای فیزیوگرافی و غنای گونه‌‌ای درختان حاشیه بین طبقه‌های سطحی روشنه‌‌ها، تغییرات معنی‌‌دار نشان داد. همچنین، ارتفاع خال‌‌گروه‌‌ها تنها با متغیر سطح روشنه و ارتفاع پایه‌‌های پیش‌‌به‌‌جا فقط با فراوانی درختان حاشیه روشنه‌‌ها، همبستگی وارونه معنی‌‌دار داشتند (ضریب‌های همبستگی به‌ترتیب 34/0- و 7/0-). نتایج این پژوهش نشان داد که مساحت بهینه روشنه‌‌ها برای استقرار انواع مراحل زادآوری راش با احتساب ویژگی‌‌های فیزیوگرافی، غنای گونه‌‌ای و فراوانی درختان حاشیه، شامل طبقه‌های سطحی کمتر از دو آر تا حداکثر 10 آر است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Introducing canopy gap optimum size for established regeneration of oriental beech (Fagus orientalis Lipsky) in the Hyrcanian mixed-forests

نویسنده [English]

  • A.A. Vahedi
Assistant Prof., Forests and Rangelands Research Department, Mazandaran Agricultural and Natural Resources Research and Education Center, AREEO, Sari, Iran
چکیده [English]

     Establishment and growth of tree regeneration in association with the canopy gap (CG) and its related parameters such as topography and surrounding tree diversity guarantee turnover and dynamics of forest ecosystems. This research was conducted in the control parcel within the third district of Glandroud forests in Mazandaran province and aimed to clarify influences of gap area with respect to the species diversity of surrounding trees and physiography on the density and height responses for established regeneration of oriental beech (Fagusorientalis Lipsky) in various growth stages, in order to suggest an optimum gap size for the mentioned regenerations. After measuring and calculating area of each CG using radial method, the gap sizes were classified based on full census. The established regeneration was divided into three classes of 1.3–2.5 cm (saplings), 2.5–5 cm (thickets), and > 5 cm (pole- or advanced regenerations). Following statistical tests, results generally showed that the variation of density of saplings, thickets and poles was not significantly correlated with the CG size and other associated parameters. However, significant difference among the CG size classes was observed for height of saplings in relation with physiographic units and frequency of marginally surrounding trees. In addition, height of thickets and pole individuals were significantly affected by gap size and frequency of surrounding trees. The findings indicated that all CG size classes consisting of an area less than 200 m2 and the maximum area of 1000 m2 are the environmentally and ecologically optimum areas for beech regeneration based on establishment proportion of growth stages recruitment in the forest ecosystem, taking account of frequency of surrounding trees and physiographic units.

کلیدواژه‌ها [English]

  • Beech regenerations
  • gap surrounding trees
  • natural disturbances
  • physiographic units
  • species diversity

مراجع

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