تأثیر چرای دام و عامل‌های محیطی بر ساختار توده‌های بلوط زاگرس (پژوهش موردی: پارک دالاب ایلام)

نوع مقاله : علمی- پژوهشی

نویسنده

استادیار پژوهشی، مرکز تحقیقات استان مرکزی

چکیده

ترکیب گونه‌ای و ساختار توده‌های جنگلی در طول زمان در اثر آشفتگی‌های انسانی یا طبیعی تغییر می‌کند. بررسی این تغییرات در ارتباط با عامل‌های محیطی و آشفتگی‌ها، نقش مهمی در تجزیه‌وتحلیل پویایی و مدیریت بوم‌سازگان‌ها دارد. بنابراین در این تحقیق عامل‌های محیطی و چرای دام  به‌عنوان عامل آشفتگی بر ساختار توده‌های بلوط، در مقایسه با مناطق بدون آشفتگی در پارک دالاب ایلام بررسی شد. اطلاعات مربوط به پوشش گیاهی، خاک و سایر متغیرهای محیطی در این دو منطقه در قالب 51 قطعه نمونه 0/1 هکتاری و به‌صورت تصادفی برداشت و اطلاعات مربوط به ساختار جنگل در آن‌ها اندازه‌گیری شد. برای مشخص کردن ارتباط گروه‌های گیاهی با عامل‌های مختلف موردبررسی از روش رسته‌بندی تحلیل تطبیقی متعارفیاستفاده شد. نتایج نشان داد که آشفتگی ایجادشده به‌دلیل چرای دام در کنار فاکتورهای خاکی به‌ترتیب با بیان 7/7 و 6/2 از تغییرات موجود در ساختار توده‌های بلوط، به‌عنوان تأثیرگذارترین عامل‌ها بر ساختار این جنگل شناخته شدند. وجود طبقات قطری بالا (قطر برابرسینه و قطر تاج) در مناطق دارای آشفتگی چرای دام حاکی از وجود توده‌های مسن بود و نشان‌دهنده عدم زادآوری آن‌ها برای مدت طولانی است. از طرف دیگر وجود طبقات قطری پایین (قطر برابرسینه و قطر تاج) و همچنین طبقات ارتفاعی کم در کنار طبقات قطری بالا در منطقه فاقد آشفتگی، حاکی از وجود توده‌های ناهمسال و نامنظم است و نشان‌دهنده زادآوری گونه‌های درختی به‌خصوص گونه بلوط، پس از قرق در این منطقه است.

کلیدواژه‌ها

عنوان مقاله [English]

Effect of grazing and environmental factors on the structure of Brant`s oak stands of Zagros (Case study: Dalab Park, Ilam)

نویسنده [English]

  • Hamid Reza Mirdavoodi
Assistant Professor, Agricultural and Natural Resources Research Center of Markazi Province, Arak, Iran
چکیده [English]

Species composition and structure of forest stands are subject to temporal changes as a function of anthropogenic or natural disturbances. The investigation of such changes in association to environmental factors plays an important role in analyzing of the ecosystem dynamics and in turn in ecosystem management. In this study, forest structural attributes, soil and other environmental variables were collected across 51 sample plots (each encompassing 0.1 ha) by using the random sampling method across two “grazed” and “protected” forest sites located in northwest of Ilam. Canonical correspondence analysis was used to identify patterns in stand structure of the sites and their association to environmental attributes or livestock grazing. Results showed the stand structure to be affected by the grazingand soil factors, which explained 7.7% and 6.2% of the total variation in stand structure, respectively. In addition, the occurrence of trees with high diameter classes within the grazing-disturbed class was an indication of old growth stands in such sites, in which the natural regeneration has not been taken place for a long time. On the other hand, the lower diameter classes as well as classes of lower height were predominantly observed beside the classes of higher diameter in undisturbed sites, which suggests for the existence of uneven-aged and irregular stand structure. The results of this study suggest that natural regeneration in Brant`s oak trees is mainly enabled following a preservation of such sites against grazing.

کلیدواژه‌ها [English]

  • Disturbance
  • environmental factors
  • ordination
  • stand structure

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