تأثیر کوبیدگی خاک بر متغیر زی‌توده و رشد نهال بلندمازو در شرایط گلخانه‌ای

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشکده منابع طبیعی دانشگاه تهران، دکترای جنگلداری

2 دانشگاه تهران

3 گروه جنگلداری و اقتصاد جنگل، دانشکده منابع طبیعی، دانشگاه تهران

چکیده

استفاده از ماشین‌آلات سنگین برای فعالیت‌های جنگل مانند عملیات بهره‌برداری در طول چند دهۀ گذشته افزایش یافته است که همین امر پیامدهای منفی بر اکوسیستم خاک جنگل شامل کوبیدگی، به‌هم‌خوردگی و شیاری شدن خاک را در پی داشته است. این تحقیق در پی اثبات این فرضیه است که افزایش مقاومت به نفوذ با تحت تأثیر قراردادن الگوهای اندام هوایی و زیرزمینی، سبب ایجاد اثرهای منفی بر متغیرهای مورفولوژی نهال (اندازه) و رشد (زی‌توده) می‌شود. در این تحقیق چهار تیمار کوبیدگی خاک اعمال شده تا یک طیف پیوسته از کوبیدگی با استفاده از افزایش وزن مخصوص ظاهری ایجاد شود (تیمار شاهد بدون کوبیدگی و سطح دوم تا سطح چهارم کوبیدگی به ترتیب با 3، 5 و 7 ضربه چکش). اثرهای کوبیدگی خاک در خاکی با بافت لومی تا رسی- لومی با شرایط بهینه از نظر آب (آبیاری روزانه) در یک مقیاس پیوستۀ مقاومت به نفوذ (1/0 تا 0/1 مگاپاسکال) بر متغیرهای رشد نهال‌های گونه بلندمازو در شرایط گلخانه بررسی شد. با افزایش مقاومت به نفوذ، متغیرهای رشد شامل اندازۀ نهال (طول و قطر ساقه، طول برگ، طول و قطر ریشۀ اصلی و طول ریشۀ جانبی) و زی‌توده (اندام هوایی و ریشه) از نظر آماری به‌طور معنی‌داری کاهش یافتند. پارامترهای رشد با افزایش کوبیدگی خاک به‌صورت رابطه‌ای غیرخطی تغییر یافتند. به‌طور کلی می‌توان نتیجه‌گیری کرد که رشد ریشه و ارتفاع نهال بلندمازو با هر گونه افزایش در مقاومت خاک محدود می‌شود.
 

کلیدواژه‌ها


عنوان مقاله [English]

The Effects of Soil Compaction on Morphology and Biomass Variables of Chestnut-leaved Oak (Quercus castaneifolia C.A.M.) in Greenhouse Situations

نویسنده [English]

  • Meghdad Jourgholami 1
چکیده [English]

The use of heavy machinery in forestry operations such as logging has increased worldwide during the last decades. However, these machines may seriously influence the soil ecosystem as they induce rutting, disturbing the upper soil layers, and soil compaction. Severe compaction of soil adversely affects the growth of plants.This study was done by using a penetration resistance experiment in a greenhouse to test the hypotheses that increasing soil strength would affect adversely the seedling morphology (size) and growth (biomass) by changing the above- and below-ground patterns. We created four soil compaction intensity treatments. The lowest compaction intensity (no compaction, control), low, moderate, and high intensities of compaction were achieved by manually applying 3, 5 and 7 blows with a compaction hammer from a height of 20 cm above the soil surface, respectively. We studied the effects of soil compaction in a loam to clay-loam textured soil with optimal conditions of water on a continuous scale (0.1–1.0 MPa penetration resistance) on the growth responses of the deciduous Quercus castaneifolia (C.A.M.). Above- and below-ground metrics of seedling size (i.e., stem length and diameter, leaf length, main root length and diameter, and lateral root length) and biomass (i.e., total, shoot, and total root) were negatively affected by soil compaction. Seedling sizes and growth parameters responded nonlinearly to increasing the soil strength. We conclude that growth of roots and height of oak seedlings are restricted with any increases in soil strength.

کلیدواژه‌ها [English]

  • Hyrcanian forest
  • penetration resistance
  • seedling morphology
  • relative growth rate
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