تأثیر روشنه‌های تاجی جنگل بر فعالیت آنزیمی، مواد آلی محلول و اسیدهای آلی خاک

نوع مقاله: علمی- پژوهشی

نویسندگان

1 استادیار، گروه جنگل‌داری، دانشکده منابع طبیعی، دانشگاه تربیت‌مدرس، نور، ایران

2 استادیار، دانشکده کشاورزی و منابع طبیعی، دانشگاه آزاد اسلامی، واحد کرج، کرج، ایران

چکیده

روشنه‌های تاجی نقش مهمی در پویایی جنگل­‌های نواحی معتدله بر عهده دارند. پژوهش پیش‌رو با هدف بررسی سطوح مختلف روشنه‌های تاجی بر فعالیت­‌های بیوشیمی خاک در منطقه خانیکان نوشهر انجام شد. سی و دو روشنه با سطوح کوچک (205- 195 متر مربع)، متوسط (406- 397 متر مربع)، بزرگ (604-593 متر مربع) و خیلی­ بزرگ (807-792 متر مربع) با هشت تکرار از هر سطح حفره تاجی درنظر گرفته شد. در داخل هر حفره، نمونه‌­های ترکیبی خاک برای تجزیه مشخصه­‌های فیزیکی و شیمیایی، بیولوژی و بیوشیمی برداشت شد. نتایج حاکی از اثر معنی­‌دار سطوح مختلف روشنه‌های تاجی بر مشخصه‌­های فیزیکی و شیمیایی (به‌جز محتوی سیلت) و بیولوژی خاک بود. همچنین، بیشترین فعالیت اوره‌­آز در روشنه‌های متوسط و کوچک (µg NH4+–N g−1 2 h−1 54/22 و 97/22) مشاهده شد. اسید فسفاتاز (µg PNP g−1 h−1 75/633)، آریل­‌سولفاتاز (µg PNP g−1 h−1 38/153) و اینورتاز (µg Glucose g1 3 h−1 25/273) خاک دارای بیشینه مقدار خود در روشنه‌های متوسط بودند. روشنه‌های تاجی با سطح خیلی بزرگ بیشترین مقادیر کربن آلی محلول (73/94 میلی­‌گرم بر کیلوگرم) را به‌خود اختصاص دادند، در حالی‌که بیشترین نیتروژن آلی محلول (66/34 میلی­گرم بر کیلوگرم) در روشنه‌های تاجی متوسط مشاهده شد. حضور روشنه‌های تاجی خیلی بزرگ منجر به تجمع اسیدهای آلی فولویک و هیومیک (به‌ترتیب 62/454 و 88/888 میلی­‌گرم در 100 گرم خاک خشک) در خاک جنگل مورد مطالعه شده بود. درمجموع، برای مدیریت پایدار جنگل پیشنهاد می­‌شود از ایجاد روشنه‌های بزرگ یا خیلی بزرگ اجتناب شود. 

کلیدواژه‌ها


عنوان مقاله [English]

Effect of forest canopy gap on soil enzyme activity, dissolved organic matter and organic acids

نویسندگان [English]

  • Yahya Kooch 1
  • Katayoun Haghverdi 2
1 Assistant Prof., Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Iran
2 Assistant Prof., College of Agriculture and Natural Resources, Karaj Branch, Islamic Azad University, Karaj, Iran
چکیده [English]

Canopy gaps play an important role in the dynamics of temperate forests. The present study aimed to evaluate the effect of canopy gaps area on soil biochemical activities in Khanikan region of Nowshahr. In this study, 32 canopy gaps with small (195-205 m2), medium (397-406 m2), large (593-604 m2) and very large (792-807 m2) areas, 8 replications for each, were considered. Five points were selected within each canopy gap; soil samples were taken and mixed due to transferring to laboratory for analysis of physico-chemical, biological and biochemical properties. According to findings, whole of soil physico-chemical (except for silt content) and biological properties were significantly affected by different canopy gaps areas. The highest urease activity was found under medium and small (22.97 and 22.54 µg NH4+–N g−1 2 h−1) canopy gap areas, respectively. Medium gaps showed the most values of acid phosphatase (633.75 µg PNP g−1 h−1), arylsulfatase (153.38 µg PNP g−1 h−1) and invertase (273.25 µg Glucose g1 3 h−1). Greater amounts of dissolved organic carbon (94.73 mg/kg) and dissolved organic nitrogen (34.66 mg/kg) were found under very large and medium canopy gap areas, respectively. Creation of very large canopy gaps was due to increasing of fulvic (454.62 mg/100g) and humic (888.88 mg/100g) acids in the studied forest ecosystem. As a general conclusion, based on forest sustainable management, it is proposed to avoiding of large and very large canopy gaps creation. 

کلیدواژه‌ها [English]

  • Broad-leaved forest
  • canopy gap area
  • Nowshahr
  • relative light
  • soil biochemical
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