تأثیر اندازه‏های مختلف روشنه‏های طبیعی بر تنوع و ترکیب گیاهان در توده‏های آمیختة اسالم

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری علوم جنگل، دانشکدﮤ منابع طبیعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران

2 دانشیار، دانشکدﮤ منابع طبیعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران

3 دانشیار پژوهش، مؤسسة تحقیقات جنگل‏ها و مراتع کشور، تهران، ایران

چکیده

به‌ منظور بررسی تأثیر اندازة سطح روشنه در تنوع گونه‏های گیاهی و ترکیب و میزان زادآوری در توده‏های آمیخته، قطعة شاهد واقع در سری 3 ناو اسالم انتخاب شد. روشنه‏های موجود در سطح قطعة مورد بررسی شناسایی و مختصات مکانی آن‌ها ثبت شد. روشنه‏های موجود در اندازه‌هایی با وسعت کم (کمتر از 2 آر)، متوسط (2 تا 5 آر)، بزرگ (5 تا 10 آر)، و بسیار بزرگ (بیش از 10 آر) طبقه‏بندی و در هر طبقه تعدادی روشنه با مشخصات نسبتاً همگن از نظر جهت و شیب انتخاب ‏شد. طول دو قطر عمود بر هم (قطر کوچک و بزرگ) هر روشنه اندازه‏گیری و سطح آن به کمک معادلة بیضی محاسبه شد. گونه‏های چوبی و علفی زیر قطعه‌نمونه‌های 4 متر مربعی (2×2) در چهار گوشه، محل تقاطع دو قطر کوچک و بزرگ، و همچنین در ربع قطر بزرگ هر روشنه برداشت و شاخص‏های تنوع و یکنواختی و غنا محاسبه و تفاوت آن‌ها در طبقات مختلف، با آزمون‏ یک‌طرفه و آزمون ناپارامتری کروسکال والیس ارزیابی شد. نتایج نشان داد متوسط سطح روشنه‏ها 6/442 متر مربع است و از نظر شاخص‏های تنوع گونه‏های چوبی و علفی اختلاف معنادار بین طبقات مختلف روشنه مشاهده نمی‏شود؛ اما از نظر ترکیب زادآوری بین روشنه‏ها اختلاف معنادار مشاهده شد. مناسب‏ترین اندازة سطح روشنه برای حفظ تنوع گونه‏های چوبی، در توده‏های آمیخته، روشنه‏هایی با ابعاد متوسط (200 تا 500 متر مربع) بود.

کلیدواژه‌ها

عنوان مقاله [English]

Impact of Canopy Gap Size on Plant Species Diversity and Composition in Mixed Stands, case study: Reserve Area, District No.3 Asalem Forests

نویسندگان [English]

  • Beitollah Amanzadeh 1
  • Mohammad Reza Pourmajidian 2
  • Khosro Sagheb-Talebi 3
  • Seyed Mohammad Hojjati 2
1 Ph.D Student, Faculty of Natural Resources, Sari Agricultural Sciences and Natural Resources University, Sari, I. R. Iran
2 Associate Professor, Faculty of Natural Resources, Sari Agricultural Sciences and Natural Resources University, Sari, I. R. Iran
3 Associate Professor, Research Institute of Forests and Rangelands, Tehran, I. R. Iran
چکیده [English]

In order to study the effect of canopy gap size on species diversity and composition in mixed stands, a reserved area which located in Asalem forests was selected. All of gaps in this area identified and were divided into four categories: Small gaps (<200 m2), Medium gaps (200-500 m2) large gaps (500-1000 m2) and Extra large gaps (>1000 m2). In each category, 21 of gaps with a relatively homogeneous in terms of an aspect and slope were selected. The major and minor diameter of the gaps were measured and the area of the gaps was calculated based on an ellipse. Then, 2 m×2 m sampling micro-plots were systematically taken along two diameters of each gap. The number of individuals of tree seedlings and saplings and shrubs were counted and coverage percent of herbaceous species were estimated in each sampling plot based on Braun-Blanquet criterion. Number of species were counted and the Simpson (1-D), Shannon-Wiener (H') indices, species richness, Camagaro and Smith- Wilson’s evenness indices were calculated in different vegetation layers. The Kolomogrov-Smirnov test was used to study the normality of diversity, richness and evenness data in different gaps, then One-Way and Kruskal- Wallis tests were performed using SAS software. The results showed that mean expanded gap sizes were 442.6 m2. Also, the results revealed that there was not significant differences among different size gap categories in terms of diversity, but the composition of regeneration was significant among different gaps. Therefore, based on the results of this study, the medium gaps which area 200- 500 m2 in these mixed-species forests are recommended the species diversity.

کلیدواژه‌ها [English]

  • Biodiversity
  • canopy gap
  • mixed stands
  • Regeneration

مراجع

 
[1]. Yamamoto, S. I. (2000). Forest gap dynamics and tree regeneration. Journal of Forest Research, 5(4): 223-229.
[2]. Dobrowolska, D., and Veblen, TT. (2008). Treefall-gap structure and regeneration in mixed Abies alba stands in central Poland. Forest Ecology and Management, 255(8): 3469-3476.
[3]. Naaf, T. and Wulf, M. (2007). Effects of gap size, light and herbivory on the herb layer vegetation in European beech forest gaps. Forest Ecology and Management, 244(1): 141-149.
[4]. Sapkota, IP., Tigabu, M., and Odén, P. C. (2009). Species diversity and regeneration of old-growth seasonally dry Shorea robusta forests following gap formation. Journal of Forestry Research, 20(1): 7-14.
[5]. Sefidi, K., Maravie Mohadjer, M. R., Mosandle, C., and Copenheaver, A. (2011). Canopy gaps and regeneration in old-growth Oriental beech (Fagus orientalos Lipsky) stands, northern Iran. Forest Ecology and Management, 262(2): 1094-1099.
[6]. Shabani, S., Akbarinia, M., Jalali, G., and Aliarab, A. (2009). The effect gap size on biodiversity of plant species in Lalis forest –Nowshar. Iranian Journal of Forest, 1(2): 125-135.
[7]. Abrari Vajari, K., Jalilvand, H., Pourmajidian, M. R., Espahbodi, K., and Moshki, A. (2012). Effect of canopy gap size and ecological factors on species diversity and beech seedlings in managed beech stands in Hyrcanian forests. Journal of Forestry Research, 23(2): 7-14.
[8]. Parhizkar, P., Sagheb-Talebi, Kh., Mataji, A., Nyland, R., and Namiranian M. (2011). Silvicultural characteristics of oriental beech (Fagus orientalis Lipsky.) regeneration under different RLI and positions within gaps. Forestry 84 (2): 177-185.
[9]. Kern, Ch. C., Montgomery, R. A., Reich, P. B., and Strong, T. F. (2014). Harvest-Created canopy gaps increase species and functional trait diversity of the forest ground-layer community. Forest Science, 60(2): 335-344.
[10]. Shahnavazi, H., Sagheb Talebi, Kh., and Zahedi Amiri, Gh. (2005). An evaluation of quality and quantity of natural regeneration in gaps created in Golband beech forests (Jamand district). Iranian Journal of Forest and Poplar Research, 13(2): 141-153.
[11]. Nagel, T. A., Svoboda, M., Rugani, T., and Diaci, J. (2010). Gap regeneration andreplacement patterns in an old-growth Fagus-Abies forest of Bosnia-Herzegovina. Plant Ecology, 208: 307-318.
[12]. Marvie Mohadjer, M. R. (2005). Silviculture. University of Tehran Press, Tehran, Iran.
[13]. Anonymus. (2004). Forestry plan of Asalem booklet. Forest Range and Watershad Management Organization, Iran.
[14]. Siahipour, Z., Rostami, T., Sagheb Talebi, Kh., and Taheri, K. (2003). An investigation on Picea abies(L) karst growth rate in Guilan afforstations. Iranian Journal of Forest and Poplar Research, 10: 1-53.
[15]. Nagel, .T. A. and Svoboda, M. (2008). Gap disturbance regime in an old growth Fagus–Abies forest in the Dinaric Mountains, Bosnia- Herzegovina. Canadian Journal of Forest Research, 38: 2728-2737.
[16]. Sagheb Talebi, Kh. and Schüts, J. P. (2002). The structure of natural oriental beech (Fagus orrientalis Lipsky) forest in the Caspian region and the application of the group selection system. Forestry, 75(4): 465-472.
[17]. Van der Maarel, E. and Franklin, J. (2013). Vegetation Ecology, 2nd. ed.  Wiley-Blackwell (John Wiley & Sons, Ltd.), Chichester, UK, XVI.
[18]. Whitmore, T. C. (1989). Canopy gaps and the two major group of forest trees. Ecology, 70(3): 536-538.
[19]. Huth, F. and Wagner, S. (2006) Gap structure and establishment of Silver birch regeneration (Betula pendula Roth.) in Norway spruce stands (Picea abies L. Karst.). Forest Ecology and Management, 229(1): 314-324.
[20]. Sagheb Talebi, Kh., Ghorchi Beigi, K., Eslami, A., Shahnavazi, H., and Mousavi Mir Kelayee, S. (2001). Structure of Caspian beech forests and the potential of applying selection system in them; Proceeding Second International Conference of Forest and Industrial, 1: 107-138.

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