ارزیابی اثرات شدت چرای دام بر ساختار و تنوع گونه‌های چوبی در جنگل تنگ دالاب ایلام

نوع مقاله: علمی- پژوهشی

نویسندگان

1 دانشجوی دکتری مرتع‌داری، دانشکده منابع طبیعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، ایران

2 استادیار، گروه مرتع‌داری، دانشکده منابع طبیعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری،‌ ساری، ایران

3 دانشیار، بخش تحقیقات منابع طبیعی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان ایلام، سازمان تحقیقات، آموزش و ترویج کشاورزی، ایلام، ایران

چکیده

DOR: 98.1000/1735-0883.1397.26.306.73.3.1575.1605
 
تنوع زیستی و ساختار توده­‌های جنگلی در پایداری و پویایی بوم‌سازگان‌های جنگلی نقش مهمی دارند، اما چرای دام می‌تواند در این پایداری اختلال ایجاد کند. پژوهش پیش‌رو با هدف ارزیابی اثرات شدت چرای دام بر تنوع و ساختار جنگل در منطقه تنگ دالاب استان ایلام اجرا شد. بر اساس تعداد دام، سه ناحیه قرق، چرای متوسط و چرای سنگین مشخص شد. در هر ناحیه سه خط‌‌نمونه به‌صورت تصادفی- منظم که بر روی هر کدام 10 قطعه‌نمونه قرار داشت، درنظر گرفته شد. در هر قطعه‌نمونه، مشخصه­‌های کمی درختان و تعداد نهال­­‌ها اندازه‌گیری شد و شاخص­‌های تنوع، غنا، یکنواختی و غالبیت با استفاده از نرم‌افزار 3.04 PAST محاسبه شدند. نتایج نشان داد که مقدار شاخص‌­های غالبیت و یکنواختی در وضعیت قرق کمتر از دو وضعیت چرایی دیگر بود، اما شاخص‌های تنوع و غنا در شرایط چرای دام کمتر از وضعیت قرق بود. بررسی ساختار نشان داد که شدت چرا هم درصد حضور گونه‌ها در قطعه‌های نمونه را نسبت به منطقه قرق کاهش داد و هم بر مشخصه‌های قطر برابر سینه، ارتفاع تنه، طول تاج، متوسط قطر تاج، تعداد شاخه اصلی و زادآوری درختان بلوط ایرانی، بنه، کیکم، بادام، راناس، زالزالک و دافنه تأثیر گذاشت، به‌طوری که اغلب مشخصه‌های مورد بررسی درختان در وضعیت قرق نسبت به دو وضعیت دیگر متفاوت بود. همچنین، برای اکثر مشخصه‌ها بین وضعیت‌های چرای متوسط و شدید تفاوت معنی‌داری مشاهده نشد. به‌طور کلی می‌­توان نتیجه گرفت که چرای دام با هر شدتی موجب اختلال در عملکرد بوم‌سازگان جنگلی می‌­شود، بنابراین ضروری است که از چرای بیشتر از ظرفیت چرا در عرصه­‌های جنگلی جلوگیری شود.

کلیدواژه‌ها


عنوان مقاله [English]

Investigating the effects of grazing intensity on the structure and diversity of woody species in the Ilam Strait Dalab forest

نویسندگان [English]

  • Mashaallah Mohammadpour 1
  • Mohammad Reza Tatian 2
  • Reza Tamartash 2
  • Jafar Hosseinzadeh 3
1 Ph.D. Student of Rangeland Science, Faculty of Natural Resources, Sari Agricultural Sciences and Natural Resources University, Sari, Iran
2 Assistant Prof., Faculty of Natural Resources, Sari Agricultural Sciences and Natural Resources University, Sari, Iran
3 Associate Prof., Research Division of Natural Resources, Ilam Agricultural and Natural Resources Research and Education Center, AREEO, Ilam, Iran
چکیده [English]

Biodiversity and forest stand structure play important roles in the sustainability and dynamics of forest ecosystems, but grazing of livestocks can affect on the sustainability. In order to study the effects of grazing on forest diversity and structure, this research was carried out in Dalab region of Ilam province. Based on the number of livestock, three areas including enclosure, medium grazing and heavy grazing were identified. In each area, three transects which located on each of them ten plots, were considered. In each plot, quantitative characters and number of seedlings were measured. Indices of diversity, richness, evenness and dominance were calculated using PAST 3.04 program. The results showed that the values ​​of dominance and evenness indices in the enclosure condition status were less than two other conditions However, diversity and enrichment indices in livestock grazing conditions were less than the enclosure status. The study of structure shows that the grazing intensity has reduced the percentage of species in samples in comparison to the protected area. The intensity grazing effected on the parameters of DBH, trunk height, crown length, mean of crown diameter, number of branches and regeneration of Quercus brantii Lindl., Pistacia atlantica Desf., Acer monsopessulanum L., Amygdalus orientalis Duh., Crataegus pontica C. Koch, Cerasus microcarpa (C. A. Mey.) Boiss., and Daphne mucronata Royle. Most of this parameters studied on these trees are different from the grazing situations than the enclosure status. Because intensity grazing cause restriction the growth or deployment of young seedlings in recent years or indirectly causing soil compaction to reduce fertility and permeability of the soil and cause changes in the structure of the forest. There was no significant difference between the moderate and severe grazing conditions, and in general it can be said that grazing of livestock with any intensity would disrupt forest ecosystem performance so, it is necessary to determine the grazing capacity of livestocks and prevention of overgrazing capacity in the forests.

کلیدواژه‌ها [English]

  • Grazing
  • oak forest
  • structural characteristics
  • Zagros
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