تحلیل وضعیت خشکیدگی جنگل‌های بلوط زاگرس با استفاده از روش‌های آمار مکانی (پژوهش موردی: جنگل زرآب استان ایلام)

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشیار پژوهش، مؤسسۀ تحقیقات جنگل‌ها و مراتع کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران،‌ ایران

2 دانشیار، گروه علوم جنگل‌، دانشگاه ایلام

3 کارشناس ارشد جنگل‌داری، اداره منابع طبیعی و آبخیزداری شهرستان دهلران، ایلام، ایران

چکیده

 DOR: 98.1000/1735 0859.1397.16.129.32.2.1578.41

    حدود یک دهه است که پدیده خشکیدگی در جنگل‌های بلوط زاگرس مشاهده شده است. یکی از کانون‌های اصلی و ابتدایی این پدیده جنگل‌های استان‌ ایلام هستند. در این پژوهش جنگلی به مساحت 83 هکتار در منطقه زرآب ایلام که مبتلا به خشکیدگی بود انتخاب و نوع گونه، قطر برابرسینه، فرم پرورشی، ارتفاع کل، درصد خشکیدگی و سطح تاج کلیه درختان خشکیده بررسی و مختصات جغرافیایی آنها تعیین شد. ساختار، الگو و همبستگی مکانی این متغیر‌ها به­ترتیب با استفاده از  تحلیل واریوگرام، آماره او-رینگ و تابع همبستگی نشان‌دار (MCF) بررسی شد. نتایج نشان داد که تراکم درختان دچار خشکیدگی 27 پایه در هکتار است که بیشتر شامل جست‌گروه‌های شاخه‌زاد با بیشترین فراوانی در پایه‌های کم‌قطر و میان‌قطر بوده است. الگوی پراکنش درختان دچار خشکیدگی تا شعاع 35 متری خوشه‌ای و پس از آن یکنواخت بود. تحلیل واریوگرم نشان داد که درصد خشکیدگی و قطر برابرسینه دارای ساختار مکانی قوی قابل مدل‌سازی و سطح تاج و ارتفاع کل دارای ساختار مکانی ضعیف هستند. نمودار MCF نشان داد که قطر برابرسینه درختان خشکیده مجاور مشابه نیستند، اما درصد خشکیدگی آنها به هم شباهت دارند. به‌طور کلی نتایج این پژوهش نشان داد که خشکیدگی در تمام درختان منطقه پژوهش با متغیرهای زیست‌سنجی مختلف و در جهات مختلف جغرافیایی اتفاق افتاده است. نتایج به­دست­آمده می‌تواند راهنمایی برای مدیریت پایدار این توده‌ها و جنگل‌شناسیکاربردی آنها بوده و به­هنگام برش‌های بهداشتی مدنظر قرار گیرد تا براساس نوع الگوی پراکنش و ابعاد لکه‌ها و خوشه‌ها و فواصل موجود دخالت صورت گیرد.

کلیدواژه‌ها

عنوان مقاله [English]

Analysis of the decline status of Zagrosian oak forests using spatial statistics (Case study: Zarab forests of Ilam)

نویسندگان [English]

  • R. Akhavan 1
  • Ali Mahdavi 2
  • M. Kianfar 3
2 Associate professor, Forestry Department, University of Ilam
چکیده [English]

Recently, forest decline has outburst in Zagros forests region in the west of Iran, especially in Ilam province. In this research, we selected an 83 ha infected forest area in Zarab, Ilam and the dried trees were fully investigated for variables including dbh, height, drought intensity, crown cover, origin and Cartesian coordinates. Their spatial structure, spatial patterns and spatial correlation were analyzed using variogram analysis, O-ring statistic and Mark correlation function (MCF), respectively. Results showed that the density of dried trees was 27 N/ha which is more comprised of coppice trees in small and medium diameter classes. A cluster spatial pattern of dried trees was determined up to 35 m and after that it was uniform, implying dried trees created patches with 3850 m2 surface area. Variogram analysis showed that only dbh and drought intensity of dried trees had strong spatial structure which was mapped using Kriging interpolation method of Geostatistics. Mark correlation function graph showed that adjacent dried trees were similar according to drought intensity while were not similar based on their dbh. In general, the results illustrated that all of the trees in the studied area were infected by drought with different biometric characteristics as well as at different geographical aspects. These results can be used as an instruction for sustainable management of the stands based on their spatial characteristics. 

کلیدواژه‌ها [English]

  • Forest decline
  • Geostatistics
  • Spatial patterns
  • Spatial correlation
  • Zagros forests

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سابقه مقاله

  • تاریخ دریافت: 01 آذر 1396
  • تاریخ بازنگری: 25 اسفند 1397
  • تاریخ پذیرش: 26 اسفند 1397

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