ارزیابی روش‌های اندازه‏گیری تاج درختان شاخه‏زاد در جنگل‌های زاگرس با استفاده از تصاویر هوایی UltraCam-D

نوع مقاله: مقاله پژوهشی

نویسندگان

1 استادیار، بخش مدیریت مناطق بیابانی، دانشکدة کشاورزی دانشگاه شیراز، شیراز، ایران

2 دانشجوی کارشناسی ارشد، بخش مدیریت مناطق بیابانی، دانشکدة کشاورزی دانشگاه شیراز، شیراز، ایران

چکیده

تاج پوشش مهم‌ترین ویژگی زیست‏سنجیِ مورد استفاده در مدیریت جنگل‌های زاگرس بوده که اندازه‏گیری این ویژگی در درختان شاخه‏زاد با شکل تاج نامتقارن اهمیت بیشتری دارد. بنابراین، این مطالعه با هدف بررسی صحت و دقت روش‌های میدانی تعیین مساحت تاج درختان شاخه‏زاد بلوط ایرانی و امکان برآورد قطر متوسط تاج این درختان با استفاده از تصاویر هوایی UltraCam-D انجام گرفت. بدین‌منظور، در یک محدوده به مساحت 30 هکتار در جنگل‌های بلوط ایرانی در جنگل‌های استان کهگیلویه و بویراحمد دو قطر بزرگ و کوچک تاج 125 پایه درخت بلوط ایرانی شاخه‏زاد اندازه‏گیری شد. مساحت تاج هر‌یک از آن‌ها نیز از تصاویر هوایی UltraCam-D منطقة مورد مطالعه محاسبه شد. سپس دو شکل بیضی و دایره و دو روش محاسبۀ قطر تاج متوسط هندسی و حسابی ارزیابی شدند. نتایج نشان داد مساحت واقعی تاج درختان با هر‌یک از روش‌های اشاره‌شده اختلاف معنی‏داری نداشته و از صحت کافی برخوردارند. البته محاسبة مساحت تاج درختان مذکور با شکل دایره با قطر متوسط حسابی، 9/8 درصد، و با شکل دایره با قطر متوسط هندسی و شکل بیضی، 7/7 درصد بیشتر از مقدار واقعی بود. همچنین استفاده از شکل بیضی بیشترین دقت را در برآورد مساحت تاج در مقایسه با دو روش دیگر ارائه داد. برآورد قطر متوسط تاج درختان شاخه‏زاد بلوط ایرانی نیز از روی تصاویر هوایی مذکور و با استفاده از یک مدل درجة سوم بدون اختلاف معنی‌‌دار از مقدار واقعی ممکن است.

کلیدواژه‌ها


عنوان مقاله [English]

Assessment of Crown Measurement Techniques in Coppice Trees of Zagros Forests by UltraCam-D Aerial Imagery

نویسندگان [English]

  • Yousef Erfanifard 1
  • Masoumeh Mouselo 2
1 Assistant Professor, Department of Desert Region Management, College of Agriculture, Shiraz University, Shiraz, I.R. Iran
2 M.Sc. student, Department of Desert Region Management, College of Agriculture, Shiraz University, Shiraz, I.R. Iran
چکیده [English]

Crown cover is one of the most important biometric characteristics applied in Zagros forests
management that its measurement is more important in coppice trees because of their asymmetric
crown shape. The aim of this research was investigating on the accuracy and precision of different
mensuration methods of crown area measurement in Persian Oak coppice trees and the possibility of
mean crown diameter estimation of these trees by UltraCam-D imagery. The maximum and minimum
crown diameters of 125 Persian Oak coppice trees were inventoried in a 30 ha plot in the forests of
Kohgiluye-BoyerAhmad province. The crown area of each tree was measured on UltraCam-D aerial
imagery of the study area. Two circular and elliptical shapes and two mathematical and geometric
methods of calculating mean crown diameter were analyzed in this respect. The results showed that
the applied methods have no significant difference with the true crown area and they were accurate
enough. Although the crown area of the trees with circular shape and mathematical mean diameter
were 8.9 percent and with circular shape and geometric mean diameter and elliptical shape were 7.7
percent greater than the true values. The elliptical shape was also more precise in measuring the crown
area than two other methods. It was also possible to estimate the mean crown diameter of Persian Oak
coppice trees applying the aerial imagery and cubic models with no significant difference from the
true values.

کلیدواژه‌ها [English]

  • circular crown shape
  • Coppice
  • crown cover
  • elliptical crown shape
  • Persian Oak
  • UltraCam-D aerial imagery
  • Zagros
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