مقایسه روش نمونه‌برداری چنددرختی با روش قطعه‌نمونه در برآورد تراکم درختان جنگل‌های زاگرس

نوع مقاله : علمی- پژوهشی

نویسندگان

1 کارشناسی ارشد جنگلداری، دانشگاه شهرکرد

2 دانشجوی کارشناسی ارشد جنگلداری، دانشگاه شهرکرد

چکیده

روش نمونه‌برداری چنددرختی ازجمله روش‌های نمونه‌برداری فاصله‌ای است که نسبت به روش‌های قطعه‌نمونه با شعاع ثابت دارای سرعت بیشتر و هزینه کمتری است. برای این پژوهش یک قطعه 4029/36 هکتاری از جنگل‌های حفاظت‌شده هلن در استان چهارمحال و بختیاری انتخاب و آماربرداری صددرصد انجام شد. در این بررسی برآوردکننده‌های Moore و Kleinn-Vilcko با روش قطعه‌نمونه با توجه به معیارهای اریبی نسبی (RB) و جذر میانگین مربع خطای نسبی (RRMSE) برای تعداد دو تا 12 درخت سنجیده شدند. برای هر تخمین‌گر 30 تکرار و برای هر تکرار 50 نقطه نمونه انتخاب شد. نتایج نشان داد که در شرایط جنگل‌های موردمطالعه و تعداد در هکتار 25/154 با الگوی پراکنش کپه‌ای، روش نمونه‌برداری قطعه‌نمونه با شعاع ثابت دارای دقت زیاد و روش Kleinn-Vilcko در برآورد تعداد در هکتار از پنج درخت بیشتر، دارای دقت قابل‌قبولی است و رابطه Moore برای تخمین تعداد در هکتار با توجه به خطای زیاد، برآورد کننده مناسبی نیست.

کلیدواژه‌ها

عنوان مقاله [English]

N-Tree Distance Sampling vs. Fixed-Radius Plots methods for tree density estimation in central Zagros forests

نویسندگان [English]

  • Hamdollah Sadeghi Kaji 1
  • Iman Zafarian 2
  • Kobra Badfar 2
1 M. Sc. Forestry, Department of Forestry, Faculty of Natural Resources and Earth Sciences, Shahrekord University, Shahrekord, I.R. Iran.
2 M. Sc. Student, Department of Forestry, Faculty of Natural Resources and Earth Sciences, Shahrekord University, Shahrekord, I.R. Iran
چکیده [English]

N-tree Distance Sampling (NTDS) is a well-known distance sampling method which is considered as cost-and time effective compared to fixed-Radius Plots. This study was conducted across an area of 36.40 ha in Helen forest reserve in Chaharmahal and Bakhtiari Province. The study area mostly comprises of natural, old-growth Brant`s oak (Quercus brantii) stands. Here, the stands were first fully callipered. Two estimators of Moore and Kleinn-Vilcko sample plot methods were applied to derive the diagnostic measures of relative bias (RB) and relative root mean square error (RRMSE) for a number of 2 to 12 trees. For each estimator, 30 repeats with each encompassing 50 Sample points were selected. The results showed the fixed plot sampling (FPS) to be of higher performance in the clumpy-distributed trees within stands with 154.25 trees per ha. In addition, the Kleinn-Vilcko estimator was shown to be most efficient for N ≥ 5 trees. Due to its high error rate, the Moore estimator yet returned poor performances in density estimation across the study area.

کلیدواژه‌ها [English]

  • Forest inventory
  • N-tree distance sampling
  • Bias
  • fixed-radius plots
  • Helen reservation forest area

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