بررسی سه روش خط‌نمونه در برآورد سطح مقطع برابر سینه درختان جنگلی (مطالعه موردی منطقه دالاب استان ایلام)

نوع مقاله : علمی- پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد جنگلداری، دانشگاه گیلان

2 عضو هیأت علمی دانشگاه گیلان

چکیده

به‌منظور مدیریت صحیح و برنامه‌ریزی اصولی در جنگل، به جمع‌آوری اطلاعات کمی و کیفی مناسب نیاز است. جمع‌آوری اطلاعات معمولاً با استفاده از روش‌های مختلف نمونه‌برداری مانند روش خط‌نمونه انجام می‌شود. هدف از این تحقیق، تعیین مناسب‌ترین روش نمونه‌برداری در برآورد سطح مقطع برابر سینه درختان در جنگل‌های دالاب استان ایلام بود. بدین‌منظور پس از جنگل‌گردشی، 2/37 هکتار از جنگل‌های منطقه دالاب ایلام که معرف جنگل‌های منطقه بود، انتخاب و به‌صورت صددرصد آماربرداری شد. سپس نمونه‌برداری با استفاده از سه روش خط‌نمونه با طول ثابت 50 متر، خط‌نمونه براساس تئوری احتمالات و خط‌نمونه با تعداد ثابت 5 درخت انجام شد. برای هر روش، تعداد 37 قطعه‌نمونه براساس الگوی منظم تصادفی با ابعاد شبکه آماربرداری 100×100 متر برداشت شد. نتایج نشان داد که اختلاف معنی‌داری بین میانگین برآوردشده از روش‌های نمونه‌برداری با میانگین واقعی که از آماربرداری صددرصد به‌دست آمده است، وجود دارد. به‌منظور ارزیابی بهتر روش‌های نمونه‌برداری از معیار  E%) 2 × T) استفاده شد. نتایج نشان داد که روش خط‌نمونه با تعداد ثابت 5 درخت، از بین روش‌های فوق، مناسب‌ترین روش برای برآورد سطح مقطع برابر سینه درختان در جنگل‌های منطقه دالاب ایلام است.

کلیدواژه‌ها

عنوان مقاله [English]

Defining the most appropriate transect method for estimation of Basal area: case study in Dalab forests, Ilam Province

نویسندگان [English]

  • Mehrdad Mirzaei 1
  • Amir Eslam Bonyad 2
1 M.Sc. Student, Department of Forestry, Faculty of Natural Resources, University of Guilan, Sowme Sara, Iran
2 Associate Professor, Department of Forestry, Faculty of Natural Resources, University of Guilan, Sowme Sara, Iran.
چکیده [English]

Forest management and planning require a proper level of quantitative and qualitative information on forest stands. Such data is usually collected by means of different sampling methods e.g. transect method. This study aims at exploring the most appropriate sampling method for estimating basal area incorporating their on precision and cost in a case study of Dalab forests of Ilam province. To this aim, a representative area encompassing 37.2 hectares of forests was selected and surveyed by a 100% inventory. Three sampling methods (transect based on probability theory, transect with fixed 50 m length and transect with fixed number of 5 trees) were applied. Based on a regular random sampling pattern, 37 samples were selected for each sampling method in a 100 × 100m grid. The results showed significant difference between the measured basal area and those estimated by any of the three sampling methods. The E%2×T criteria was additionally applied for a better evaluation of the applied sampling methods .These cost and precision criteria turned out the transect method with fixed number of 5 trees to be the superior to other tested methods, which can be further suggested  for estimation of basal area of trees in Dalab Forests of Ilam province.

کلیدواژه‌ها [English]

  • Ilam
  • transect method
  • basal area estimation
  • Sampling

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