نشریه علمی - پژوهشی مرتع و آبخیزداری

نوع مقاله : مقاله پژوهشی

نویسنده

دانشیار گروه مرتع و آبخیزداری دانشگاه شهرکرد، دانشکده منابع طبیعی و علوم زمین، دانشگاه شهرکرد، ایران

چکیده

پوشش گیاهی و تولید همواره دو شاخص مهم در اندازه گیری و ارزیابی مراتع بوده که گاهی به عنوان نماینده­ی دیگری نیز اندازه گیری می­شوند. این دوشاخص در مطالعات وسیعی مورد استفاده قرار گرفته و نقشی تعیین کننده در ارزیابی ساختار و عملکرد مراتع دارند. در بعضی موارد در زمان یا مکان­های متفاوت، آماربرداران مختلفی پوشش گیاهی و تولید را اندازه گیری می­کنند. این تحقیق تأثیر آماربرداران و فرم‏های رویشی مختلف را بر برآورد رابطه بین پوشش گیاهی و تولید را بررسی کرده است. بدین منظور، تأثیر سه گروه آماربردار و پنج فرم رویشی مختلف (فاکتورها) بر برآورد رابطه بین پوشش گیاهی (کواریانس) و تولید (متغیر وابسته) در قالب طرح فاکتوریل کاملی در مراتع چهارطاق ناغان استان چهارمحال و بختیاری مورد بررسی قرار گرفت. نتایج نشان داد، متغیر پیشگوی پوشش گیاهی شاخص مناسبی (P≤0.05) برای بیان تولید فرم‏های رویشی می­باشد، اما گروه­های آماربردار مختلف بر برآورد رابطه بین پوشش گیاهی و تولید فرم‏های رویشی به­طور معنی داری (P≤0.05) تأثیر گذارند. فرم‏های رویشی تفاوت معنی داری (P≤0.05) در برآورد رابطه بین پوشش گیاهی و تولید ایجاد نمی­کنند. ولی، تأثیر متقابل گروه­های آمار بردار و فرم‏های رویشی بر برآورد رابطه بین پوشش گیاهی و تولید معنی دار (P≤0.05) است. از این­رو می­توان نتیجه گرفت، اگرچه متغیر پیشگوی پوشش گیاهی عامل مناسبی برای بیان تولید است، ولی، باید در صورت امکان به طور همزمان از گروه­های آماربردار مختلف به ویژه هنگامی که اندازه­گیری تولید فرم‏های رویشی مختلف مد نظر است، استفاده نشود.

کلیدواژه‌ها

عنوان مقاله [English]

Effect of sampling group and life-form on estimation ofrelationship between forage production and canopy cover

نویسنده [English]

  • Ataollah Ebrahimi

University Staff

چکیده [English]

Canopy cover and forage production have always been two important indicators in rangeland assessment, which sometimes are applied as surrogates of each other. These two indicators are widely used in rangeland studies and have a vital role in evaluation of rangeland structure and functions. Occasionally, different sampling groups (estimators) evaluate forage production and canopy cover of different spaces and times. This research was aimed at investigation of different sampling groups and life-forms' effects on relationship between canopy cover and forage yield estimation. To do so, the impact of three sampling groups and five life forms (Fixed factors) on estimation of relationship between canopy cover (covariate) and forage yield (dependent variable) in a full factorial model in rangeland of Chahrtagh of Naghan, Chahrmhal-va-Bakhtiari Province, was estimated. Results shows that predictor variable of canopy cover is a god surrogate for forage production (P≤0.05) of different life-forms, but different sampling groups significantly (P≤0.05) effects on relationship between canopy cover and forage production estimation. Nevertheless, different life-forms do not significantly (P≤0.05) influence estimation of canopy cover and forage production relationship. By the way, interaction between sampling group and life forms considerably (P≤0.05) affects the relation. Therefore, we conclude that, although, the canopy cover is a good predictor of forage production, nonetheless, different sampling groups should not be engaged in sampling and monitoring vegetation cover and forage production estimation, specifically, if estimation of different life-forms' production is intended.

کلیدواژه‌ها [English]

  • Rangeland
  • Rangeland assessment and evaluation
  • Canopy cover
  • Forage production
  • Surveying
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