ارزیابی اثر آشفتگی و ویژگی‌های مکانی بر تجدید حیات با استفاده از معادلات ساختاری (مطالعه موردی: جنگل خیرود)

نوع مقاله : علمی- پژوهشی

نویسندگان

1 استادیار، گروه محیط زیست، دانشکده منابع طبیعی، دانشگاه زابل، زابل، ایران

2 استاد، گروه محیط زیست، دانشکده منابع طبیعی، دانشگاه تهران، کرج، ایران

3 دانشیار، دانشکده شیلات و محیط زیست، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، گرگان، ایران

4 دانشیار، گروه جنگل‌داری و اقتصاد جنگل، دانشکده منابع طبیعی، دانشگاه تهران، کرج، ایران

چکیده

اثر آشفتگی‌های انسانی از قبیل چرای دام، بهره‌برداری از جنگل و استفاده افراد محلی و ویژگی‌های مکانی (شیب، جهت، ارتفاع و خاک) بر تجدید حیات گونه‌های درختی و در نتیجه سلامت جنگل اجتناب‌ناپذیر است. در این پژوهش، اثر آشفتگی‌ها و ویژگی‌های مکانی بر تجدید حیات گونه‌های درختی در جنگل خیرود نوشهر بررسی شد. برخی از نمایه‌های نهال، خال و درخت در 100 قطعه‌نمونه 10 متر مربعی اندازه‌گیری شد و به‌همراه نمایه‌هایی از مجموعه‌هایی معروف به "سازه" شامل سازه آشفتگی و سازه ویژگی‌های محیطی در قالب معادلات ساختاری- حداقل مربعات جزئی (SEM-PLS) مورد تجزیه و تحلیل قرار گرفت. در نتیجه این بررسی مشخص شد که نقش سازه آشفتگی بر سازه نهال در سطح اطمینان 99 درصد معنی‌دار بود. همچنین، سازه نهال بر سازه خال، سازه خال بر سازه درخت و سازه درخت بر سازه نهال در سطح اطمینان 99 درصد اثرگذار بود. تأثیر تعدیل‌گری سازه ویژگی‌های مکانی بر مسیر آشفتگی به نهال (در سطح اطمینان 99 درصد) و مسیر آشفتگی به خال (در سطح اطمینان 95 درصد) معنی‌دار بود. بنابراین، آشفتگی‌ها و ویژگی‌های مکانی منطقه مورد مطالعه، بیشترین تأثیر را به‌ترتیب بر نهال و سپس خال گذاشته و از این مسیرها به‌طور غیرمستقیم بر سازه درخت اثرگذار بودند.

کلیدواژه‌ها

عنوان مقاله [English]

Evaluation of disturbance and spatial attribute on regeneration using structural equation modeling (Case study: Khyrud forest- Nowshahr)

نویسندگان [English]

  • Malihe Erfani 1
  • Afshin Danehkar 2
  • Abdolrasoul Salmanmahiny 3
  • Vahid Etemad 4
1 Assistant Prof., Department of Environmental Engineering, Faculty of Natural Resources, University of Zabol, Zabol, Iran
2 Prof., Department of Environmental Engineering, Faculty of Natural Resources, University of Tehran, Karaj, Iran
3 Associate Prof., Faculty of Fisheries and environmental Sciences, Gorgan Agricultural Sciences and Natural Resources University, Gorgan, Iran
4 Associate Prof., Department of Forestry and Forest Economic, Faculty of Natural Resources, University of Tehran, Iran
چکیده [English]

Effects of anthropogenic disturbances through livestock grazing, wood harvesting, and direct utilization by local people plus spatial heterogeneity on the regeneration of forest tree species and forest health have been recognized worldwide. In this research, effects of disturbances and site features (Aspect, slope percent, altitude, and soil) were investigated on tree species regeneration in Khyrud forest-Nowshahr, north of Iran. Indicators pertaining to saplings, large sapling and trees were measured in 100 plots, 10 m2 each, for disturbance and spatial constructs of Structural Equation Modeling- Partial Least Squares method. Results showed disturbance has a significant (α = 0.01) effect on regeneration. Effects of sapling on large sapling and large sapling on tree constructs were significant (α = 0.01), too. The moderating effect of spatial construct on disturbance to sapling path (α = 0.01) and disturbance to large sapling path (α = 0.05) was significant. We conclude that disturbance and spatial attributes have high influence on sapling and large sapling in the study area, respectively which affect trees indirectly.

کلیدواژه‌ها [English]

  • Disturbance construct
  • Forest health
  • large sapling
  • sapling
  • spatial construct

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