ارزیابی کنش های متقابل درون گونه ای درختچه های اشنان (Seidlitzia rosmarinus) در مناطق خشک با استفاده از تحلیل الگوی نقطه ای (مطالعه موردی: منطقه حفاظت شده قهی استان اصفهان)

نوع مقاله: علمی- پژوهشی

نویسندگان

1 استادیار، دانشکده کشاورزی، دانشگاه شیراز

2 دانشجوی کارشناسی‌ارشد، دانشکده کشاورزی، دانشگاه شیراز

چکیده

تحلیل توزیع مکانی گیاهان چوبی در مناطق خشک و نیم ه­خشک، کنش­های متقابل آنها و چگونگی تأثیرشان بر یکدیگر را توضیح می­دهد. این پژوهش با هدف ارزیابی کنش ­های متقابل درون­ گونه­ ای درختچه­ های اشنان (Seidlitzia rosmarinus) در مناطق خشک مرکزی ایران با استفاده از آماره­ های اختصاری مختلف (تابع همبستگی جفتی g(r)، تابع O-ring O(r)، تابع توزیع نزدیک­ترین همسایه D(r)، تابع توزیع تماس کرویHs(r)  و تابع همبستگی نشان­دار kmm(r)) انجام شد. یک قطعه­ نمونه با ابعاد 160 × 160 متر که به­ طور خالص پوشیده از اشنان بود، در منطقه حفاظت‌شده قهی استان اصفهان انتخاب شد. نقشه نقطه­ ای تمام 989 درختچه اشنان با استفاده از سامانه موقعیت ­یاب جهانی تفاضلی سه‌فرکانسه تریمبل R8 با دقت سه میلی­ متر ± 0/1 پی ­پی­ ام تهیه شد. مقایسه با فرآیند پوآسون ناهمگن نشان داد که الگوی مشاهده شده درختچه­ ها دارای ناهمگنی مکانی معنی­ دار (در سطح اطمینان 95 درصد) بود. نتایج g(r) و O(r) نشان­دهنده تجمع معنی­ دار (در سطح اطمینان 95 درصد) درختچه­ های اشنان تا فاصله سه متر در کنار یکدیگر بود. نتایج D(r) و Hs(r) نیز نشان داد که بیشترین فاصله تا نزدیک­ترین درختچه شش متر بود و توزیع اندازه فضاهای خالی تا این مقیاس به­ طور معنی ­داری با توزیع تصادفی تفاوت داشت. درنهایت، kmm(r) برای ارتفاع، قطر متوسط تاج و مساحت تاج همبستگی مثبت ویژگی­ های زیست­ سنجی اشنان­ ها را نشان داد. به­ طور کلی، نتیجه­ گیری شد که در منطقه مورد مطالعه بین پایه­ های گروهی اشنان یک کنش متقابل مثبت وجود دارد که با توجه به اثر تسهیل­ کنندگی درون­ گونه­ ای آنها بر یکدیگر در کنار هم تجمع کرده­ اند.

کلیدواژه‌ها


عنوان مقاله [English]

Evaluating the intraspecific interactions of Eshnan (Seidlitzia rosmarinus) shrubs in arid lands by point pattern analysis (Case study: Qehi protected area, Isfahan Province)

نویسندگان [English]

  • Yousef Erfanifard 1
  • Elahe Khosravi 2
1 M.Sc. Student, College of Agriculture, Shiraz University, Shiraz, Iran
2 Assistant Prof., College of Agriculture, Shiraz University, Shiraz, Iran
چکیده [English]

The spatial distribution analysis of woody plants in arid and semi-arid environments explains their interactions and how they influence one another. This study was aimed to evaluate the intraspecific interactions of Eshnan (Seidlitzia rosmarinus) shrubs across a portion of central Iranian arid lands using different summary statistics including pair correlation g(r), O-ring O(r), nearest neighbor distribution D(r), spherical contact distribution Hs(r) and mark correlation kmm(r) functions. A 160 × 160 m2 plot purely covered by Eshnan was selected in Qehi protected area, Isfahan province. The point map of all 989 Eshnan shrubs was obtained by Trimble R8 differential global positioning system with a positional accuracy of 3 mm ± 0.1 ppm. The observed pattern of shrubs showed significant spatial heterogeneity as compared to inhomogeneous Poisson process (α=0.05). The results of g(r) and O(r) revealed the significant aggregation of Eshnan shrubs up to scale of 3 m (α=0.05). The results of D(r) and Hs(r) also showed maximum distance to nearest shrub to be 6 m. It was additionally shown that the distribution of gap sizes was significantly different from random up to this spatial scale. Finally, kmm(r) for height, mean crown diameter, and crown area indicated the aggregation of Eshnan individuals at all scales. In general, positive interactions were concluded to exist amongst Eshnan shrubs at small scales, and they were aggregated due to their intraspecific facilitation effects in the study area. 

کلیدواژه‌ها [English]

  • Eshnan
  • O-ring function
  • spherical contact distribution function
  • nearest neighbor distribution function
  • mark correlation function
  • Qehi protected area
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