تعيين مناسب‌ترين سطح قطعه نمونه به منظور بررسي الگوي مكاني درختان ارس (Juniperus excelsa) (مطالعه موردي: منطقه آتشگاه كرج)

Determination of the Optimum Plot Size to Study the Spatial Patterns of Juniperus Excelsa Trees (Case study: Atashgah, Karaj)

زﻣﯿﻨﻪ و ﻫﺪف: اﺧﯿﺮاً در ﺗﺤﻠﯿﻞﻫﺎي ﻣﺮﺗﺒﻂ ﺑﺎ اﻟﮕﻮي ﻣﮑﺎﻧﯽ درﺧﺘﺎن، روشﻫﺎي ﻧﻮﯾﻨﯽ ﺗﻮﺳﻌﻪ ﯾﺎﻓﺘﻪاﻧﺪ ﮐﻪ ﺑﻪ ﻣﻨﻈﻮر ﺑﺮرﺳﯽ، ﺑﻪ ﯾﮏ ﻧﻘﺸﻪ ﮐﺎﻣﻞ از ﻣﻮﻗﻌﯿﺖ ﻣﮑﺎﻧﯽ درﺧﺘﺎن ﻧﯿﺎز دارﻧﺪ. ﺑﻪ ﮐﺎرﮔﯿﺮي اﯾﻦ روشﻫﺎ ﺑﻪ ﻣﻘﯿﺎس ﻣﻄﺎﻟﻌﻪ ﺑﺴﺘﮕﯽ دارد ﺑﻪ ﻧﺤﻮي ﮐﻪ ﺗﻐﯿﯿﺮ ﻣﻘﯿﺎس ﻣﻄﺎﻟﻌﻪ ﻣﯽ-ﺗﻮاﻧﺪ ﺳﺒﺐ ﺗﻐﯿﯿﺮاﺗﯽ در اﻟﮕﻮي ﻣﮑﺎﻧﯽ درﺧﺘﺎن ﺷﻮد. ﭘﮋوﻫﺶ ﺣﺎﺿﺮ ﺑﺎ ﻫﺪف ﺗﻌﯿﯿﻦ ﻣﻨﺎﺳﺐﺗﺮﯾﻦ ﺳﻄﺢ ﻗﻄﻌﻪ ﻧﻤﻮﻧﻪ ﺟﻬﺖ ﮐﻤﯽ ﺳﺎزي اﻟﮕﻮي ﻣﮑﺎﻧﯽ درﺧﺘﺎن ارس داﻣﻨﻪ ﺟﻨﻮﺑﯽ اﻟﺒﺮز ﺻﻮرت ﭘﺬﯾﺮﻓﺖ. روش ﺑﺮرﺳﯽ: ﺑﺪﯾﻦ ﻣﻨﻈﻮر ﻗﻄﻌﻪ ﻧﻤﻮﻧﻪاي ﺑﻪ ﻣﺴﺎﺣﺖ ﺷﺶ ﻫﮑﺘﺎر اﻧﺘﺨﺎب و اﻟﮕﻮي ﻣﮑﺎﻧﯽ درﺧﺘﺎن ﺑﺎ اﺳﺘﻔﺎده از ﺗﺎﺑﻊ )g(r ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮار ﮔﺮﻓﺖ. ﺳﭙﺲ ﺳﻄﺢ اﯾﻦ ﻗﻄﻌﻪ ﻧﻤﻮﻧﻪ ﺑﻪ ﭘﻨﺞ، ﭼﻬﺎر، ﺳﻪ، دو و ﯾﮏ ﻫﮑﺘﺎر ﮐﺎﻫﺶ و اﻟﮕﻮي ﻣﮑﺎﻧﯽ درﺧﺘﺎن ﺑﺎ اﺳﺘﻔﺎده از ﺗﺎﺑﻊ )g(r ﺑﺮرﺳﯽ و ﻧﺴﺒﺖ ﺑﻪ ﺳﻄﺢ ﻣﺒﻨﺎي ﺷﺶ ﻫﮑﺘﺎري ﻣﻘﺎﯾﺴﻪ ﺷﺪ. ﯾﺎﻓﺘﻪﻫﺎ: ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ از اﯾﻦ ﺗﺎﺑﻊ ﻧﺸﺎن دﻫﻨﺪهي اﻟﮕﻮي ﻣﮑﺎﻧﯽ ﯾﮑﻨﻮاﺧﺖ در ﻓﻮاﺻﻞ ﺑﯿﻦ درﺧﺘﯽ ﺗﺎ ﭼﻬﺎر ﻣﺘﺮ، اﻟﮕﻮي ﮐﭙﻪاي در ﻓﻮاﺻﻞ ﺷﺶ ﺗﺎ ده ﻣﺘﺮ و اﻟﮕﻮي ﺗﺼﺎدﻓﯽ در ﺳﺎﯾﺮ ﻓﻮاﺻﻞ ﻣﯽﺑﺎﺷﺪ. ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ از ﻣﻘﺎﯾﺴﻪ ﻧﻤﻮدارﻫﺎي ﺗﺎﺑﻊ )g(r در ﻣﺴﺎﺣﺖ ﻫﺎي ﻣﺨﺘﻠﻒ ﻧﺸﺎن داد ﮐﻪ روﻧﺪ ﮐﻠﯽ ﺗﺎﺑﻊ )g(r ﺗﺎ ﺳﻄﺢ ﺳﻪ ﻫﮑﺘﺎر ﺗﻘﺮﯾﺒﺎً ﺛﺎﺑﺖ و در ﺳﻄﻮح ﮐﻮﭼﮏﺗﺮ، ﺗﻐﯿﯿﺮ ﻣﯽﮐﻨﺪ، ﺑﻨﺎﺑﺮاﯾﻦ ﺣﺪاﻗﻞ ﺳﻄﺢ ﻣﻨﺎﺳﺐ در اﯾﻦ ﺑﺮرﺳﯽ، ﺳﻪ ﻫﮑﺘﺎر ﺑﻪ دﺳﺖ آﻣﺪ. ﺑﺤﺚ و ﻧﺘﯿﺠﻪﮔﯿﺮي: ﺗﻌﯿﯿﻦ ﻣﻨﺎﺳﺐ ﺗﺮﯾﻦ ﺳﻄﺢ ﻗﻄﻌﻪ ﻧﻤﻮﻧﻪ در ﻣﻄﺎﻟﻌﺎت ﺳﺎﺧﺘﺎري ﺿﻤﻦ اﻓﺰاﯾﺶ دﻗﺖ ﻣﻄﺎﻟﻌﺎت ﻣﯽﺗﻮاﻧﺪ ﺳﺒﺐ ﮐﺎﻫﺶ زﻣﺎن و ﻫﺰﯾﻨﻪ ﻣﻄﺎﻟﻌﻪ ﮔﺮدد.

Abstract Background and Objective: In recent years, new methods have been developed for analyzing spatial pattern of trees, and for verifying the spatial pattern, they need to complete map of spatial location of these trees. The use of these methods depends on study scale in a way that changes in study scale cause changes in spatial pattern. In this regard, present study aims to determine the optimum area of sample plots to quantify the spatial pattern of Juniperus Excelsa M. Beib. In southern facing slopes of Alborz mountains. Method: A plot with area of six hectares was selected and spatial pattern of trees were evaluated by using g(r) function. In next step, area of plot decreased to five, four, three, two, and one hectare and spatial pattern of trees were determined by using g(r) function and were compared with six hectare plot. Findings: The results of this function indicates regular spatial pattern in trees distances to four meter, cluster pattern at distances of six to ten meter, and random pattern shows in other distances. The results of comparing figures of g(r) functions in different area showed that the overall trend of this functions almost constant up to three hectares. Hence, in this study the appropriate area is achieved three hectares. Discussion and Conclusion: It should be noted that in structure studies to determine the best area of plot could reduce time and costs while increasing the precision of the study.