پديد آورندگان :
اﻣﯿﻨﯽ، ﺷﻤﯿﻢ داﻧﺸﮕﺎه ﻋﻠﻮم ﮐﺸﺎورزي و ﻣﻨﺎﺑﻊ ﻃﺒﯿﻌﯽ ﮔﺮﮔﺎن - داﻧﺸﮑﺪه ﻋﻠﻮم ﺟﻨﮕﻞ , ﻣﻌﯿﺮي، ﻣﺤﻤﺪ ﻫﺎدي داﻧﺸﮕﺎه ﻋﻠﻮم ﮐﺸﺎورزي و ﻣﻨﺎﺑﻊ ﻃﺒﯿﻌﯽ ﮔﺮﮔﺎن - داﻧﺸﮑﺪه ﻋﻠﻮم ﺟﻨﮕﻞ , ﺷﺘﺎﯾﯽ ﺟﻮﯾﺒﺎري، ﺷﻌﺒﺎن داﻧﺸﮕﺎه ﻋﻠﻮم ﮐﺸﺎورزي و ﻣﻨﺎﺑﻊ ﻃﺒﯿﻌﯽ ﮔﺮﮔﺎن - داﻧﺸﮑﺪه ﻋﻠﻮم ﺟﻨﮕﻞ , رﺣﻤﺎني، راﻣﯿﻦ داﻧﺸﮕﺎه ﻋﻠﻮم ﮐﺸﺎورزي و ﻣﻨﺎﺑﻊ ﻃﺒﯿﻌﯽ ﮔﺮﮔﺎن - داﻧﺸﮑﺪه ﻋﻠﻮم ﺟﻨﮕﻞ
كليدواژه :
روشنه پوشش تاجي , شاخص شكل روشنه , تنوع‌گونه‌اي , زادآوري درختي , تراكم گونه‌اي
چكيده فارسي :
ﺳﺎﺑﻘﻪ و ﻫﺪف: روﺷﻨﻪ ﻫﺎي ﭘﻮﺷﺶ ﺗﺎﺟﯽ ﯾﮑﯽ از ﻣﻨﺎﺳﺐﺗﺮﯾﻦ ﺷـﺮاﯾﻂ ﺑـﺮاي زادآوري ﺑﺴـﯿﺎري از ﮔﻮﻧـﻪ ﻫـﺎ ﻣﺤﺴـﻮب ﻣﯽ ﺷﻮﻧﺪ. ﻣﻄﺎﻟﻌﻪ ﻧﺤﻮه زادآوري در روﺷﻨﻪ ﻫﺎي ﻃﺒﯿﻌﯽ و اﻧﺴﺎنﺳﺎﺧﺖ اﻃﻼﻋﺎت ﮐﺎرﺑﺮدي را ﺑﺮاي اﻓﺰاﯾﺶ ﮐﻤﯽ و ﮐﯿﻔـﯽ
زادآوري اﻧﻮاع ﮔﻮﻧﻪ ﻫﺎي درﺧﺘﯽ ﻓﺮاﻫﻢ ﻣﯽ ﮐﻨﺪ. اﯾﻦ ﭘﮋوﻫﺶ ﺑﺎ ﻫﺪف ﺑﺮرﺳﯽ راﺑﻄﻪ ﻣﺸﺨﺼـﻪ ﻫـﺎي ﻫﻨﺪﺳـﯽ روﺷـﻨﻪ ﺑـﺎ
ﻣﺸﺨﺼﻪ ﻫﺎي ﺗﻨﻮع و ﺗﺮاﮐﻢ زادآوري ﮔﻮﻧﻪ ﻫﺎي درﺧﺘﯽ در روﺷﻨﻪ ﻫﺎي ﻃﺒﯿﻌﯽ و اﻧﺴﺎنﺳﺎﺧﺖ اﻧﺠﺎم ﺷﺪ. ﻣﻮاد و روش ﻫﺎ: دو ﻗﻄﻌﻪ ﻧﻤﻮﻧﻪ 16 ﻫﮑﺘﺎري ﺑﺎ ﻣﻮﻗﻌﯿﺖ روﯾﺸﮕﺎﻫﯽ ﺗﻘﺮﯾﺒﺎً ﯾﮑﻨﻮاﺧﺖ در ﺑﺨﺸﯽ از ﺳﺮي ﯾﮏ )ﻣﺪﯾﺮﯾﺖ ﺷﺪه( و ﺳﺮي دو )ﻣﺪﯾﺮﯾﺖ ﻧﺸﺪه( ﻃﺮح ﺟﻨﮕﻠﺪاري دﮐﺘﺮ ﺑﻬﺮام ﻧﯿﺎ )ﺷﺼﺖﮐﻼﺗﻪ، ﮔﺮﮔﺎن( اﻧﺘﺨـﺎب ﮔﺮدﯾـﺪ . ﻣﻮﻗﻌﯿـﺖ 56 روﺷﻨﻪ ﺑﺎ اﺳﺘﻔﺎده از ﺳﯿﺴﺘﻢ ﻣﻮﻗﻌﯿﺖ ﯾﺎب ﺗﻔﺎﺿﻠﯽ DGPS ﺛﺒﺖ ﺷﺪ. ﺷﺎﺧﺺﻫﺎي اﺻﻠﯽ ﻫﻨﺪﺳﻪ روﺷﻨﻪ ﺷﺎﻣﻞ: ﻣﺴـﺎﺣﺖ )A(، ﻣﺤﯿﻂ )P( و ﻧﺴﺒﺖ ﻣﺤﯿﻂ ﺑﻪ ﻣﺴﺎﺣﺖ )P/A( اﻧﺪازهﮔﯿﺮي و ﺳﭙﺲ ﺷﺎﺧﺺ ﮔﺮدي )C( و ﭘﯿﭽﯿﺪﮔﯽ ﺷﮑﻞ روﺷـﻨﻪ )GSCI( ﻣﺤﺎﺳﺒﻪ ﮔﺮدﯾﺪ. ﻫﻤﭽﻨﯿﻦ ﻓﺮاواﻧﯽ و ﺗﻨﻮع ﮔﻮﻧﻪ اي زادآوري درون روﺷـﻨﻪ ﻫـﺎ در ﻗﻄﻌـﺎت 25 ﻣﺘﺮﻣﺮﺑﻌـﯽ ﺛﺒـﺖ ﮔﺮدﯾﺪ. روﺷﻨﻪ ﻫﺎ در ﺳﻪ ﮐﻼس ﻣﺴﺎﺣﺖ ﮐﻮﭼﮏ )150-20 ﻣﺘﺮﻣﺮﺑﻊ(، ﻣﺘﻮﺳﻂ )300-150 ﻣﺘﺮﻣﺮﺑﻊ( و ﺑﺰرگ )ﺑﯿﺶ ﺗﺮ از 300 ﻣﺘﺮﻣﺮﺑﻊ( ﮐﻼسﺑﻨﺪي ﺷﺪﻧﺪ. ﺷﺎﺧﺺ ﻫﺎي ﺗﻨﻮع ﮔﻮﻧﻪاي ﺑﻪ ازاي ﻫﺮ روﺷﻨﻪ در ﻣﺤﯿﻂ ﻧﺮم اﻓﺰار PAST ﻣﺤﺎﺳﺒﻪ ﺷﺪ. ﺗﺠﺰﯾﻪ و ﺗﺤﻠﯿﻞ آﻣﺎري ﺟﻬﺖ ﺗﻌﯿﯿﻦ ﻣﻌﻨﯽ داري اﺧﺘﻼف ﻫﺎ و رواﺑﻂ ﺑﯿﻦ ﺷﺎﺧﺺ ﻫﺎي ﻫﻨﺪﺳﯽ و ﺗﻨـﻮع ﮔﻮﻧـﻪ اي زادآوري اﻧﺠﺎم ﺷﺪ. ﯾﺎﻓﺘﻪ ﻫﺎ: ﻣﯿﺎﻧﮕﯿﻦ ﻣﺴﺎﺣﺖ روﺷﻨﻪ ﻫﺎي ﻃﺒﯿﻌﯽ 206 ﻣﺘﺮﻣﺮﺑﻊ و روﺷﻨﻪ ﻫـﺎي اﻧﺴـﺎن ﺳـﺎﺧﺖ 176 ﻣﺘﺮﻣﺮﺑـﻊ ﺑـ ﻪ دﺳـﺖ آﻣـﺪ. ﻣﯿﺎﻧﮕﯿﻦ ﺷﺎﺧﺺ ﮔﺮدي روﺷﻨﻪﻫﺎي اﻧﺴﺎنﺳﺎﺧﺖ )0/72=C( ﺑﺰرگ ﺗﺮ از روﺷﻨﻪﻫﺎي ﻃﺒﯿﻌﯽ )0/66=C( ﺑﻮده؛ ﻫﺮ ﭼﻨﺪ از ﻧﻈﺮ آﻣﺎري اﺧﺘﻼف ﻣﻌﻨﯽدار ﻧﺪاﺷﺘﻨﺪ. ﺷﮑﻞ روﺷﻨﻪ ﻫﺎي ﻃﺒﯿﻌﯽ ﻣﺘﻨﺎﺳﺐ ﺑﺎ اﻓﺰاﯾﺶ ﻣﺴﺎﺣﺖ، از ﻓﺮم داﯾﺮه ﻓﺎﺻﻠﻪ ﮔﺮﻓﺘـﻪ، ﮐﺸﯿﺪه ﺗﺮ ﺷﺪ و ﻧﯿﺰ ﭘﯿﭽﯿﺪﮔﯽ ﺷﮑﻞ آن ﻫﺎ اﻓﺰاﯾﺶ ﯾﺎﻓﺖ. ﺷﺎﺧﺺ ﭘﯿﭽﯿﺪﮔﯽ ﺷﮑﻞ روﺷﻨﻪ ﻫﺎي اﻧﺴﺎنﺳـﺎﺧﺖ ﺑـﺎ اﻓـﺰاﯾﺶ ﻣﺴﺎﺣﺖ اﺧﺘﻼف ﻣﻌﻨﯽ داري ﻧﺸﺎن ﻧﺪاد. ﻫﻢ ﭼﻨﯿﻦ در ﻫﺮ دو ﻧﻮع روﺷﻨﻪ، ﻧﺴﺒﺖ ﻣﺤﯿﻂ ﺑﻪ ﻣﺴﺎﺣﺖ روﺷﻨﻪﻫﺎي ﺑـﺰ رگ، در ﻣﻘﺎﯾﺴﻪ ﺑﺎ ﺳﺎﯾﺮ ﮐﻼسﻫﺎي روﺷﻨﻪﻫﺎ ﮐﻤﺘﺮ ﺑﻮد. ﺗﺮاﮐﻢ زادآوري ﮔﻮﻧﻪ ﻫﺎي اﻓﺮا ﭘﻠﺖ، اﻧﺠﯿﻠـﯽ و ﻓﺮاواﻧـﯽ ﮐـﻞ زادآوري در روﺷﻨﻪ ﻫﺎي اﻧﺴﺎنﺳﺎﺧﺖ ﺑﺎ ﻣﺴﺎﺣﺖ ﻣﺘﻮﺳﻂ ﺑﻪ ﻃﻮر ﻣﻌﻨﯽ داري ﺑﯿﺶ ﺗﺮ از روﺷﻨﻪ ﻫـﺎي ﻃﺒﯿﻌـﯽ ﺑـﺎ ﻣﺴـﺎﺣﺖ ﻣﺸـﺎﺑﻪ ﺑـﻮد ﻏﻨﺎ، ﻓﺮاواﻧﯽ ﮐﻞ زادآوري، ﺗﻨﻮع ﮔﻮﻧﻪ اي، ﻏﺎﻟﺒﯿﺖ و ﯾﮑﻨﻮاﺧﺘﯽ در روﺷﻨﻪ ﻫﺎي ﺑﺎ ﻣﺴﺎﺣﺖ ﻣﺘﻮﺳـﻂ ) 150-300 ﻣﺘﺮﻣﺮﺑـﻊ( ﺣﺪاﮐﺜﺮ ﻣﻘﺪار و اﺧﺘﻼف ﻣﻌﻨـ ﯽداري ﺑـﺎ روﺷـﻨﻪ ﻫـﺎي ﺑـﺰرگ )ﻣﺴـﺎﺣﺖ ﺑـﺰرگ ﺗـﺮ از 300 ﻣﺘﺮﻣﺮﺑـﻊ( ﻧﺸـﺎن دادﻧـﺪ. در روﺷﻨﻪ ﻫﺎي ﻃﺒﯿﻌﯽ، ﺑﺎ اﻓﺰاﯾﺶ ﻣﺴﺎﺣﺖ ﺗﺮاﮐﻢ زادآوري ﮔﻮﻧﻪ ﻫﺎي اﻓﺮا ﭘﻠﺖ و ﺧﺮﻣﻨﺪي، ﻏﻨـﺎي ﮔﻮﻧـﻪ اي، ﻓﺮاواﻧـﯽ ﮐـﻞ و ﺗﻨﻮع ﮔﻮﻧﻪ اي زادآوري ﺑﻪ ﻃﻮر ﻣﻌﻨﯽداري ﮐﺎﻫﺶ ﯾﺎﻓﺖ. در روﺷﻨﻪ ﻫﺎي ﻃﺒﯿﻌـﯽ ﺑـﯿﻦ ﺷـﺎﺧﺺ P/A ﺑـﺎ ﺗـﺮاﮐﻢ زادآوري ﮔﻮﻧﻪﻫﺎي اﻓﺮا و ﻣﻤﺮز، ﻫﻤﺒﺴﺘﮕﯽ ﻣﺜﺒﺖ ﻣﺸﺎﻫﺪه ﺷﺪ )ﺑﻪ ﺗﺮﺗﯿﺐ 0/480=r و 0/356=r(. ﺷﺎﺧﺺ ﻏﻨﺎ ﻫﻤﺒﺴﺘﮕﯽ ﻣﻨﻔﯽ ﺑﺎ ﻣﺤﯿﻂ )0/317- =r( و ﻣﺴﺎﺣﺖ روﺷﻨﻪﻫﺎي ﻃﺒﯿﻌﯽ )0/310- =r( داﺷﺘﻪ اﺳﺖ. در روﺷـﻨﻪ ﻫـﺎي اﻧﺴـﺎن ﺳـﺎﺧﺖ ﺗـﺮاﮐﻢ زادآوري اﻓﺮا و ﺷﯿﺮدار ﻫﻤﺒﺴﺘﮕﯽ ﻣﻌﮑﻮس ﺑﺎ ﺷـﺎﺧﺺ ﮔـﺮدي )ﺑـﻪ ﺗﺮﺗﯿـﺐ 0/546- =r و 0/560- =r( و ﻫﻤﺒﺴـﺘﮕﯽ ﻣﺴﺘﻘﯿﻢ )ﺑﻪ ﺗﺮﺗﯿﺐ 0/588=r=0/628 ،r( ﺑﺎ ﭘﯿﭽﯿﺪﮔﯽ ﺷﮑﻞ ﻧﺸﺎن دادﻧـﺪ. ﭘـﺲ ﻫﺮﭼـﻪ روﺷـﻨﻪ ﮐﺸـﯿﺪه ﺗـﺮ و ﺷـﮑﻞ آن ﭘﯿﭽﯿﺪه ﺗﺮ، ﺗﺮاﮐﻢ اﯾﻦ دو ﮔﻮﻧﻪ ﺑﯿﺸﺘﺮ ﺑﻮد ﮐﻪ اﯾﻦ ﻣﻘﺪار در روﺷﻨﻪ ﻫﺎي اﻧﺴﺎنﺳﺎﺧﺖ ﺑﺎ ﺳﻄﺢ ﻣﺘﻮﺳﻂ )300-150 ﻣﺘﺮﻣﺮﺑﻊ( ﻣﺸﺎﻫﺪه ﺷﺪ. در روﺷﻨﻪ ﻫﺎي اﻧﺴﺎن ﺳﺎﺧﺖ ﺷﺎﺧﺺ ﯾﮑﻨﻮاﺧﺘﯽ ﻫﻤﺒﺴﺘﮕﯽ ﻣﻌﮑﻮس و ﻏﻨﺎي ﮔﻮﻧﻪ اي ﻫﻤﺒﺴﺘﮕﯽ ﻣﺴﺘﻘﯿﻢ ﺑـﺎ ﻧﺴﺒﺖ ﻣﺤﯿﻂ ﺑﻪ ﻣﺴﺎﺣﺖ )ﺑﻪ ﺗﺮﺗﯿﺐ 0/553- =r و 0/578=r( ﻧﺸﺎن داد. ﻧﺘﯿﺠﻪ ﮔﯿﺮي: روﺷﻨﻪﻫﺎي اﻧﺴﺎنﺳﺎﺧﺖ در ﻣﻘﺎﯾﺴﻪ ﺑﺎ روﺷﻨﻪ ﻫﺎي ﻃﺒﯿﻌﯽ، ﻣـﻨﻈﻢ ﺗـﺮ و ﮔﺮدﺗـﺮ ﺑﻮدﻧـﺪ . ﻫﺮﻗـﺪر روﺷـﻨﻪ ﻫـﺎي اﻧﺴﺎن ﺳﺎﺧﺖ از ﻓﺮم داﯾﺮه ﻓﺎﺻﻠﻪ ﮔﺮﻓﺘﻪ، ﺷﮑﻞ آن ﮐﺸﯿﺪهﺗﺮ ﺷﺪ، ﺷﮑﺴﺘﮕﯽ ﻫﺎ و ﭘﯿﭽﯿﺪﮔﯽ ﻫﺎي آن اﻓﺰاﯾﺶ ﯾﺎﻓﺘﻪ و ﺗـﺮاﮐﻢ زادآوري ﭘﻠﺖ و ﺷﯿﺮدار ﻧﯿﺰ اﻓﺰاﯾﺶ ﯾﺎﻓﺖ. روﺷﻨﻪ ﻫﺎي اﻧﺴﺎنﺳﺎﺧﺖ ﺑﺎ ﺳﻄﺢ ﻣﺘﻮﺳﻂ )150-300 ﻣﺘﺮﻣﺮﺑـﻊ(، ﺑـﯿﺶ ﺗـﺮﯾﻦ ﻣﻘﺪار ﻏﻨﺎ، ﺗﻨﻮع و ﺗﺮاﮐﻢ زادآوري را ﻧﺴﺒﺖ ﺑﻪ دﯾﮕﺮ ﮐﻼس ﻫـﺎي ﻣﺴـﺎﺣﺖ روﺷـﻨﻪ ﻧﺸـﺎن داد ؛ ﺑﻨـﺎﺑﺮاﯾﻦ، ﻣـﯽ ﺗـﻮان اﯾـﻦ ﻣﺴﺎﺣﺖ روﺷﻨﻪ را ﻣﺴﺎﺣﺖ ﺑﻬﯿﻨﻪ ﺑﺮاي ﺗﯿﭗ ﻏﺎﻟﺐ ﺗﻮده در ﻧﻈﺮ ﮔﺮﻓﺖ.
چكيده لاتين :
Background and objectives: Canopy gaps are the most important environments for many species regenerations. Studying regeneration in natural and Man-made canopy gaps provides practical information to enhance the quantity and quality of tree species regeneration. This study aimed to investigate the relation between geometrical characteristics of canopy gaps with diversity and density of tree species regeneration in natural and Man-made canopy gaps.
Materials and methods: Two 16 ha plots were selected with relatively similar site conditions in part of series one and two of Dr. Bahram-nia 's forestry plan, Shastkalateh, Gorgan. The position of 56 canopy gaps was recorded using a differential positioning system (DGPS). The main indices of the gap’s geometry including area (A), perimeter (P), and perimeter to area ratio (P/A) were measured and then the circular index (C) and the Gap shape complexity Index (GSCI) were calculated. Also, the frequency and diversity of tree species regeneration were recorded within 25 m2 plots centered on each gap. Gaps were classified into three small (20-150 m2), medium (150-300 m2), and large (more than 300 m2) area classes, and indices of species diversity were calculated for each gap using PAST software environment. Statistical analysis was performed to determine the significance of differences and relationships between geometric indices and diversity of regenerative species.
Results: The average area of natural and Man-made canopy gaps were 206 and 176 m2, respectively. The mean circular index of Man-made canopy gaps (C = 0.72) was higher than natural ones (C = 0.66); although, their difference was not significant. Increasing the area, the shape of the natural gaps shifted away from the circular, elongated, and the complexity of their shape increased. The shape complexity index of Man-made gaps did not show a significant difference with increasing the area. Perimeter to area ratio of large gaps was smaller than other classes in both types of gaps. Regeneration density of Velvet maple and Ironwood species were significantly higher in medium Man-made gaps than other species, other classes, and natural mediums gaps. As a result, richness, total individual regeneration, diversity, dominance, and evenness in the medium gaps (300-150 m2) showed the maximum value and significantly different from the large gaps (greater than 300 m2). In natural gaps, with increasing area regeneration density of Velvet maple and Date-plum species, species richness, total individual regeneration, and species diversity of regeneration decreased significantly. A positive correlation was observed between the gap’s P/A with the regeneration density of maple and hornbeam species in natural gaps (r = 0.480 and r = 0.356, respectively). The richness index had a negative correlation with the perimeter (r = -0.337) and with area of natural gaps (r = -0.103). In Man-made gaps, the evenness index showed an inverse correlation and the species richness showed a direct correlation with P / A (r = -0.553 and r = 0.578, respectively).
Conclusion: Man-made gaps were more regular and rounder than natural gaps. As the shape of the Man-made gaps shifts away from the circle form, it was elongated and increased in fractures and complexities, and also the density of maple’s regeneration increased. Medium-sized Man-made gaps (150-300 m2) showed the highest value of richness, diversity, and regeneration density compared to other categories of gap area. Therefore, this range of gap size could be considered as the optimum range
