ارزﯾﺎﺑﯽ ﮐﻤﯽ ﭘﯿﻮﺳﺘﮕﯽ ﻟﮑﻪ ﻫﺎي ﺟﻨﮕﻞ در ﺣﻮﺿﮥ آﺑﺮﯾﺰ درﯾﺎي ﺧﺰر ﺑﺎ اﺳﺘﻔﺎده از ﺷﺎﺧﺺ ﻫﺎي ﺳﯿﻤﺎي ﺳﺮزﻣﯿﻦ و ﻧﻈﺮﯾﮥ ﮔﺮاف

Quantitative assessment of connectivity of forest patches in Caspian Sea catchment using landscape and graph theory indexes

ﺟﻨﮕﻞﻫﺎي ﻧﺎﺣﯿﻪ ﺧﺰري از ﻣﻬﻤﺘﺮﯾﻦ ﻣﻨﺎﯾﻊ ﺟﻨﮕﻠﯽ ﮐﺸﻮرﻧﺪ، اﻣﺎ آﻧﭽﻪ ﺑﻪ ﺻﻮرت ﯾﮏ ﺧﻼ ﺑـﺰرگ در ﺗﺤﻘﯿﻘـﺎت اﯾـﻦ ﺣـﻮزه دﯾـﺪه ﻣﯽ ﺷﻮد ﻟﺰوم ﺗﻮﺟﻪ ﺑﻪ اﺑﻌﺎد ﺳﺎﺧﺘﺎري ﺑﻪ وﯾﮋه ﺣﻔﻆ ﭘﯿﻮﺳﺘﮕﯽ ﺳﺎﺧﺘﺎري اﯾﻦ ﺟﻨﮕﻠﻬﺎ اﺳـﺖ . ﺗﺤﻘﯿـﻖ ﺣﺎﺿـﺮ ﺑـﺎ ﻫـﺪف ارزﯾـﺎﺑﯽ و ﻣﻘﺎﯾﺴﻪ ﺷﺎﺧﺺﻫﺎي ﭘﯿﻮﺳﺘﮕﯽ ﺳﯿﻤﺎي ﺳﺮزﻣﯿﻦ در ﻣﻮرد ﻟﮑﻪﻫﺎي ﺟﻨﮕﻠﯽ ﺣﻮزه آﺑﺮﯾﺰ درﯾﺎي ﺧﺰر اﻧﺠﺎم ﺷـﺪ . ﺑـﺮاي اﯾـﻦ ﻣﻨﻈـﻮر اﺑﺘﺪا ﻻﯾﻪ ﺟﻨﮕﻞ از ﻧﻘﺸﻪ ﭘﻮﺷﺶ ﺳﺮزﻣﯿﻦ اﺳﺘﺨﺮاج و ﺗﻌﺪاد 25 ﺣﻮزه آﺑﺨﯿﺰ ﮐﻼن اﻧﺘﺨﺎب ﺷـﺪﻧﺪ . ﭘﯿﻮﺳـﺘﮕﯽ ﺳـﯿﻤﺎي ﺳـﺮزﻣﯿﻦ از ﻣﻨﻈﺮ ﺳﻨﺠﻪﻫﺎي ﺳﯿﻤﺎي ﺳﺮزﻣﯿﻦ )ﭼﻬﺎر ﺷﺎﺧﺺ( و ﺷﺎﺧﺺﻫﺎي ﺗﺌﻮري ﮔﺮاف )11 ﺷﺎﺧﺺ( ﺗﺤﻠﯿﻞ و ﻣﺤﺎﺳـﺒﻪ ﺷـﺪ . ﺳـﭙﺲ ، ﺑـﺎ اﺳﺘﺎﻧﺪاردﺳﺎزي ﺷﺎﺧﺺﻫﺎي ﭘﯿﻮﺳﺘﮕﯽ ﻣﺤﺎﺳﺒﻪ ﺷﺪه در ﻣﺤﺪوده ﺻﻔﺮ ﺗﺎ 1، و ﺗﻠﻔﯿﻖ آﻧﻬﺎ، ﯾﮏ ﻋﺪد ﻧﻬﺎﯾﯽ ﭘﯿﻮﺳﺘﮕﯽ ﺑﺮاي ﻫﺮ ﺣﻮزه آﺑﺨﯿﺰ ﺑﺪﺳﺖ آﻣﺪ ﮐﻪ ﺑﯿﻦ 0/571 ﺗﺎ 0/274 ﻣﺘﻐﯿﺮ ﺑﻮد. اﯾﻦ ﻣﺤﺪوده در ﭼﻬﺎر ﻃﺒﻘﻪ از ﮐﻢ ﺑﻪ زﯾﺎد، ﻃﺒﻘﻪﺑﻨﺪي ﺷـﺪ . ﻧﺘـﺎﯾﺞ ﻧﺸـﺎن داد ﺷﺎﺧﺺﻫﺎي ﭘﯿﻮﺳﺘﮕﯽ ﻟﮑﻪﻫﺎي ﺟﻨﮕﻠﯽ در ﺗﻤﺎم ﻧﺎﺣﯿﻪ ﺧﺰر، ﺑﺴﯿﺎر ﭘﺎﯾﯿﻦ ﺑﻮده ﺑﻪ ﻃﻮري ﮐﻪ 80% ﺣﻮزهﻫﺎ در ﻃﺒﻘﻪ ﭘﯿﻮﺳﺘﮕﯽ ﺧﯿﻠـﯽ ﮐﻢ و ﮐﻢ ﻗﺮار ﻣﯽﮔﯿﺮﻧﺪ. ﺣﻮزه ﺷﻤﺎره 9 )ﺳﺮدآﺑﺮود، ﺷﻠﻤﺎﻧﺮود( و ﺣﻮزه ﺷﻤﺎره 7 )ﭼﺎﻟﻮس( ﺑﻪ ﺗﺮﺗﯿـﺐ ﺑـﺎ ﻋـﺪد ﭘﯿﻮﺳـﺘﮕﯽ ﻧﻬـﺎﯾﯽ 0/274 و 0/276 در وﺿﻌﯿﺖ ﺑﺴﯿﺎر ﻧﺎﻣﻄﻠﻮب ﻗﺮار دارﻧﺪ و ﺗﻨﻬﺎ دو ﺣﻮزه ﺷـﻤﺎره 14 )ﭼـﻼو و ﭘﻨﺠـﺎب( و ﺷـﻤﺎره 4 )ﭘﺴـﯿﺨﺎن و ﺷﺎﺧﺮز( ﺑﻪ ﺗﺮﺗﯿﺐ ﺑﺎ ﻋﺪد ﭘﯿﻮﺳﺘﮕﯽ ﻧﻬﺎﯾﯽ 0/571 و 0/540 وﺿﻌﯿﺖ ﻣﻨﺎﺳﺐﺗﺮي از ﻧﻈﺮ ﺷﺎﺧﺺﻫﺎي ﭘﯿﻮﺳـﺘﮕﯽ دارﻧـﺪ . ﺑـﺎ ﺗﻮﺟـﻪ اﻫﻤﯿﺖ ﺣﻔﻆ ﭘﯿﻮﺳﺘﮕﯽ ﻟﮑﻪﻫﺎي ﺟﻨﮕﻞ، و ﻧﻘﺶ آن در ﺣﻔﻆ ﺗﻨﻮع زﯾﺴﺘﯽ و ﮐﺎرﮐﺮدﻫﺎي ﺟﻨﮕﻞﻫﺎي ﺧﺰري، ﻧﺘﺎﯾﺞ اﯾﻦ ﭘـ ﮋوﻫﺶ در ﺑﺮﻧﺎﻣﻪﻫﺎي ﻣﺪﯾﺮﯾﺖ و اﺣﯿﺎ ﺟﻨﮕﻞ ﮐﺎرﺑﺮد ﺧﻮاﻫﺪ داﺷﺖ؛ ﺑﻪ ﻃﻮري ﮐﻪ در ﺣﻮزهﻫﺎﯾﯽ ﺑﺎ ﭘﯿﻮﺳﺘﮕﯽ ﭘﺎﯾﯿﻦ ﮐﻪ در آﻧﻬﺎ ﮔﺴﺴﺘﮕﯽ ﻟﮑﻪﻫﺎ و از ﻫﻢ ﮔﺴﯿﺨﺘﮕﯽ ﺷﺪﯾﺪ آﻧﻬﺎ دﯾﺪه ﺷﺪ، ﻧﯿﺎزﻣﻨﺪ ﺑﺮﻧﺎﻣﻪﻫﺎي وﺳﯿﻊ اﺣﯿﺎ و ﺟﻠﻮﮔﯿﺮي از ﮔﺴﺴﺘﮕﯽ ﺑﯿﺸﺘﺮ اﯾﻦ ﻟﮑﻪﻫﺎ ﻫﺴﺘﻨﺪ.

The forests of the Caspian region are one of the most important forest resources in Iran, but what is seen as a large gap in research is the need to pay attention to the structural dimensions, especially to maintain the structural connectivity of these forests. The aim of this study was to assess and compare the indicators of forest landscape in the Caspian Sea watersheds. At first, the forest layer was extracted from the land cover map and 25 large watersheds were selected to study and compare the connectivity indicators. The connectivity of the terrestrial landscape was analyzed using landscaping metrics and graph theory indicators, by Fragstats and Conefor softwares respectively. Finally, by standardizing the calculated connectivity indicators, a final connectivity score was obtained for each watershed. The results showed that the indicators of forest patches connectivity in the whole Caspian catchment are very low, so that 80% of the watersheds are in the category of very low and low connectivity. Watershed 9 (Sardabroud, Shalmnroud) and 7 (Chalous) are in a very unfavorable situation, and only two watersheds of 14 (Chalav, Panjab) and 4 (Pasikhan), in the area of Chalav and Punjab, in the Haraz River, and the Shakharz, Pesikhan rivers, are in a better situation in terms of connectivity indicators. Considering the importance of preserving the structure and connectivity of forest patches, the results of this study show the need for special attention to the management and restoration programs of these forests.