ارزيابي اثرات محيط زيستي بهره برداري حاصل از قطع درختان بر روي توده باقيمانده (مطالعه موردي: جنگل خيرود)

Environmental Impact Assessment of Forest Harvesting to Residual Stand (Case Study: in Kheyrud Forest)

ﻫﺪف ﻋﻤﻠﯿﺎت ﺟﻨﮕﻞ، اﺟﺮاي ﻃﺮح ﻫﺎ و ﻋﻤﻠﯿﺎﺗﯽ اﺳﺖ ﮐﻪ از ﻧﻈﺮ ﻓﻨﯽ و ﺗﮑﻨﯿﮑﯽ اﻣﮑﺎن ﭘﺬﯾﺮ، از ﻟﺤﺎظ اﻗﺘﺼﺎدي ﻣﻨﺎﺳﺐ رﺷﺪ و ﺗﺮﻗﯽ، از ﻧﻈﺮ ﻣﺤﯿﻂ زﯾﺴﺘﯽ ﺳﺎﻟﻢ و ﮐﻢ ﺧﻄﺮ و از ﻧﻈﺮ ﺣﻘﻮﻗﯽ ﻗﺎﺑﻞ ﻗﺒﻮل ﺑﺎﺷﺪ. ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ اﻋﻤﺎل ﺷﯿﻮه ﺟﻨﮕﻞ داري ﻧﺰدﯾﮏ ﺑﻪ ﻃﺒﯿﻌﺖ ﺑﺮاي ﻣﺪﯾﺮﯾﺖ ﺟﻨﮕﻞ ﻫﺎي ﺷﻤﺎل و ﭘﺮاﮐﻨﺪﮔﯽ ﺑﺮداﺷﺖ در اﯾﻦ ﺷﯿﻮه، ﮐﺎﻫﺶ آﺳﯿﺐ ﻫﺎي وارده ﺑﻪ ﺗﻮده ﺳﺮﭘﺎ و زادآوري، اﻫﻤﯿﺖ ﺑﯿﺸﺘﺮي ﭘﯿﺪا ﻣﯽ ﮐﻨﺪ. اﯾﻦ ﺗﺤﻘﯿﻖ ﺑﺮاي ارزﯾﺎﺑﯽ زﯾﺮ ﻣﺆﻟﻔﻪ ﻗﻄﻊ درﺧﺖ در ﭘﺎرﺳﻞ 221 از ﺑﺨﺶ ﻧﻢ ﺧﺎﻧﻪ ﺟﻨﮕﻞ آﻣﻮزﺷﯽ و ﭘﮋوﻫﺸﯽ ﺧﯿﺮود اﻧﺠﺎم ﺷﺪ. اﻫﺪاف اﯾﻦ ﺗﺤﻘﯿﻖ، ﻋﺒﺎرت از ﺗﻌﯿﯿﻦ ﻣﯿﺰان ﺧﺴﺎرت ﻫﺎي وارده ﺑﻪ ﺗﻮده ﺳﺮﭘﺎ و ﺗﺠﺪﯾﺪ ﺣﯿﺎت ﺟﻨﮕﻞ ﻣﯽ ﺑﺎﺷﺪ. ﺑﻪ ﻣﻨﻈﻮر ﺑﺮرﺳﯽ ﻣﻘﺪار ﺧﺴﺎرت ﺑﻪ ﺗﻮده ﺳﺮﭘﺎ در ﺣﻔﺮه ﻫﺎي ﻗﻄﻊ، از روش آﻣﺎرﺑﺮداري ﺻﺪدرﺻﺪ اﺳﺘﻔﺎده ﺷﺪ. ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ از ﺑﺮرﺳﯽ ﭘﻼت داﯾﺮهاي ﺷﮑﻞ در ﺣﻔﺮه ﻫﺎي ﻗﻄﻊ ﻧﺸﺎن داد: %1/2 از درﺧﺘﺎن ﻣﻮﺟﻮد در ﭘﻼت ﻫﺎ ﺑﺮ اﺛﺮ ﻋﻤﻠﯿﺎت ﻗﻄﻊ ﻣﺘﺤﻤﻞ ﺧﺴﺎرت ﺷﺪﻧﺪ. %73 از درﺧﺘﺎن ﺧﺴﺎرت دﯾﺪه در ﭘﻼت ﻫﺎي ﻗﻄﻊ را ﮔﻮﻧﻪ راش، %25 ﻣﻤﺮز و %2 ﮔﻮﻧﻪ ﻫﺎﯾﯽ ﻣﺎﻧﻨﺪ اﻓﺮا، ﺑﻠﻮط، و ﺗﻮﺳﮑﺎ ﺗﺸﮑﯿﻞ داد. ﺿﻤﻦ اﯾﻦ ﮐﻪ ﺑﯿﺸﺘﺮﯾﻦ ﺧﺴﺎرت ﻣﺘﻮﺟﻪ درﺧﺘﺎن ﺑﺎ ﻗﻄﺮ ﺑﺮاﺑﺮ ﺳﯿﻨﻪ ﮐﻤﺘﺮ از 40 ﺳﺎﻧﺘﯽ ﻣﺘﺮ اﺳﺖ. ﺑﺮرﺳﯽ ﺣﺎﺿﺮ ﻧﺸﺎن داد ﮐﻪ ﻣﻘﺪار ﺧﺴﺎرت ﺑﻪ ﻧﻬﺎل ﻫﺎ ﮐﻤﺘﺮ از ﺳﺎﯾﺮ ﮔﺮوه ﻫﺎي زادآوري (ﺷﻞ و ﺧﺎل) اﺳﺖ. ﺑﺮرﺳﯽ زﺧﻢ ﻫﺎي اﯾﺠﺎد ﺷﺪه ﺑﺮ روي ﺗﻨﻪ درﺧﺘﺎن ﺑﺎﻗﯿﻤﺎﻧﺪه در ﺣﻔﺮه ﻫﺎي ﻗﻄﻊ ﻧﯿﺰ ﻧﺸﺎن داد ﮐﻪ اﯾﻦ زﺧﻢ ﻫﺎ ﺑﯿﺸﺘﺮ در ارﺗﻔﺎع ﮐﻤﺘﺮ از 2 ﻣﺘﺮي ﺗﻨﻪ درﺧﺖ ﺣﻀﻮر دارﻧﺪ. ﻫﻤﭽﻨﯿﻦ زﺧﻢ ﻫﺎي ﻣﺬﮐﻮر اﻏﻠﺐ ﺳﻄﺤﯽ ﻫﺴﺘﻨﺪ، ﯾﻌﻨﯽ ﺑﻪ ﮐﺎﻣﺒﯿﻮم ﺧﺴﺎرﺗﯽ وارد ﻧﺸﺪه اﺳﺖ. آﻣﻮزش ﮐﺎرﮔﺮان ﺑﻬﺮه ﺑﺮداري و اﮐﯿﭗ ﻗﻄﻊ و ﺗﺒﺪﯾﻞ، از ﻋﻮاﻣﻞ ﺗﺄﺛﯿﺮﮔﺬار در ﺟﻠﻮﮔﯿﺮي و ﮐﺎﻫﺶ ﺧﺴﺎرت ﻫﺎي ﻧﺎﺷﯽ از ﺑﻬﺮه ﺑﺮداري ﻫﺴﺘﻨﺪ. ﺻﺪﻣﻪ ﺑﻪ ﺗﻮده ﺑﺎﻗﯿﻤﺎﻧﺪه ﺑﺮ اﺛﺮ ﻋﻤﻠﯿﺎت ﻗﻄﻊ در ﺟﻨﮕﻞ آﻣﯿﺨﺘﻪ ﻧﺎﻫﻤﺴﺎل ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻋﻮاﻣﻞ ﻣﺨﺘﻠﻒ ﻣﺆﺛﺮ ﺑﺮ ﺻﺪﻣﻪ ﺑﻪ ﺗﻮده ﺑﺮرﺳﯽ ﺷﺪ. ﻗﻄﻊ درﺧﺘﺎن در ﺗﻮده ﺟﻨﮕﻠﯽ ﺑﻪ ﺻﻮرت ﻫﺪاﯾﺖ ﺷﺪه و اﺳﺘﻔﺎده از اﺑﺰارﻫﺎي ﮐﻤﮑﯽ ﻣﺜﻞ ﮔﻮه ﻣﯽ ﺗﻮاﻧﺪ در ﮐﺎﻫﺶ ﺻﺪﻣﻪ ﺑﻪ ﺗﻮده ﺑﺎﻗﯿﻤﺎﻧﺪه ﻣﺆﺛﺮ ﺑﺎﺷﺪ.

Forest operations aims at delivering plans and operations that is technically feasible, economically viable, environmentally sound, and institutionally acceptable. Reducing the impact of harvesting on residual stand and regeneration is very important, considering the use of close-to-nature forestry for Hyrcanian forest management and the low cutting volume distribution of this method. This research was carried out in compartment no. 221 in Namkhaneh district of Kheyrud Forest. The Objects of this study were to evaluate damages to the residual stand. To investigate the effect of damages on residual trees and regeneration in felling areas, 100% inventory was used. Considering the results of all felling areas in sample plots showed that 1.2 percent of trees were damaged because of felling operation. 73% of damaged trees were Beech, 25% Hornbeam and 2% other species like Acer, Oak and Alder. Most damages were on trees with less than 40 cm (d.b.h) diameter. This study showed that the most damages to regeneration groups in felling areas were large sapling with 19.7% and least damages of 10.8% were to seedling. Evaluation of quality of scars on the trunk of tree stand in felling areas with regards to position of scars showed that most scars were present at 2 m heights and were mostly superficial scars (no bark removed and damages to cambium). Training of tree cutting crews is the most important factor for decreasing residual stand damage after harvesting. The residual stand damage from a cutting operation was studied in an uneven-aged mixed forest to examine the main factors (i.e. tree species, location, size, and type) affecting stand damages. Directional tree felling in a forest stand and using some helping instrument could be useful for decreasing the residual stand damage.