تغييرات مكاني ذخاير كربن آلي و غير آلي در چند رده خاك جنگلي و مرتعي شمال ايران

Spatial Variations of Organic and Inorganic Carbon Stocks in Some Forest and Rangeland Soils of Northern Iran

ﺑﺮرﺳﯽ ﺗﻐﯿﯿﺮات ﻣﮑﺎﻧﯽ ﮐﺮﺑﻦ آﻟﯽ ﺧﺎك در ﮐﺎرﺑﺮيﻫﺎي ﻣﺨﺘﻠﻒ، ﮐﻤﮏ ﺷﺎﯾﺎﻧﯽ در ﺗﻔﺴﯿﺮ و ﺷﺒﯿﻪﺳﺎزي رﻓﺘﺎر اﮐﻮﺳﯿﺴﺘﻢﻫﺎي ﺧﺎﮐﯽ در ﻣﻮاﺟﻬﻪ ﺑﺎ ﺗﻐﯿﯿﺮات اﻗﻠﯿﻤﯽ و زﯾﺴﺖﻣﺤﯿﻄﯽ ﻣﯽﮐﻨﺪ. اراﺿﯽ ﺗﭙﻪاي و ﺷﯿﺐدار روﺳﺘﺎي ﺑﺎﻧﺪر ﺑﻪ دﻟﯿﻞ اﮐﻮﺳﯿﺴﺘﻢ ﻣﻨﺤﺼﺮ ﺑﻪ ﻓﺮد و ﺗﺄﺛﯿﺮ ﺷﯿﺐ در اﯾﺠﺎد ﺧﺮد اﻗﻠﯿﻢﻫﺎ و ﺗﻐﯿﯿﺮات ﭘﻮﺷﺶ ﮔﯿﺎﻫﯽ، از اﻫﻤﯿﺖ ﺧﺎﺻﯽ ﺑﺮﺧﻮردار اﺳﺖ. ﺗﻐﯿﯿﺮات ﻣﮑﺎﻧﯽ ﻣﯿﺰان ﻣﺤﺘﻮا و ذﺧﯿﺮه ﮐﺮﺑﻦ آﻟﯽ و ﻏﯿﺮآﻟﯽ ﺧﺎك در اﻋﻤﺎق ﻣﺨﺘﻠﻒ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ ﻗﺮار ﮔﺮﻓﺖ. ﺗﺄﺛﯿﺮ ﻧﻮع ﮐﺎرﺑﺮي اراﺿﯽ، ﻣﻮاد ﻣﺎدري، وﯾﮋﮔﯽﻫﺎي ﺗﻮﭘﻮﮔﺮاﻓﯽ و ﺑﺮﺧﯽ از وﯾﮋﮔﯽﻫﺎي ﺧﺎك ﻧﯿﺰ ﺑﺮ روي ﻣﯿﺰان ﻣﺤﺘﻮا و ذﺧﯿﺮه ﮐﺮﺑﻦ آﻟﯽ و ﻏﯿﺮآﻟﯽ ﺧﺎك در 56 ﺧﺎﮐﺮخ ﺑﺮرﺳﯽ ﺷﺪ. ﺑﻪ ﻃﻮر ﻣﺘﻮﺳﻂ ﺑﯿﺸﺘﺮﯾﻦ ﻣﯿﺰان ذﺧﺎﯾﺮ ﮐﺮﺑﻦ آﻟﯽ و ﻏﯿﺮآﻟﯽ ﺧﺎك )SOC=196/6Mg/ha، SIC=88/2Mg/ha( در ﻣﺎﻟﯽﺳﻮلﻫﺎ و ﮐﻤﺘﺮﯾﻦ ﻣﻘﺎدﯾﺮ در اﻧﺘﯽﺳﻮلﻫﺎ )SIC=11/3 ،SOC=59/9 Mg/ha( ﺑﻪ دﺳﺖ آﻣﺪ. ﺑﯿﺸﺘﺮﯾﻦ ﻣﯿﺰان ذﺧﯿﺮه ﮐﺮﺑﻦ ﮐﻞ ﻧﯿﺰ ﺑﻪ ﻃﻮر ﻣﺘﻮﺳﻂ در ﻣﺎﻟﯽﺳﻮلﻫﺎ 284/9 Mg/ha و ﮐﻤﺘﺮﯾﻦ آن در اﻧﺘﯽﺳﻮلﻫﺎ 71/2 Mg/ha ﺑﻪ دﺳﺖ آﻣﺪ. ﻫﻤﺒﺴﺘﮕﯽ ﺑﯿﻦ ذﺧﺎﯾﺮ ﮐﺮﺑﻦ آﻟﯽ و ﻏﯿﺮآﻟﯽ ﺧﺎك ﻧﺸﺎن دﻫﻨﺪه آن اﺳﺖ ﮐﻪ ﮐﺮﺑﻦ ﻏﯿﺮ آﻟﯽ ﺧﺎك در اﯾﻦ ﻣﻨﻄﻘﻪ از ﮐﺮﺑﻦ آﻟﯽ ﺳﺮﭼﺸﻤﻪ ﻣﯽﮔﯿﺮد. در ﮐﺎرﺑﺮي ﺟﻨﮕﻞ ﻗﺴﻤﺖ اﻋﻈﻢ ذﺧﺎﯾﺮ ﮐﺮﺑﻦ آﻟﯽ ﺧﺎك در اﻓﻖﻫﺎي ﺳﻄﺤﯽ ﻗﺮار داﺷﺘﻪ و ﮐﺮﺑﻦ آﻟﯽ آن ﻧﯿﺰ ﺑﯿﺸﺘﺮ از ﻧﻮع ﺗﺎزه و ﻧﯿﻤﻪ ﺗﺠﺰﯾﻪ ﺷﺪه و در ارﺗﺒﺎط ﺑﺎ ﺟﺰء ﺳﯿﻠﺖ ﺧﺎك ﻣﯽﺑﺎﺷﺪ. ﺑﻨﺎﺑﺮاﯾﻦ ﺧﺎكﻫﺎي ﺟﻨﮕﻠﯽ ﻧﺴﺒﺖ ﺑﻪ ﺧﺎكﻫﺎي ﻣﺮﺗﻌﯽ ﮐﻪ ﻗﺴﻤﺖ اﻋﻈﻢ ﮐﺮﺑﻦ آﻟﯽ آنﻫﺎ در اﻓﻖﻫﺎي زﯾﺮﺳﻄﺤﯽ و در ارﺗﺒﺎط ﺑﺎ ﺟﺰء رس ﺧﺎك ﻗﺮار دارد، در ﭘﺎﺳﺦ ﺑﻪ ﺗﻐﯿﯿﺮ ﮐﺎرﺑﺮي و اﻗﺪاﻣﺎت ﻣﺪﯾﺮﯾﺘﯽ ﺷﮑﻨﻨﺪهﺗﺮ ﻣﯽﺑﺎﺷﺪ.

Spatial variability of soil organic carbon in different land uses could be effective in interpreting and simulating the behavior of ecosystems in encountering the climate and environmental changes. The hilly lands of the study area are unique ecosystem with particular importance due to the effect of slope in creating microclimates with different vegetation. The spatial variability of soil organic and inorganic carbon contents and storages were studied at various depths. The effects of land use, parent material, topographical properties and some of soil characteristics on soil organic and inorganic carbon contents and storages were investigated in 56 soil pedons. In average, the highest (SOC=196.6 Mg/ha, SIC=88.2 Mg/ha) and lowest (SOC=59.9 Mg/ha, SIC=11.3 Mg/ha) storage contents of soil organic and inorganic carbon were found in Mollisols and Entisols, accordingly. The highest average total carbon storage also was found in Mollisols (284.9 Mg/ha) while the lowest was in Entisols (71.2 Mg/ha). Increasing soil inorganic carbon with increasing soil organic carbon indicates that inorganic carbon originates from soil organic carbon. In forestland, most amounts of soil organic carbon stocks are located in surface horizons, in fresh and semi-decomposed forms and in combination with silt fractions. Therefore, forest soils are more fragile in response to the changes in management rather than rangelands that contain most of their organic carbon stocks in subsurface horizons and in combination with clay fractions.