ارزيابي ارتباط بين ويژگي‌هاي كمي پوشش گياهي و وضعيت مرتع در روش‌هاي چهار و شش فاكتوري در مراتع نيمۀ شمالي استان اردبيل

Evaluation of the relationship between the quantitative characteristics of vegetation and rangeland condition in the northern rangelands of in Ardebil province

ﮔﺰﯾﻨﺶ ﻣﺘﻐﯿﺮﻫﺎي ﺑﻮمﺷﻨﺎﺧﺘﯽ ﻣﻨﺎﺳﺐ ﺑﺮاي درك ﭼﮕﻮﻧﮕﯽ ﻋﻤﻠﮑﺮد و اﻧﺪازهﮔﯿﺮي وﺿﻌﯿﺖ ﻣﺮﺗﻊ ﺣﯿﺎﺗﯽ وﻟﯽ ﺑﻪدﻟﯿﻞ ﺗﻌﺪد و ﭘﯿﭽﯿﺪﮔﯽ رواﺑﻂ ﺑﯿﻦ اﺟﺰاء اﮐﻮﺳﯿﺴﺘﻢ، دﺷﻮار اﺳﺖ. ﻫﺪف اﯾﻦ ﺗﺤﻘﯿﻖ، ﺗﺴﻬﯿﻞ ﺷﯿﻮة ارزﯾﺎﺑﯽ ﮐﻤﯽ ﻋﻮاﻣﻞ ﺑﻮمﺷﻨﺎﺧﺘﯽ در ﺗﻌﯿﯿﻦ وﺿﻌﯿﺖ ﻣﺮﺗﻊ ﺑﻪ روشﻫﺎي ﭼﻬﺎرﻓﺎﮐﺘﻮري و ﺷﺶﻓﺎﮐﺘﻮري ﺑﺎ اﺳﺘﻔﺎده از ﺑﺮﺧﯽ ﻣﺘﻐﯿﺮﻫﺎي ﺳﺎﺧﺘﺎري و ﻋﻤﻠﮑﺮدي ﭘﻮﺷﺶ ﮔﯿﺎﻫﯽ اﺳﺖ. در اﯾﻦ ﻣﻄﺎﻟﻌﻪ، اﺑﺘﺪا وﺿﻌﯿﺖ 28 ﻣﺮﺗﻊ در ﺷﻤﺎل اﺳﺘﺎن اردﺑﯿﻞ ﺑﺎ روشﻫﺎي ﭼﻬﺎرﻓﺎﮐﺘﻮري و ﺷﺶﻓﺎﮐﺘﻮري ﺑﻪﺗﻔﮑﯿﮏ روﯾﺸﮕﺎهﻫﺎي ﺑﻮﺗﻪ-ﻋﻠﻔﺰار و ﻋﻠﻒ-ﺑﻮﺗﻪزار ﺗﻌﯿﯿﻦ و ﺑﺮﺧﯽ ﻣﺘﻐﯿﺮﻫﺎي ﭘﻮﺷﺶ ﮔﯿﺎﻫﯽ آنﻫﺎ اﻧﺪازﮔﯿﺮي ﮐﻤﯽ ﺷﺪ. ﺳﭙﺲ اﻣﺘﯿﺎزات وﺿﻌﯿﺖ ﺣﺎﺻﻞ از دو روش ﻣﺬﮐﻮر ﻣﻘﺎﯾﺴﻪ ﮔﺮدﯾﺪ و ﺿﻤﻦ ﺑﺮرﺳﯽ ارﺗﺒﺎط ﺑﯿﻦ ﻣﺘﻐﯿﺮﻫﺎي ﮐﻤﯽ ﭘﻮﺷﺶﮔﯿﺎﻫﯽ ﺑﺎ اﻣﺘﯿﺎزات وﺿﻌﯿﺖ ﻣﺮﺗﻊ، رواﺑﻂ رﮔﺮﺳﯿﻮﻧﯽ ﺧﻄﯽ ﭼﻨﺪﻣﺘﻐﯿﺮه ﺑﻪروش ﮔﺎمﺑﻪﮔﺎم اﺳﺘﺨﺮاج ﺷﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﻣﺘﻮﺳﻂ اﻣﺘﯿﺎز ﺗﺮازﺷﺪة وﺿﻌﯿﺖ ﻣﺮﺗﻊ در روش ﭼﻬﺎرﻓﺎﮐﺘﻮري در دو روﯾﺸﮕﺎه ﻋﻠﻒ-ﺑﻮﺗﻪزار و ﺑﻮﺗﻪ-ﻋﻠﻔﺰار ﺑﻪﺗﺮﺗﯿﺐ 69 و 60 اﻣﺘﯿﺎز( ﺑﺎﻻﺗﺮ از روش ﺷــﺶﻓﺎﮐﺘﻮري )ﺑﻪﺗﺮﺗﯿﺐ 64 و 54 اﻣﺘﯿﺎز( ﺑﺮآورد ﮔﺮدﯾﺪه اﺳــﺖ. ﻣﻘﺎﯾﺴــﺎت آزﻣﻮن ﺗﯽ-زوﺟﯽ اﻣﺘﯿﺎز وﺿﻌﯿﺖ روشﻫﺎي ﭼﻬﺎر و ﺷﺶﻓﺎﮐﺘﻮري ﮔﻮﯾﺎي اﺧﺘﻼف ﻣﻌﻨﯽدار )0/05≤P( ﺑﯿﻦ دو روش اﺳﺖ. ﻣﺘﻐﯿﺮﻫﺎﯾﯽ ﻫﻤﭽﻮن ﺗﺎج ﭘﻮﺷﺶ ﮔﻮﻧﻪﻫﺎي ﮐﻼس ﯾﮏ، ﺗﺎج ﭘﻮﺷــﺶ ﮐﻞ، ﺗﺎج ﭘﻮﺷــﺶ ﭘﻬﻦﺑﺮﮔﺎن، ﺗﺎج ﭘﻮﺷــﺶ ﭘﻬﻦﺑﺮﮔﺎن ﯾﮑﺴــﺎﻟﻪ و ﺗﻮﻟﯿﺪ داراي ﺑﯿﺶﺗﺮﯾﻦ ارﺗﺒﺎط ﻣﺜﺒﺖ ﻣﻌﻨﯽدار )0/05≤P( و ﻣﺘﻐﯿﺮﻫﺎي ﺗﺎج ﭘﻮ ﺷﺶ ﮔﻮﻧﻪﻫﺎي ﮐﻼس ﺳﻪ و ﭘﻮ ﺷﺶ ﺳﻨﮓ و ﺳﻨﮕﺮﯾﺰه داراي ﺑﯿﺶﺗﺮﯾﻦ ارﺗﺒﺎط ﻣﻨﻔﯽ ﻣﻌﻨﯽدار )0/05≤P( ﺑﺎ وﺿـﻌﯿﺖ ﻣﺮﺗﻊ ﻣﯽﺑﺎﺷـﻨﺪ. ﻣﺪلﻫﺎي رﮔﺮﺳـﯿﻮﻧﯽ ﮔﻮﯾﺎي ارﺗﺒﺎط ﻗﻮي )R2 =72/50-88/41( ﺑﯿﻦ ﻣﺘﻐﯿﺮﻫﺎي ﻣﻮرد ارزﯾﺎﺑﯽ ﺑﺎ اﻣﺘﯿﺎز و ﺿﻌﯿﺖ ﻣﺮﺗﻊ ﺑﻮدﻧﺪ. ﻧﺘﺎﯾﺞ اﻋﺘﺒﺎر ﺳﻨﺠﯽ ﻣﺪلﻫﺎ ﺑﯿﺎﻧﮕﺮ ﻗﺎﺑﻠﯿﺖ ﻣﺘﻐﯿﺮﻫﺎي ﮐﻤﯽ اﻧﺘﺨﺎﺑﯽ در ﭘﯿﺶﺑﯿﻨﯽ اﻣﺘﯿﺎز و ﺿﻌﯿﺖ ﻣﺮاﺗﻊ ﺑﻮﺗﻪ ﻋﻠﻔﺰار و ﻋﻠﻒ-ﺑﻮﺗﻪزار در ﻫﺮ دو روش اﺳﺖ و ﻣﺘﻐﯿﺮﻫﺎي ﻣﺬﮐﻮر ﻣﯽﺗﻮاﻧﻨﺪ در ارزﯾﺎﺑﯽ ﮐﻤﯽ وﺿﻌﯿﺖ ﻣﺮﺗﻊ ﻣﺪ ﻧﻈﺮ ﻗﺮار ﮔﯿﺮﻧﺪ.

The purpose of this research is to facilitate the quantitative evaluation of various ecological factors in determining the rangeland condition by four-factors method and six-factors method using mainly structural variables of vegetation. In this study, the condition of 28 sites located in the northern part of Ardebil province was determined by 4 and 6 factors methods, separately for grassland and shrubland habitats, and some parameters of vegetation were quantitatively measured. The results of condition determination were compared in the two mentioned methods. Finally, using Pearson correlation test, the relationship between variables of vegetation and the scores of rangeland condition were compared and regression relations were extracted. The results indicated that the average score of the rangeland condition in the modified four-factors in both grasslands and shrublands (69 and 60 scores, respectively) was higher than the six-factors method (64 and 54 respectively), and paired t-test comparison showed a significant difference (P≤ 0.05) between the two methods. Also, the results showed that variables such as canopy cover of decreasing specious canopy cover, forbs canopy cover, annual forbs canopy cover and production had the most significant positive relationship (P≤ 0.05), and the variables of invaders and pebble-gravel cover had the highest negative correlation (P≤ 0.05) with rangeland condition. The results of extraction of multivariate linear regression models by step-by-step method showed strong relationship (R2=68.46-88.41) between evaluated variables with condition score. Also, validation analysis of the models indicated the ability of both methods to predict the rangeland condition score.