BMI | BMI = ( 4 − ∑ i = 1 n s i h i g i ∑ i = 1 n h i g i ) × 25 si : Unit pollution index of i specieshi = Appearance of i speciesgi = Indicator weight of i species | H’ | H ’ = − ∑ i = 1 S ( p i × log 2 p i ) , ( p i = N i N ) Ni : Population of i speciesN : Total appearing population |