Forest style

Single factor pollution index

Composite pollution index

Composite pollution level

Cr

Cu

Zn

P. massoniana

0.62

1.29

0.37

1.06

light pollution

S. superba

0.85

1.30

0.42

1.10

light pollution

L. formosana

0.66

1.38

0.40

1.13

light pollution

P. massoniana × L. formosana

0.79

1.36

0.40

1.13

light pollution

P. massoniana × S. superba

1.13

1.57

0.51

1.34

light pollution

Mean

0.81

1.38

0.42

Individual pollution grade

early warning

light pollution

Non- pollution