Species | 1997 | 1998 | 1999 | Overall average |
---|---|---|---|---|
F. chinensis | 3.9 a | 3.7 a | 4.1 a | 3.92 |
F. pennsylvanica | 3.3 a | 2.3 b | 3.1 bc | 2.88 |
F. mandshurica | 3.3 a | 1.5 bc | 2.6 bc | 2.47 |
F. angustifolia | 1.4 b | 2.6 ab | 3.2 abc | 2.42 |
F. excelsior | 2.0 b | 2.6 bc | 2.0 cd | 2.21 |
F. tomentosa | 1.6 b | 1.5 c | 1.8 cd | 1.61 |
F. americana | 1.3 b | 1.3 c | 1.4 d | 1.31 |
F. quadrangulata | 1.8 b | 1.0 d | 1.0 d | 1.27 |
Overall average | 2.3 | 2.1 | 2.4 | 2.26 |