Table 6. Relative density (RD), relative frequency (RF), relative coverage (RC), and importance percentage (IP) of tree species growing in the P. densiflora forests.

Species	No. of trees (trees/ha)	Appearance rate (%)	Basal area (m2/ha)	RD (%)	RF (%)	RC (%)	IP (%)
Pinus densiflora	759	100.0	26.7	60.5	18.9	77.6	52.3
Quercus mongolica	127	43.2	1.8	10.1	8.2	5.3	7.9
Quercus variabilis	77	47.3	1.8	6.1	8.9	5.1	6.7
Quercus serrata	49	44.1	0.7	3.9	8.3	2.0	4.7
Prunus serrulata var. pubescens	23	33.6	0.3	1.9	6.3	0.9	3.0
Castanea crenata	18	21.3	0.3	1.5	4.0	0.8	2.1
Pinus rigida	20	14.9	0.5	1.6	2.8	1.5	2.0
Juniperus rigida	16	20.8	0.1	1.3	3.9	0.3	1.8
Styrax japonicus	17	13.0	0.1	1.4	2.5	0.3	1.4
Quercus acutissima	9	12.1	0.2	0.7	2.3	0.7	1.2
Quercus dentata	9	13.7	0.1	0.7	2.6	0.4	1.2
Robinia pseudoacacia	13	10.8	0.2	1.1	2.0	0.6	1.2
Quercus aliena	9	11.4	0.1	0.7	2.2	0.4	1.1
Pinus thunbergii	10	6.7	0.2	0.8	1.3	0.7	0.9
Fraxinus rhynchophylla	7	8.9	0.1	0.5	1.7	0.2	0.8
Platycarya strobilacea	6	7.4	0.1	0.5	1.4	0.2	0.7
Alnus sibirica	4	7.6	0.1	0.3	1.4	0.2	0.6
Ilex macropoda	5	5.0	0.0	0.4	0.9	0.1	0.5
Carpinus laxiflora	5	4.5	0.1	0.4	0.8	0.2	0.5
Toxicodendron trichocarpum and so on (137 spp.)	70	-	0.9	5.5	19.6	2.6	9.2
Total	1,256	-	34.4	100.0	100.0	100.0	100.0