Two new methods applied to crown width additive models: a case study for three tree species in Northeastern China

Table 2 Descriptive statistics of the tree size and competition variables of larch, birch, and poplar

Classification	Variable	Larch (n = 11216)				Birch (n = 4863)				Poplar (n = 1039)
Classification	Variable	Min	Max	Mean	SDV	Min	Max	Mean	SDV	Min	Max	Mean	SDV
Tree size	CRE (m)	0.1	7.9	1.4	0.6	0.1	5.1	1.3	0.6	0.1	4.5	1.4	0.6
	CRS (m)	0.1	6.0	1.4	0.6	0.1	5.5	1.4	0.6	0.2	5.1	1.6	0.6
	CRW (m)	0.1	5.1	1.3	0.6	0.1	4.9	1.3	0.6	0.2	5.3	1.5	0.7
	CRN (m)	0.1	6.3	1.3	0.6	0.1	5.5	1.3	0.6	0.1	4.5	1.4	0.6
	CW (m)	0.45	10.95	2.72	0.96	0.45	9.95	2.65	0.90	0.80	8.45	2.92	0.90
	DBH (cm)	5.0	42.2	11.7	5.2	5.0	38.6	11.0	4.8	5.1	38.7	14.1	6.2
	THT (m)	3.4	28.3	12.0	3.7	4.1	30.7	12.8	3.5	3.4	31.6	15.1	4.8
	HCB (m)	0.4	18.7	6.5	2.8	0.2	17.0	6.8	2.1	1.4	22.1	8.9	3.6
	HDR (m cm⁻¹)	0.28	3.28	1.10	0.28	0.28	3.17	1.25	0.32	0.38	3.25	1.15	0.29
Competition	QMD (cm)	8.1	26.3	12.4	2.4	8.1	26.3	12.1	3.0	8.5	22.7	13.3	3.9
	DQR	0.28	3.22	0.94	0.36	0.25	3.08	0.91	0.33	0.32	3.32	1.06	0.37
	BA (m² ha⁻¹)	5.1	38.0	20.4	6.4	5.1	38.0	19.0	4.4	9.4	38.0	20.7	5.8
	BApor (m² ha⁻¹)	0.004	1	0.76	0.21	0.005	0.93	0.44	0.23	0.005	0.87	0.27	0.18
	BAL (m²)	0	5.20	1.45	0.91	0	5.21	1.47	0.90	0	5.07	1.61	1.19
	N (trees ha⁻¹)	325	3320	1772	635	325	3320	1801	598	475	2916	1642	565

Note: CRE = east crown radius, CRS = south crown radius, CRW = west crown radius, CRN = north crown radius, CW = crown width, DBH = over-bark diameter at breast height, THT = total height, HCB = height to crown base, HDR = THT-to-DBH ratio, QMD = quadratic mean diameter, DQR = DBH-to-QMD ratio, BA = basal area, BApor = basal area proportion of target species, BAL = the basal area of trees larger than the subject tree, N = stem numbers, Min = minimum value, Max = maximum value, Mean = average value, and SDV = standard deviation

ISSN: 1297-966X