Predictor Importance Values for black spruce (Picea mariana)

Predictor Name	Importance Score	Rank
Annual precipitation (mm)	15.8	18
Mean May-September precipitation (mm)	17	11
Mean annual temperature (°C)	13.51	29
Mean May-September temperature (°C)	19.94	4
Mean temperature of coldest month (°C)	16.09	16
Mean temperature of warmest month (°C)	19.4	5
Annual aridity index	14.72	25
Minimum elevation	16.05	17
Maximum elevation	14.87	22
Average elevation	18.86	6
Median elevation	17.37	9
Range of elevation	15.2	20
Elevation coefficient ofvariation	15.26	19
Elevation standard deviation	16.44	15
Annual daylength coefficient of variation	17.14	10
Total available water capacity (cm, to 150 cm)	14.86	23
Total available water supply (cm, to 150 cm)	21.08	1
Depth to water table (cm)	12.89	32
Soil permeability rate (cm/hr)	14.67	26
Soil calcium carbonate (% by weight)	12.88	33
Soil cation-exchange capacity	16.58	14
Soil pH	10.4	39
Soil bulk density (g/cm3)	13.32	31
Organic matter content (% by weight)	14.02	28
Potential soil productivity	15.03	21
Soil erodibility factor, rock fragment free	17.45	8
Soil erosion by wind (tons/acre/year)	14.43	27
Percent soil passing sieve No. 10 (coarse)	20.03	3
Percent soil passing sieve No. 200 (fine)	16.86	12
Percent clay (< 0.002 mm size)	11.25	38
Percent sand (< 0.002 mm size)	13.38	30
Percent silt (< 0.002 mm size)	16.77	13
Percent of texture clayey	9.75	41
Percent of texture loamy	14.85	24
Percent of texture sandy	17.62	7
Percent of texture other	12.64	35
Alfisol (%)	9.89	40
Aridisol (%)	-1	45
Entisol (%)	5.97	42
Histosol (%)	11.9	37
Inceptisol (%)	20.06	2
Mollisol (%)	12.07	36
Spodosol (%)	12.78	34
Ultisol (%)	0.26	44
Vertisol (%)	3.86	43