High nutrient supply and interspecific belowground competition enhance the relative performance of Picea mariana (Mill). B.S.P seedlings over Picea glauca [Moench] Voss. under elevated CO2

Table 1 Average total root length (m), root diameter (mm), root length density (cm root per cm³ soil), seedling height (cm), and root collar diameter (RCD, mm, refer to Dang et al. 2020 for the complete results on biomass and growth) in black spruce (Sb) and white spruce (Sw) seedlings under different CO₂, belowground competition (BGC), and nutrient supply (N) combinations (n = 8). The seedlings were exposed to two CO₂ concentrations (380 and 720 µmol mol⁻¹) with or without and belowground competition (BGC-1 and BGC-0, respectively) at two nutrient levels

CO₂	BGC	N	SP	Root length	Root diameter	Root density	Height	RCD
Ambient	BGC-1	High	Sb	11	0.6	0.69	30	4.6
		High	Sw	8	0.61	0.52	20	4.6
		Low	Sb	11	0.68	0.66	28	4.2
		Low	Sw	8	0.62	0.51	19	4.2
	BGC-0	High	Sb	15	0.65	0.85	39	5.9
		High	Sw	10	0.66	0.57	31	5.8
		Low	Sb	15	0.65	0.87	27	4.4
		Low	Sw	11	0.67	0.6	22	5
Elevated	BGC-1	High	Sb	17	0.56	1.06	36	5.1
		High	Sw	14	0.59	0.84	25	5.1
		Low	Sb	15	0.54	0.94	31	4.4
		Low	Sw	7	0.58	0.41	25	4.5
	BGC-0	High	Sb	15	0.79	0.84	42	6.6
		High	Sw	12	0.69	0.67	39	6.4
		Low	Sb	18	0.69	1.03	32	5.5
		Low	Sw	11	0.7	0.64	27	5.7

ISSN: 1297-966X