Continuous planting under a high density enhances the competition for nutrients among young Cunninghamia lanceolata saplings

Table 3 The gas exchange parameters, chlorophyll pigment contents, and leaf δ¹³C values in C. lanceolata as affected by a high planting density under soils that were first (control) and continuously planted with Chinese fir (rotation)

Soils	Planting density	A (μmol m⁻² s⁻¹)	g _s (mol m⁻² s⁻¹)	C _i (μmol mol⁻¹)	E (mmol m⁻² s⁻¹)	Chl a (mg g⁻¹ Fw)	Chl b (mg g⁻¹ Fw)	Total Chl (mg g⁻¹ Fw)	Chl a/Chl b ratio	Foliar δ ¹³C (‰)
Control	Low	8.15 ± 0.44 b	0.09 ± 0.00 c	203.51 ± 5.73 a	1.62 ± 0.09 b	0.54 ± 0.01 ab	0.28 ± 0.01 a	0.82 ± 0.03 a	1.92 ± 0.03 b	−28.02 ± 0.16 a
Control	High	5.15 ± 0.31 a	0.06 ± 0.01 ab	205.76 ± 7.91 a	1.40 ± 0.14 ab	0.56 ± 0.02 ab	0.30 ± 0.01 ab	0.86 ± 0.03 ab	1.89 ± 0.03 b	−28.14 ± 0.12 a
Rotation	Low	7.37 ± 0.47 b	0.08 ± 0.01 bc	190.69 ± 7.75 a	1.35 ± 0.12 ab	0.51 ± 0.03 a	0.27 ± 0.02 a	0.79 ± 0.05 a	1.90 ± 0.05 b	−28.18 ± 0.05 a
Rotation	High	3.93 ± 0.37 a	0.05 ± 0.01 a	202.00 ± 8.36 a	1.03 ± 0.15 a	0.60 ± 0.01 b	0.36 ± 0.02 b	0.97 ± 0.04 b	1.69 ± 0.07 a	−28.47 ± 0.20 a
	P _S	0.000	0.000	0.372	0.038	0.669	0.182	0.352	0.037	0.162
	P _D	0.018	0.004	0.277	0.015	0.007	0.007	0.006	0.024	0.096
	P _{S × D}	0.588	0.988	0.550	0.716	0.115	0.070	0.086	0.098	0.551

Each value is the mean ± SE (n = 8). Within a column, values followed by different letters are significantly different at P < 0.05 according to Tukey’s test
P _S soil effect, P _D density effect, P _{S × D} soil and density interaction effect

ISSN: 1297-966X