. 2021 Apr 12;118(16):e2020790118. doi: 10.1073/pnas.2020790118

Table 1.

Responses of soil carbon physical fractions to long-term N additions in the N-saturated tropical forest of South China

	Treatment	C stock, Mg C/ha	N stock, Mg N/ha	Percent of bulk soil C
Heavy fraction	Control	21.32 (1.02)^a	1.71 (0.09)^a	75.45 (2.28)^a
	Low N	25.15 (1.39)^ab	2.01 (0.07)^b	79.30 (0.72)^ab
	Medium N	28.07 (1.67)^b	2.28 (0.07)^c	81.23 (0.08)^b
	High N	28.36 (1.90)^b	2.25 (0.09)^bc	82.97 (0.42)^b

Light fraction	Control	6.91 (0.58)	0.30 (0.03)^a	24.55 (2.28)^a
	Low N	6.54 (0.18)	0.29 (0.00)^ab	20.70 (0.72)^ab
	Medium N	6.49 (0.38)	0.27 (0.01)^ab	18.77 (0.08)^b
	High N	5.82 (0.40)	0.26 (0.01)^b	17.03 (0.42)^b

Notes: Soils were sampled at the upper 0- to 10-cm mineral layers after 11 y of N addition. Values are means and SE (in parentheses); different letters indicate significant differences between treatments (P < 0.05).