Table 1.

Summary of the main characteristics of the forests and the trends presented by NEP, GPP, Re, and maximum LAI.

Forest	Code	Climate	Forest Type	Age	Maturity Age	Corrected Mat. Age	Initial year	Finalyear	Y	NEP TS Trend	P	GPP TS Trend	P	Re TS Trend	P	LAITS Trend	P
Brasschaat1	BE-Bra	Temp	M	80	90	0.89	1997	2011	14	17.5 ± 7.5	0.0773	21.4 ± 13.9	0.0313	9.7 ± 19.8	0.2556	0.000 ± 0.008	0.6329
Castelporziano2	IT-Cpz	Temp	EB	61	75	0.81	1997	2008	10	2.8 ± 6.9	0.3603	−12.8 ± 16.9	0.7629	−22.1 ± 12.8	0.8145	0.100 ± 0.010	0.0173
Collelongo3	IT-Col	Temp	DB	118	95	1.24	1997	2012	12	4.1 ± 9.6	0.2686	16.8 ± 11.9	0.1219	8.5 ± 6.4	0.0574	−0.014 ± 0.015	0.8299
Hainich4	DE-Hai	Temp	DB	275	95	2.89	2000	2012	13	−7.3 ± 4.6	0.9197	−11.2 ± 7.3	0.8502	−6.3 ± 5.9	0.7489	0.047 ± 0.018	0.0466
Harvard5	US-Ha1	Temp	DB	81	75	1.07	1992	2011	20	12.6 ± 5.9	0.0372	34.7 ± 5.1	<0.0001	20.2 ± 9.6	0.0075	0.000 ± 0.005	0.6539
Hesse6	FR-Hes	Temp	DB	43	95	0.45	1996	2010	15	26.4 ± 11.0	0.0374	18.3 ± 15.4	0.1381	0.5 ± 15.3	0.5000	0.017 ± 0.007	0.2737
Howland MT7	US-Ho1	Temp	EC	109	90	1.21	1996	2008	13	6.5 ± 2.8	0.0293	−5.8 ± 7.5	0.7489	−16.2 ± 7.2	0.9364	−0.050 ± 0.008	0.9934
Howland F7	US-Ho2	Temp	EC	109	90	1.21	1999	2009	11	5.4 ± 4.8	0.1751	7.7 ± 8.2	0.2667	2.6 ± 11.0	0.3202	−0.025 ± 0.011	0.7621
Hyytiala8	FI-Hyy	Bor	EC	47	90	0.52	1997	2012	16	6.2 ± 2.5	0.0172	14.7 ± 4.0	0.0017	10.4 ± 3.5	0.0051	0.000 ± 0.004	0.5201
Lavarone9	IT-Lav	Temp	EC	120	90	1.33	2003	2012	10	41.8 ± 10.3	0.0100	37.2 ± 12.8	0.0159	−2.7 ± 5.1	0.7042	0.114 ± 0.022	0.1008
Le Bray10	FR-LBr	Temp	EC	38	90	0.42	1997	2008	11	7.2 ± 18.8	0.4381	10.8 ± 25.6	0.3777	−18.3 ± 12.6	0.8935	−0.033 ± 0.014	0.8465
Loobos11	NL-Loo	Temp	EC	88	90	0.98	1997	2012	16	21.5 ± 4.9	0.0009	−6.0 ± 4.2	0.9186	−27.1 ± 5.9	0.9991	−0.017 ± 0.008	0.6559
Metolius12	US-Me2	Temp	EC	64	90	0.71	2002	2012	11	13.4 ± 9.8	0.1379	29.0 ± 13.7	0.0806	10.6 ± 13.4	0.2667	0.156 ± 0.028	0.0866
Morgan Monroe7	US-MMS	Temp	DB	70	75	0.93	1999	2013	15	−2.6 ± 3.9	0.8619	−1.8 ± 5.5	0.6897	0.7 ± 5.0	0.5000	−0.041 ± 0.009	0.8677
Niwot ridge13	US-NR1	Bor	EC	98	90	1.09	1999	2010	12	1.9 ± 2.8	0.4185	−0.1 ± 3.4	0.5000	−1.3 ± 2.3	0.6341	0.060 ± 0.005	0.0166
Park Falls14	US-PFa	Temp	DB	44	65	0.68	1997	2013	16	9.6 ± 3.7	0.0172	0.1 ± 4.3	0.4820	−12.1 ± 6.2	0.9425	−0.008 ± 0.008	0.5873
Puechabon2	FR-Pue	Temp	EB	66	75	0.88	2001	2013	13	−10.3 ± 6.6	0.9197	−28.4 ± 13.3	0.9502	−18.5 ± 8.7	0.9880	0.114 ± 0.014	0.0108
Renon15	IT-Ren	Bor	EC	90	75	1.20	1998	2011	13	37.9 ± 5.3	0.0001	51.9 ± 8.7	0.0006	10.2 ± 6.3	0.0636	0.030 ± 0.007	0.1202
Sodankyla16	FI-Sod	Bor	EC	75	90	0.83	2000	2012	13	−0.2 ± 1.6	0.5000	−2.8 ± 7.1	0.5243	0.6 ± 6.8	0.4757	0.047 ± 0.005	0.1346
Soroe17	DK-Sor	Temp	DB	78	95	0.82	1997	2009	13	27.3 ± 4.8	0.0004	22.9 ± 8.4	0.0164	−0.2 ± 8.8	0.5000	−0.017 ± 0.007	0.7336
Tharandt18	DE-Tha	Temp	EC	117	90	1.30	1997	2013	17	−1.2 ± 3.6	0.6446	16.1 ± 8.3	0.0383	20.4 ± 6.7	0.0178	−0.025 ± 0.014	0.6730
UMBS19	US-UMB	Temp	DB	79	65	1.22	1999	2012	14	5.4 ± 3.1	0.0080	−3.5 ± 5.4	0.7444	−10.4 ± 4.5	0.9373	0.058 ± 0.005	0.0017
Vielsalm20	BE-Vie	Temp	M	83	95	0.87	1996	2008	13	17.0 ± 6.9	0.0062	15.1 ± 6.8	0.0120	−0.3 ± 7.2	0.5243	0.2330

Trends were computed using the robust Theil-Sen slope estimator. P indicates a one-tailed P (H1: trend > 0). Corrected maturity age was calculated by dividing the mean stand age by the logging maturity tree age as described by Stokland et al.⁶⁰ for average productivity classes. Abbreviations: Y, years; TS, Theil-Sen; Clim for Climate; Temp, temperate; Bor, boreal; for, Forest type; M, mixed; E, evergreen; D, deciduous; B, broadleaved; C, coniferous; EC, eddy covariance. Upperscript numbers indicate reference numbers, see additional References in Supplementary Material.