Unprecedented pluri-decennial increase in the growing stock of French forests is persistent and dominated by private broadleaved forests

Table 6 Summary statistics of regression models of GS change including areal changes over the two previous between-inventory periods as predictors

Model	Partition	Time span of studied between-inventory periods	R ²	GS_i (coefficient sign) partial R²	GSD_i (coefficient sign) partial R²	∆S_−1,i (coefficient sign) partial R²	∆S_−2,i (coefficient sign) partial R²	RSE (m³)
M1’	None	(1961)–1976–2010	0.34	(+) ***0.08		(+) ***0.02	(+) ***0.05	629
M2’	Private forests		0.45	(+) ***0.28		(+) ***0.03		578
M3’	OPF		0.16		(+) *0.00	(+) ***0.01	(+) ***0.01	400
M4’	State’s Forests		0.14			(+) **0.04	(+) **0.03	284
M5’	Private broadleaved forests	(1971)–1987–2010	0.54	(+) ***0.35	(−) **0.05			492
M6’	Private coniferous forests		0.81	(+) ***0.04		(+) *0.06		588
M7’	Broadleaved OPF		0.46	(−) ***0.04	(+) ***0.00	(+) **0.02	(+) ***0.15	341
M8	Coniferous OPF		0.43			(+) ***0.06	(+) ***0.06	332
M9’	State’s broadleaved forests		0.43	(−) *0.09			(+) ***0.16	230
M10’	State’s coniferous forests		0.34	(−) *0.06		(+) **0.04	(+) **0.10	304

The time span indicates the dates of the first available inventory (in parentheses), the date when 80% of dau were available and the date of the last inventory. GS_i: initial growing stock of dau unit i, GSD_i: initial mean density of growing stock, ΔS_−1,i(resp − 2): forest area increases over first (resp. second) previous between-inventory periods. RSE: residual standard error. Test significance: P < 0.1: (*), P < 0.05: *, P < 0.01: **, P < 0.001: ***. OPF refers to ‘other public forests’, essentially belonging to municipalities, and subjected to a legal management plan

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