Table 2 Description of the 36 explanatory variables used in the models Abb = abbreviation. The Source column indicates the origin of the data: collected by the NFI (Field), calculated using the NFI information (Calc) or extracted from models available with geographic Information System (Mod.). See Appendix Table 5 for the values.

 Circumference

Circ

Circumference of the tree measured at 1.30 m height.

cm

Field

 Relative circumference

RelCirc

Ratio of the Circ of the tree over the mean Circ of all the trees in the plot.

/

Calc.

 Plot basal area

BA

Sum of the tree basal areas in the plot.

m²/ha

Calc.

 Number of trees per hectare

NB

Number of trees, all species considered, with a diameter ≥ 7.5 cm measured in the plot and related to a value per hectare.

nb.ha⁻¹

Calc.

 Canopy cover

CC

Proportion of the forest floor covered by the vertical projection of the tree crowns.

%

Calc.

 Quadratic mean diameter

QMD

Quadratic mean diameter of the trees on the plot.

cm

Calc.

 Gini coefficient

Gini

Gini coefficient of the tree circumferences in each plot.

/

Calc.

 Proportion of BA occupied by the species growing in the plot

PropBA

Percent of basal area occupied by the species in each plot.

%

Calc.

 Number of tree species

Nb_sp

Total number of tree species in each plot.

/

Calc.

 Skidding distance

Dist

Indicator of the distance from the center of the plot to the nearest existing skid trail.

/

Field

 Skid trails

Trails

Indicator of the presence of already existing skid trails and of the possibility to create new ones.

/

Field

 Recent cut

Cut

Type and intensity of a recent cut in the plot (less than 5 years).

/

Field

 Available water content

AWC

Maximum volume of water that can be stored in the soil calculated from the Al-Majou pedotransfer functions.

mm

Mod.

 Permanent waterlogging

PW

pH, C/N, permanent, and temporary waterlogging index: bio-indicator values calculated from the floristic survey of each plot.

/

Mod.

 Temporary waterlogging

TW

/

Mod.

 pH

pH

/

Mod.

 carbon-to-nitrogen ratio

CN

/

Mod.

 Surface runoff

Topo

Surface runoff estimated from the site topography

Field

 Winter mean T° 1961–1987

Tm_winRef

Mean seasonal temperatures in winter, spring, summer, and autumn, and mean total seasonal rainfall in spring and summer calculated over the 1961–1987 period.

°C

Mod

 Spring mean T° 1961–1987

Tm_sprRef

°C

Mod.

 Summer mean T° 1961–1987

Tm_sumRef

°C

Mod.

 Autumn mean T° 1961–1987

Tm_autRef

°C

Mod.

 Spring rainfall 1961–1987

RF_sprRef

mm

Mod.

 Summer rainfall 1961–1987

RF_sumRef

mm

Mod.

 Winter mean T° evolution

Tm_winEvo

Climate change anomalies between the reference period 1961–1987 period and shifting 15-year sub-periods based on the date of the survey of each plot for the same variables and seasons as for the reference period.

°C

Mod.

 Spring mean T° evolution

Tm_sprEvo

°C

Mod.

 Summer mean T° evolution

Tm_sumEvo

°C

Mod.

 Autumn mean T° evolution

Tm_autEvo

°C

Mod.

 Spring rainfall evolution

RF_sprEvo

mm

Mod.

 Summer rainfall evolution

RF_sumEvo

mm

Mod.

 Interaction between temperature and its evolution

Tm_winRef*Evo

Interaction between temperature evolution and the reference period temperature calculated as a product of these two values for each season.

°C²

Mod.

Tm_sprRef*Evo

°C²

Mod.

Tm_sumRef*Evo

°C²

Mod.

Tm_autRef*Evo

°C²

Mod.

 Relative rainfall evolution

RF_sprevo/RF_sprRef

RF_sumevo/RF_sumRef

Relative rainfall evolution calculated as the ratio of rainfall evolution over the reference-period rainfall, for spring and summer

%

Mod.