A2.

List of variable names used, as well as their description and unit. Tissue types considered are foliage (f), fine roots (r) and woody (w) biomass. C, carbon; N, nitrogen; DW, dry weight.

Variable	Description	Unit
ai	Fractional allocation to tissue type i	–
AET	actual evapotranspiration	mm yr−1
Bi	Biomass of tissue type i	g DW m−2
Corg	Ecosystem organic carbon	g C m−2
CSOM	Soil organic matter carbon (including the litter layer)	g C m−2
Cveg	Vegetation carbon	g C m−2
CUE	Carbon-use efficiency (NPP/GPP)	– (g C g−1 C)
CWD	coarse woody debris	g C m−2
DON	dissolved organic nitrogen	g N m−2 yr−1
GPP	Area-based gross primary production	g C m−2 yr−1
GPPN	N-based gross primary production	g C g−1 Ncan yr−1
fNdep	Atmospheric nitrogen deposition	g N m−2 yr−1
fNfix	Biological nitrogen fixation	g N m−2 yr−1
fNgas	Ecosystem loss of nitrogen through gaseous emission	g N m−2 yr−1
fNleach	Ecosystem loss of nitrogen through leaching	g N m−2 yr−1
fNmin	Net nitrogen mineralization	g N m−2 yr−1
fNup	Plant nitrogen uptake	g N m−2 yr−1
ftrans	Fraction of tissue N translocated before abscission	–
fveg	Fraction of organic ecosystem nitrogen in vegetation	–
LAI	leaf area index	m2 m−2
ni	Nitrogen concentration of tissue type i	g N g−1 DW
Ncan	Canopy nitrogen	g N m−2
Norg	Ecosystem organic nitrogen	g N m−2
Ninorg	Inorganic nitrogen in the ecosystem	g N m−2
nsom	Soil organic matter nitrogen (including the litter layer)	g N m−2
Nveg	Vegetation nitrogen	g N m−2
NNE	Net ecosystem nitrogen exchange	g N m−2 yr−1
NPP	Area-based net primary production	g C m−2 yr−1
NPPN	N-based net primary production	g C g−1 Ncan yr−1
NUE	Nitrogen-use efficiency (NPP/fNup)	g C g−1 N
PAR	photosynthetically active radiation	μmol m−2  s−1
Ra	Autotrophic respiration	g C m−2 yr−1
ρi	tissue carbon density	g C g−1 DW
SOM	soil organic matter	g C|N m−2
	Turnover time of nitrogen in vegetation	yr−1
	Turnover time of nitrogen in soil organic matter (including the litter layer)	yr−1